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General: Air to air heat pump

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      CommentAuthordjh
    • CommentTimeOct 21st 2020
     
    Posted By: Jeff BI came across this:
    https://ampair.co.uk/products/?product_types=ducted
    Is this the kind of thing you are looking for?

    Posted By: WillInAberdeenHow about https://www.orionairsales.co.uk/ducted-air-conditioning-28-c.asp ? Presumably they don't heat the air as hot as a direct electric heater does (to keep the CoP up) so you need to move more air?

    Thanks, chaps. They're getting towards what I had in mind. They're all the wrong form factor for what I have in mind - fitting into a circular duct, so would require some metal bashing to adapt. Most of them are too powerful as well, although there are a few lower power ones. The wall-mounted conventional indoor units look more attractive at this point, for features such as better controls, R32 and noise levels etc.

    It's perhaps worth changing tariff yourself before anyone forces you to - if you stay on a legacy tariff for too long then the price will only go in one direction

    Yes, I'll be keeping an eye on the prices. I don't like the idea of fixed-price-limited-time tariffs and constantly looking for new best deals, let alone having a robot choose my deals :shocked: So I'll see how it goes.

    If it turns out that I need to change tariff then one of the ones like Octupus offers might well be next. I can't do much about cooking in th epeak period, but being able to spread my heating over a bit more than the seven hours would give me more flexibility.
    • CommentAuthorowlman
    • CommentTimeOct 21st 2020 edited
     
    •  
      CommentAuthordjh
    • CommentTimeOct 21st 2020
     
    Posted By: owlmanIs this the type of thing you're after.

    That's the type of thing I've got at the moment and which I want to consider replacing with something similar but powered by an ASHP instead of a resistive heater. Actually, they say they're pre-heaters while mine is a post-heater; I've no idea if there's a difference.
    • CommentAuthorowlman
    • CommentTimeOct 21st 2020
     
    The ducted indoor units usually come without inlet or outlet plenums.
    Because I wanted two circular inlets and outlets on either end of the unit I simply handed the whole unit to a local sheet metal fabricator. Their guy was a pleased as punch that the had the whole thing to play with, rather than some drawings and he soon had the plenums made. The job wasn't expensive either.
    In your case, if I understood correctly, you just need the two rectangular inlet and outlets each converting into a single circular male spigot. In my case I then fixed them onto the unit and insulated with neoprene sheet. Having done that you can then position the unit anywhere,- it doesn't have to be atop the duct,- and break the existing ductwork and send everything via the indoor unit. Or put in a diverter, all that's fairly straightforward.
    •  
      CommentAuthordjh
    • CommentTimeOct 21st 2020
     
    Ah, thanks for that - useful to know.
  6.  
    My Genvex 185 Combi LS has a built in 585W EASHP which warms the ventilation supply air when required. I believe Genvex produce other ventilation units with built in ASHPs and I don't know but it may be possible to buy them as spare parts.
    • CommentAuthorEd Davies
    • CommentTimeOct 23rd 2020
     
    John Ward on E7/E10 wiring options:

    https://www.youtube.com/watch?v=JJ6Chd9GjpY

    Once he starts opening the box up at around 22 minutes in there's nothing more of interest.
    • CommentAuthorJeff B
    • CommentTimeOct 23rd 2020
     
    Posted By: Ed DaviesJohn Ward on E7/E10 wiring options:

    https://www.youtube.com/watch?v=JJ6Chd9GjpY" rel="nofollow" >https://www.youtube.com/watch?v=JJ6Chd9GjpY

    Once he starts opening the box up at around 22 minutes in there's nothing more of interest.


    This video confirms what I have recently discovered, that is, it is not worth having Economy 7 just to power an immersion heater because I would end up paying more for daytime electricity which negates any gains from the night-time rate.
    • CommentAuthorJeff B
    • CommentTimeOct 23rd 2020
     
    I have been quoted between £11K to £14K for an ASHP (supply and install) to replace my wood pellet boiler, depending on the complexity of the job i.e. subject to energy usage survey, whether larger radiators needed etc.

