[BurningNaturalGas]

The RHI should pay for the majority of your HP installation.

Can multiple RHIs be used for multiple GSHPs?

Apparently I would receive £28k over 7 years, for a GSHP, but this amount could reduce by 10%-20%. Even after accounting for the time value of money that is possibly a small profit, but my impression is that I would need an additional source of heating.

One disincentive is that if I were to switch from being employed to being some kind of trader then I would need to pay income tax on those RHI payments!

 

[Jimbo]

I don't think you can have multiple RHIs for the same category, but not an expert!

 

[Ralkbirdy]

but my impression is that I would need an additional source of heating.

Why? A heat pump if correctly sized will meet your needs. It does however, need to used as a thermal store type heating, no use if people expect it to give heat only in the evening when they are home.

 

[SHL-Kelso]

Why? A heat pump if correctly sized will meet your needs. It does however, need to used as a thermal store type heating, no use if people expect it to give heat only in the evening when they are home.

I’ve used it for intermittent and fully zoned underfloor heating since day 1, as the idea of relying on weather compensation simply does not work well in my climate, especially autumn and spring. My house responds slowly to outside temperature changes, yet can experience 10-15 degree swings in outside temperature over 24 hours. Couple that with only requiring 35 degree flow temperature to the underfloor manifolds to allow it to achieve comfortable room temperatures then there is almost no scope for much flow temperature variation anyway! In all but the coldest of weather I can heat rooms in the morning and evening (or just the evening in some cases) and keep room temperatures where I want them. If the weather goes sub-zero for any length of time then I do go for 24 operation, but this has only been for a few weeks each winter.

I do have to allow for the warm up period needed to guarantee comfort levels are reached, and that adds 2-3 hours preheat depending on the room, but it also gives the compressor a decent load initially which keeps it running more continuously rather than the higher number of shorter cycles it runs if the heating is running 24/7.

 

[BurningNaturalGas]

Why? A heat pump if correctly sized will meet your needs. It does however, need to used as a thermal store type heating, no use if people expect it to give heat only in the evening when they are home.

Leaving it on is perfect but I have a difficult to insulate home.

 

[BurningNaturalGas]

I am looking for something that can actually match the cost of new gas boiler over 10 years. Today I received an estimate of £40k for GSHP 🤷‍♂️

 

[dk6780]

Compared to what?

Apparently I would receive £28k over 7 years, for a GSHP

If you are getting £28k on RHI you are getting close. I presume that you are also including the cost of insulation in that figure which you would need anyway.

 

[BurningNaturalGas]

I might go for a phased approach - are any cylinders compatible with all heater types?

 

[BurningNaturalGas]

Compared to what?

Compared with new gas system. The current main heating consists of two fireplaces and a back boiler 🤷‍♂️

If you are getting £28k on RHI you are getting close. I presume that you are also including the cost of insulation in that figure which you would need anyway.

Apparently it might even be £32k but that is not as close as I would like after accounting for the time value of money. The insulation is a moot point as it needs doing anyway - not that it can have much impact my particular house.

 

[dk6780]

Compared with new gas system.

Apparently it might even be £32k but that is not as close as I would like after accounting for the time value of money. The insulation is a moot point as it needs doing anyway - not that it can have much impact. The current main heating is a fireplace and a back boiler 🤷‍♂️

So how can you compare the amount of energy required for a poorly insulated house using a gas boiler with the amount required by a well insulated property for a GSHP? Or is the quoted cost of the GSHP ignoring the cost of the insulation/the cost of the insulation is included in the price of the gas boiler?

 

[BurningNaturalGas]

Yes the quotes are for the heating only and based on worst case scenario, which is that the insulation has no impact at all. I am told I need 18kWh of heating, which translates into three GSHP bore holes.

Of course the insulation will be done, but its a higgledy piggledy house with various roofs added at various times with a raft of materials and qualities. Added to that, COVID19 is making any renovation difficult.

 

[dk6780]

I had forgotten that you have a limited area for installing coils for a GSHP, and hence why you are having to consider boreholes. From other people's reported experience of boreholes I'd give it up as a bad idea and choose either an ASHP or remain on Gas and hope that the change to H2 comes quicker than the CO2 penalties.

 

[BurningNaturalGas]

I had forgotten that you have a limited area for installing coils for a GSHP, and hence why you are having to consider boreholes.

Apparently boreholes add only a few thousand pounds. How many acres are needed to deliver GSHP without boreholes?

 

[SHL-Kelso]

My 11kW GSHP has around 700m of buried pipe, no slinkies, just straight bore. My trenches are 25m long and were dug with a 1m wide bucket on the JCB to allow two pipe runs per trench, then a metre gap, so a 1m separation to the next tench. So with 50m per trench that’s 14 trenches over an area roughly 25x28m. It took a digger and mate just over a day to dig all trenches, lay the pipe, and back fill.

 

[Ralkbirdy]

I used 25,000kWh of gas in a cast iron gas boiler, some 50mm Celotex, 100mm wool underfloor insulation and now down to 20kWh of electricity daily for ASHP and general house stuff in October. What are your typical winter temperatures, in Birmingham we rarely get frosty days anymore, frequently had to clear the windscreen of frost but no longer.

 

[BurningNaturalGas]

Global warming is certainly changing UK lives and reducing our (very high) demands for heating. How many of us now drive on summer tyres all year round?

I was discouraged from considering 18kWh ASHP because single phase electricity supply means multiple pumps would be needed.

 

[JDleaf]

Lots of interesting stuff here, I know I’m doing a bit of a thread dredge, sorry! We’re in the process of buying a house with electric storage heaters and (currently) an economy 10 meter. No gas. I’m considering getting central heating and ASHP fitted pretty much as soon as we move in if we can afford it. Have to double check insulation too, but current owners say there is lots, they never qualify for the free loft insulation schemes and there is cavity wall insulation. Obviously I’ll get contractors locally to quote us if it all goes through, but wondered if any of the knowledgeable folk here can spot or suggest anything I’ve missed for consideration. Cheers.

 

[BornAgainEcoWarrior]

Lots of interesting stuff here, I know I’m doing a bit of a thread dredge, sorry! We’re in the process of buying a house with electric storage heaters and (currently) an economy 10 meter. No gas. I’m considering getting central heating and ASHP fitted pretty much as soon as we move in if we can afford it. Have to double check insulation too, but current owners say there is lots, they never qualify for the free loft insulation schemes and there is cavity wall insulation. Obviously I’ll get contractors locally to quote us if it all goes through, but wondered if any of the knowledgeable folk here can spot or suggest anything I’ve missed for consideration. Cheers.

Maybe check if the economy tariff is tied to a separate circuit. Some installs had a separate circuit that only goes live during E7/10 period that adds some headaches.
If you've got to install all the pipework and radiators etc then that's a significant job. You might consider some alternatives to wet heating systems, but I know many people don't like them.

 

[DragonQ]

Personally I'd just go for ducting if there aren't any radiators anyway. You can use the ASHP to best and cool effectively then. Also MVHR will be an option.

 

[JDleaf]

Maybe check if the economy tariff is tied to a separate circuit. Some installs had a separate circuit that only goes live during E7/10 period that adds some headaches.
If you've got to install all the pipework and radiators etc then that's a significant job. You might consider some alternatives to wet heating systems, but I know many people don't like them.

Thanks both for your thoughts. Yes there is a separate circuit for the storage heaters on the low period electric. It would be a complete pipe work/radiator instal, and I know nothing of alternatives to ‘wet heating’. I’ll look into ducting/MVHR as well then. any other thoughts gratefully received.