Air to water or boiler

Perez2017

I am building a bungalow for 1400 sq feet. My plumber wants me to go with a boiler but engineer air to water. My budget is small and boiler system will be cheaper but a lot of people are advising me to go air to water. What would people recommend?

dathi

Perez2017 wrote: »

I am building a bungalow for 1400 sq feet. My plumber wants me to go with a boiler but engineer air to water. My budget is small and boiler system will be cheaper but a lot of people are advising me to go air to water. What would people recommend?

depends on how are you going to meet the requirements of part L of the building regulations if your engineer is asking for air to water it is because he has designed it into the calculations required to pass the building regs.

B-D-P--

As above, what does your planning say?
Boiler is old news these days really.
Ask the plumber why he suggests that, whats his reasoning?

sydthebeat

the new Part L which comes in next year will make fossil fuel boilers extremely difficult to comply with minimum regulations.

essentially they are being phased out.

anyway, if your building in the rep of ireland, you simply MUST get a preliminary Part L report carried out before you start.
otherwise neither you, your builder, nor your certifying professional will know that what is being built complies with regulations.

B-D-P--

@SYD Wheres the details of new Part L?

More interest than anything, is there much changed than current?

sydthebeat

B-D-P-- wrote: »

@SYD Wheres the details of new Part L?

More interest than anything, is there much changed than current?

attached the draft consultation document

the biggest change is the EPC going from 0.4 to 0.3 ... which equates to about 25% increase in energy efficiency across the already very onerous board.

some other comments:

• It will bring all new houses into the realm of A2 or A1 BERs to comply.
• Heat pumps will become the standard and oil and gas boilers will become very uncommon.
• MHRV will become practically compulsory as natural ventilated dwellings wont comply.
• U value for windows will be determined now by the DEAP assessment, rather than % of openings, as windows over 1.0 will become obsolete.
• they are getting rid of the much maligned 10kwhr/m2
  And turning it into a renewable energy ratio of 0.2 to be met.... And determined by DEAP.

Carrickbeg

Go with the heat pump. I've a new build near completion and I went with gas as I have access to the natural gas line. I will have two bills now always and two standing charges. If u go with oil there is always the possibility of tank running low or empty. Heat pump, one bill, one utility and no fuel.

mickdw

By all accounts air to heat systems are suffering badly here in the west salty costal air.
I know of a few early installations that have had to be substantially replaced.

Carrickbeg

mickdw wrote: »

By all accounts air to heat systems are suffering badly here in the west salty costal air.
I know of a few early installations that have had to be substantially replaced.

Interesting to hear that. I've also heard that in the North not many are putting them (heat pumps) in as the regs are different up there? Not sure if that is accurate tho.

John.G

Carrickbeg wrote: »

Go with the heat pump. I've a new build near completion and I went with gas as I have access to the natural gas line. I will have two bills now always and two standing charges. If u go with oil there is always the possibility of tank running low or empty. Heat pump, one bill, one utility and no fuel.

Apart from the perceived savings in using a GSHP or a ASHP instead of a condensing Gas/Oil Boiler and getting a better BER rating?, do you have to install
(when opting for Gas/Oil) some other form of energy saving items like Solar PV or Solar Thermal to meet the building regulations for new builds?.

sydthebeat

John.G wrote: »

do you have to install
(when opting for Gas/Oil) some other form of energy saving items like Solar PV or Solar Thermal to meet the building regulations for new builds?.

You have to provide renewable energy

Gas / oil are not renewable

Carrickbeg

John.G wrote: »

Apart from the perceived savings in using a GSHP or a ASHP instead of a condensing Gas/Oil Boiler and getting a better BER rating?, do you have to install
(when opting for Gas/Oil) some other form of energy saving items like Solar PV or Solar Thermal to meet the building regulations for new builds?.

Yes. I put up a PV array.

Tom44

Install a wood pellet boiler


Oooop's
That was last decades recommended energy efficiency FLOP !!!!!


We won't discuss that anymore, let's discuss those wonderful carbon free heat pumps that
use electricity, that doesn't burn any fossil fuel in it's generation.



2025
Let's all go nuclear ��



It's a mad old world.

_Brian

The biggest failures I’ve seen with heat pumps isn’t withnthe heating system but rather with the detailing in the remainder of the house.

The system relies on a consistent low energy input into the building to build and maintain a level of heat. If the detailing of insulation, cold bridges and air tightness isn’t being achieved then it will be a disaster, I’ve seen it first hand. You have lads building houses which would have been comfortable with oil heating but are a disaster with Air to water as they are loosing heat as fast as the system can push it in.
We had friends fall into this trap and they had huge esb bills while sitting with coats on in the house.

