Green Building Forum - Heating and cooling

MVHR & Open Windows on hot nights

richardelliot — Tue, 19 Jul 2016 13:23:47 +0100

We are two weeks into living in our new house. The first few days were very hot internally (I fear we have a bit too much solar gain), but once the MVHR was turned on the internal temperature regulated itself a lot better and we were trying to keep the windows closed (which is what I understand you should do with MVHR). Generally this was working ok, but I did notice that two of us sleeping in the bedroom overnight definitely heated up that one room quite a bit.

Last night in London was very warm (as was the rest of the country I think). The MVHR, even on night time purge, didn't seem to be cutting it so we threw open the windows to get a cooling cross breeze coming through the house.

Interested to know what other people with MVHR did last night / will be doing over the next few days. Do you open your windows? Or should the MVHR be able to cope?

Can i avoid an ASHP and still comply with the SAP requirements?

treeplanter — Tue, 05 Jul 2016 10:31:10 +0100

I am building a new house, 158m2 internal space. I have to meet sustainable regulations as it was on a 'greenfield' site (between two houses, on a road in a village - but it had cows on it), so i am not passive house standard, they call it an 'eco-house' which in reality seems to be only a bit higher than standard building regs.

There is no town gas here so the SAP report says to use an ASHP to UFH with an electric emersion heater for DHW.
â€¦.however my preference would be to drop the ASHP altogether and have Calor gas, a PV array and a small wood burner with a back boiler. I have also downloaded all the Accredited Details forms, which i will document as i go, to improve my SAP rating.

Question is how can i calculate if this is possible? Do i go back to the report writer or can i do it myself? I'm concerned that if i wasn't to pass the SAP rating i wouldn't get my VAT back :sad:

How not to install a mini-split

Ed Davies — Mon, 11 Jul 2016 10:27:51 +0100

https://twitter.com/passivistas/status/751714535074127872

Why am I not surprised at this news, re a quietly abondonded biomass heating scheme

orangemannot — Wed, 29 Jun 2016 11:44:30 +0100

https://www.theguardian.com/environment/2016/mar/03/uea-abandons-ambitious-biomass-scheme
sigh!

MVHR and stove

Davegilsenan — Sat, 25 Jun 2016 22:23:21 +0100

Hi all,
First post on here.

I have searched around and the subject of wood burning stoves and mvhr has been covered but not quite the situation I have.
I am building an extension - the part of the original house that remains is old, leaky etc. The new extension is being built with lots of care and attention to detail but without a particular air tightness target.
I am installing an MVHR mostly to avoid having to install little useless extract fans in the kitchen, utility, downstairs toilet, bathrooms as required by building control. I hate those little fans which do nothing except make noise.
I want to install a small stove in the living/dining area. Can anyone see a reason these won't be compatible or is there anything in particular I should look out for? I know on really airtight houses there can be issues.
Unfortunately, the location for the stove is not on an outside wall so a direct air supply isn't possible.
I guess I'll have to have the requisite free ventilation area although there is plenty of leakage available already in the house.

Thanks,
Dave.

Speccing my air to air heat pump system

GarethC — Thu, 16 Jul 2015 12:08:49 +0100

While I struggle to find a sound consultant that can provide the necessary analysis, I'm beginning to spec the heating system I'd like to install.

Current requirements:

1. Single outdoor unit (better cost/benefit than multiple units + easier to get permission, but louder and slightly lower COPs than two smaller units)

2. SCOP of 4+ (to cut CO2 by 40%, and heating costs by 25%, vs. my high efficiency combi boiler). Ideally, Iâ€™d like an official SCOP of nearer 5, as I apply a 20% haircut to official figures, but Iâ€™d need an R32 system and suitable ones arenâ€™t available yet. Maybe by the time planning comes throughâ€¦

3. Circa Â£2k for equipment (including ducting etc. if necessary)

4. 10kW max output

5. Heat distribution to three zones (had hoped that one central zone would suffice, with heat flowing to other rooms naturally, but donâ€™t think it would work)

Point 4 is taxing me. Which would be better, a single internal unit ducted to three zones or a multi split system with three internal units? I -think- the latter, as:

1. Running the narrow pipework to each zone would be a lot easier than installing outward and return ducting between each zone and a single central unit, plus thermostats for each zone.
2. The wall mounted units will mix the warm air in faster and better than air delivered through a duct.

A single indoor unit is cheaper than three indoor units, but I think the hassle and cost of ducting, plus the less efficient air mixing, offsets the benefits.

Would appreciate any thoughts on this issue, and any others please.

Cutting UK heating + hot water C02 by 56%, subsidy free

GarethC — Wed, 09 Sep 2015 12:44:37 +0100

This is pursuant to another thread. And Iâ€™ve touched on this before. Itâ€™s an interesting thought experiment. Iâ€™m sure itâ€™s full of holes, but if not, thereâ€™s a knighthood in there for someone. Discuss!

â€œHow to reduce UK space heating and hot water carbon emissions by 56% compared to current levels over twenty years, subsidy free, cheaply and with no other government intervention (maybe).â€

An air source heat pump system which provides heating and hot water for Â£3k at an SCOP of 4.0 would reduce space heating and hot water C02 emissions by 42% (see note 1) compared to a high efficiency natural gas boiler at current grid intensity (0.519kg/kWh, 2) and cut running costs by 25% (3).

The average household gas bill is Â£752. A 25% decrease saves Â£188 per year, Â£940 in five (say Â£1k). A replacement boiler costs Â£2k installed. Our system costs Â£1k more, but savings would cover this in 5 years â€“ an excellent payback incentivising homes to adopt just for financial, let alone green, reasons. Note, no subsidies anywhere here, in fact delivering long term reductions in domestic heat bills.

