Air/Ground Source heat pumps.

lollymob

Hi all, I'm about to embark on a new build. Provisional BER has stated that we need to have a ground or air source heat pump. House is 3000 sq foot. I'm trying to research both and we've decided we'll probably go with the air source (Mainly due to costs) House will be fitted with an airtight membrane, HRV and solar panels. Underfloor throughout. Rated A3 I'm wondering can anyone recommend some reputable companies that supply these heat pumps by PM. I'm based in the midlands. Do these companies have their own installers or is it up to you to find a good plumber?
Really appreciate any advice.
Thanks, Lollymob

BryanF

lollymob wrote: »

Hi all, I'm about to embark on a new build. Provisional BER has stated that we need to have a ground or air source heat pump. House is 3000 sq foot. I'm trying to research both and we've decided we'll probably go with the air source (Mainly due to costs) House will be fitted with an airtight membrane, HRV and solar panels. Underfloor throughout. Rated A3 I'm wondering can anyone recommend some reputable companies that supply these heat pumps by PM. I'm based in the midlands. Do these companies have their own installers or is it up to you to find a good plumber?
Really appreciate any advice.
Thanks, Lollymob

Hang on a sec why is your one week to be qualified BER assessor dictating the need for heat pumps? Want other options have you considered to achieve the renewable requirements?

MOTM

+1.
Lollymob, it seems odd that you "need" to have a heat pump installed. There are other means to meet TGD L requirements if that is the reason why the heat pump is "needed". Consider the alternatives, of which there are probably plenty cheaper than a heat pump.

lollymob

BryanF wrote: »

Hang on a sec why is your one week to be qualified BER assessor dictating the need for heat pumps? Want other options have you considered to achieve the renewable requirements?

Don't quite know what you mean by 'one week to be qualified BER assessor'?? Anyway he said he tried a number of different heating combinations but they were all falling just short of meeting regulations!!

MOTM

lollymob wrote: »

Don't quite know what you mean by 'one week to be qualified BER assessor'?? Anyway he said he tried a number of different heating combinations but they were all falling just short of meeting regulations!!

What aspect of the regulations exactly?

BryanF

lollymob wrote: »

Don't quite know what you mean by 'one week to be qualified BER assessor'?? Anyway he said he tried a number of different heating combinations but they were all falling just short of meeting regulations!!

There are more options available to you. For a start send the BER Deap file to a solar supplier, pv supplier, and log gasification boiler supplier + the heat pump people and ask their opinion/ cost of integration/ running costs & cost of compliance. It's not clear from your post what other factors such as Mvhr or open fire etc are at play here, but perhaps you should seek a second opinion. Also has the assessor put the min values in for insulation & air-tightness?

blast06

For a 3,000 sq ft house you would probably need 4-6 m2 of solar panels which would probably be 4-6K. I'm sure others will have more accurate figures.
My point though is that if you go with a heat pump (ballpark 10K) then that will meet the requirements for part L and you won't need solar.

seaniefr

Hi as an air sourcepump and solar flat panel user ( I have both fitted in our house) I would advise you to spend as long as you can researching ALL options! Our air source heat pump is fantastic (2200 sq. ft house) but they are not worth a s*** below 4 degrees c they will run but very inefficiently and as for solar panels you need a little thing not often seen in Ireland ........sunlight! (:-)

blast06

Seaniefr .... when did you get your system installed ? what model is it ? what insulation spec has your house (e.g.: air tight membrane, etc ?) ? have you UFH throughout or rads ?
When you say inefficient under 4 degrees, do you know what COP that means ?
Cheers

Condenser

blast06 wrote: »

Seaniefr .... when did you get your system installed ? what model is it ? what insulation spec has your house (e.g.: air tight membrane, etc ?) ? have you UFH throughout or rads ?
When you say inefficient under 4 degrees, do you know what COP that means ?
Cheers

Up until 5yrs ago all air source units were quoted at the European standard of A2/W35 but since the advent of the cheaper A2W units they have suddenly started listing them a A7/W35. Most of these units have a COP of about 3.8 when tested to the european standard. If ground source units were afforded the same latitude them most would be listed with COP's approaching 6 and the better ones approaching 7.
COP's usually depend to a greater extent on the flow temp and is usually where most installations fall down.

blast06

Condenser wrote: »

Up until 5yrs ago all air source units were quoted at the European standard of A2/W35 but since the advent of the cheaper A2W units they have suddenly started listing them a A7/W35. Most of these units have a COP of about 3.8 when tested to the european standard. If ground source units were afforded the same latitude them most would be listed with COP's approaching 6 and the better ones approaching 7.
COP's usually depend to a greater extent on the flow temp and is usually where most installations fall down.