    Yet I can get a Panasonic air-to-air split system with one outdoor unit and five x 2.5kW indoor units for less than £3.5K (supply only, admittedly). Surely not more than £1K to £2K to install? I could do a lot of the prep work myself too which could reduce the cost.
    • CommentAuthorjms452
    • CommentTimeOct 24th 2020 edited
     
    Posted By: Jeff BYet I can get a Panasonic air-to-air split system with one outdoor unit and five x 2.5kW indoor units for less than £3.5K (supply only, admittedly). Surely not more than £1K to £2K to install? I could do a lot of the prep work myself too which could reduce the cost.


    I decided on a top of the range gas boiler for £3k rather than an ASHP (air to water) for us based on similar pricing (and as much of our demand is hot water).

    More thinking (i.e. this thread) shows me that we (as a country) are somewhat hamstrung by conventional thinking - that we need a drop in boiler replacement to run radiators and hot water.

    For many it seems like an A2A heat pump for £2-3k for heating, an for immersion hot water on some form of timer/smart box (e.g. on agile octopus tariff) and optional rooftop PV is more carbon and wallet friendly.
    •  
      CommentAuthordjh
    • CommentTimeOct 24th 2020
     
    I don't understand why air-water units are so much more expensive than air-air units? They seem simpler in principle since they don't need indoor units, just a water pipe connection. Is it simply production volume economies? Far more A/C units in the world than ASHP water heaters?
    • CommentAuthorJeff B
    • CommentTimeOct 24th 2020
     
    Posted By: djhI don't understand why air-water units are so much more expensive than air-air units? They seem simpler in principle since they don't need indoor units, just a water pipe connection. Is it simply production volume economies? Far more A/C units in the world than ASHP water heaters?


    With my cynical hat on, could it be because there is no RHI payment for air-to-air hence no scope for charging rip-off prices, unlike for air-to-water? The company I got the quote from for an air-to-water system specifically said they do not do air-to-air because it does not qualify for RHI payments.
    • CommentAuthorJeff B
    • CommentTimeOct 24th 2020
     
    Posted By: jms452
    Posted By: Jeff BYet I can get a Panasonic air-to-air split system with one outdoor unit and five x 2.5kW indoor units for less than £3.5K (supply only, admittedly). Surely not more than £1K to £2K to install? I could do a lot of the prep work myself too which could reduce the cost.


    I decided on a top of the range gas boiler for £3k rather than an ASHP (air to water) for us based on similar pricing (and as much of our demand is hot water).

    More thinking (i.e. this thread) shows me that we (as a country) are somewhat hamstrung by conventional thinking - that we need a drop in boiler replacement to run radiators and hot water.

    For many it seems like an A2A heat pump for £2-3k for heating, an for immersion hot water on some form of timer/smart box (e.g. on agile octopus tariff) and optional rooftop PV is more carbon and wallet friendly.


    We do not have mains gas in our area so an alternative for us is simply to revert to an oil boiler based system and keep the wood pellet boiler as a back up/alternative system. With the assistance of my plumber brother-in-law I could install a new oil boiler and bunded tank for around £3K and pay a lot less for fuel too; but it seems criminal to do so when we are all trying to reduce our carbon footprint!
  14.  
    Think it's like solar panels, they charge the price they think the market will bear. The A-W ashp market is mainly enthusiastic early adopters, often bringing many £k of subsidies and paying high prices, like the early days of the rooftop PV boom. This maybe deliberate policy to tempt more installers into the market.
    Eventually the supply should increase, but there will be a big increase in demand when fossil boilers are banned, so could be a bumpy ride.
    • CommentAuthorJeff B
    • CommentTimeOct 24th 2020
     
    I should have added that where we are (rural Pembrokeshire) practically every man and his brother has an oil boiler, to a lesser extent LPG, and the remainder have wood burners (very, very few wood pellet boilers I suspect). The mind boggles as to how anyone can expect all these folk to go down the ASHP route at current prices - there has to be a dramatic cost reduction either by means of some post-RHI grant system or a cheap and cheerful green deal loan scheme. (Note: the new green grant scheme is for England only, not Wales, as yet anyway).
    • CommentAuthorowlman
    • CommentTimeOct 24th 2020 edited
     
    <blockquote><cite>Posted By: WillInAberdeen</cite>Think it's like solar panels, they charge the price they think the market will bear. The A-W ashp market is mainly enthusiastic early adopters, often bringing many £k of subsidies and paying high prices, like the early days of the rooftop PV boom. This maybe deliberate policy to tempt more installers into the market.




