Im in the process of planning a self build 170m2 house in the countryside, no gas available so thinking ill need to go for an ASHP, could anyone advise me of what type of ASHP to go for and a rough cost? Also should i be looking at underfloor heating to increase effficiency?

 

Thanks

Your house is a similar size to @joe90s, he fitted his own I think.

And yes to UFH if you have a decent amount of insulation under it.

Edited October 26, 20205 yr by SteamyTea

New self build, about 280sqm,  Had 8.5 Ecodan supplied and fitted for £8514.

Just filling out the RHI application. Payments over 7 years  £6370. Will depend on your EPC.

Many have self fitted similar system.

 

 

Edited October 26, 20205 yr by JamesP

45 minutes ago, SteamyTea said:

Your house is a similar size to @joe90s, he fitted his own I think.

And yes to UFH if you have a decent amount of insulation under it.

yes, I bought a new ASHP on Ebay fir cash and installed it myself, not difficult (with help on this forum from others), my new build is passive esk (I.e passive principles but not certified levels or equipment). UFH is a must IMO with lots of insulation under the floor.

I would look for an inverter driven monoblock one of the latest ones that run on the more environmentally friendly R32 

COP, size and noise levels are important factors. Price so depends on your needs, preferences and expectations.

I think underfloor heating is a no brainer in a self build, I know it is a lot harder to retro fit.

Good luck

 

Edited October 27, 20205 yr by Simtronic

13 minutes ago, Simtronic said:

more environmentally friendly R32 

Still has a GWP of 675.

CO₂ is 1

 

I really wish the industry would hurry up and move over to CO₂ pumps.

Maybe there are other reasons why they aren't using CO_{2, how effective is it and at what cost?}

2 minutes ago, SteamyTea said:

Still has a GWP of 675.

CO₂ is 1

 

I really wish the industry would hurry up and move over to CO₂ pumps.

They tried. Sanyo had them in the market over 10 years ago and we had one installed on a commercial build. Nightmare to get spares for and need lots of specialist tools and equipment to service due to different gas pressures that are used in the units. From memory Sanyo left that market in about 2012 and went back to the standard refrigerants. 

3 minutes ago, Simtronic said:

Maybe there are other reasons why they aren't using CO₂

Yes, I think it is the lack of skills in the plumbing industry.  CO₂ heat pumps have been around decades now.

Just been reading up on it and Denso and Stiebel Eltron are bringing a CO2 heat-pump out for residential use. As far as I can see it is only available in Japan at the moment.

Hopefully it will see a revival but how long until available here?

42 minutes ago, Simtronic said:

I would look for an inverter driven monoblock one of the latest ones that run on the more environmentally friendly R32 

COP, size and noise levels are important factors. Price so depends on your needs, preferences and expectations.

I think underfloor heating is a no brainer in a self build, I know it is a lot harder to retro fit.

Good luck

 

ok origionally i wasnt going to fit underfloor heating to save money but hearing it works best with this system it looks like ill now need to look into it, can anyone give me a rough cost for it?

 I built my own from bits from ebay around £500 for pipes spreader plates, 8 port manifold and blender. But if I factor in my time a lot more

 

edit: this was 8 years ago and doesn't include a whole lot of insulation 

Edited October 27, 20205 yr by Simtronic

5 minutes ago, Simtronic said:

 I built my own from bits from ebay around £500 for pipes spreader plates, 8 port manifold and blender. But if I factor in my time a lot more

would a wet or electric system work best with the ASHP? not needing to have radiators will bring the costs down a bit?

ASHPs take heat from the air and move it to water so wet is the only option using ashp. Electric underfloor heating is very expensive to run unless you only use it when sunny and have a massive solar array. Not really viable in the UK unless you have money to burn 

Biggest expense/work with UFH is the insulation/digging required. With a new build this can be planned fir so less hassle/expense, I have 200mm of PIR on my slab and 70mm flow screed with UFH pipes in it. Some put their  pipes in the slab Tied to the mesh. Installing pipes is a DIY job and pipework not too expensive.

Edited October 27, 20205 yr by joe90

What would be the minimum viable insulation for UFH ( retro fit concrete slab) only 150mm available...?

18 minutes ago, Jilly said:

What would be the minimum viable insulation for UFH ( retro fit concrete slab) only 150mm available...?

So your slab is already in?. That only gives you 100mm insulation if you had 50mm screed with pipes in!!!.

Finished floor surface @Jilly ..?

 

Could always float an engineered timber floor over the top of battens with a pug mix between so you could get away with 120mm of insulation with 15mm pipe and then 18mm flooring 

1 minute ago, PeterW said:

so you could get away with 120mm of insulation

 

Also if that insulation wasn't standard PIR with an R value of 0.022, but of a higher spec like phenolic foam with an r value of 0.018.

19 hours ago, joe90 said:

So your slab is already in?. That only gives you 100mm insulation if you had 50mm screed with pipes in!!!.

 

Yes, it's a conversion. To dig out the old slab would have necessitated underpinning...

 

 

You may find that UFH is not the best option. Have you considered 'skirting radiators'?

2 hours ago, SteamyTea said:

You may find that UFH is not the best option. Have you considered 'skirting radiators'?

how not? at the moment im considering uh downstairs and radiators upstairs

41 minutes ago, Amateur bob said:

how not? at the moment im considering uh downstairs and radiators upstairs

Because of the thermal losses through the floor and into the ground.

Just a case of working out the losses and see what comes out in the wash.

 

On 29/10/2020 at 12:57, Amateur bob said:

how not? at the moment im considering uh downstairs and radiators upstairs

 

I think @steamytea  meant me, sorry my question hijacked the thread! 

7 minutes ago, Jilly said:

I think @steamytea  meant me, sorry my question hijacked the thread! 

Yes I did.