Air to Water Heat Pumps

Katienewbuild

hi all
Thanks again for all the help. Its great!!. However, i must apologise to my architect!!! he actually recommended AIr to water as main heat system, somewhere along the line i got completely confused with all these systems!!! anyways, here we are......Air to water...not MHRV!!!! woops!!!

if any of u have information about this...let me know!!!!

Tomo87

Katienewbuild wrote: »

hi all
Thanks again for all the help. Its great!!. However, i must apologise to my architect!!! he actually recommended AIr to water as main heat system, somewhere along the line i got completely confused with all these systems!!! anyways, here we are......Air to water...not MHRV!!!! woops!!!

if any of u have information about this...let me know!!!!

A2W works well especially if your planning underfloor heating. Lots of products out there at mo but you should be looking for one that has a DC inverter meaning it starts up slowly rather than drawing a lot of electricity at the beginning, make sure you get quoted for one that's adequately sized to heat your house without help of electric booster heaters as they will hurt your pocket! Also avoid units that use electric elements for defrost cycle.

tred

Tomo87 wrote: »

A2W works well especially if your planning underfloor heating. Lots of products out there at mo but you should be looking for one that has a DC inverter meaning it starts up slowly rather than drawing a lot of electricity at the beginning, make sure you get quoted for one that's adequately sized to heat your house without help of electric booster heaters as they will hurt your pocket! Also avoid units that use electric elements for defrost cycle.

Nibe Air to heat system is heating radiators in my buddys timber frame house in gottenberg sweden. So it works there as well

fclauson

Comparing us to sweden not fair

1 - they get colder than we do
2 - they get warmer than we do
3 - they get dryer than we do
and most importantly
4 - they get C02 free electriciy - its typically all hydro

Condenser

Tomo87 wrote: »

A2W works well especially if your planning underfloor heating. Lots of products out there at mo but you should be looking for one that has a DC inverter meaning it starts up slowly rather than drawing a lot of electricity at the beginning, make sure you get quoted for one that's adequately sized to heat your house without help of electric booster heaters as they will hurt your pocket! Also avoid units that use electric elements for defrost cycle.

There are no DC invertor units on the market without immersions. The two main players that manufacture them both have at least 6kw of back up immersions and one of them have 2 6kw immersion in their larger size units.

The main reason for an invertor is to match the heatload required by the house throughout the year, not to keep electrical draw on the compressor low on start up. In the greater scheme of things the electricity consumed at that point is not even an issue.

The unit would need to be oversized by at least 25% for the heatload of your house as the efficiency drops 3% with every degree the outside temp drops. When it gets down below -10 you'll have a COP of about 2.

For what its worth, I disagree with your architect. You should always try to go groundsource before you go air source. The yearly bills are far more predictable.Air source may seem like a cheaper option, but your bills will be higher and your lifetime will be about half of what a groundsource would be.

tred

fclauson wrote: »

Comparing us to sweden not fair

1 - they get colder than we do
2 - they get warmer than we do
3 - they get dryer than we do
and most importantly
4 - they get C02 free electriciy - its typically all hydro

45 percent of swedish electricity is nuclear and he read out his bill to me, it aint free and it aint cheap. Fixed charge monthly. I just threw it out there so people dont discount, and its a possiblity maybe retrofitting. Not sure now if the rads he has are aluminium or standard.

Troy McClure

Condenser wrote: »

For what its worth, I disagree with your architect. You should always try to go groundsource before you go air source. The yearly bills are far more predictable.Air source may seem like a cheaper option, but your bills will be higher and your lifetime will be about half of what a groundsource would be.

Condenser are there other reason why you would go ground source as I have heard others say air source is better. Also I have been talking to some company's and they more expensive ones of course say others dont have the expertise to install ufh and hp et al and have it run properly and efficiently. That, and the line 'these new start up will be out of business next year' anyway etc.
If you know any good companies you would recommend please PM me. Thanks

Condenser

Troy McClure wrote: »

Condenser are there other reason why you would go ground source as I have heard others say air source is better. Also I have been talking to some company's and they more expensive ones of course say others dont have the expertise to install ufh and hp et al and have it run properly and efficiently. That, and the line 'these new start up will be out of business next year' anyway etc.
If you know any good companies you would recommend please PM me. Thanks

The air source units that are causing such a stir in the market due to their pricing are merely modified Air Conditioning units. They were not designed as heat pumps from the ground up and as such have alot of design faults which leads to poor performance in harsh weather such as being unable to defrost efficiently. They also come with pretty poor controls as standard and even upgrading them to a decent level the outcome is not very satisfactory. They're cheap because they're cheap to buy for the installer, cheap to fit and don't last very long. You'll see heavy corrosion on most of these machines within 6-7 years.