Gas boilers last about 20 years. Almost all must be replaced by then. All boilers might be replaced with our new systems over that period without forced ditching of working boilers. This would deliver a 42% cut in total UK domestic heating and DHW emissions by the end of the period.

If some of the gas displaced (wouldnâ€™t need all of it) instead generated electricity in new gas power stations, they would deliver electricity with marginal emissions of 396kg/kWh (4), 24% lower than current grid intensity. Powering our systems with this electricity would deliver emission cuts of 56%. It should also lower electricity costs, improving system payback and incentives to adopt.

If, over that 20 years, other measures reduce grid intensity, as they will, then emissions cuts would be even larger. These measures might raise electricity costs by a third, and homes would still pay no more than today for heating and hot water due to the lower running costs of the new systems.

We need to cut emissions by 90% vs. 1990 to be sustainable. If domestic heating + DHW emissions have already fallen by 15% (donâ€™t know!), then our systems would help cut emissions by 1-0.85*0.44 = 63% vs 1990 by, say 2035 (if we start replacing soon). With cuts in grid intensity, better heat pumps and fabric improvements (lower demand) by then, we could be done for domestic heating + DHW (businesses too?).

So, we need to design a system fitting the requirements chaps! Really should be doable.

1. Natural gas space heating emissions are 0.184 kg/kWh (http://tinyurl.com/nwc4rlq) divided by 82.5% efficiency = 0.224 kg/kWh. Therefore a system with an SCOP of 4.0 will deliver emission reductions of 1-0.519/4.0/0.224=42%.

2. Not 0.462kg/kWh and 47% as used previously. Previous figure used doesnâ€™t include 7% grid losses, and the emission intensity of imported energy. Although advised by DEFRA, I canâ€™t think why you would exclude these.

3. Average domestic price of gas in Q1 2015 was 5.0p/kWh, and price of electricity was 15.6p/kWh (http://tinyurl.com/o8zybas). So 4 SCOP delivers 1-15.6/5/4=25% saving.

4. Taken gas turbine emissions as 370 kg/kWh from the 2014 IPCC report (http://tinyurl.com/nub25kr)*1.07=396kg/kWh including grid losses. Divided by 4.0 SCOP= 0.099. 1-0.099/0.224 = 56% reduction. This intensity figure doesnâ€™t include â€˜life cycleâ€™ add-ons, but I donâ€™t think other figures Iâ€™ve used do either. Should they?? If so, gas boiler emissions figures should probably have a life cycle figure included too if not already. Check IPCC report for figures.

Connecting PEX (or Pex-Al-Pex) to aluminium

gyrogear — Mon, 30 May 2016 01:13:36 +0100

I want to make a solar absorber comprising a series of aluminium channels, and have got the picture that brass unions are out...

I want to use screw connections into the aluminium wall (1mm thick), but am having a time tracking something down. I thought that nylon might be OK.

Collector will be outside :shamed: and in potentially saline atmosphere...

All help much appreciated.

gg

thermostatic valves for ventilation duct

tychwarel — Sat, 21 May 2016 16:33:46 +0100

We have just completed a 100kW community hydro scheme in which the building is cooled by a passive ventilation system (near floor level vents for incoming cool air and heated air leaving through high level vents).
Today the generator set got a little to warm (running flat out at 100kW). This suggests as we thought during the design phase that we need a little more ventilation, however we donâ€™t want the building getting too cold in the winter so would like to put thermostatic valves on the vents.
Has anyone know a supplier for basic mechanical thermostatic dampers that would fit the 100mm ducting we are using.

"Smart" wall thermostat to maximise use from solar thermal panels

gohuwgo — Wed, 18 May 2016 08:02:08 +0100

Iâ€™m after advice for a wall thermostat to maximise the use we make of the solar heat we generate from our thermal panels. Hereâ€™s the issue:-
In an Alpine climate, on sunny days, our solar system generates lots of lovely hot water. However, production stops when we run out of cold water to heat, and when this happens Iâ€™d like to use the excess to start the UFH, using the wall thermostats connecting to the bottom of the water store tank. We can already achieve the same manually when at the building by looking at the temperature stats on the water store, but weâ€™re often not there so would like to do this automatically, and be able to monitor over wifi.

Currently we have 3 (non wifi) thermostats over the building (one on each of the 3 floors), and they are set to start the heating when the building is used most of the time (post 4pm, and pre 9am). On cloudy / foggy / snowy days I want to keep the heat in the tank, so itâ€™s ready for night time heating / DHW, when itâ€™s needed most. Note the DHW and UFH comes from the same tank â€“ see below.
Iâ€™d like to find a Wifi connected smart wall thermostat that connects to our Akvatherm 1000ltr water store, so we can:-
1) Control Wall Thermostat remotely via Wifi, and be able to set rules such as: if temp > 35 degs at bottom of tank between 10am and 5pm then direct heat to UFH.
2) Control the immersion heaters on the water store remotely (the Akvatherm water store has 2 immersion heaters, 6kw each â€“ one for DHW, and the other for heating backup), and check they are working properly.

I looked at the Nest system, but not sure if this will work for what I want to do (but maybe it doesâ€¦). There seems so many thermostat variants out there, and am very confused which one would work for our situation. HELP!

Description of system & environment
French Alpine chalet for 12 pax (170m2 â€“ 6 bedrooms), situated at 1350 meters. Heating & DHW load required early morning and post skiing (post 4pm). Usually most people are out in the day. Some weeks have zero occupancy, so much reduced DHW load â€“ in these weeks, we have very little cold water to heat for the solar panels to heat.
Power generation: Solar array of 17.5m2; woodburning fire (16 KW); 2x 6KW immersion heater electric backup for DHW & heating
Heat Storage: water storage tank (Akvaterm 1000 ltr) plus thermodynamic store of 250ltr acting as a pre heater. The Akvaterm supplies DHW from the top of the tank, and feeds building UFH from the middle of the tank (as per manufacturerâ€™s spec)
Other: x3 wall thermostats to control UFH. Currently set to times when heating is most required (morning / evening, with lower temps in the day). No direct link from thermostats to water stores, but it would be good to have this.

