Heating Systems - which scheme?

mrsWhippy

Hi

We have two heating schemes for our new build which both meet Part L requirements. I'm swinging wildly between the two options and would like to hear your opinions please.

MVHR and stove are common to both schemes - house will be as airtight as financially possible, sub 3 anyway. UFH on both floors under engineered oak.

1) Gas boiler with solar tubes and 3* PV panels
2) Air to water heat pump.

The cost to install is more or less the same for both systems, plus or minus a few thousand.

Can anyone comment on the long term costs of either options please?
Thanks

delfagio

Hi mrswhippy

You mention that there is not much in cost difference between the 2 options. However with both options do you not require some form of solar to meet the renewable requirements of Part L?

I assume you would so this may change the cost difference between the two options.

mrsWhippy

delfagio wrote: »

Hi mrswhippy

You mention that there is not much in cost difference between the 2 options. However with both options do you not require some form of solar to meet the renewable requirements of Part L?

I assume you would so this may change the cost difference between the two options.

No - there is no solar required for option 2. The heat pump in addition to the stove is enough to meet reqs.

Though we were wondering if it would make financial sense to add some solar tubes here, or would it be cheaper to just use the pump for heating water - tubes are surprisingly expensive!

Coles

If you have access to mains gas then I'd be inclined towards it over a heat pump, but either way I'd definitely consider additional solar (water heating and PV).

The heat pump would work well for UFH, but you'd lose about 10-15% efficiency if you were also using it to produce hot water. Having a solar collector to boast your water temperature would work well.

I think you could save €3-4k with the gas option which could be spent on better insulation and windows. Also make sure that the contractor focuses on the airtightness. It really makes a big difference to the performance and comfort of a house when it's done properly and it doesn't have to add any extra cost.

Best of luck with it,

mrsWhippy

Coles wrote: »

If you have access to mains gas then I'd be inclined towards it over a heat pump, but either way I'd definitely consider additional solar (water heating and PV).

The heat pump would work well for UFH, but you'd lose about 10-15% efficiency if you were also using it to produce hot water. Having a solar collector to boast your water temperature would work well.

I think you could save €3-4k with the gas option which could be spent on better insulation and windows. Also make sure that the contractor focuses on the airtightness. It really makes a big difference to the performance and comfort of a house when it's done properly and it doesn't have to add any extra cost.

Best of luck with it,

That's really helpful. Thank you!

If you were going to invest 3 or 4k into additional renewables for the Heat Pump option, would you go for tubes or PV?

DeeJunFan

If it were me i wouldn't bother with the solar tubes. They only ever make hot water, which PV can do with a iboost/immersun and you don't need to worry about heat dump in the summer.

Gas boiler or ASHP is pretty much whichever you think would suit you and your house best.

With Gas boiler you are going to be heating water to a high temp and blending down, if you get a decent PV system you wont probably use much during warmer months. and will it be mains or tanked?

With ASHP you are going to be heating water to a low temp and perhaps bumping up with immersion/PV.

My initial plan was to go with ASHP and 4kw PV.

And i know there are a lot of people who will say i'm mad that the tubes are the best for hot water, but i personally don't see the payback, for the cost and complexity in comparison to PV.

Coles

+1 DeeJunFan.

Solar PV has become very affordable, but it's just a shame that our stupid government won't allow homeowners to be reimbursed for supplying excess power to the National Grid. Every other country allows it! A device like the Immersun goes some way towards making use of excess production but really there should be Net Metering or a proper feed-in-tariff. Another option that is worth considering when doing the sums on a large PV array (3kW+) would be the possibility of using the excess power for an electric vehicle but that would only really suit if the vehicle was usually parked at home.

I'd have some concerns with the ASHP, plus MHRV, plus Stoves, plus Solar might be overkill. A well insulated and airtight house built to the current regulations really needs relatively little heating energy and the ASHP might lock up a lot of money that could be spent better.

DeeJunFan

Coles wrote: »

+1 DeeJunFan.

Solar PV has become very affordable, but it's just a shame that our stupid government won't allow homeowners to be reimbursed for supplying excess power to the National Grid. Every other country allows it! A device like the Immersun goes some way towards making use of excess production but really there should be Net Metering or a proper feed-in-tariff. Another option that is worth considering when doing the sums on a large PV array (3kW+) would be the possibility of using the excess power for an electric vehicle but that would only really suit if the vehicle was usually parked at home.

I'd have some concerns with the ASHP, plus MHRV, plus Stoves, plus Solar might be overkill. A well insulated and airtight house built to the current regulations really needs relatively little heating energy and the ASHP might lock up a lot of money that could be spent better.

I'm luckily building in NI so we have a Feed in Tariff in place, its being phased out so need to get setup asap.

Our regs are also somewhat leaner so my current thinking is i would be able to get rid of the ASHP, and run my system just PV, stove and immersion.

The hope would be that during summer months we would have enough supply from the PV, and in the winter months use E7 to get hot water from immersion.

Any top up would come from stove and possible a duct heater.

adrianm1234

DeeJunFan wrote: »

If it were me i wouldn't bother with the solar tubes. They only ever make hot water, which PV can do with a iboost/immersun and you don't need to worry about heat dump in the summer.

Gas boiler or ASHP is pretty much whichever you think would suit you and your house best.

With Gas boiler you are going to be heating water to a high temp and blending down, if you get a decent PV system you wont probably use much during warmer months. and will it be mains or tanked?

With ASHP you are going to be heating water to a low temp and perhaps bumping up with immersion/PV.

My initial plan was to go with ASHP and 4kw PV.

And i know there are a lot of people who will say i'm mad that the tubes are the best for hot water, but i personally don't see the payback, for the cost and complexity in comparison to PV.

any co.s you would recommend for PV.Who did you go with for a2w and PV. How much is a 4kw PV set up and whats the payback in comparison with solar tubes. Thanks in advance

adrianm1234

How much PV needed for a 2400 sq ft house a3 rated and how much would it cost??

DeeJunFan

I'm getting mine through a company in NI. You can PM if you want details but i'm not sure if that would be the best option for you. As there is a FIT scheme in NI and there is usually a bit of a cost associated with getting into the scheme and certification

For me the cost for a 4kw system with 16 panels and in-roof mounting system is 5200 (stg)

But i have seen 4kw systems on ebay for 2500 (stg)

All you would need is a qualified electrician to install.

I would go with the 4kw system if you could. Also and iboost/immersun type device as this will give you hot water when you have excess PV generation (during the day while you are at work for eg)