Does a GSHP make sense in a Grade 2 listed building in need of complete renovation

matt_drummer

Your thread title.

Does it make sense?

I don't think so!

Do you?

The best Kensa gshp I can see has a SCOP of 3.6

If you're going to do it, go for something decent, preferably Stiebl Eltron.

QrizB

fizio said:

I have had the quote below from Kensa.

What you've been given is not a quote.

fizio said:

I have looked into the project details you have sent across and would anticipate a budget cost starting from:

£25,000.00

So this is just a rough estimate and "starting from" makes me think the final price coulfd be considerably higher. They've left a lot of likely costs out from their estimate.

fizio said:

.. the next stage would be for us to conduct a feasibility study for your project, the cost of this is £500.00 (+VAT) and will be inclusive of an MCS accredited heat loss report and a geological study, everything required to enable us to provide a concise quote and move your project forward.

So you wont get an actual quote until you've paid them £600 (£500+VAT).

It's your money, but I can't see a £25k+ GSHP providing good value when compared to an ASHP that might cost less than half as much.

Reed_Richards

I looked into getting a GSHP before opting for an ASHP.  My estimate for a GSHP came in at a similar cost to the sum you have been quoted.

Strummer22

Reed_Richards said:

I looked into getting a GSHP before opting for an ASHP.  My estimate for a GSHP came in at a similar cost to the sum you have been quoted.

I had quotes for both too. Apparently the calculated heat demand was too high for a single ASHP; it would have needed two. Even then, the install cost of the two ASHPs was significantly less than the GSHP. Install cost of my GSHP (22kW) was £29,300 (in 2022) and the two ASHPs (14kW each) would have been £17,820.

We use considerably less heat than stated on our EPC, which is 27,600 kWh heating and 2,700 kWh hot water. In total the heat pump produced 16,200 kWh last year. We do only heat to 18.5°C. In practice a single ASHP might have done the job.

Anyway, the only reason we chose GSHP was because of the RHI, which closed in March 2022. The cap for payments was much higher for GSHP, and the demand on our EPC just exceeded the GSHP cap (way exceeded the ASHP cap). So although the installation cost was very high, we are currently getting over £5,000 per year back from the RHI which will continue increasing with inflation until payments end in 2029. The government has paid US to have a GSHP. Without such a generous incentive we would definitely have gone with an ASHP.

fizio

Given I am being told that I have e to have boreholes rather than low trench GSHP - is there advantages or disadvantages with this route from a cost/efficiency/ongoing maintenance etc perspective. 

I agree that ASHP is looking the most cost effective but would like to give the GSHP option a fair shot. I have read in various places that ASHP is least efficient in cold weather so that’s not filling me with confidence, especially as I have limited insulation options. I’m assuming sizing correctly etc can be used to ensure the ASHP is able to do the job in the cold weather plus some backup electric heaters or wood burner. 

FreeBear

The following is my opinion only. Boreholes take up less space and have potential to produce more heat than slinkies (subject to depth & geology). Deep boreholes need bigger, more powerful pumps to circulate the brine. If the pipe springs a leak, it is a major headache extracting it (but the same can be said for slinkies).

Yes, a GSHP returns a better COP than an ASHP on real cold days, and the COP is fairly constant throughout the year. On warmer days, an ASHP can knock the socks off a GSP with a much higher COP. So with an ASHP, you need to play the numbers game and look at the averages over the heating season. Down here in the SE of England, we don't get many days when it is freezing outside, so an ASHP would be returning a decent COP offsetting the sub-zero days when the COP is pants.

Reed_Richards

A problem with boreholes is that the drilling company can find out what the land is like in your area but they won't know how easy or difficult your particular terrain is for drilling until they try.  The GSHP company will refer you to a drilling company and the drilling company will not give you a firm quote, just an estimate.  

Patrol

Things might vary by company but when I had my GSHP (new build, 2007) installed, the unit was supplied. I hired a digger driver for a morning to dig 2 38x1x1m trenches and lay a course of sand. I laid the external pipework myself and the plumber who installed the heat pump pressure tested the external pipes before I backfilled the trenches. Then the supplier commissioned the heat pump.

When you say 200-300m space I'd say it depends on the layout. A longer run is probably better than a compact rectangular area, and I ran them from the house to as far as they would go. If you have trees that may be hard or impossible to achieve. Even at 1m depth I don't think I'd want to encircle the house so can see why borehole may be recommended.

A properly sized heat pump will keep the property warm and supply hot water. Lack of insulation and/or unsuitable radiators will increase running costs - "excessive" cost I would say is more likely than being unable to heat the house. You can mitigate that e.g. batteries with Octopus Cosy tariff (charging batteries at the 3 low rates so you are buying cheaper electricity) - solar panels will help primarily in March / April / October but less so during winter when heating demand is highest and if grade 2 listed you may not be able to install any.

In your position I'd be looking to obtain oil consumption from previous owners, or stick with present heating for a year to baseline heating costs and be confident about what size of heat pump is required to achieve that

fizio

Thanks for your comments Patrol, and it does seem that there are too many variables with GSHP in terms of the land and layout I have plus the Listed Building angle about housing all the bits - which generally increases my risk and hence costs so I am thinking ASHP with some back electric heating may be the best bet (most of the rooms have a chimney so possible to stick in a flu and electric stove or some-such.
Sizing will be tricky as the place needs a full renovation including various insulation elements so I will have to get someone in once the insulation work is done (floors, walls, loft, etc). 

FreeBear

fizio said: Sizing will be tricky as the place needs a full renovation including various insulation elements so I will have to get someone in once the insulation work is done (floors, walls, loft, etc). 

If you are ripping up floors, float the idea of wet UFH with the CO. It would also pay to get someone on board early on to advise on plumbing & radiator sizing so that you can get pipes in as the renovations progress.

Oh, and if you have space outside for a log store, a wood stove or two makes for a valuable addition. Maybe not if you have a thatched roof though...