Recommendations for Gas System Boiler with Heat Store

ComeOnPilgrim — Mon, 09 May 2016 19:20:36 +0100

Hello, I'd like to have a largish heat store that can be used with a wood burner in the winter and solar in the summer. It will also need a gas boiler. I understand that I will need a 'system' boiler, but not sure what boilers to be looking at. Does anybody have any recommendations for a suitable gas boiler that would be robust and good value for money?

Best Insulation for Central Heating Pipes?

brighton_dude — Thu, 21 Apr 2016 21:45:42 +0100

Myself and a friend are insulating the floors in my 1957 bungalow. We have the floors all removed so now the joists are visible. The insulation will be of the hard type and it will go between the joists.

Underneath the joists are the pipes for the central heating. These currently have foam insulation probably put on in the 80s when I guess the central heating went in. It is 9 mm thick. I am planning on replacing it all with 25 mm thick foam pipe insulation mainly because I can. While I have access it seems sensible to improve this insulation.

I'm wondering if there is anything out there that is better than the 25 mm thick foam insulation? While I have the floorboards up it would be nice to get the best possible insulation onto those pipes.

Do I need to use a Thermal Store?

MagsonDave — Wed, 04 May 2016 12:53:44 +0100

We have a large Victorian house heated by a floor standing gas boiler situated in one of the cellar rooms. The CH system has separate ground/cellar floor and 2nd floor zones with a third set of pipes for DHW. The adjoining cellar room has been converted into a study with heating provided by 2 radiators and I am also going to fit a wood burner into the old fireplace for additional heating in the winter.
I have been considering upgrading the wood burner to include a back boiler and use it to feed a Thermal Store along with the gas boiler so that I can also use the plentiful supply of wood that I have to help reduce the considerable gas heating bill throughout the winter months.
I know that a Thermal Store is the most elegant solution but I am questioning why I need it in my particular application and why I cannot simply put the wood burner in series immediately before the gas boiler and use it as a "pre-heater" for the water? The gas boiler will always be my main source of heating and the wood burner will only be used during the cold winter months - I can't see any pitfalls with my plan not to use a TS.
Any input/comments gratefully received....

Best Value Combi?

Victorianeco — Tue, 26 Apr 2016 18:40:31 +0100

Worcester Bosch Greenstar 28i Â£600

Any good?

Oddity in this heating diagram from Vaillant

cjard — Wed, 04 May 2016 07:16:46 +0100

My air source HP comes with a nice diagram of where to put the volts. Some connections are volt free, hence extra relays but the main thrust of my query is the timer and immersion relay. In short, the heat pump is effectively controlled by some on off switches that activate it, toggle ufh or dhw, toggle heat/cool etc on terminals 3 6 7 13 and 15. The command unit just sets parameters of Heat performance and reports on sensors, it doesn't seem to issue and control commands unless it is functioning as sole thermostat (it doesn't have dhw orogramming)

In this diagram, a time clock activates it for dhw.. But unless the stat has a temperature below which it is open eg 40 degrees, and then it is closed up to 65 at which point it opens again, then it looks like a call for dhw means both HP and immersion activate? If the stat has a range then I can see how a tank at 0 would be first heated by the pump, which would then tail off as it peaked at eg 40, and the immersion take over til whatever temp is dialled in..

I just don't seem to find stats that work that way, so im wondering if this diagram is not really a situation one would create in practice. I think instead if it had a 2 channel progger, I could ask for dhw on channel 1, and really just do pasteurising on channel 2 using the immersion.. But if I did want a larger volume of very hot water regularly, configure channel 2 to coincide with channel 1 ending its call for dhw from the pump and use the immersion to top off? (Or fit an inline heater)

Edit: added a couple of other pics from a different manual that help explain the inputs 3,6,7,13,15 etc

Over heating from south facing windows

hebden-passive-house — Mon, 02 May 2016 19:33:28 +0100

Hi all I imagine this will have been discussed before but I can't find it. I am about to move into rented apartment it has a large south facing window. There is electric heating in the flat so I am glad of the window for the solar gains in winter but I am worried about it over heating in summer. I know on passive houses they put louvers to stop this. I was thinking of doing something similar on the balcony on the out side of the window. The other two windows face west so hopefully they should be okay. Any ideas?

Heat loss calculations

cascina — Mon, 25 Apr 2016 20:06:18 +0100

I am trying to put together a plan for a heating system on a new project. We are based in italy and the house is of concrete construction. I installed heating systems commercially in the uk for a number of years and did heat loss calculations on most of my installs to make sure the right boiler was selected for the job. To do this, I used the 'whole house heat loss method' using software from www.idhee.org.uk. Using this I had options to enter the dimensions of the property, current insulation, glazing, aspect, location etc. to come up with a heat loss figure which I would then use to size the boilers central heating load and de-rate the boiler as required.

I am now looking at a concrete house which appears to have no insulation in it. It is over four floors including the basement and the roof has 3 rooms and a bathroom within it under the pitched roof. Looking at the openings for the velux windows, the roof appears to be approximately 10" thick and is described by the builder and agent as 'cemento armature' which I think is reinforced concrete. What we want to do initially is to add EWI to the external structure, but the large roof was recently replaced due to a leak, with new battens and the original coppi tiles. This means within the roof space mostly pitched, we will be using IWI. Given all the surfaces are pitched concrete, I presume that this would be done in the same way as external wall, using an adhesive and then insulation screws/bolts drilled into the roof?

I will be doing the IWI straight away before winter, but the EWI may have to wait until next spring due to the rest of the work required from the builder. The question then is: how do I go about calculating heat loss before and after improvements?

