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Heating and cooling: Why are we not allowed to talk about heat pumps?

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    • CommentAuthorCWatters
    • CommentTimeFeb 4th 2009 edited
     
    I think ASHP have great potential but oil boilers are not as bad as Mark tries to make out..

    Mark posted.

    • Oil boilers do not modulate as some fuels do. (This means if the boiler is set at 50,000 btu’s it produces it with all the oil pouring in until it reaches temperature, this has the effect of peaks in usage).


    It's true that domestic oil boilers don't modulate and that this can cause boiler cycling but if correctly sized this is minimal and a thermal store can eliminate the problem totally.


    • Oil fired combi boilers in the main are working 24 / 7 to heat the hot water store which allows the user to have hot water at any time, even at night which is a wasteful use of oil.


    Huh? Haven't you heard of time clocks? I guess not, neither have I so perhaps I should point out that ... ASHP boilers in the main are working 24 / 7 to heat the hot water store which allows the user to have hot water at any time, even at night which is a wasteful use of electricity.


    • Oil boilers are like cars if you run them at a low temperature it’s like having the choke out and they need regular service to check burner and baffles.


    At least it's easy to find a service engineer familiar with oil boilers locally.


    • Oil boilers are connected to oil tanks, these can be problematic and again maintenance is a must as a leak can cause all sort of problems for the environment.


    ASHP are connected to Nuclear power stations.. a leak can cause all sort of problems for the environment. Old single skin oil tanks should be replaced by twin wall bunded tanks.


    • I have mentioned baffles as most oil boilers with faulty baffles are down on efficiency which the user would not pick up on until a service is undertaken.


    True but how frequently do baffles actually become faulty?


    • Oil boilers have burners which draw air from the room they are fitted in and this can draw in debris. It can cause problems; if the burners have nozzles with debris in then the oil pump will continue to push oil at high pressure through the nozzle which can reduce the efficiency. This pattern or spread that the manufactures designed the boiler with can reduce efficiency if any slight deviation is present.


    Most oil boilers installed these days (in the UK at least) have balanced flues which don't draw air from the room.

    ASHP systems produce more CO and cost more to run than mains gas according to..
    http://www.nottenergy.com/energy-costs-comparison3
  2.  
    Hi,
    For my tuppence worth anything that does not consume solely 100% green produced electricity can not claim to be helping or should state it can make contribution but no more, and that probably dams 99% of us. I think some advertisers have been held up for the false claims of "greenness" and cost savings.
    I have looked into ASHP and am certainly not an expert.

    Cheers, Mike up North
  3.  
    ASHP are useful, however only in well to superinsulated homes, where the heating demand is very low. At COP 1.5 to 2 you are still better than resistance heating. And in the depths of winter they may only provide partial heating with resistance heating topping up.

    If the home is not well insulated/air-tight then they are not the best choice if natural gas is around and even oil. Servicing of boilers and capital cost has to factored in as well, which may swing the balance to an ASHP.

    They have a place, but it has to be carefully calculated to feasibility.

    If there is a natural gas pipe adjacent, it is hard to justify using any other form of heating on running and capital cost grounds.
    •  
      CommentAuthoragu
    • CommentTimeFeb 4th 2009
     
    Wow interesting discussion, would it be possible for me to get the figures backed up by the Uni please, I would be interested in having a little look.

    I have to say I thought Paul from Canada would be in on this one as most of the houses over there have ASHP ( at least i think that's what he said) and I am assuming it is generally colder there than here. I think i would agree with Water systems that if you are building air tight then they would be a good option but on a renovation etc unless you are focusing on airtightness ( which I think you should but am sure most don't) then they would probably struggle, however I think ( as i know a lot do here ) that buildings should always have insulation and air tightness as the main starting points. Also I would suggest that's true for GSHP too.
  5.  
    Oil Boilers:
    These tend not to cycle that much as they have high water content heat exchangers. The mass of water reduces cycling. Modern gas boiler have little water content and require the pcb to reduce cycling when connected directly to a radiator loop - still cycling can be an inefficient nuisance. Thermal store with two anti-cycle stats prevent boiler cycling. In effect the thermal store is an extension of the boilers heat exchanger. Old large cast-iron boilers rarely cycled because of the thermal mass of the iron and water.