There are good Air to water units on the market that were designed as heat pumps from day one but these will cost as much if not more than a groundsource unit. Its for this reason and the fact that there are more parts than can fail in an airsource unit (and the fact that they will be far more efficient)that I say groundsource should be your first option, borehole after that and then air if the others aren't an option.

spillcoe

I'm looking at the possibility of installing an Air to Water Heat system as well, the other option is a combination of solar panels and oil boiler. I've been given rough figures stating that the ATW would be about 1000 Euro more expensive to install with an annual saving of 650. Seems a no-brainer on the face of it. Ground source is not an option because of the higher initial cost.

Would be interested in a few more opioions on how reliable the ATW systems are and does anyone know how well it would work combined with a 30KW stove with back boiler? Given the fact that I will be using rads and not underfloor is it still worth my while going with the ATW?

So many questions..........

Condenser

spillcoe wrote: »

I'm looking at the possibility of installing an Air to Water Heat system as well, the other option is a combination of solar panels and oil boiler. I've been given rough figures stating that the ATW would be about 1000 Euro more expensive to install with an annual saving of 650. Seems a no-brainer on the face of it. Ground source is not an option because of the higher initial cost.

Would be interested in a few more opioions on how reliable the ATW systems are and does anyone know how well it would work combined with a 30KW stove with back boiler? Given the fact that I will be using rads and not underfloor is it still worth my while going with the ATW?

So many questions..........

Who gave you the figure of €650 a year savings and what did they base it on. Heat pumps are not suited to radiators and should not be married to them. The temperature they require is too high, your COP will be very poor and the extended times running at high temperature will shorten the life of the heat pump. I'd stick to oil and solar panels if you are going to use rads. You'll make next to no savings.

BryanF

Its scary how many people are talking about installing, air to water heat pumps!
I agree with you condenser, there glorified AC. It's like re-marketing coal as a green technology:D

I'm absolutely disgusted at BER assessors and even some Architects are recommending them! it just shows there are huge education gaps in the industry.

I can see the benefit of using them for example if you were in a studio apartment and could not get anything better sorted other than an electric storage rad.. I'd probably go for the storage rad:D

therightangle

It would be good to also hear some positives about the air to water here. I would have thought that the GSHP is a risker venture, one big risk being the reliance on the salesperson/installer to know your soil suitability. Ive heard of a monthly ESB bill that ran into 4 figures with GSHP.
The extra kit involved, ie the collector in the garden, could possibly be another item to go wrong.

As houses are becoming more energy efficient and airtight, with less heating costs in general, I wonder will any high up-front cost heat pump find it hard to get a good payback.

BryanF

therightangle wrote: »

It would be good to also hear some positives about the air to water here. I would have thought that the GSHP is a risker venture, one big risk being the reliance on the salesperson/installer to know your soil suitability. Ive heard of a monthly ESB bill that ran into 4 figures with GSHP.
The extra kit involved, ie the collector in the garden, could possibly be another item to go wrong.

As houses are becoming more energy efficient and airtight, with less heating costs in general, I wonder will any high up-front cost heat pump find it hard to get a good payback.

Positives: there are other options to heat pumps...

you answered your own question: airtightness, good insulation and good windows etc, can reduce your energy costs to next to nothing. for get the heat pumps and build properly.

therightangle

I'm absolutely disgusted at BER assessors and even some Architects are recommending them! it just shows there are huge education gaps in the industry.

BryanF wrote: »

for get the heat pumps and build properly.

I think we know by now your "educated" opinion on heat pumps. If you are that biased, can you share your negative experiences of them?

I would ask what renewable alternatives you would recommend, but this is meant to be a discussion on heat pumps, if thats okay with you.

BryanF

therightangle wrote: »

I think we know by now your "educated" opinion on heat pumps. If you are that biased, can you share your negative experiences of them?

I would ask what renewable alternatives you would recommend, but this is meant to be a discussion on heat pumps, if thats okay with you.

I think we know by now my "personal" opinion particularly of ASHP's! its their short lifespan, electricity consumption, problems in cold weather. just not convinced of their title as 'renewable'..