Currently there is a 30 year old oil boiler and dead oil tank, so we are starting fresh. I am looking to install a wood burning boiler and have significant storage available in the adjacent barns for the wood storage. I would then be looking at having a pellet boiler to act as a reserve for when I am not there and my wife is unable due to childcare etc. I also like the redundancy of multiple input systems for when one breaks down in the depths of winter and I am away.

I have installed a few thermal stores before but normally to act as a buffer between wood burning stove with back boilers and gas boilers in SE England, but not to enable batch burning from log boilers. I would like the ability to batch burn as infrequently as possibly, so having calulated the heat loss, would want to size a thermal store appropriately to the log boiler, but oversize the log boiler for the house's heat loss to enable less frequent burning and also utilise the larger logs that appear compatible with larger log boilers.

We would also be looking to add thermal solar (I have a 30 tube ET setup in storage from a previous project) which should be able to provide most of our house DHW during the non-heating season. The main house is approximately 550m2 not including the basement.

Any help in formulating a plan would be most gratefully received as reading this forum has given me a massive appetite for getting this right first time round.

Thanks in advance.

Boiler Size & Thermal Store

clawlor — Thu, 17 Dec 2015 14:17:27 +0000

We're renovating a double upper which comprises the entire first floor and attic of a Georgian house. We've done some heat loss calcs and are in the process of doing a SAP calc. So far with the heat loss calcs we estimate that we will need approx 22kW boiler which the results of the SAP will hopefully clarify. We are hoping to use a thermal store and I was wondering if anyone has experience of how this would effect the boiler size? If the thermal store reduces boiler cycling and heat up time we therefore believe that a smaller boiler will be required although I can't seem to find a definitive answer to this on the manufacturers website.

Also I was wondering how the boiler should be sized for dhw load? -I've been told to allow 3kW for heating water.

We are spec'ing & installing the heating system from scratch so it's an opportunity to get the most efficient system possible for the flat.
Thanks C

Dumping hot water

tony — Wed, 20 Apr 2016 10:21:42 +0100

This is a hotel situiation,

Monster HW system, loads of outlets.

As it took too long for HW to get to taps someone installed solenoid valves in each services rooms associated with the any HW outlets and web linked them.

This is the regime, 5:30 dump hot water to drain through all of them for 20 mins, then every half hour dump hot water to drain for five mins until 11:30, similar in the evening

How widespread is this practice? What are we up against here.

ISO pipe thread designations

Shevek — Tue, 12 Aug 2014 11:27:28 +0100

I've entered the dark world of ISO pipe thread designations. For instance I have a plumbing fitting with an R 1/2 thread and one with a G1B thread.

Am I right in saying that 1/2" and 3/4" brass fittings will fit these respectively?

And what does the R, G and B stand for? And what does the 1 in G1B stand for?

Most secure heating and backup

ChrisEngland — Tue, 05 Apr 2016 11:18:15 +0100

Various problems meant I couldn't get to my second home over the winter - visited recently to find oil heating had failed and there was flooding from burst pipe/tank in loft (even through water was turned off and drained). The question is what to do about the heating to preclude a possible repeat, with lowest carbon footprint. My initial thought would be ASHP with inline immersion heaters in case of ASHP failure. Any thoughts about reliablilty and alternative systems would be appreciated. There is no gas to the cottage and single phase electricity - would flicker be a problem with ASHP?

Ventilation heat loss calculation

jwd — Thu, 07 Apr 2016 16:47:19 +0100

Hi
Im doing a project for a course that needs a simple calculation for the heat loss via ventilation for an office and have got myself in a muddle as the number I have found seems way too large.
The office is 6 m X 10m by 3.5m. It has an occupancy of 10 people and a photocopier. The CIBSE standards tell me I need to allow 10l/s for each person and part F tells me I need another 20 l/s for the copier in order to keep Co2 to an acceptable level. That would make a total of 120 l/s. It is 22 deg c inside and 4 deg c out side. what would be the heat losses due to ventilation? I have assumed it is naturally ventilated. I used a formula where heat extracted is 1.2 x q (the req ventilation rate in l/s) x dt (temp differential - 18 degrees).

Can anyone tell me if I am a)barking up the right tree or b) where I hae gone wrong ?

Cheers
JW

Vent Axis HR100

jemhayward — Thu, 27 May 2010 14:53:44 +0100

This unit is not very efficient (70% claimed) and uses a significant amount of power 18W low, 30W high, but it has two advantages for me:
1. its quite small so may well fit above my bathroom ceiling
2. its cheap (<Â£200), and as I need a decent extractor fan anyway the extra for HR is quite small

It would be used for extracting stale damp air from a small shower room, and would vent fresh into the adjacent (huge) living room.

Would the efficiency and power consumption tip the balance into energy consumption, rather than energy saving?

Disappearing Heat

gyrogear — Fri, 01 Apr 2016 18:48:40 +0100

Desirous to get green, I thought I'd try heating my crawlspace using house air.

I installed a couple of inline fans and started pulling air out of a warm basement room, and my (warmer) lounge.

However, the Crawlspace temperature immediately started *DROPPING* ! and kept dropping until I reduced the fans to half-speed, then it rose slightly.

When I turned the fans OFF, the CS temp returned to its normal level.

Would appreciate an explanation of what is happening, in layman terms if at all possible :sad:

cheers,

gg

ASHP Large House

newnight — Sat, 06 Feb 2016 15:53:18 +0000

I have been reading this Forum for the last few years and really appreciate the knowledge I have gained from the members.

About to start a New build On Arran off the west coast of Scotland

The house is large 2 1/2 story 6 Bedroom 6 Bathroom SIPs Build

Interior Space 396 m2 .