    I think what you say Will, is true in part, and the subsidies that A2W attract, which A2A doesn't is skewing the market, and not for the greater good. Whoever decides these things, I believe, has in mind "Air Conditioning", which is the alternative name for A2A. This appears to carry with it a twisted mentality, of Summer cooling profligacy, within the powers that be, hence no subsidy, IMO. From my perspective, I may be wrong, we have a system which appears to subsidise inefficiency, compare COP figures, because of ill educated dogma.
    Any use of A2A/Aircon for Summer cooling, if at all, can be more than matched with PV production, after all you don't generally aircon cool when the Sun isn't shining, at least not usually in the UK.
    The heat-pump industry is also to blame, I feel, when many manufacturers and suppliers refer to heat-pump hardware as "Aircon Products". Although I have noticed a slight change in the last year or so. Maybe they read threads like this.
    Although I have the facility to cool with my heat-pump I've maybe only used it two or three times this year, and at times when my solar PV is producing in excess of 55kW. So the few kW being used by the heat-pump is negligible, still loads going into the grid.
    •  
      CommentAuthordjh
    • CommentTimeOct 24th 2020
     
    I just found this document: https://www.agas.com/media/8536/f-gas-guide8-final-emailer.pdf

    There's a bunch of marketing stuff. But it's interesting because it has info about the various refrigerants and when they were/will be banned :devil:
    • CommentAuthorowlman
    • CommentTimeOct 24th 2020
     
    I'm so glad I read the runes before I fitted my system, and opted for R32, although R410 was, and I think still is available.
    I felt Toshiba were ahead of the curve in this respect, which is why I opted for them. Most reputable manufacturers now offer a selection of R32 units.
    • CommentAuthorEd Davies
    • CommentTimeOct 24th 2020
     
    Posted By: owlmanAny use of A2A/Aircon for Summer cooling, if at all, can be more than matched with PV production, …
    Precisely. There's a lot of frothing about well-insulated air-tight houses overheating but if those houses use a bit of cheap PV-harvested energy in the summer for a bit of cooling rather than larger quantities of more-expensive gas-sourced energy in the winter for heating then it's a net win.
    •  
      CommentAuthordjh
    • CommentTimeOct 24th 2020 edited
     
    Posted By: owlmanI felt Toshiba were ahead of the curve in this respect, which is why I opted for them.

    Could well be. I did just happen to read a puff-piece by Daikin though that said they were the first to produce such units. Maybe Tosh were second? :devil:
    • CommentAuthorjms452
    • CommentTimeOct 24th 2020
     
    Posted By: Jeff B

    We do not have mains gas in our area so an alternative for us is simply to revert to an oil boiler based system and keep the wood pellet boiler as a back up/alternative system. With the assistance of my plumber brother-in-law I could install a new oil boiler and bunded tank for around £3K and pay a lot less for fuel too; but it seems criminal to do so when we are all trying to reduce our carbon footprint!


    Sounds like if your house is well insulated and you have a hot water tank you can put in an air to air heat pump inexpensively and heat the water off peak for less than an oil boiler.

    We had oil briefly and an ugly tank in the garden with risk of both leakage and theft not to mention having another thing to arrange when you run low wouldn't be something that I would install [again] and that's before you get onto the climate benefits.
  22.  
    Posted By: djh
    Posted By: Jeff BI came across this:
    https://ampair.co.uk/products/?product_types=ducted
    Is this the kind of thing you are looking for?