BryanF

one recent study states "12% less carbon that an equivalent condensing gas boiler system, but was around 10% more expensive to run." http://www.mendeley.com/research/analysis-of-retrofit-air-source-heat-pump-performance-results-from-detailed-simulations-and-comparison-to-field-trial-data/ I understand grants for ASHP'sare currently on hold in the UK... are ASHP's really 'renewable'?

Condenser

Heat pumps are by far the cheapest way to heat your house regardless of insulation levels once the application is right (i.e a low temperature distribution system) and the installation correct.

Rightangle, regarding this statement "I would have thought that the GSHP is a risker venture, one big risk being the reliance on the salesperson/installer to know your soil suitability. Ive heard of a monthly ESB bill that ran into 4 figures with GSHP."
Do you honestly think that a company who does not know how to properly install a GSHP will someone know how to install an airsource? And believe me, the GSHP's that are underperforming around the country have very little to do with the collector area and all to do with the indoor installation. Out of every poorly performing heat pump out there I'd hazard a guess that less than one in one hundred of them is due to poor collector conditions or design.

A properly installed GSHP will out perform a properly installed ASHP by at least 50% and generally more.

therightangle

Condenser wrote: »

Heat pumps are by far the cheapest way to heat your house regardless of insulation levels once the application is right (i.e a low temperature distribution system) and the installation correct.

Do you honestly think that a company who does not know how to properly install a GSHP will someone know how to install an airsource?

Honestly, yes Out of every poorly performing heat pump out there I'd hazard a guess that less than one in one hundred of them is due to poor collector conditions or design.

A properly installed GSHP will out perform a properly installed ASHP by at least 50% and generally more.

I think the renewables survey poll here on boards indicates that the ASHP is far more popular than the GSHP. I havent heard any negatives yet about the ASHP over the last 2 hard winters, when I expected I would have.

I have no preference for either, only that the extra cost that I see in the GSHP makes the payback longer in better and better insulated homes.

And regarding getting the soil aspect of the GSHP right, if this is a very rare problem, then what do you see as the main contributor to heat pump problems/issues?

Condenser

therightangle wrote: »

I think the renewables survey poll here on boards indicates that the ASHP is far more popular than the GSHP. I havent heard any negatives yet about the ASHP over the last 2 hard winters, when I expected I would have.

I have no preference for either, only that the extra cost that I see in the GSHP makes the payback longer in better and better insulated homes.

And regarding getting the soil aspect of the GSHP right, if this is a very rare problem, then what do you see as the main contributor to heat pump problems/issues?

The problem with HP installations rarely lies in the garden. The problems mostly lie in poor installation practices such as installing thermostats without installing a buffer cylinder, undersizing pipework and having poor flow rates through the heat pump, undersizing the heat pump and falling back on immersion back up to attain the room temp required, poorly designed ufh systems that require too high a temp, wrong application i.e heating rads, not seperating the heating and hot water circuits so running to too high a temp constantly.

There are far more problems caused with heat pumps on the heating side than there ever is on the cooling side.
I'd also disagree with your view that ASHP's are more reliable and less problematic than ASHP. ASHP's do go wrong more than GSHP's and have far more things that can go wrong and that I can guarantee you as I deal with HP's on a daily basis.

galwaytt

Condenser wrote: »

I'd also disagree with your view that ASHP's are more reliable and less problematic than ASHP. ASHP's do go wrong more than GSHP's and have far more things that can go wrong and that I can guarantee you as I deal with HP's on a daily basis.

Confused ? I know am now

ASHP's are more reliable and less problematic than.. ASHP's ??




On a lighter note: doesn't this just show the state of confusion on the whole subject ??

creedp

galwaytt wrote: »

Confused ? I know am now

ASHP's are more reliable and less problematic than.. ASHP's ??




On a lighter note: doesn't this just show the state of confusion on the whole subject ??

To be fair if you were being objective on this topic you would realise it's a typo but obviously .........

Juantorena

We have an ASHP - not a major name so probably a cheapo one. Coming up to two years installed.

Happy with it. 241sqm two story, ufh on ground floor only. No solar. Heats water fine. Heating needs some tweaking on the control side but still ok. First year in (Nov - Oct) all elec bill was around €2k. Hoping for a little lower this year.

Reliability - remains to be seen.

galwaytt

creedp wrote: »

To be fair if you were being objective on this topic you would realise it's a typo but obviously .........

To be fair, if you were being objective, you would acknowledge that, the content not withstanding, the quote was indicative of the confusion out there in the populace on the subject....I even said so.

And, having built houses fitted with both ASHP and GSHP system's, I think I may be more objective than you're giving me credit for.......

