Quote for GSHP

[benseb]

ASHP for me.
Manage 2 large commercial buildings, 1 started off as GSHP
And was ripped out after 10 years, the other was ASHP from initial design with an air test of 9.99.

Location NE Fife.

ASHP Works well, I use an air con company for installation and yearly maintenance as they know this technology.

How come the GS was ripped out TT?

I think my main concern with GS is that the capacity is fairly fixed by the ground array. If it’s underspecced there’s no real solution except more drilling

At least if an AS is underspecced it’s much easier to pull the unit out and replace with a bigger one. Plenty more air to go around!

We live at the bottom of a hill which does have its fair share of fog tho, so just need to ensure that doesn’t lead to it icing up a lot

[benseb]

Air/air ASHP both here Wales and Sweden.  The Swedish house was well but not super insulated (as new builds are now), most houses had one, only one person had a GSHP.  The 'village ' thought that he was very rich, cost was over 30000 euro for a 120m2 house.   Against our ASHP install of 2500 euro.  Winter temps dropped to -15c.

How did the Wales unit fair? What sort of size property/HP?

Cheers

[benseb]

I’m definitely coming around to the ASHP I think

Any recommended installers in the NW of England?

Also what brand heat pumps have people used?

Our HL now says peak loss of 13kW at design temps (-2) so is it best to go one step up - 15kW just to ensure the emit doesn’t work too hard at the low temps?

In reality we have a 4kW and a 8kW WBS downstairs we would crank up at low temps to ensure we don’t need to run the system at too high a temp but I think I’d feel happier with a bit of margin

[brackwell]

"In reality we have a 4kW and a 8kW WBS downstairs we would crank up at low temps to ensure we don’t need to run the system at too high a temp but I think I’d feel happier with a bit of margin"

After all this time we eventually get there.  These stoves are the reason why the original cals catered for large air changes which presumably you have ignored?   To go with these stoves you must have large air ingress otherwise you would not be able to run the stoves adequately.   If you are unable to completely close off these stoves you need to replace them perhaps with ones that take outside air directly,  or remove them, or use them more 24/7.  Stoves and more so open fires and the attendent draughts are possibly the biggest heat loss in a building.

PS as your oil boiler got a balanced flue? or another big draught/

[benseb]

I’d like to give them credit for thinking about the stove air changes but in reality that first HL didn’t. It had 10 air changes per hour in every room. That’s an entire house air change every 6 mins!

They had also specced all the doors/windows as single glazed when they are double. Etc etc.

The stoves are sealed, with twin wall flue which heats upstairs. The one without an air intake kit has a closable vent (naughty!)

The oil boiler is old so there’s a vent in the wall but that will be going when the oil boiler is ripped out.

Here’s the new heat loss if anyone’s interested. Seems to make sense. Also great to see which rooms to improve first.

[todthedog]

Welsh install was for the kitchen/lounge about 35m2, this is where we live. The idea was to take over heating into the shoulder months and perhaps into the winter if it's mild. We went with Mitsubishi based on reputation and previous installs. It was also the Swedish consumer organisation choice.

3.5kW cost about £650 install £650 of which £500 for refrigeration  engineer,£150 for electrician to run dedicated line and circuit breakers etc.
Bonus to run it in aircon mode if we have a really hot evening powered by the pv.

[JonG]

Hi Ben, we are installers and have worked in the industry for around 12-13 years, vast bulk of our work is retro and we have installed in everything from 400 year old farmhouses to semis and heat pumps can often be made to work and work well in a wide range of applications.

With your heat loss, you are right on the cusp of what a single phase unit can deliver and as I am sure you will know the MCS cannot take into account other forms of heating if the heat pump does not directly control them.

Generally the MCS fabric heat loss calculations do come up above requirements by circa 20-30% if completed correctly but the paperwork has to be in order for the MCS/RHI.

Havent read the whole thread, but main options could be to improve air tightness or insulation to bring the heat loss down, or consider a hybrid perhaps, this is our least favoured option though.

[benseb]

Hi JonG

For this sort of install would you recommend GSHP (would need to be borehole) or ASHP?

We do have three phase so can get whatever size unit we need. It’s looking like about 15Kw

[JonG]

Efficiency wise in a direct comparison there isn't a significant difference between the 2 now in all honesty with inverter driven ASHP and GSHP (fixed speed GSHP actually operate slightly more efficiently than inverters). The main differences are infrastructure cost, lifecycle cost (i.e. outdoor unit degrades quicker than GSHP) and tariff. On boreholes though the additional revenue will soon be offset by the up front cost.

That said choice is an issue, in so far that 3 phase 16kw GSHPs are easily available but you are stretching the envelope on a single phase ASHP at the same duty, many manufacturers are now only offering the single phase range and then there is a jump up to larger outdoor units or a preference for cascades of singles, which are not a bad option given the higher turndown ratio/reducndancy, but at a higher initial infrastructure cost.

There is at least 1 high temp capable of around 16kw from memory, using a cascade of refrigerant that could be an option, it runs on low temp unless bivalent is reached and then fires the 2nd compressor to achieve higher temps and outputs. This does increase complexity and failure points though.

The 14-16kw area is a bit tricky from a specification POV and it can be that if the calcs are correct a hybrid may make the most economic sense.

[JonG]

At 30,000kwh u are over the cap for ASHP so a hybrid becomes more of an option because you will only be remunerated for the value stated on the EPC, which will be lower than the 30k that the heat loss suggests.

[benseb]

Thanks Jon

We had originally been looking at a 15Kw Heliotherm GSHP which looked quite good but the company kept messsing us around and not returning calls etc.

I was thinking GS would be better as our cap would be 30,000 rather than 20,000. We have n old EPC which states approx 33,000 for heating.

We do still have a working oil boiler but presumed this would just get messy from an RHI point of view and with it being old we didn’t really want to spend extra on oil in the future.

I think going forward we just need to know what options are available so will drop you a message

[JonG]

Strangely enough we were the first to bring Heliotherm into the UK!

Think we still have the partner rights for distribution but would have to check, we installed one back when fixed speed were easy enough to route through DNO's so didnt fit another, with the creaking grid now, pretty much everything is inverter.

It's a dear option, very well made, I trained at their plant in Austria on it, but the costs don't reflect in higher savings against other units IMHO.

EPC has to be 2 years old to qualify now.

Oil is harder to integrate due to usually high, fixed output, fixed flow temp (and has to be high enough to avoid condensation at the boiler) but is doable with BEP and a mixer, also a heat meter is needed for a hybrid, but this can be a blessing plus you can MMSP if you want.