    Posted By: WillInAberdeenHow about https://www.orionairsales.co.uk/ducted-air-conditioning-28-c.asp ? Presumably they don't heat the air as hot as a direct electric heater does (to keep the CoP up) so you need to move more air?

    Thanks, chaps. They're getting towards what I had in mind. They're all the wrong form factor for what I have in mind - fitting into a circular duct, so would require some metal bashing to adapt. Most of them are too powerful as well, although there are a few lower power ones. The wall-mounted conventional indoor units look more attractive at this point, for features such as better controls, R32 and noise levels etc.


    Had a look through the Ampair site, there is a Panasonic S-15MF2E5A ducted unit that does 1.7kW heating. But the airflow is ~840m3/h which is way too much for a MHRV afaics, too much flow for small circular ducts or heat exchanger, and too many ac/h.

    The problem (for all such units) is they need to heat each m3 of air by only a few degC (to keep CoP high) so need many m3/h of air to carry all the kW of heat away. Not sure that any such unit could be built-in to a MHRV happily.

    You're probably right to look at an indoor unit separate from the MHRV, but it will heat just the one room, you'd need to think how the heat could be transferred round the house.

    Possibly one of the ducted units could be used with its own large-bore ducting system, separate from the MHRV, sucking from all the coldest rooms (bedrooms) and blowing heat into the warmer rooms (bathrooms, lounge)... The air circulation might conflict vs the MHRV tho.
    •  
      CommentAuthordjh
    • CommentTimeOct 24th 2020
     
    Posted By: WillInAberdeenThe problem (for all such units) is they need to heat each m3 of air by only a few degC (to keep CoP high) so need many m3/h of air to carry all the kW of heat away. Not sure that any such unit could be built-in to a MHRV happily.

    I suppose you're right :cry: With an 'electric' duct heater I can heat the air by 30@C or so and that works as long as my MVHR is set to my normal 125 m³/hr and works a bit more if I boost it to 165 m³/hr. But if an ASHP can't heat the air to just under 50°C then it will have a problem.

    You're probably right to look at an indoor unit separate from the MHRV, but it will heat just the one room, you'd need to think how the heat could be transferred round the house.

    I don't fret about that anywhere near as much now as I did before we built/lived in the house. It seems that as long as the heat gets into the house somewhere, things will sort themselves out. There are limits, of course!

    If I was willing to live with the outdoor unit outside the front of the house, then an indoor unit in the hall would do pretty well at distributing the heat I suspect.

    Possibly one of the ducted units could be used with its own large-bore ducting system, separate from the MHRV, sucking from all the coldest rooms (bedrooms) and blowing heat into the warmer rooms (bathrooms, lounge)... The air circulation might conflict vs the MHRV tho.

    Yes, you wouldn't really want the MVHR extracting from the wet rooms and the heating blowing into them at a high rate. I'm trying to remember what the hot-air system I had in my first house did. I think it might have sucked air in through a large vent in the hall straight into the 'furnace' and then blown it out in several places. That was before I was interested in houses and building design etc, so I forget.
    • CommentAuthorJeff B
    • CommentTimeOct 24th 2020
     
    Posted By: jms452
    Posted By: Jeff B

    We do not have mains gas in our area so an alternative for us is simply to revert to an oil boiler based system and keep the wood pellet boiler as a back up/alternative system. With the assistance of my plumber brother-in-law I could install a new oil boiler and bunded tank for around £3K and pay a lot less for fuel too; but it seems criminal to do so when we are all trying to reduce our carbon footprint!


    Sounds like if your house is well insulated and you have a hot water tank you can put in an air to air heat pump inexpensively and heat the water off peak for less than an oil boiler.

    We had oil briefly and an ugly tank in the garden with risk of both leakage and theft not to mention having another thing to arrange when you run low wouldn't be something that I would install [again] and that's before you get onto the climate benefits.


    Yes, it is well insulated and pretty well draught-proofed. I think I made a really bad decision to go down the biomass (wood pellet) route for various reasons which I have described at different times on this forum. As with heating oil, I still have to keep an eye on pellet level and reorder as/when necessary. It so happens I am lucky in that the bulk hopper we have holds 3000 kg which is exactly enough for one heating season (end of September to mid-May usually), so I empty it out completely by May and refill in August when the price should be low.