Wow, i didn't think the difference was that big.
My understanding had been that on average for a geothermal system, the COP was more 4 to 1 when the cost of pumping the water through the pipes was considered.... e.g.: 4 to 1 implied here http://www.seai.ie/Renewables/Geothermal_Energy/Ground_Source_Heat_Pumps/ ........ "for every unit of electricity used to pump the heat, 3-4 units of heat are produced"
..... and that air to water heat pumps aren't so far off that (or at least claim to be): http://www.heatpumps.danfoss.co.uk/PCMFiles/67/Heat_pump/Sales%20Literature/Datasheets/Air%20Source/DHP-AQ%20JULY%202012.pdf

I've decided on an air to water heat pump (just yesterday !) and figured that 'yes, it would be a bit cheaper to have geo-thermal' but i haven't dwelved into the maths that much cos both suppliers i narrowed it down to calculated all heating and hot water costs for the year of between €800-900 ...... and couldn't see geothermal knocking more than 200-300 a year off that.
For me to go with geothermal it would be a bore hole (ground conditions are not suitable for digging up .... all gravel (with soil yet to go on top of course !!))..... and i know that would cost around 4K so cost benefit doesn't add up.
Clearly i am just trying to convince myself that i have made the correct decision :) .... any thoughts though ?!
Cheers !

Condenser

blast06 wrote: »

Wow, i didn't think the difference was that big.
My understanding had been that on average for a geothermal system, the COP was more 4 to 1 when the cost of pumping the water through the pipes was considered.... e.g.: 4 to 1 implied here http://www.seai.ie/Renewables/Geothermal_Energy/Ground_Source_Heat_Pumps/ ........ "for every unit of electricity used to pump the heat, 3-4 units of heat are produced"
..... and that air to water heat pumps aren't so far off that (or at least claim to be): http://www.heatpumps.danfoss.co.uk/PCMFiles/67/Heat_pump/Sales%20Literature/Datasheets/Air%20Source/DHP-AQ%20JULY%202012.pdf

I've decided on an air to water heat pump (just yesterday !) and figured that 'yes, it would be a bit cheaper to have geo-thermal' but i haven't dwelved into the maths that much cos both suppliers i narrowed it down to calculated all heating and hot water costs for the year of between €800-900 ...... and couldn't see geothermal knocking more than 200-300 a year off that.
For me to go with geothermal it would be a bore hole (ground conditions are not suitable for digging up .... all gravel (with soil yet to go on top of course !!))..... and i know that would cost around 4K so cost benefit doesn't add up.
Clearly i am just trying to convince myself that i have made the correct decision :) .... any thoughts though ?!
Cheers !

Theres no such thing as a set COP. COP's vary on a minute by minute basis and are determined by the temperature of the collected energy and the temperature of the distributed energy. The further these two figures apart the lower the COP. The converse is also true. It comes down to about a 2% increase or decrease per degree C.

Your efficiency depends on your distribution system, your collection system and your hot water system. All three have to be designed towards maximum efficiency i.e. low temp in order for the machine to maximise performance. A2W suffer far more in fluctuations due to the fact that air temperature changes daily whilst ground conditions remain relatively static. They also have to defrost which costs energy for no net return. The cheaper units also contain the compressor in the outdoor unit and the oil in this must be kept warm so it doesn't congeal and hinder compressor start up. This heater consumes about 200W per hour. None of these costs are allowed for in the COP.

Ground source units are more expensive but they're more expensive for a reason. They're more efficient, have longer life span (approx twice what a cheaper A2W would) and require less maintainence. Also if you look at the running costs across all heating systems over 20yrs and factor in fuel increases GSHP's are miles in front. A2W have their place in townhouses etc but for decent one off builds I'd go GSHP everytime.