Condenser

galwaytt wrote: »

To be fair, if you were being objective, you would acknowledge that, the content not withstanding, the quote was indicative of the confusion out there in the populace on the subject....I even said so.

And, having built houses fitted with both ASHP and GSHP system's, I think I may be more objective than you're giving me credit for.......

So a one letter typo is indicative of the confusion surrounding heat pumps? Thats a new angle.

Surely anyone reading the rest of the text and with a modicum of intelligence could decipher the general point of the post.

BryanF

Juantorena wrote: »

We have an ASHP - not a major name so probably a cheapo one. Coming up to two years installed.

Happy with it. 241sqm two story, ufh on ground floor only. No solar. Heats water fine. Heating needs some tweaking on the control side but still ok. First year in (Nov - Oct) all elec bill was around €2k. Hoping for a little lower this year.

Reliability - remains to be seen.

can you clarify how much of this is related to your normal energy consumption and how much is ASHP. thanks

creedp

galwaytt wrote: »

To be fair, if you were being objective, you would acknowledge that, the content not withstanding, the quote was indicative of the confusion out there in the populace on the subject....I even said so.

And, having built houses fitted with both ASHP and GSHP system's, I think I may be more objective than you're giving me credit for.......

Well Galwaytt you can argue with semantics all you wish but the point remains that you deliberately picked on an obvious typo and used this to further your own personal vendatta against heat pumps.

On the issue of objectivity I am installing a heat pump and therefore obviously are positively disposed to them. My hand are up!! However, you won't find me posting on here badmouthing other heating systems. I have no difficulty with oil/gas/wood pellet/SP/etc but decided that I wanted a heat pump. While it may be more expensive to install now, IMHO it will not be any or at least much more expensive in the long term. Btw not everyone decides everything on whether it will be cheaper over a 15 year time span. Im sure another prominent anti HP poster (name beginning with H and ending with d) will call me and everyone else who opts for HPs an idiot for doing so but in my view its a matter of personal choice. What if its a little more expensive! I also opted for natural slate; granite cills; aluclad windows; etc. What is their payback period? Im obviously an idiot because there are plenty cheaper and equally effective alternatives out there and I ignored them. I didn't want a smelly oil tank nor didn't want an oil truck tearing up my drive. I don't have a passive houese and I wanted UFH so in my mind a HP is a very reasonable option in these circumstances. You obviously wil think otherwise and contine to use all ammunition at your disposal to bad mouth the option.

The good thing about this forum though it that personal opinions are allowed!

Juantorena

BryanF wrote: »

can you clarify how much of this is related to your normal energy consumption and how much is ASHP. thanks

In a word - and not to be short about it - no.

I've tried hooking up a Wattson onto it to get some idea but I can't get the clamp to fit....

fclauson

Katienewbuild wrote: »

hi all
Thanks again for all the help. Its great!!. However, i must apologise to my architect!!! he actually recommended AIr to water as main heat system, somewhere along the line i got completely confused with all these systems!!! anyways, here we are......Air to water...not MHRV!!!! woops!!!

if any of u have information about this...let me know!!!!

Before deciding on your heating system have you determined your heat demand - this can be down either with DEAP or PHPP (or both as you get a more holistic picture while checking you BER rating complience)

Once you have this you can then think about which type of system to use. Each have +ve and -ve (you can see the comments on this thread)

My preference would be lots of solar, big thermal store, high levels of insulation - which means bigger upfront costs - but reduces you exposure to the rise in energy prices

off topic - 1990 - 1 gallon of petrol 65p and 20 years later close on £6 per gallon - who could have predicted that when inflation alone would make it worth about £2

BryanF

The AECB's month article is out and about ASHP’s

http://aecb.net/PDFs/HeatPumpsArticleJuly2011.pdf

The article suggests the need to use SPF over COP (seasonal performance factor), the results of the Energy Savings Trust survey simplified on p4 of the AECB report make interesting reading: "Of the 22 ASHP installations evaluated, 50% fell within the range of 1.6 to 2.2, with one as low as 1.2, and only one achieving a measured efficiency of 3." 6-10k sterling is the EST set-up cost with ASHP in a detached house, with the need to install an efficient system that achieves a SPF of at least 3 to compete with conventional energy sources.



Poor installation, design/ spec, controls and lack of regulations were suggested as reasons for the poor efficiency and for causing the general bad press.

Its great to see the AECB highlight the need for the building fabric and the heat/ HW system to be optimised when using ASHP, as many people seem to install them with less than adequate insulation and air-tightness.