If the whole house is built to tie right standard fine, but if detailing has been shabby it won’t be a success.

John.G

Tom44 wrote: »

Install a wood pellet boiler


Oooop's
That was last decades recommended energy efficiency FLOP !!!!!


We won't discuss that anymore, let's discuss those wonderful carbon free heat pumps that
use electricity, that doesn't burn any fossil fuel in it's generation.



2025
Let's all go nuclear ��



It's a mad old world.

We will be all fracked if we go nuclear.

agusta

_Brian wrote: »

The biggest failures I’ve seen with heat pumps isn’t withnthe heating system but rather with the detailing in the remainder of the house.

The system relies on a consistent low energy input into the building to build and maintain a level of heat. If the detailing of insulation, cold bridges and air tightness isn’t being achieved then it will be a disaster, I’ve seen it first hand. You have lads building houses which would have been comfortable with oil heating but are a disaster with Air to water as they are loosing heat as fast as the system can push it in.
We had friends fall into this trap and they had huge esb bills while sitting with coats on in the house.

If the whole house is built to tie right standard fine, but if detailing has been shabby it won’t be a success.

i have seen this in retrofits. If the house shell is not up to a certain spec,they just wont work correctly and cost a fortune to run

John.G

agusta wrote: »

i have seen this in retrofits. If the house shell is not up to a certain spec,they just wont work correctly and cost a fortune to run

Irrespective of the energy requirement and assuming the retrofit to a heat pump is done properly with UFH etc then I just cant see what the house shell has to do with it for comparison purposes. Surely its logical to assume that the COP of the HP is all to do with its correct sizing etc for that energy requirement and has nothing to do with the house shell?.
For example if my house energy requirement is 10000 Kwh/year and I have a condensing oil boiler with a seasonal efficiency of 85%, then with oil at €0.07/Kwh it will cost me €824/year. If I install a heat pump properly sized for that 10000 Kwh and installed properly using UFH etc then just assuming a seasonal COP of say 3.8 and full price electricity at €0.17/Kwh, it will cost me €447/year, a saving of €377/year.
On the other hand if I go away and spend some (a lot of) money on insulation etc and get the energy requirement down to 5000 Kwh/year then my energy costs will be €412 & €224/year, a saving of €188/year assuming the same HP COP of 3.8, again by sizing the HP properly etc for that (new) energy requirement.
To me, at any rate, before I would even dream of retrofitting to a HP or any other form of heating for that matter, then I would seriously think of spending some money on getting my energy requirements down and then do the sums again.

antoinolachtnai

John.G wrote: »

Irrespective of the energy requirement and assuming the retrofit to a heat pump is done properly with UFH etc then I just cant see what the house shell has to do with it for comparison purposes. Surely its logical to assume that the COP of the HP is all to do with its correct sizing etc for that energy requirement and has nothing to do with the house shell?.
For example if my house energy requirement is 10000 Kwh/year and I have a condensing oil boiler with a seasonal efficiency of 85%, then with oil at €0.07/Kwh it will cost me €824/year. If I install a heat pump properly sized for that 10000 Kwh and installed properly using UFH etc then just assuming a seasonal COP of say 3.8 and full price electricity at €0.17/Kwh, it will cost me €447/year, a saving of €377/year.
On the other hand if I go away and spend some (a lot of) money on insulation etc and get the energy requirement down to 5000 Kwh/year then my energy costs will be €412 & €224/year, a saving of €188/year assuming the same HP COP of 3.8, again by sizing the HP properly etc for that (new) energy requirement.
To me, at any rate, before I would even dream of retrofitting to a HP or any other form of heating for that matter, then I would seriously think of spending some money on getting my energy requirements down and then do the sums again.

Not exactly. The size of heat source you need depends on the peak demand on the coldest day. A cheap enough condensing boiler will knock out plenty for most houses.

Heat pumps are a lot more expensive per kilowatt, and if there is no three-phase, there is an upper limit to the size of heat pump you can install.

If the peak demand of your house is higher than the peak heat output of the heat pump on a cold day, then you will find yourself in trouble. The fact that your heat source is cheap and is more than adequate to heat the house on an average day will be of no help to you as the snow falls and the water freezes.

Carrickbeg

antoinolachtnai wrote: »

Not exactly. The size of heat source you need depends on the peak demand on the coldest day. A cheap enough condensing boiler will knock out plenty for most houses.

Heat pumps are a lot more expensive per kilowatt, and if there is no three-phase, there is an upper limit to the size of heat pump you can install.