Condenser

blast06 wrote: »

Wow, i didn't think the difference was that big.
My understanding had been that on average for a geothermal system, the COP was more 4 to 1 when the cost of pumping the water through the pipes was considered.... e.g.: 4 to 1 implied here http://www.seai.ie/Renewables/Geothermal_Energy/Ground_Source_Heat_Pumps/ ........ "for every unit of electricity used to pump the heat, 3-4 units of heat are produced"
..... and that air to water heat pumps aren't so far off that (or at least claim to be): http://www.heatpumps.danfoss.co.uk/PCMFiles/67/Heat_pump/Sales%20Literature/Datasheets/Air%20Source/DHP-AQ%20JULY%202012.pdf

I've decided on an air to water heat pump (just yesterday !) and figured that 'yes, it would be a bit cheaper to have geo-thermal' but i haven't dwelved into the maths that much cos both suppliers i narrowed it down to calculated all heating and hot water costs for the year of between €800-900 ...... and couldn't see geothermal knocking more than 200-300 a year off that.
For me to go with geothermal it would be a bore hole (ground conditions are not suitable for digging up .... all gravel (with soil yet to go on top of course !!))..... and i know that would cost around 4K so cost benefit doesn't add up.
Clearly i am just trying to convince myself that i have made the correct decision :) .... any thoughts though ?!
Cheers !

Just to elaborate on the figures a little further. All heat pumps are meant to work off a level playing of an evaporating temp of -5 (gas temp cooling side). In their wisdom the powers that be muddied the waters by listing each heat pump type at the applicable source temp that would correspond to -5 e.g an air temp of 2 would mean you were evaporating at -5 and a Brine temp of Zero would also mean an evaporating temp of -5. This left the way open for people to confuse customers with figures such as A7/W35 or even worse A7/W30 just to make their product seem more efficient and comparable to other systems.

seaniefr

blast06 wrote: »

Seaniefr .... when did you get your system installed ? what model is it ? what insulation spec has your house (e.g.: air tight membrane, etc ?) ? have you UFH throughout or rads ?
When you say inefficient under 4 degrees, do you know what COP that means ?
Cheers

Hi heat pump was a retro fit (last year)as the house was built in 2004 and air tightness was never mentioned (house is also block construction) and even though underfloor was installed i couldn't find a heatpump supplier that could sell me a system that didn't dim the lights of my neighbours when it started and the prices and the BS i got from almost all of the suppliers put me right off it as it was plainly obvious that these 'experts' at the time had a lot of growing up to do. The one company that seemed to know what they were at had gone belly up when i tried to contact them about going ahead with the sale. I went with oil condensing at the time and over compensated with insulation for the standards back then which worked fine while oil was reasonably priced but the price has gone in to the stratosphere so i found out that the new generation of air heat pumps which now have inverter control which was my initial problem as excessively high starting current from one supplier had made the ESB extremely wary about heat pumps in general so they were asking a lot of questions about starting currents etc.
Anyway re-think your order and go with ground source! My neighbour also has an air source heat pump which pre-date's mine by 4 years and he has exactly the same problem when temperatures drop below 4 degrees outside his heat pump is not worth a s**** at that temp. I kept the oil burner so that i use it to get the temp up for the heat pump which seems the be the problem because at any temp over 4 degrees the heat pump works fine. I just run it on night rate and i also have a multi-fuel stove in the kitchen. So basically the oil might run for 1 hour in the evening only when the weather is really cold other than that it is never used. Forgot to mention that the guy that sold me the air heat pump came in was very matter of fact about it and the figures he gave me added up and that was last april have had no problems touch wood it has not given an ounce of bother since it went in.

lollymob

Thanks for all the info.. Back to the drawing board it is!!

seaniefr

lollymob wrote: »

Thanks for all the info.. Back to the drawing board it is!!