    I would welcome a boiler where the heat exchanger is the thermal store (the ACV HeatMaster is like this) and the pcb prevents boiler cycling. Look inside most boiler cases and it is mainly air. A square thermal store neatly fitted in taking up all space with an integral burner would be a winner. The DHW and CH could be taken off the store as per usual. But I am dreaming.
  6.  
    Posted By: agu I think i would agree with Water systems that if you are building air tight then they would be a good option but on a renovation etc unless you are focusing on airtightness ( which I think you should but am sure most don't) then they would probably struggle, however I think ( as i know a lot do here ) that buildings should always have insulation and air tightness as the main starting points. Also I would suggest that's true for GSHP too.


    In a UK climate, the more insulated and air-tight and do not forget passive solar orientation, the high capital cost heating systems are dropped from the equation. And the likes of GSHP can be horrendous in capital cost. In short, spend the money on insulation not machines. We live in a society that thinks machines can solve all problems. Machines can enhance and must not be the basic core.
  7.  
    <blockquote><cite>Posted By: CWatters</cite><blockquote><cite>Posted By: bot de paille</cite>While millions of people tap into Google without considering the environment, a typical search generates about 7g of CO2 Boiling a kettle generates about 15g.</blockquote>

    Very unfair to pick on Google though. What they fail to mention is the amount of CO that would be produced if we didn't have the internet to help us.</blockquote>

    I didnt pick on Google

    "A recent report by Gartner, the industry analysts, said the global IT industry generated as much greenhouse gas as the world’s airlines - about 2% of global CO2 emissions. “Data centres are among the most energy-intensive facilities imaginable,” said Evan Mills, a scientist at the Lawrence Berkeley National Laboratory in California. Banks of servers storing billions of web pages require power."
  8.  
    A lot of companies are relocating data centres to Canada - the power is cheap and the climate is cooler than California so that A/C requirements are reduced. For instance, the largest collection of servers for the on-line gambling industry is in the Native reserve of Kahnawake just outside of Montreal and therefore has access to pretty much the cheapest and greenest (in strict CO2 emission terms) electricity on the continent.

    Of course one thing that's missing in those statistics is that in former times companies would have their own large data centres - these are now being outsourced into server farms (e.g. "Cloud" computers) so it's somewhat disingenuous to concentrate on the data centres. In the old days industries used heavy machines (which also consumed a lot of energy) and now they use datacentres.

    Paul in Montreal.
  9.  
    It is an interesting discussion but where it gets confusing to me is the concern for being green on the hand and then saying gas is better because it costs less.

    Is is me or is this not a bit confused? In an ideal world you would have both the greenest and cheapest solution but if we are talking about green solutions then you are making a choice that might have to cost more than the other alternatives.

    I have a GSHP and I buy my electricity to run it from a green energy supplier, whats the problem?
  10.  
    Posted By: aguI have to say I thought Paul from Canada would be in on this one as most of the houses over there have ASHP ( at least i think that's what he said) and I am assuming it is generally colder there than here.


    I don't think I said most houses have them, but a lot certainly do. It is generally a lot colder in winter but a lot hotter in summer so the main advantage of an ASHP is that it can do both heating and air conditioning. A lot of people have A/C and use regular gas or oil furnaces or boilers (less common) for heating. In the colder areas often a heatpump is configured as a dual-fuel setup - the heatpump provides the bulk of the heat down to some temperature and then the fossil fuel device takes over - there's even differential electricity rates that switch over based on an outdoor temperature sensor for these setups.

    Like all heating systems, the more insulation and the better the air tightness you have, the smaller the system that can be installed and hence the cheaper it is. There's nothing particular about ASHP and GSHP systems here except that they tend not to be so massively oversized as fossil-fuel based systems - plus overhere intermittent heating is not so common as it is in more moderate climates.

