Air-to-Water Heat Pump + Underfloor heating vs LPG+PV

Monfreid

Hello,

The advisory report from the energy consultant gives me 2 options for my house:

- Option 1: Air-to-Water Heat Pump + Underfloor heating
- Option 2: LPG+PV

I have read and eard more bad stories than good ones regarding Option 1. You could end up having to pay much more than expected ... that's my fear that Option 1 will cost me a fortune in electricity ...
Option 2 on the other end seems more expensive on paper but al least you can control it when, the heat pump, correct me if I'm wrong, is on all the time.
Option 2 could give me more freedom wheras to change to oil or go to Heat pump solution afterwards.
I don't know what to think and if you have some experience with these systems, I'd like to ear from you.
Once I choose Option 1 or 2 then I'll be able to get a tender package and things will start moving

Thank you

quentingargan

I built a near-passive house recently and opted not to have underfloor heating, because I think the response is too slow. If the sun comes out, you can't instantly turn down the heating.

If you opt for LPG and radiators, you can perhaps use rads that would be large enough to work with he heat pump if you opt for that later. Heat pumps get less efficient the higher the radiator temp required, hence the tendency to use them with underfloor where lower fluid temperatures work better.

The saving on fuel has to be seen in the context of houses that are much better built than they were in the past. If your house's space heating energy requirement is only 5,000 KwHrs per year, then using oil or gas will cost you about €400. If a heat pump brings that down to €300, it is hard to see the return on investment. Your DEAP analysis done by the assessor should be able to give you ballpark requirements and you will find operating costs for various options (oil, gas, electricity) on the SEAI site.

ROI on solar PV is also difficult at present, but the captital cost is low. If ESB re-introduces its microgeneration scheme (and most observers expect this to return in some shape or form) then it would wash its face financially, and is a trouble-free option.

Monfreid

thanks for your reply

the house is 2400 sqf and BER will be A2 with option 1 and A3 with option 2.
estimated running cost €950/year for option 1 and €1800 for option 2.
so it's nearly double with LPG so you think that you would be mad to go with LPG but when you see posts of people spending 400-600 eur in ESB bills every 2 months and have to open windows for to cool down the house, it does not seem like a good idea after all to go for option 1
still don't know ... Option 2 is my favorite for the moment but just want to be sure not too make a mistake on that.

KCross

Monfreid wrote: »

thanks for your reply

the house is 2400 sqf and BER will be A2 with option 1 and A3 with option 2.
estimated running cost €950/year for option 1 and €1800 for option 2.
so it's nearly double with LPG so you think that you would be mad to go with LPG but when you see posts of people spending 400-600 eur in ESB bills every 2 months and have to open windows for to cool down the house, it does not seem like a good idea after all to go for option 1
still don't know ... Option 2 is my favorite for the moment but just want to be sure not too make a mistake on that.

For that size house and an A-rating I'm amazed that the running costs for either option would be anything more than a few hundred. I'd say something is wrong with the figures here.

quentingargan

KCross wrote: »

For that size house and an A-rating I'm amazed that the running costs for either option would be anything more than a few hundred. I'd say something is wrong with the figures here.

I'd agree. If your energy assessor will share the xml file from the DEAP assessment, you can see how many KwHrs is for water heating, and how much is space heating.

Water heating with a heat pump is usually at a much reduced COP. I have seen some assessments for larger houses which hugely exaggerated the water heating element. It is related to the house size irrespective of whether you have two people or ten living there and usually with generous assumptions.

Monfreid

the DEAP programm now gives me another option to go with AWHP + Rads if I improve the air-tighness

3 options

- Option 1: Air-to-Water Heat Pump + Underfloor heating
- Option 2: Air-to-Water Heat Pump + radiators downstairs and upstairs
- Option 3: LPG+PV

So UFH is not mandatory anymore with AWHP but the drawback is that the heatpump will have to run longer so annual running cost will rise.

so the difference between gas and heat pump will be 1200 vs 1800 eur per year so 50 eur per month "only". I said "only" because when you read posts about people paying huge electricity bills because of the heat pump, I'd say that the difference might not even be 50 eur per month in the end.

so now that the underfloor heating is out of the equation (I didn't like the slow response (to heat or cool down) and the fact that you can't have carpet unless you planned this during the build), it's really down to heat pump vs gas. Oil price will go up and down so gas price too but electricity will also follow.

I'm still looking at the LPG option to be the best for me because of the unknown cost of the heat pump.