PLANS
http://kvisit.com/zymQ
http://kvisit.com/zyWQ
http://kvisit.com/zy2Q

Heating and Hot water ASHP

Ground Floor: 3 beds, Sitting room,Plant Utility

1st Floor Kitchen/Dining Living room & Toilet

Top floor 3 Beds ensuite

UFH for ground floor Living Room, Hall and part of the Plant/utility room

UFH in dry cement pug mix between joists for 1st floor

UFH in all 6 bathrooms and toilet

Radiators for all bedrooms and upper hall Landing.

I would prefer if UFH could be split into 3 zones ( Ground, Middle ,Top Floor)+ 1 zone for rads( but I am unsure if all this zoning will compromise the efficiency of the system)

Would also like pipe spacing <100mm on ground floor and Bathrooms to keep the flow temp low ,perhaps the spacing on the first floor can be more as I also have A double sided Wood Burner 7KW between the lounge and kitchen that I would like to be able to use occasionally.

I have used the BRE - Calculation tool for design of low temperature domestic heating systems and filled it out to the best of my ability . http://kvisit.com/zyGQ

Total DHL 12.5kw 4.2kw of this to Rads

This will be a Holiday Let a good part of the year, sleeping up to 12 people so large water demand (Heat Store/Buffer).Though at times only 2-4 of us

I am planning 2 x Nibe F2040 12w

I have already purchased 1 Nibe f2040 with VVM 320 indoor unit as I managed to get a good deal on EBAY

VVM320 stores180L, do I need 500L or 750L cylinder or 2 smaller units for flexibility when the Hot water demand is lower

Although I will get a MCS accredited Designer I would be grateful for an Ideas or suggestions regarding the design and setup beforehand

Thanks
JB

Ufh. One pump and mixing valve to run 3 manifolds?

cubbs — Thu, 24 Mar 2016 23:20:14 +0000

Hi again

Am looking to keep my higher temp water in/near to the thermal store. So I'm thinking of having an ufh pump and mixing valve in the boiler room.

I presume I will need 2pumps?

Will it work to then run in 22pipe to my ufh manifolds?

How would this affect wiring?

Are motorised 2port valves needed? Is so where?

Thanks

Small Thermal Store or twin/seperate dhw/heating

smudger — Wed, 16 Mar 2016 13:29:11 +0000

We have a large (26kw - 16kw to water) boiler stove, yet to be installed. We also use PV and off peak (economy 10) elec for both space and dhw heating. Currently its seperate and not sure if we should combine for flexibility or install two cylinders (or small TS) with controls to switch between them. Our objectives:

1. Off peak / PV hw in summer and largely in spring/autumn when boiler stove not being run (or run as long)
2. Some storage of hw to heat the wet rad system in the morning for a few hours and avoid using elec boiler (6kw) -we do have storage heaters to give background heat all day
3. Mains pressure HW

We are at 1000ft so 'summers' are short, so we can live with boiler stove being lit for 9 months of the year, but not in the mornings to get any heat. Water demand varies but typically 4 showers per day but could be more with visitors. Limited by space and access so decided 500l TS was optimal, but alternative is 2 x300l HW Cylinders.

If TS is only option for mains pressure hw, what are the key specs to ensure we have proper stratifixation and dont end up heating 500l of hw when we dont need it.

Thoughts / advice welcome, along with recomendations for manufacturers.

Kingspan Range Tribune Xe hot water cylinders

cjard — Sun, 13 Mar 2016 07:42:44 +0000

I like the look of these from the brochure - thicker insulation, cold diffuser, compact coil in coil, side mounted outlet for a fully insulated lid, 25% lower standing heat losses and integrated air bubble acting as an EV so no external EV. Very neat. Good price too

Buuut, as best I can determine (one reference in a sales brochure) the coil is 24kw on the 300l. The solar option has an additional 1sqm coil and, as far as I can find, you multiply the area by 33.333 and you get your kW, which means the solar coil is actually a greater transfer capacity than the primary coil..

So, i'm confused.. A dedicated heat pump cylinder (there seems no dedicated "low grade heat" version of a Tribune - the sales brochure mentions renewables as biomass, micro-chp, solar thermal, wbs) from a rival co will have a 3 to 3.3 sqm coil, knocking on for 110kw. Apparently, a large coil is used for a better reheat time with low grade heat but surely if the coil transfer ability is greater than the heat source supply kw, then it functions adequately?

Why does a 15kw heat pump input to a 110kw coil, and a 28kw boiler input to a 18-24 kw coil? doesn't make sense to me...

Is there some function of the maths i'm missing, like the delta T making a difference?

Hot water option in a tiny house

Triassic — Tue, 15 Mar 2016 22:24:29 +0000

I'm in the process of building a small cabin in which to live in during the self build of the main house. I'm wondering about hot water options and wondered if anyone had any advice?

The cabin has one bedroom, a bath room and a kitchen / living space. I had in mind to use an electric 10kw shower, but how would you supply hot water to the kitchen and bathroom sinks?

GSHP is this slinky array ok??

agu — Mon, 01 Jun 2009 15:29:35 +0100

Firstly I know that GSHP aren't renewable as such but was unsure where else to put this disscussion so hope this is alright.

I am specing to put a GSHP slinky under an astroturf pitch that is to be built, this will obviously have a subbase. What I wanted to know was if any problems would occur with this set up. I can't see any major reason why it shouldn't work but a couple of things I did think of are the following.

1, If too much heat is extracted and the ground freezes could it cause the subbase to crack?
2, being under the astro and subbase will the CoP drop off due to less solar gains on the ground?

Can anybody advise if this will work fine ( I think it probably will ) or if there is anything major that I am missing or any reason if just wont work???

THanks if advance

Agu

Under-stair PEX heat dump...

gyrogear — Sat, 15 Aug 2015 20:33:16 +0100

Hello to one and all, New member hereâ€¦

I have searched the forum (and the Web) but cannot find any reference to using uncoiled PEX as-is.