If the peak demand of your house is higher than the peak heat output of the heat pump on a cold day, then you will find yourself in trouble. The fact that your heat source is cheap and is more than adequate to heat the house on an average day will be of no help to you as the snow falls and the water freezes.

That's similar to the advice I got for my new build. Heat loss at -2 degrees Celsius was calulated as 17kw. No three phase so the biggest heat pump I could get would be 14kw. So I got a 24kw gas boiler. But my point now would be....does the heat pump out perform the gas boiler the other 99% of the time (as in when temps are above -2) which is most of the year?

Water John

I think there are 16kw HP single phase on the market.
The problem with rerofits is more a question of airtightness. Easy enough to improve insulation except for the floor.
New builds without MHRV drive me spare. You'll have a sick smelly building.

Carrickbeg

Water John wrote: »

I think there are 16kw HP single phase on the market.
The problem with rerofits is more a question of airtightness. Easy enough to improve insulation except for the floor.
New builds without MHRV drive me spare. You'll have a sick smelly building.

Agreed. Especially with babies puking and pooing everywhere.

Perez2017

antoinolachtnai wrote: »

Not exactly. The size of heat source you need depends on the peak demand on the coldest day. A cheap enough condensing boiler will knock out plenty for most houses.

Heat pumps are a lot more expensive per kilowatt, and if there is no three-phase, there is an upper limit to the size of heat pump you can install.

If the peak demand of your house is higher than the peak heat output of the heat pump on a cold day, then you will find yourself in trouble. The fact that your heat source is cheap and is more than adequate to heat the house on an average day will be of no help to you as the snow falls and the water freezes.

So should I go with air to water or oil? Need to make a decision, my head is wrecked.

Water John

Do you want the engineer to sign off on the house?
If the answer is yes, then the decision is made, for you.

Perez2017

Water John wrote: »

Do you want the engineer to sign off on the house?
If the answer is yes, then the decision is made, for you.

Air to water so,ha.

Water John

Funnily enough, the same conversation going on with a relative's OH ATM. I'm not getting involved, just letting his wife knock a bit of sense into him.
There is no decision to be made.

John.G

Perez2017 wrote: »

Air to water so,ha.

OK, thats fine then, but as a matter of interest were both options costed with simple assumed pay back?.

autumnbelle

We were told that MHRV are not effective unless the house is a passive airtight house? Is it the case that all new builds should have it

darrmolo

I am currently at the footings stage of a build now in the midlands,. like yourself we are building on a budget. we decided to go with an oil boiler over the air to water heat pump purely because of the budget. i was advised by a good get people to go with the heat pump.
However even tho we are going with an oil boiler now we still comply with regs. i was thinking going with a gas boiler would be better but its not the efficiency of the oil boiler is a lot higher

Water John

Wouldn't say a house needs to be passive air tight for MHRV. If you haven't enough air changes, and you wont with a good modern build, you need it.

sydthebeat

autumnbelle wrote: »

We were told that MHRV are not effective unless the house is a passive airtight house? Is it the case that all new builds should have it

Nah, its generally accepted that you need to be reaching air tightness figures of less than 3 for it to be effective.

passive is 0.6

John.G

darrmolo wrote: »

I am currently at the footings stage of a build now in the midlands,. like yourself we are building on a budget. we decided to go with an oil boiler over the air to water heat pump purely because of the budget. i was advised by a good get people to go with the heat pump.
However even tho we are going with an oil boiler now we still comply with regs. i was thinking going with a gas boiler would be better but its not the efficiency of the oil boiler is a lot higher

I have put together a spreadsheet to try and get some feel myself for projected savings. I have assumed a few things which are apparent in the sheet. The $20000 question is the SCOP of the heat pump....I have just assumed 3.8 but it can be changed to whatever is deemed more appropriate. I have also assumed that the HP will produce all the hot water required at 40C but that, once per week, the electric immersion will raise the cylinder temperature to 60C for Legionella protection.

Wearb

John.G wrote: »

I have put together a spreadsheet to try and get some feel myself for projected savings. I have assumed a few things which are apparent in the sheet. The $20000 question is the SCOP of the heat pump....I have just assumed 3.8 but it can be changed to whatever is deemed more appropriate. I have also assumed that the HP will produce all the hot water required at 40C but that, once per week, the electric immersion will raise the cylinder temperature to 60C for Legionella protection.

Nice workbook to have for comparing different heat sources. Excuse my laziness, but what BER gives 60kwh/M2 PA?

Wearb

John.G wrote: »

I have put together a spreadsheet to try and get some feel myself for projected savings. I have assumed a few things which are apparent in the sheet. The $20000 question is the SCOP of the heat pump....I have just assumed 3.8 but it can be changed to whatever is deemed more appropriate. I have also assumed that the HP will produce all the hot water required at 40C but that, once per week, the electric immersion will raise the cylinder temperature to 60C for Legionella protection.