Hiya I did forget to mention that the air to water Hp has a 6kw backup element I chose to set it to a lower setting as I had the oil they actually claim that it will work to -5 degrees c but I would guess that is like a basic immersion below 4 degrees just another piece of useless info in case you get sidetracked by a salesman. Anyway best of luck in whatever you choose.
Sean.

weejimmeh

Hi Lollymob,
I have been looking at this issue for some years now and conclusion I have come to is build, if possible and it is in your case, a passive house. NO heating systems required, full stop! Yes you do need a HRV and solar panels to match your occupancy of the house. But isn't that expensive, you say . . . Nope it ain't. I have seen a 3,300sq.ft. dormer passive house and got a quote last year for 169,000euro. That includes foundations and basic structure built and weather proof (in four days, the building I mean). I have been in one of these houses and spoken to the owners. For example during the bad snowy winter we had a few years ago, the owner was complaining (very tongue in cheek) that his space heating bill for the whole winter came to 250euro. His average electric heating bill is about 100euro per irish winter! Just something to consider when looking at all your options again and my tuppence worth. If you need /want more info, you know where to find me . . . .

lollymob

Thanks Seaniefr,
So I got round to ringing just two companies today. Think I need to take a career break to find the time to build this house!!! One guy was very helpful talked me through both but recommended geothermal if soil is suitable. They provide a free soil suitability test. He requested site map and house plans and he sent me a quote within an hour for both with underfloor heating throughout, HRV system. Not sure if I can post quote here but quotes also included installation costs.

The second crowd I called didn't go into near as much detail, didn't ask for plans just sq foot of house. He then told me what system was suitable based on size of house and gave me a quote there and then???? Do these people not need to examine plans before they can recommend a system?? He recommended that we go with air source!!!

So I'm no further on but I'll continue my search!!

Thanks weejimmeh, as much as I'd love to go passive I don't think budget will stretch that far and I'm amazed at the figures you quoted! Fair play to them!!

creedp

weejimmeh wrote: »

Hi Lollymob,
I have been looking at this issue for some years now and conclusion I have come to is build, if possible and it is in your case, a passive house. NO heating systems required, full stop! Yes you do need a HRV and solar panels to match your occupancy of the house. But isn't that expensive, you say . . . Nope it ain't. I have seen a 3,300sq.ft. dormer passive house and got a quote last year for 169,000euro. That includes foundations and basic structure built and weather proof (in four days, the building I mean). I have been in one of these houses and spoken to the owners. For example during the bad snowy winter we had a few years ago, the owner was complaining (very tongue in cheek) that his space heating bill for the whole winter came to 250euro. His average electric heating bill is about 100euro per irish winter! Just something to consider when looking at all your options again and my tuppence worth. If you need /want more info, you know where to find me . . . .

Are passive houses easier to heat in cold bright weather than the cloudy weather we age getting this year? I dont have a passive house but its over a couple years old and pretty well insulated and airtight. I found that it is much warmer in very cold frosty and clear weather than it is over the last few weeks of cloudy relatively mild weather. We have a lot of southfacing glass and it pretty much melts the place when the sun shines. In fact the house actually heats up during sunny weather with very little space heating required. I would often see the therostats are 21c in the morning and 22c in the evening with no heating on and close to freezing outside. Would the same be the case with passive houses?

sas

creedp wrote: »

Are passive houses easier to heat in cold bright weather than the cloudy weather we age getting this year? I dont have a passive house but its over a couple years old and pretty well insulated and airtight. I found that it is much warmer in very cold frosty and clear weather than it is over the last few weeks of cloudy relatively mild weather. We have a lot of southfacing glass and it pretty much melts the place when the sun shines. In fact the house actually heats up during sunny weather with very little space heating required. I would often see the therostats are 21c in the morning and 22c in the evening with no heating on and close to freezing outside. Would the same be the case with passive houses?

It's certainly the case with mine. Outside temp has no meaningful impact on comfort. Dark damp days however tend to result in a detectable loss of comfort.

Total frigging nuisance given we get more damp mild conditions than anything else. I also get a tank of hot water on those freezing bright days and nothing in damp weather.

seaniefr

lollymob wrote: »

Thanks Seaniefr,
So I got round to ringing just two companies today. Think I need to take a career break to find the time to build this house!!! One guy was very helpful talked me through both but recommended geothermal if soil is suitable. They provide a free soil suitability test. He requested site map and house plans and he sent me a quote within an hour for both with underfloor heating throughout, HRV system. Not sure if I can post quote here but quotes also included installation costs.