The reason is, I want to install heat in an under-stairs void (concrete): given the restricted dimensions, I suppose staring infrared is a No-Go, so I guess I will placing a coil of PEX in there, and circulate hot water through it, a bit like UFH.

I would glue 30mm of XPS to the floor and two walls, leaving the stair soffit bare. I would install as much PEX as possible (whence my questionâ€¦), then cover it with concrete or mudcrete, for additional thermal mass, then brick up the open side (to keep the cats outâ€¦).

Heat circulation would be from a hot-water storage driven off a solar thermal collector built after the event.

My questions are: would such a system work? Could the coil be left as-is, or would â€œeasing it outâ€ be better, to better occupy the available floor area of one square meter. More easing = less PEX, less water, presumably less heatâ€¦

Thanks for any feedback !

gyrogear

Measuring CO2 to control ventilation

micforster — Tue, 08 Mar 2016 21:02:26 +0000

The Green Building Council of Australia gives extra credits to buildings that have installed CO2 detectors for ventilation purposes. While this makes sense for a commercial building, does it also make sense for your average home? The cost of CO2 detectors are coming down, but does it outweigh any energy savings that are gained by turning a house over to demand control ventilation (DVC)?

For those who are new to this topic, here is an article on why you need to measure CO2 inside buildings: http://www.edaphic.com.au/why-you-need-to-measure-co2-inside-buildings/

Heat networks

tony — Thu, 03 Mar 2016 23:22:03 +0000

District heating is common in Europe

There are proposals for some heat networks to be set up here in the UK

I don't think that they will work, when it comes to charging for repairs there are several ways to do this none of which are viewed as fair by Brits, and then some will refuse to pay. They will then want or have to be disconnected leaving a worse situation for the remaining users. (more for them to pay)

Then there there is the disruption of installing the network of pipes, roads up, conflict with other services, bringing the service into homes or flats.

Will it catch on, NO, will it start happening, yes but only because there is big funding, will it last NO.

radiators and ufh in series

johnnyh — Fri, 27 Nov 2015 10:42:34 +0000

Hi to all, i've been reading this forum for ages whilst getting round to installing my log burner and store. Finally it's in and working pretty well but i'm not really getting more than a day's worth of heating per charge and i had hoped for maybe two days when the weather is mild. I have ordered a tech 431 'steering' to control the CH mixer valve and in the meantime i have adjusted it right down which gives us a fairly low temp on the rads, not hot enough for a cold day. If i adjust the mixing valve back up, the tank destratifies. One solution i think would be some ufh circuits to cool the radiator return temperature but they would have to be fed from the radiator return to have this effect.
The question is simply: Will this work?

measure standing losses

johnnyh — Sat, 05 Mar 2016 22:29:47 +0000

Hi to all,

could anyone give me a method of measuring the losses from my thermal store when not being drawn from please? I have temp sensors at the top, middle(ish) and bottom.
i have lots of things on my list at the moment and i am wondering if more insulation should be a priority or not so if the figures show that losses are not so serious perhaps i can leave it til i have more time.

thanks,

UFH and Thermostat Choice

Diarmid — Wed, 02 Mar 2016 07:06:09 +0000

Trying to work out the best solution to control my UFH system.5 zones. New Combi calor gas boiler. Well insulated house with triple glazing. It's a holiday home so only occupied some weekends at present. I don't want to leave the heating on 24/7 for that reason. No internet connection. Looking at remotely controlled thermostat - perhaps a 'climote' I'd like to have control over all the zones e.g. bedroom temperatures lower etc. Any suggestions?

Cooking and heating with wood

weebookboy — Tue, 23 Feb 2016 21:51:17 +0000

Hello all, this is my first post on the forum but Iâ€™ve been using the forum as a resource for years so Iâ€™d like to thank everyone for contributing â€“ both questions and answers.
On this occasion Iâ€™m hoping for some advice on my particular situation and plans.
Iâ€™ll try to give quite a full background so thank you in advance for having the patience to read through.
We live in a three bed bungalow on the Isle of Skye, recently moved in (October) and currently have oil fired heating and an electric cooker. We hope to replace a lot of this system with wood fuelled options. We have had wood stoves before, as our sole heating on a narrowboat and as supplementary heating with gas central heating.
There is a redundant fireplace in the living room with a capped chimney and we have 9 radiators in the central heating system including two tiny ones.
Our demand on domestic hot water seems very low, our shower is electric and we usually wash our hands with cold water (the hot takes too long to come through anyway), aside from the occasional bath we just use a bowlful for the washing up in an evening.
I am thinking of putting a wood stove in the living room and a rayburn in the Kitchen for cooking, DHW and central heating. One of the features weâ€™d like to have is to be able to have the central heating on for an hour or so in the mornings so we wake up to a comfortable house and to this end I think a thermal store should suit our needs.
I am not knowledgeable about plumbing and keep getting lost in the technicalities. I didnâ€™t want the living room stove to have a back boiler as I donâ€™t think itâ€™s need in the system and it would just reduce the burn efficiency. Iâ€™m planning on retaining the electric cooker as a backup (very few people relying on wood for cooking seem to recommend it as a sole cooking source and we donâ€™t have equal dedication to it in the house).
So I suppose my question is will a thermal store be likely to answer our demands for morning luxury after an evenings burn of the rayburn? Are there any gaping holes in the rest of my plan?
Thank you very much for having the patience to read through if youâ€™ve made it this far, apologies for the scrappy details â€“ it is difficult to know how much is relevant.
Thanks again, Adam.

Basic thermal store/hot water cylinder questions

GarethC — Sun, 28 Feb 2016 11:12:47 +0000

Apologies if covered elsewhere and/or stupid, but can anyone tell me:

1. How good are high performing thermal stores/cylinders these days in terms of heat loss?

2. What are the absolute best performing ones in this regard, and how well do they do?

4. I may be wrong here, but am I right that you can't insulate around where the heating element enters, presumably since it's a fire hazard? Surely that hazard can be designed out...