Does anyone has experience with LPG? is it really expensive? The fact that you only have 2 suppliers is it really an inconvenience?

Thanks

galwaytt

....the 'too slow to respond' thing about UFH is over-sold imho.

First, it will be 'too slow' in too-heavy screeds and buildings with high thermal mass. Others, not so.
Second, in a well-built house, with good fabric, windows/doors & floors, then UFH should only be (seldom) on. If your building is heating/cooling so quickly that UFH response is influencing it that much (and noting my first point), then frankly your fabric is suffering from 'caravan syndrome'. That is, is too susceptible to external heat/cold. In other words......there's something awry.

Properly built, the idea of a good fabric in the first place is that it remains as constant as possible, with only small inputs of either cooling or heating in the first place.

Then, when it comes to choice of what drives your heat delivery system (UFH, rads etc), then the choice of primary heat become simpler, not more complex. If you have access to wood/turf etc, then you'd consider a solid fuel system. If in urban and near natural gas, you'd use that. Maybe you don't want oil for some reason, then LPG. Got a big site and don't mind the capital cost - then GSHP/ASHP comes into frame. Huge roof ? Solar (thermal/PV) comes on your radar.

Naturally, there are some synergy's: ASHP and GSHP work well with UFH, not as well with rads.

The primary heat methods are not necessarily prescriptive to heat delivery methods - you should actually be working BACK from you building performance and fitting 'heating' into that, not building a heating system and putting a building around it - imho that is.

galwaytt

Monfreid wrote: »

the DEAP programm now gives me another option to go with AWHP + Rads if I improve the air-tighness

3 options

- Option 1: Air-to-Water Heat Pump + Underfloor heating
- Option 2: Air-to-Water Heat Pump + radiators downstairs and upstairs
- Option 3: LPG+PV

So UFH is not mandatory anymore with AWHP but the drawback is that the heatpump will have to run longer so annual running cost will rise.

so the difference between gas and heat pump will be 1200 vs 1800 eur per year so 50 eur per month "only". I said "only" because when you read posts about people paying huge electricity bills because of the heat pump, I'd say that the difference might not even be 50 eur per month in the end.

so now that the underfloor heating is out of the equation (I didn't like the slow response (to heat or cool down) and the fact that you can't have carpet unless you planned this during the build), it's really down to heat pump vs gas. Oil price will go up and down so gas price too but electricity will also follow.

I'm still looking at the LPG option to be the best for me because of the unknown cost of the heat pump.

Does anyone has experience with LPG? is it really expensive? The fact that you only have 2 suppliers is it really an inconvenience?

Thanks

I don't know where you get the 'can't have carpet' with UFH thing ? I have tiles, laminate, solid wood and laminate with rugs. All with UFH.

I have LPG, and had to buy a new boiler recently. I thought I'd take the time to look at ASHP (GSHP not an option - not digging up drives & gardens !), but the sheer capital cost of ASHP put it out of contention.

I'm with Calor, and probably moving to Flogas soon - so even switching isn't a big deal anymore. The fuel is expensive to some, but I prefer it as a fuel. Clean, simple, efficient. But I use it for both heat and fireplace, so I don't have any solid fuel spend - it's all about balancing things.

Look at it this way, if you're building a really good fabric, your fuel use should be small. In which case difference in price of fuel (unless huge) is ultimately dependant on how much of it you (intend) to use. I know of a house of well over 300m2 that spends about €375 pa on LPG. He has an LGP boiler and 3 solar panels (dhw). What would spending 5k+ on a HP, instead of €1600 on an LPG boiler save, per annum, given the miniscule usage ? Very little. And as for the capital cost...........he'd never get it back.

Monfreid

galwaytt wrote: »

I don't know where you get the 'can't have carpet' with UFH thing ? I have tiles, laminate, solid wood and laminate with rugs. All with UFH.

I've read that on the net and on my advisory report too that if you plan to have carpets, it's better to have the pipe closer to the floor to compensate the heat loss

Thank you very much for your comments on LPG, very useful.

my house is not built yet. I'm not trying to build my house around the heating system. I've got a advisory report from an energy consultant on what heating system would suit best my house. The answer was AWHP+UFH as 1st choice or LPG+PV as second.

I'm just trying to get information on what system should be best and I think I'm going to choose LPG because I don't want UFH (can have rads with the heat pump but then it won't be as efficient hence higher runnig costs) and also because I've read/eard so many stories of people having huge electricity bills with HP if not set up or installed properly.

galwaytt

Monfreid wrote: »

I've read that on the net and on my advisory report too that if you plan to have carpets, it's better to have the pipe closer to the floor to compensate the heat loss .