The second crowd I called didn't go into near as much detail, didn't ask for plans just sq foot of house. He then told me what system was suitable based on size of house and gave me a quote there and then???? Do these people not need to examine plans before they can recommend a system?? He recommended that we go with air source!!!

So I'm no further on but I'll continue my search!!

Thanks weejimmeh, as much as I'd love to go passive I don't think budget will stretch that far and I'm amazed at the figures you quoted! Fair play to them!!

As far as i know if you are thinking of getting borehole ( & only know this cause i contacted a local company) if any of these companies are familiar with the area they can tell you with a free site visit whether or not they will hit bedrock i know the quote i got was 3k. I will PM you the heap pump guy & the well drilling company.
Don't be afraid of putting in the legwork now it will save you thousands in the long run even if you have to delay the build. You really have to balance it between the best you can afford and whats right for YOUR house not anyone else's opinion.

blast06

Maybe a dumb question here but how would you not hit rock with the borehole, i.e.: you have to go down a few hundred feet and would be incredibly unusual not to hit bedrock at that depth

seaniefr

blast06 wrote: »

Maybe a dumb question here but how would you not hit rock with the borehole, i.e.: you have to go down a few hundred feet and would be incredibly unusual not to hit bedrock at that depth

Not really sure of the terminology and may be wrong the dude just mentioned something about it and the fact that they could drill to 100M with no problems he did mention something about bedrock can't quite remember what but I do remember the price!

MOTM

sas wrote: »

It's certainly the case with mine. Outside temp has no meaningful impact on comfort. Dark damp days however tend to result in a detectable loss of comfort.

Total frigging nuisance given we get more damp mild conditions than anything else. I also get a tank of hot water on those freezing bright days and nothing in damp weather.

While you deffo need backup for water heating, do you use one for space heating?

Condenser

blast06 wrote: »

Maybe a dumb question here but how would you not hit rock with the borehole, i.e.: you have to go down a few hundred feet and would be incredibly unusual not to hit bedrock at that depth

Geology in Ireland is all over the place. You could hit rock in 2 metres at one place and go 80m in another and hit rock but it might be unconsolidated. Hitting bedrock is not important for a successful borehole. The borehole should be drilled as narrow as possible to accommodate the probe, it should also be grouted with thermally enhanced bentonite and a log of the different geology found while drilling should be kept to estimate the conductivity of the bore. In north west Germany very few of their bores would hit bedrock.

sas

MOTM wrote: »

While you deffo need backup for water heating, do you use one for space heating?

Yes, we definitely do.

The idea that a PH doesn't require a heating system is a myth.

Upstairs in our home we've nothing to provide heat. With the exception of 1 night we never felt below our comfort levels upstairs.

The main living area is different though. When we get spells of grey weather, the temp starts to drop off in the living area. Most nights we have a 2 kw convector heater plugged in. The temp "we" require in our living area is well above that of the bedrooms though. Bedrooms are fine at 18 - 19.
To sit and watch tv comfortable I want approx. 22 degrees.

1 evening last week when we got home the main living area was 18.8 degrees. The convector lifted it over 21 in a couple of hours. This is a room that is >60m2.

I had a look at the level on our oil tank last night. It's difficult to determine exactly how much we've used because the tanks aren'ts a regular shape.
The level in the tank is 1/3 of the way from the bottom based on the 500 litres we filled it with (first fill). In theory therefore our DHW and heating have been covered by apprx 350 litres of oil. Plus the electric usage on the heater. That's coming in around 100 euros since we start using it in late Nov.

Tommyboy08

sas wrote: »

Yes, we definitely do.

The idea that a PH doesn't require a heating system is a myth.

Upstairs in our home we've nothing to provide heat. With the exception of 1 night we never felt below our comfort levels upstairs.

The main living area is different though. When we get spells of grey weather, the temp starts to drop off in the living area. Most nights we have a 2 kw convector heater plugged in. The temp "we" require in our living area is well above that of the bedrooms though. Bedrooms are fine at 18 - 19.
To sit and watch tv comfortable I want approx. 22 degrees.

1 evening last week when we got home the main living area was 18.8 degrees. The convector lifted it over 21 in a couple of hours. This is a room that is >60m2.