3. Why are cylinders, well, cylindrical? Box shaped would be more space efficient and easier to install. Is it just due to ease of manufacture, or is it due to in-use performance considerations?

Thank you!

Pug/biscuit mix for wet UFH, can it be laid wet?

john37 — Sun, 28 Feb 2016 21:15:04 +0000

We are doing wet UFH on suspended floors with very strong timber joists (9 x 3in at approx. 400mm centres, max span 4.8m). We are setting the pipes between the joists on a 45mm thick PIR base and pug mix (8:1 sharp sand: cement) between and around the pipes, as commonly used. I understand the pug mix is usually mixed and laid dry but my builder would like to lay it wet, in fact he has already started and it looks ok.

Is there any disadvantage or problem laying the pug mix wet at 25mm depth?

Sealed system stoves

JonG — Mon, 22 Feb 2016 16:01:44 +0000

Does anyone have a good supplier/source for sealed system wood burning stoves with low outputs, I need around 7kw to water for a project but most are way over this?

Heating and dhw design - please help!

plw666 — Wed, 10 Feb 2016 16:32:36 +0000

Hello
Im new to the forum and although Ive read a lot Iâ€™m still confused as to the best option for the heating and dhw. Most installers seem to only want to do what they want to do rather than provide advice as to options and proâ€™s/cons!

I live in a little 55sqm single storey cottage in Sussex with no mains gas. Installed is a 210l DPS heatbank fuelled by a Charnwood 16B stove (8.6KW to water) burning wood with 3/6KW immersion for back up and a solar coil although I didnâ€™t have the panels fitted as I quickly decided to plan an extension. Works ok but tank is small if the stove is on all evening. Walls are single skin brick but insulated with 100mm sheeps wool and loft insulated with 250mm sheeps wool.
The new extension is planned to include demolishing 15sqm of the existing and building on the side then 1.5 storey (about 50sqm each floor) with 2 bedrooms and shower room upstairs and hall, utility and kitchen diner downstairs â€“ all insulated as per current regs and with ufh on new ground floor (about 50sqm) and rads upstairs and in existing building. Existing part will have ewi and new dg windows as well as small infill on one end to add another bathroom. Have room for a wood stove in the existing sitting room and also in kitchen diner
There isnâ€™t room to add large pellet store and narrow access makes delivery of blown pellets difficult. not much room for a chunky pellet or log boiler. Could store logs in various places on the plot.

Does anybody know anything/have thoughts on the walltherm zebru? Seems like a lot of work to operate but maybe I am wrong. Or the klover diva to have in the kitchen either of which feeding a 750 or 1000l akvatherm solar tank?

Ashp with solar thermal for summer dhw-keeping the stoves for room heating?
Can the ashp generate water hot enough for baths/showers?
what about keeping the current heatbank and using it with ashp for the ufh heating only and a separate tank for dhw fueled by the solar thermal in the summer and the back boiler in the winter? In this arrangement could the ashp be "switched" to the dhw tank in the summer to top up the solar or is solar alone enough?

At this stage the design is not fixed so I'd like to get the right combination and really dont feel confident that I know how to do itâ€“ any thoughts?

as you can see I am def "confused" from Sussex

Thermal store open vented to Plate heat exchanger sealed heating system

cubbs — Tue, 09 Feb 2016 22:54:44 +0000

Evening

Talking to a fellow plumber today and hes fitted a Gledhill TS with a mix of open vented for the store and the UFH and then the upstairs rads are heated through a plate heat exchanger and sealed mains fed system. He was worried with airlocks on the rad pipework and Gledhill advised the heat exchanger solution.

My set up will be a http://tmsthermalstore.com/ 500lt TS on ground floor along side one, possibly 2 of the UFH manifolds. Then the heating pipework is to run up and over two rooms in the floor joists then drop to ground floor UFH manifold under stairs so making a "goalposts" scenario. This will be very hard to vent with manual or AAv's.

So Im thinking of having the TS open vented of course but also some of the central heating then passing rest of UFH via a plate heat exchanger but make this side a sealed system with an expansion vessel making it all easier to fill off water mains and vent etc and less chance of airlocks.

Can any one see problems or add any comments?

TS will initially be heated via oil boiler, then next winter a solid fuel boiler stove with solar thermal panels a few years down the line.

Thanks

How much of a difference do better heating controls make?

GarethC — Mon, 01 Feb 2016 10:28:20 +0000

I have TRV's on all my radiators, but I still spend a lot of time heating bits of the house no one's in at the time, because I can't be bothered wandering round the house turning them all off when I, for example, need to heat just my home office while working. And I'm always a bit suspect of always heating the hall where the thermostat is, regardless of what rooms we're actually using.

Gut feel is I could reduce usage by 20% or so if every room had controls which could individually call for heat without affecting others (and were preferably individually programmable). My current system does feel antiquated.

Has anyone seen studies of how much difference better controls make, or personal experience? Sorry if this has been covered already. Couldn't find a thread which covers it this way.

gasifying boiler primary air control

johnnyh — Sat, 30 Jan 2016 22:39:42 +0000

Hi to all,

wondering whether anyone can tell me which parameter is best to control primary air on a gasifying boiler? Would it be better to use oxygen levels in flue gas or flue temperature or something else entirely?

Any info would be much appreciated,

regards,

john.

Calorex Heat Pumps

woodgnome — Sat, 07 Nov 2015 11:29:26 +0000

5Kw Calorex GSHP on fleabay. Considering it for my house, as its the right size and I probably won't get round to installing till after April next year. With the uncertainty regarding the RHI after March 2016, a non MCS install might be the way to go.
Any comments on the Calorex unit?
Ta.