    Paul in Montreal.
  11.  
    Of course one thing that's missing in those statistics is that in former times companies would have their own large data centres - these are now being outsourced into server farms (e.g. "Cloud" computers) so it's somewhat disingenuous to concentrate on the data centres. In the old days industries used heavy machines (which also consumed a lot of energy) and now they use datacentres.

    Paul in Montreal.</blockquote>

    http://www.datacentremanagement.com/power-management-news-79/780-energy-consumption-rising.html
    Thursday, 06 November 2008 00:00

    The research shows how the amount of energy required by servers and datacenters is climbing at a worrying speed, and has grown annually by more than 13% between 2006 and 2007.


    In 2007, servers in Western Europe consumed more than 16.3TWh, which is almost twice the amount of electricity needed every year to power all street lighting and traffic signals in the U.K. At a datacenter level, IDC estimates the consumption levels in Western Europe to have exceeded 40TWh in 2007 and this is expected to grow to more than 42TWh in 2008.

    Nathaniel Martinez, program director, European Enterprise Servers. "Unless a drastic change in products and company practices occurs, things will not get any better in the future. In 2012, we could face a scenario where for every euro spent on buying new servers, more than €0.80 will be needed to power the existing datacenter infrastructure."
    • CommentAuthorMiked2714
    • CommentTimeFeb 4th 2009
     
    Posted By: Water SystemsASHP are useful, however only in well to superinsulated homes, where the heating demand is very low. At COP 1.5 to 2 you are still better than resistance heating. And in the depths of winter they may only provide partial heating with resistance heating topping up.

    If the home is not well insulated/air-tight then they are not the best choice if natural gas is around and even oil. Servicing of boilers and capital cost has to factored in as well, which may swing the balance to an ASHP.

    They have a place, but it has to be carefully calculated to feasibility.

    If there is a natural gas pipe adjacent, it is hard to justify using any other form of heating on running and capital cost grounds.


    Agree entirely. Furthermore the use of UFH would stack in their favour.

    Personally I get a bit het up with numerous intelligent people I bump into asking me should they be REPLACING THEIR EXISTING MAINS GAS BOILER with an ASHP in their EXISTING RADIATOR HEATED HOUSE. Expecting it to dramatically reduce their fuel bills. The marketing has gone too far! The house being followed on "It's not easy being green" is another example.

    When the situation is how best to heat new well insulated houses off mains gas then the answer is different.

    ASHP + MVHR (e.g. Genvex) is another interesting concept, although the reports have been that the units are very expensive.

    Mark: I also found your description rather too full of marketing-speak, but the whole product is sufficiently interesting and some good points have been raised.
  13.  
    Posted By: bot de pailleIt is an interesting discussion but where it gets confusing to me is the concern for being green on the hand and then saying gas is better because it costs less.


    A gas condensing boiler is around COP 0.9 at point of burn. Natural gas is very clean compared to other sources of energy. It also has few line losses - some pumps to pump the gas - it is burnt at point of use. From one end to the end user it is very efficient and very clean. It is also very cheap to run too to others.

    A GSHP is horrendously expensive to install to a natural gas boiler installation and costs about the same to run if it is a good system. No contest the natural gas boiler wins.

    Now it is crystal ball gazing time. Is gas going to remain cheaper per kW than electricity? Fit a thermal store ready for a heat pump and capital costs are down on changeover.

    If a natural gas pipe is run into your home, use it and spend money aimed at a GSHP money on extra insulation and air-tightness.

    If no gas pipe then the equation is very different indeed. A friend has a stream on his land. The neighbours say the stream has never ran dry as long as anyone can remember and last year it broke its banks.

    His oil boiler need replacing soon and the oil bills are horrendous. I have suggested a heat pump extract heat from the stream. The capital cost my frighten him away. But he will gain more room if the boiler is removed.
  14.  
    Sorry if my attempt was a little to full of marketing speak. Many points i'm picking up from you all about it and a lot more research needs to go into the final draft so many thanks for all you comments as this is very interesting seeing this.