I had a look at the level on our oil tank last night. It's difficult to determine exactly how much we've used because the tanks aren'ts a regular shape.
The level in the tank is 1/3 of the way from the bottom based on the 500 litres we filled it with (first fill). In theory therefore our DHW and heating have been covered by apprx 350 litres of oil. Plus the electric usage on the heater. That's coming in around 100 euros since we start using it in late Nov.

Sorry to ask but is that 350 liters of oil and €100 in electricity since late November?

sas

Tommyboy08 wrote: »

Sorry to ask but is that 350 liters of oil and €100 in electricity since late November?

350 litres of oil since July 16. However, the solar covered all hot water up to the end of sept and made a good contribution in Oct. By end of Oct. we were into heating need and minimal solar contribution to hot water.

We started using the oil for heating (UFH downstairs) and DHW from early Oct. By end of Oct., it was used daily.

The 100 for electric is since late Nov. I have a monitor on the heater to track this.

Note: we've no immersion nor electric showers. If the solar doesn't provide DHW, the oil is must be turned on.

For a house over 3000 sq ft it's not bad.

yop

Of the heat pump options your air sourced will return the least and will not be as efficient when the weather is cold!
Geo is the next best option and borehole your best for these types of heat sources.

Spent the guts of 1 year visiting various sites and reading studies, it was 9 years ago I did my research but from those I know who have ASHP the pumps aren't as good as the equivalent GSHP's.

Insulate the hell out of the house and seal it. Keep your heat in and it will cost you a lot less!

Keep tight loops on your UFH and it will reduce the flow temp required to achieve an ambient room temp.

Good luck with it all, your going to hear 100's of different opinions and options

Tommyboy08

yop wrote: »

Of the heat pump options your air sourced will return the least and will not be as efficient when the weather is cold!
Geo is the next best option and borehole your best for these types of heat sources.

Spent the guts of 1 year visiting various sites and reading studies, it was 9 years ago I did my research but from those I know who have ASHP the pumps aren't as good as the equivalent GSHP's.

Insulate the hell out of the house and seal it. Keep your heat in and it will cost you a lot less!

Keep tight loops on your UFH and it will reduce the flow temp required to achieve an ambient room temp.

Good luck with it all, your going to hear 100's of different opinions and options

Dx is the most efficient but boreholes are great if its done correctly, yop is right about everything else underfloor etc, just do your research and ensure that the boreholes are back filled correctly as this practice is not usually carried out in Ireland,
Also get your installer to provide you with the cop ratings of your unit before you make your decision

yop

Tommyboy08 wrote: »

Dx is the most efficient but boreholes are great if its done correctly, yop is right about everything else underfloor etc, just do your research and ensure that the boreholes are back filled correctly as this practice is not usually carried out in Ireland,
Also get your installer to provide you with the cop ratings of your unit before you make your decision

Thats it Tommy. DX as opposed to the brine system OP, so ensure that is a DX system that you are getting.

MOTM

sas wrote: »

Yes, we definitely do.

The idea that a PH doesn't require a heating system is a myth.

Thanks SAS - this is what I thought (I was just thinking on the context of the previous post from Wijimmeh). I won't say any more on it though. Don't want to go off topic from the OP.

fclauson

sas wrote: »

... Outside temp has no meaningful impact on comfort. Dark damp days however tend to result in a detectable loss of comfort.
.

True these last few days house has dropped to about 19 or so

urgently need some solar gain

fclauson

there are many learned people on here but when I did my HP research AS or GS I came out with AS

Once the air temp rises above 7 degrees the AS is more efficient (assuming ground temp of 7 from the GS)

Ireland average temps are well above this for most of the year (remember I have no solar thermal but I do have PV and will be using HP in the summer for hot water)

My 9Kw HP (6 of which is the immersion which has been on for 10 mins since October) is heating a 3500 house h/w and heating for abotu 15Kw per day roughly (and I have three women who shower)

So thats €3

make sure when you do your ROI calcs you do not over egg the energy demand to reduce pay back time line

Condenser

fclauson wrote: »

there are many learned people on here but when I did my HP research AS or GS I came out with AS

Once the air temp rises above 7 degrees the AS is more efficient (assuming ground temp of 7 from the GS)

Ireland average temps are well above this for most of the year (remember I have no solar thermal but I do have PV and will be using HP in the summer for hot water)

My 9Kw HP (6 of which is the immersion which has been on for 10 mins since October) is heating a 3500 house h/w and heating for abotu 15Kw per day roughly (and I have three women who shower)

So thats €3

make sure when you do your ROI calcs you do not over egg the energy demand to reduce pay back time line

Even at an air temp of 7 the ground source is still more efficient than an air source unless its a GS with a particularly poor COP.

fclauson

so where is the switch over point from a temp perspective ?