Could you check those figures again please. I was just now looking at the SEAI comparison sheet for July 2018. Natural gas -for the annual house requirements in your spreadsheet- increases a lot for low-ish usage.

John.G

Wearb wrote: »

Nice workbook to have for comparing different heat sources. Excuse my laziness, but what BER gives 60kwh/M2 PA?

As I stated above, I just picked a BER rating of A3 which is >50 but < 75
kwh/M2/annum (B1). You can put in whatever BER rating you like in cell C7 or input the actual BER rating that your own house actually is. I have no idea what my own house BER rating is but I do know that I use ~ 15000 Kwh of oil+elect/annum.

John.G

Wearb wrote: »

Could you check those figures again please. I was just now looking at the SEAI comparison sheet for July 2018. Natural gas -for the annual house requirements in your spreadsheet- increases a lot for low-ish usage.

As above just input your own number in cell C29, I wouldn't consider over 14,500 Kwh of gas usage low?. Would you mind posting the link to SEAI for July 2018 as I dont seem to be able to get it, thanks.

Overall, as I said originally the spreadsheet only reflects the numbers inputted so if someone with a HP has some real numbers they can just input them themselves or post them here and it might just give some idea of the real savings.

Wearb

John.G wrote: »

As above just input your own number in cell C29, I wouldn't consider over 14,500 Kwh of gas usage low?. Would you mind posting the link to SEAI for July 2018 as I dont seem to be able to get it, thanks.

Overall, as I said originally the spreadsheet only reflects the numbers inputted so if someone with a HP has some real numbers they can just input them themselves or post them here and it might just give some idea of the real savings.

Link to fuel comparison

https://www.seai.ie/resources/publications/Domestic-Fuel-Cost-Comparison.pdf

Btw I don’t see where you stated Ber 3, but perhaps I’m missing it on my limited phone screen.

John.G

Wearb wrote: »

Link to fuel comparison

https://www.seai.ie/resources/publications/Domestic-Fuel-Cost-Comparison.pdf

Btw I don’t see where you stated Ber 3, but perhaps I’m missing it on my limited phone screen.

Thanks for that, I have listed the BER ratings (and also the published daily hot water consumption) in colume's G to N. in the spreadsheet. Here is the BER table.

Ber Rating
A1 < = 25 KWh/M2/Yr
A2 >25
A3 >50
B1 >75
B2 >100
B3 >175
C1 >150
C2 >175
C3 >200

Wearb

Wearb wrote: »

Link to fuel comparison

https://www.seai.ie/resources/publications/Domestic-Fuel-Cost-Comparison.pdf

Btw I don’t see where you stated Ber 3, but perhaps I’m missing it on my limited phone screen.

I have the sheet now opened on PC and can now understand it very well. I have saved it for future use. As you wrote, I can input my own figures to suit different site situations.



Thanks

John.G

Wearb wrote: »

I have the sheet now opened on PC and can now understand it very well. I have saved it for future use. As you wrote, I can input my own figures to suit different site situations.



Thanks

A small bit of confusion with my spreadsheet as there were actually 2 sheets in it and I should have deleted the first sheet, I only spotted that when I opened it myself in my Iphone.... I have deleted it now so here is the spreadsheet with the relevant info, its exactly the same as the first one.

Wearb

John.G wrote: »

A small bit of confusion with my spreadsheet as there were actually 2 sheets in it and I should have deleted the first sheet, I only spotted that when I opened it myself in my Iphone.... I have deleted it now so here is the spreadsheet with the relevant info, its exactly the same as the first one.

I noticed that, but after a cursory glance, I put it down to bad handling of the database by the phone. I didn't notice the second sheet on the PC until I searched for it just now.

shianto

John.G wrote: »

A small bit of confusion with my spreadsheet as there were actually 2 sheets in it and I should have deleted the first sheet, I only spotted that when I opened it myself in my Iphone.... I have deleted it now so here is the spreadsheet with the relevant info, its exactly the same as the first one.

Great spreadsheet. Really thoughtful of you to share makes the whole exercise of specifying the house that much easier...Many thanks.

shianto

I am well aware that no specific brand recommendations can be posted to the forum, but does anyone know if there is a comparison table anywhere in English for A2W HP's?

Apparently there is a matrix in German (for the German market) of the A2W HP that gives impartial rankings. Assuming there is nothing similar that people are aware of, would anyone be willing PM their private opinions on a brand (good or bad)?