    I agree with everybody saying that houses need to be more insulated. Heating systems could then have lower outputs so our system for example would not work as hard in achieving the set back requirtments. And in reference to one of your comments it is cheaper to keep a house warm then it is to let it go totally cold. You would then be having to heat many degrees up to be comfortable, that would make the heat source work harder???
    Plus our system can be molded to your own preference. I'm comfortable at 18 to 20 degrees but if ya fat you might like it lower as you are well insulated or higher if you are a skinny rake with no fat on ya???

    If we insulate our homes to the building regulations and the new code of sustainable level our heating systems will not have to work so hard to maintain the temperatures thus using less CO2 to generate the heat. There is still a major housing shortage in this country and it is just getting worse, if we have to follow this new code for new builds we have to figure out where the source of heat is going to come from. Oil and Gas is a fossil fuel and is scarce in some areas. There is talk that there will be no gas connections to new build homes by 2012 onwards so we need to find an answer. If we like it or not in this country the governement will push there offices to provide homes with low CO2 emmisions because if they don't meet there targets set by the Kyoto agreement then they will be fined. They will then pass on these fines to the local authorities who will then have to cough up the money. THe only people that will be building in the next few years will be the housing associations as the private market is shit and the code of sustainable homes is what they will have to follow. BY the time the new SAP software has arrived it will be out of date as technology will have advanced faster. It won't be long before the ashp, cylinder and controls we have designed will be copied by another and shrunk into a box where your combi used to be.

    Anyway got to get on with some work. Be back later.

    Mark
    • CommentAuthorModerator
    • CommentTimeFeb 4th 2009
     
    This is creating a lot of reading work for the moderator.

    The forum rules, that everyone agrees to be bound by when they join need to be followed. So, Mark Painter, I'm afraid this is your last warning to desist from your promo please.
  16.  
    ok no worries

    Mark
    • CommentAuthordelboy
    • CommentTimeFeb 4th 2009
     
    Mark do you believe in SAP?

    I have recently performed some calcs on a semi with this thermal envelope:

    U-values Wall 0.24, roof 0.13, floor 0.15, glazing 1.5, doors 2.
    Infiltration @ 50 pascales: 5, thermal bridging: psi = 0.08

    One simulation uses a gas boiler at a paltry 86% efficiency, and the other uses an ASHP at 250%. Both have 150l water cylinders, with the ASHP having immersion top-up.

    The annual space heating requirement for the ASHP is 1209.88KWh, which if you take the renewables grid CO2 saved figure of 0.568kgCO2/kwh, then the ASHP emits 687.21kg in space heating. (If you use the 0.42 figure for CO2/kwh, this comes down to 508.15kg)
    The heating requirement per annum for gas 86% is 3153.99, which at 0.194kgCO2/kwh comes out at 611.87kg.

    For hot water, the energy used for the ASHP is 2013.8kwh (an immersion is required as top up), which gives 1143.84kgCO2/year (or 845.8kg if you use the lower figure).
    For the gas, the energy is 3269.15kwh which emits 634.22kg/annum.

    Totals:
    ASHP @ 0.568kgCO2/kwh / year: 1,831.05
    ASHP @ 0.42kgCO2/kwh / year: 1,354
    86% gas @ 0.194kgCO2/kwh / year: 1,246.09

    So according to SAP ASHPs DO emit more CO2 than conventional systems.

    Does SAP do ASHPs justice when it comes to water heating? I don't fully know how it works this out (beyond it applying a factor of 0.7 to the efficiency) and perhaps it doesn't do the kit justice. For space heating, perhaps it is a runner, although the grid is already overburdened and I'm not sure if it needs a new generation of juice-suckers coming.