    With hindsight (long before I came across the GBF!) I should have improved the insulation first and then looked around for a replacement for the oil boiler. Obviously back in 2006 we did not know that the RHI scheme was coming so we were pioneers when we went for the wood pellet boiler.
    • CommentAuthorJeff B
    • CommentTimeOct 25th 2020
     
    djh - I am confused about air-to-air in as much as would I need an indoor fan unit in every room? If so, then the whole idea is a non-starter as there are 11 rooms including designating the hallway and large landing as 2 "rooms". Maybe air-to-air is better suited to an open plan type house whereby warm air will find its way around? I could of course leave doors open to achieve the same effect but with bathrooms and bedrooms that could be a bit tricky from a modesty point of view could it not!?

    Our friend has just the one unit in his hallway which heats the hall, stairwell, kitchen and lounge. If I had a unit in my hallway I would have to have the external unit at the front of the house which would not be allowed under permitted development regs in Wales, or, install extremely long runs of pipework up to/through/across the attic from an external unit at the rear of the house which would be ok aesthetically as well as complying with permitted development. The same would apply to the other 3 rooms at the front of the house. We are in a dormer bungalow so installation of pipework which enters at the back of the bungalow and feeds indoor units at the front will be an interesting exercise!
    •  
      CommentAuthordjh
    • CommentTimeOct 25th 2020
     
    Posted By: Jeff BI am confused about air-to-air in as much as would I need an indoor fan unit in every room?

    Dunno. I have no experience with split units (except on holiday) and much will depend on the arrangement of your house. You could try heating it with a radiant electric heater or three (or whatever) to get some idea of what you might need. Or turn some radiators off etc.
    • CommentAuthorJeff B
    • CommentTimeOct 25th 2020
     
    Posted By: djh
    Posted By: Jeff BI am confused about air-to-air in as much as would I need an indoor fan unit in every room?

    Dunno. I have no experience with split units (except on holiday) and much will depend on the arrangement of your house. You could try heating it with a radiant electric heater or three (or whatever) to get some idea of what you might need. Or turn some radiators off etc.


    I have indeed tried that! Putting on a fan heater (3kW) on the landing heats the entire upstairs (all doors open) comfortably in about 30 minutes raising the temperature from about 19C to 23C. This was done recently in the early evening when the outside temperature was 9C. Once warmed the rooms maintain their temperature for at least one hour. I know I need to monitor for longer but I am confident with the amount of IWI in there the temperature will be held for quite a while! The upstairs temperature is normally 19 or 20C with no radiators on as the heat rising from the ground floor is sufficient.
    •  
      CommentAuthordjh
    • CommentTimeOct 25th 2020
     
    Sounds like your upstairs is sorted then. Just need to figure out what is needed to heat the downstairs.
    • CommentAuthorJeff B
    • CommentTimeOct 25th 2020
     
    Posted By: djhSounds like your upstairs is sorted then. Just need to figure out what is needed to heat the downstairs.


    Will try a similar experiment downstairs. Being on lockdown for 2 weeks, it'll keep me occupied for some of the time!
    • CommentAuthorowlman
    • CommentTimeOct 26th 2020
     
    For Jeff B; Refrigerant pipes can be run for quite long distances but they can vary slightly between manufacturers, so it may be worth throwing that into the mix if/when you select a unit. I would guess though, the shorter the better.
    Personally I wouldn't try and put in one massive outdoor unit running too many indoor units.
    Rather go for e.g. 2 x 2 smaller splits. This would also fit in with a "suck it and see" approach. You could for instance first try a two split centrally located in the downstairs, back to back through a wall would be ideal as they could share service routing.
    You'll need four services; power, refrigerant flow and return, condensate drain, and possibly central stat control. All this stuff can be reasonably easy to route, and good quality neoprene insulation is readily available, as is exterior trunking for neatly hiding pipework etc

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