Cheapest option for screeded UFH materials

cubbs — Sat, 23 Jan 2016 18:52:32 +0000

Hi

Re- screeded ufh

Labour is not really an issue within reason but which method is cheapest?

Pipes clipped straight into insulation?
Pipes in clip rails on insulation?
Or the plastic egg box method?

You guys have lots of experience in Ufh

Thanks

Wooden floors and UFH - with ref to wood types

Landsrud — Sat, 23 Jan 2016 21:30:23 +0000

Hello,

We installed UFH in both bathrooms in or 1830 wooden house in Norway. Down stairs we tiled, but when we came to tile the up-stairs we suddenly thought why not just use a wooden floor as this room isn't going to be a true wet room (even though its wet room tanked). I did a bit of research and found out that placing UFH under wooden floors is possible but depends on the type of wood, for example soft woods like pine might form a insulating barrier and the heating effect would be lost. What are people thoughts on this? Any advise on wood types and thickness. I have read the flor thickness should not be more than 14mm(?)

what is the purpose of 'blow through'?

johnnyh — Sun, 20 Dec 2015 18:13:46 +0000

Hi to all,

My orligno 40kw log boiler has the above mentioned function and i don't know what it's for. Nor does the manual explain.
I am not sure if it's related but when i want to stop the boiler (rather than let it force-burn the last few lumps of charcoal for no good reason that i can think of), i am unable to. If i stop it by pressing the off button it soon takes it upon itself to restart. Only the main switch can stop it but this also stops the laddomat pump which means the boiler doesn't transfer the last of the heat to the store.

maybe this is blow-through, i m not sure. Either way, what is the purpose of this?

Thanks,

john.

Inverter or no?

cjard — Mon, 18 Jan 2016 23:09:26 +0000

SWMBO has decided an ASHP is a good idea, mainly because it's ideally fit n forget and I have enough on my plate with everything else.

She asks pointy questions like "why is this Chinese one a grand and that other one with the same rating is 5 grand"

At best I can explain that the performance of the jap one holds out a lot longer as air temps fall and that it has an inverter driven compressor so it shouldn't cycle as much, but I have no answer for the follow ups like "does it matter?"

I dunno.. Does it? With a big enou buffer, who cares about the inverter or lack thereof? And when one can buy a new Chinese ASHP every year and it be a long time before the outlay reaches that of a Japanese one, does it make sense to get a Japanese one?

I have he tluxury of living next door to a house that is broadly similar to mine, and I watch it's development. A Certain Supplier from every building mag going, has specked a 14kw ecodan for that property. Interestingly they tell me the final bits of paperwork (which I presume includes a decision about which ASHP to go for) will be done when the as-built configuration is given, which is done after the pump is installed. This seems arse about face to me, but who am o to judge?

So right now I'm looking at one of 2 options:

* Diy.a cheap non inverter one, mate it to a big heat pump cylinder and let it cycle if needs be, sod the RHI
* MCS install of a high end one, add umpteen thousands to the mortgage, use the RHI

There is also the option of buying a high end one for cheaper than RRP and not using the RHI, though financially there might be a limited circumstance where that's viable..

Prices wise, a DIY job would be around 1k plus the unit price I think
Ecodan is just shy of 7k commissioned (note, that doesn't mean installed) and rhi'd
Calor guesstimated 9k for a daikin altherma hybrid, RHI compliant
Samsung ones have been floating around for circa 4k as a second hand system, no RHI

I don't doubt my technical ability to do the DIY route, I just can't decide (with everything else on my plate from second fix, plasterboarding, flooring, kitchening, stairing, decorating and landscaping whether this is just one of those jobs where it's worth handing off to someone else. Essentially it looks like the expensive option, plus the extra mortgage, minus the RHI comes to about the same cost of buying a cheap pump and not using the RHI.. I just have to front the cash, which is a bind.. In essence my query is (I think):

Are inverter driven HPs worth the premium or is a somewhat agricultural Chinese pump that simply cycles on and off for a quarter of the price a better bet for a user who is prepared to have a large tank of hot water sitting there wi the aim of smoothing things out?

Dehumidification, better controls + maybe ventilation significant benefits of air conditioners?

GarethC — Thu, 21 Jan 2016 08:49:06 +0000

My mania for A2A heat pumps is well known on this forum. I've a few questions.

1. Is the controllability they offer a significant benefit?

I'm looking forward to the controllability they offer. I intend to have three indoor units. Each will be independently controllable and programmable via the handset or an app on my phone. That's significantly better than my current radiator TRV based system. Even a tree hugger like myself can't be bothered to switch off TRVs that I don't need to be on, and so I often heat areas that don't need to be. I think the independent controllability will reduce this.

2. Is their ability to dehumidify a significant benefit?

Secondly, modern air conditioners appear to be able to dehumidify, if necessary, without lowering the indoor temperature much. Given I try to keep air leakage down, and do suffer from humidity in some areas, this feels useful. Would probably mean I would need to worry less about, for example, drying laundry in the house, or humidity from cooking and showers etc.

3. Is a unit that can also ventilate a good idea?

Finally, there are some units (like the ururu sarara one in catalogues available here: http://tinyurl.com/zlmmbrs) that can bring in fresh air at the same time. Feels sensible. As long as you are knocking a hole in the wall for these things, might as well add a channel for fresh air. Which feels like it can kind of provide MHRV in to the bargain.

This last one is basically me trying to justify buying the ururu sarara unit to myself. The claimed COPs are stratospheric (well over 5), but it's twice the price of a high performing R401a unit. I'm trying to persuade myself that the added ventilation provided, in addition to slightly higher COP, makes it worth it.

Incidentally, more manufacturers are rolling out the new, higher performing R32 refrigerant across their range. Reckon it gives a 10% boost to COPs for all types of heat pump, a good thing.