    Finally, I do know that SAP is not the best way to do these calcs, but I also reckon it's in the right ball park when it gives ASHPs a bad result. Now we just need to sort ENE1 out...
  18.  
    Totally agree my friend who is a sap officer stated that the software he has only allows for the heat pump which would achieve level 3 of the code if the u values of the property are at the current requirements. We have a cylinder and controls that all works in conjuction with it but the software has no entry for this so this is why the software needs updating. Not promoing just answering to Delboy:tongue:
    • CommentAuthorSimonH
    • CommentTimeFeb 4th 2009 edited
     
    Posted By: Paul in Montreal

    A lot of people have A/C and use regular gas or oil furnaces or boilers (less common) for heating. In the colder areas often a heatpump is configured as a dual-fuel setup - the heatpump provides the bulk of the heat down to some temperature and then the fossil fuel device takes over - there's even differential electricity rates that switch over based on an outdoor temperature sensor for these setups.
    Paul in Montreal.


    Paul - do you know who makes the controllers for this type of setup - I came to the conclusion I needed something like this too. ASHP down to 5 degrees and keep my old 80% efficient fan assisted gas boiler with auto ignition for when it's below 5 degrees. It means keeping a spreadsheet of energy prices / carbon mix to decide what to set on the controller, but not too difficult to work out.

    Simon
  20.  
    Simon, you need a staged thermostat. There are many that will deal with multi-stage heating where you can program the switch-over point (with an external temperature sensor). The multi-stages could be different compressor output levels with an additional "stage" of auxiliary resistance heating - or maybe one stage could be the different fuel in a dual-fuel setup.

    See for example http://www.smarthome.com/30412/7-Day-Programmable-Thermostat-Dual-Fuel/p.aspx

    Paul in Montreal.
    • CommentAuthorJulian
    • CommentTimeFeb 5th 2009
     
    Posted By: Mark PainterSorry if my attempt was a little to full of marketing speak. Many points i'm picking up from you all about it and a lot more research needs to go into the final draft so many thanks for all you comments as this is very interesting seeing this.
    Mark

    I think you definitely need to do a bit more research Mark.

    Posted By: Mark Painter if we have to follow this new code for new builds we have to figure out where the source of heat is going to come from. Mark

    Maybe I need to do more research as well. I thought that improving the thermal performance of the building would mean less requirement for heating?

    Posted By: Mark Painter Oil and Gas is a fossil fuel and is scarce in some areas.

    Certainly fossil fuels are finite resources and may not be uniformly distributed across the planet unlike...er...electricity.
    • CommentAuthorjon
    • CommentTimeFeb 5th 2009
     
    "Why are we not allowed to talk about heat pumps?"

    Perhaps because they are pointless carbon-wise except in low carbon generation generation areas (such as those that have a high Nuclear and Hydro proportion) and this is largely a UK forum?
    • CommentAuthorralphd
    • CommentTimeFeb 5th 2009
     
    Posted By: jon"Why are we not allowed to talk about heat pumps?"

    Perhaps because they are pointless carbon-wise except in low carbon generation generation areas (such as those that have a high Nuclear and Hydro proportion) and this is largely a UK forum?


    But green building isn't all about low carbon. If it were, we all should move to temperate climates where heating and cooling is not needed.

    In fact I'm into green building for it's low cash impact, not for low carbon impact.

    -Ralph
    • CommentAuthorjon
    • CommentTimeFeb 5th 2009
     
    What is green building for Ralph?
    • CommentAuthorralphd
    • CommentTimeFeb 5th 2009
     
    Posted By: jonWhat is green building for Ralph?

    A healthy and comfortable indoor environment, along with energy efficiency.
    A low environmental impact is important, but not more important than low cost.

    For example I like to build myself; yesterday I was nailing sheets of OSB on the roof of the indoor pool I'm building as an addition to my house. I save money vs. hiring a framing crew, I walk to the job site vs. a framers that tend to drive big gas-guzzling trucks so it's easier on the environment, and it is good excercise (vs. typing on a keyboard) so it's healthy for me (as long as I don't fall off the roof!).

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