Thank you very much for your comments on LPG, very useful.

I can't see the difference in the position of the pipe as being measurable tbh, especially when you consider the small dimensions we're talking about. Consider a 75mm screed, with the pipe centrally located - so 30mm from the top of the screed. Relocating that pipe to, say, 20mm from the top would not only (imho) be indistinguishable in performance, I'd actually say would be more likely to cause other problems (likelihood of damage from people installing and working on floors over, maybe cracking of screed etc etc).

And, thermally, the mass of the floor screed is still 75mm deep, and until that mass reaches the (required) temperature, the heat won't enter the room until all of that mass reaches equilibrium. I can't see the moving of the pipe by a few mm having any measurable difference one way or the other - the heat load is the same either way. There is no heat loss due to pipe position. Actually, if there was a loss, I'd suggest there's something wrong with the insulation under the UFH in the first place..........

Of course, UFH with a thinner wet screed would respond better than sand/cement, and would be more akin to a 'radiator' which may in fact be the best of both worlds.

I am in my 2nd UFH house, the first dating back to 1997 and still working perfectly, so I do have one of the longer-term experiences of UFH generally.

Monfreid

Thanks again fr your feedback on this.

I have decided to go with LPG & Rads + stove & back boiler.

The house's BER will be A3 so a good insulated house (2400 sqf) so hopefully the bills won't be too high.

I don't trust Heat Pumps, it only works great if it's properly installed and set up so it's a gamble on your future electricity bills, might be low as expected, might be very high like so many people have reported on this forum and you're stuck with this system until you can afford to convert to a different one.

The energy consultant said that I need to add 7 PV to be compliant with the regulations but these PV won't be used for Heating Water, just generate electricity that is "pumped" into the house so savings on Electricity bills. The Solar Water Heating system are not efficient enough or too costly

galwaytt

Monfreid wrote: »

Thanks again fr your feedback on this.

I have decided to go with LPG & Rads + stove & back boiler.

The house's BER will be A3 so a good insulated house (2400 sqf) so hopefully the bills won't be too high.

I don't trust Heat Pumps, it only works great if it's properly installed and set up so it's a gamble on your future electricity bills, might be low as expected, might be very high like so many people have reported on this forum and you're stuck with this system until you can afford to convert to a different one.

The energy consultant said that I need to add 7 PV to be compliant with the regulations but these PV won't be used for Heating Water, just generate electricity that is "pumped" into the house so savings on Electricity bills. The Solar Water Heating system are not efficient enough or too costly

Sounds good, although I disagree with the solar (thermal) panels part. I got all the way from Dec 27th last until 2 weeks ago with no boiler, purely reliant on my solar to keep me in DHW, so they do work.

Btw, even if you do put PV, you can't use them to heat water (via element) or you'd be hammered by DEAP anyway. Thanks to SEAI, heating your own water with your own electricity doesn't count as efficiency :rolleyes::rolleyes: and they consider it the same as connecting an immersion to the mains......... :rolleyes::rolleyes::eek:

quentingargan

galwaytt wrote: »

Btw, even if you do put PV, you can't use them to heat water (via element) or you'd be hammered by DEAP anyway. Thanks to SEAI, heating your own water with your own electricity doesn't count as efficiency :rolleyes::rolleyes: and they consider it the same as connecting an immersion to the mains......... :rolleyes::rolleyes::eek:

Yes, though in fairness, you need 10KwHrs of heat or 4kwhrs of electricity. The difference is because it takes 2.5kw of gas at the power station to produce 1kw of electricity. (well, actually 2.37 apparently).

So if you use the electricity to heat your water, they treat it as heat and you lose that multiplier.

There is broad expectation that a feed in tariff for electricity will be introduced in the next year once they go through the white and green paper nonsense used to kick a ball into touch. Once that happens, then it would be cheaper to use gas to heat your water and export your electricity.

freddyuk

Are we expecting this incentive to include existing systems (early adopters) or only new installations. If only for new installations we can expect the UK problem of de commissioning existing systems to then re apply for a new system to get any tariff. Sadly I suspect the same old problem will prevail in that those in charge will have little actual experience of the actual discipline they are in fact controlling and possibly the scheme will be skewed to generating jobs via certifications and over regulation rather than encouraging renewable energy production on a local scale.