Condenser

fclauson wrote: »

so where is the switch over point from a temp perspective ?

Depends on the heat pump but it would be unusual to have a return Brine temp of less than 3-4C so that alone would add 8-10% to the rated COP of the Ground source unit. Assuming a poor heat pump would give you a COP of 4.4 that would raise your COP to 4.84. Which would match any air to water at A7/W35. A good ground source unit could have a COP of over 6. Thats not allowing for defrosts or immersions on the A2W.
If you stacked an A2W up against a good GSHP you could be looking at a switchover temp of 15C+.

creedp

o

sas wrote: »

350 litres of oil since July 16. However, the solar covered all hot water up to the end of sept and made a good contribution in Oct. By end of Oct. we were into heating need and minimal solar contribution to hot water.

We started using the oil for heating (UFH downstairs) and DHW from early Oct. By end of Oct., it was used daily.

The 100 for electric is since late Nov. I have a monitor on the heater to track this.

Note: we've no immersion nor electric showers. If the solar doesn't provide DHW, the oil is must be turned on.

For a house over 3000 sq ft it's not bad.

Its very interesting to hear how different houses perform once the building excitement wears off. I followed your build pretty closely here on Boards so its nice to hear how it going now. Im afraid I didn't go down the passive road and instead put in UFH downstairs and upstairs with GSHP. (My builder wasn't up to the passive game!) I have no solar panels only solar gain from southfacing glazing.

I have found that the HP works very well for DHW heating a 300lt tank for 35cents a day. The space heating only comes on at night and costs between €1.50 and €2.25 a day depending on the amount of sunshine the day before. It has been consistently in the region of €2 a day over the last month. During cloudy weather the living room which has a lot of glass and vaulted ceiling regularly cools off to 20c and a couple of times down to 19c and I would often throw a couple of logs into the stove and this would leave the room pleasantly warm. From October 2012 to end Jan 2013 the total cost of the HP worked out at just over €193 (I have a meter on the HP). Add to this the cost of the few logs and I'm pretty happy with the performance of the HP.

fclauson

and to give my feedback - only been in the house a couple of months but mine is working out at about 15Kw primery energy for h/w and heating per day - some of that is cheap over night elec and some is PV during the day and some standard day rate

as SAS mentioned on another forum this dully muggy weather is the worst - the HP thinks the house needs no heat as the OAT is 6 or 7 so the house temp down to 19.5/20 in the early hrs of the morning

Had the stove on last night and still this morning its warming effects can be felt (the wall above the stove is positivily warm to touch) 10hrs later !!!!

one other thing - heat curve set to 28deg - i.e. at 0deg outside it will feed in 28degs

Wegian

creedp wrote: »

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Its very interesting to hear how different houses perform once the building excitement wears off. I followed your build pretty closely here on Boards so its nice to hear how it going now. Im afraid I didn't go down the passive road and instead put in UFH downstairs and upstairs with GSHP. (My builder wasn't up to the passive game!) I have no solar panels only solar gain from southfacing glazing.

I have found that the HP works very well for DHW heating a 300lt tank for 35cents a day. The space heating only comes on at night and costs between €1.50 and €2.25 a day depending on the amount of sunshine the day before. It has been consistently in the region of €2 a day over the last month. During cloudy weather the living room which has a lot of glass and vaulted ceiling regularly cools off to 20c and a couple of times down to 19c and I would often throw a couple of logs into the stove and this would leave the room pleasantly warm. From October 2012 to end Jan 2013 the total cost of the HP worked out at just over €193 (I have a meter on the HP). Add to this the cost of the few logs and I'm pretty happy with the performance of the HP.

Hi, I know I am dragging up an old post but could you share
- what kind of heat pump did you install?
- more recent data on usage, costs and overall impression?

Thanks