The report suggests backup heat is required at -2 and goes on to question the benefits of it as a ‘renewable’ system that has its highest electrical consumption in the coldest high power demand conditions.


Renewable?
page 1 of the AECB "the total heat available is generally two to four time greater than the electrical input" So if the heat pump is say 3 times as efficient as a gas boiler, is the primary energy factor accounted for? If the primary energy factor in Ireland is circa 2.7, does this cancel out the gains of using the heat pump over say a conventional gas boiler? Given that the majority of our electricity is powered by gas I think it’ll be some time before the word renewable should be used. On page 21 the Green label of ASHP is questioned, given that the current case studies don’t give the required COP for ASHP’s to be consider ‘renewable’. I think there’s also the EROI associated with the manufacture, along with seasonal adjusted carbon factor mentioned in the report (not efficient when its very cold) and the lifespan which can be considered currently questionable given the payback of lesser efficient installations.



Also interesting are Cantors concerns of power shortages in the extreme cold weather spells if ASHPs were more widely used in the UK...

creedp

Renewable?
page 1 of the AECB "the total heat available is generally two to four time greater than the electrical input" So if the heat pump is say 3 times as efficient as a gas boiler, is the primary energy factor accounted for? If the primary energy factor in Ireland is circa 2.7, does this cancel out the gains of using the heat pump over say a conventional gas boiler? Given that the majority of our electricity is powered by gas I think it’ll be some time before the word renewable should be used. On page 21 the Green label of ASHP is questioned, given that the current case studies don’t give the required COP for ASHP’s to be consider ‘renewable’. I think there’s also the EROI associated with the manufacture, along with seasonal adjusted carbon factor mentioned in the report (not efficient when its very cold) and the lifespan which can be considered currently questionable given the payback of lesser efficient installations. Also interesting are Cantors concerns of power shortages in the extreme cold weather spells if ASHPs were more widely used in the UK.../QUOTE]

While all of the above is interesting and informative it still doesn't mean that someone should not install a air to water or ground source HP. There is a personal choice issue here and even in the worst case scenario I don't think hp's are considered much more expensive to run than conventional heat sources. Granted the emphasis of the renewable aspect of air to water HP is Q in low temps and of course this should be taken into account but even so are they so much worse - more inefficient than oil fired burners when coupled with UFH?

I always find it interesting to listen to the argument about Ireland's inefficient and dirty electricity generation as if this is a reason not to select electrically powered heating systems. Is it the case that we should just accept this will always be the case and will never change? Why is it that we accept this inefficiency and therefore build our lives around it rather than insist on improved performance and value from our electricity generation. I also read with interest about the increased contribution renewables are making to electrivity generation and the millions that will be spent in the future to improve this contribution. Surely then this so called 2.7 factor can only improve and therefore increase the argument in favour of HP?

Finally, why is it that we are all goey eyed and warm all over about how electric cars will save the world and reduce CO2 etc etc when their energy also comes from the same dirty electricity? Can't have it everyway.

BryanF

creedp wrote: »

While all of the above is interesting and informative it still doesn't mean that someone should not install a air to water or ground source HP. There is a personal choice issue here and even in the worst case scenario I don't think hp's are considered much more expensive to run than conventional heat sources. Granted the emphasis of the renewable aspect of air to water HP is Q in low temps and of course this should be taken into account but even so are they so much worse - more inefficient than oil fired burners when coupled with UFH?

BUt I wonder would people be so inclined on ASHP's if the 'Eco bling' titles were removed. and wasn't this all supposed to be about reducing energy consumption? this report suggests there is not much of that being done compared to conventional gas, that was my point

creedp wrote: »

I always find it interesting to listen to the argument about Ireland's inefficient and dirty electricity generation as if this is a reason not to select electrically powered heating systems. Is it the case that we should just accept this will always be the case and will never change? Why is it that we accept this inefficiency and therefore build our lives around it rather than insist on improved performance and value from our electricity generation. I also read with interest about the increased contribution renewables are making to electrivity generation and the millions that will be spent in the future to improve this contribution. Surely then this so called 2.7 factor can only improve and therefore increase the argument in favour of HP?

yes but is this 'fingers crossed stuff' with the way things are going currently. its like the ghosts estates the infrastructure should have been built first!

creedp wrote: »

Finally, why is it that we are all goey eyed and warm all over about how electric cars will save the world and reduce CO2 etc etc when their energy also comes from the same dirty electricity? Can't have it everyway.

I agree, infrastructure first.