ASHP in a new build - any advice, dos or donts to a complete newbie

[saveasteading]

1 hour ago, JohnMo said:

Output could be rubbish at low flow temps

For bedrooms , a short run could be plenty. It will transfer 30° into the aluminium an radiate it, so a quicker response than in screed, and tidier than rads.

[TerryE]

4 hours ago, saveasteading said:

For bedrooms , a short run could be plenty

So is ~£100 plugin rad in the hall. Yes, it costs more to run, but no installation costs. How many years before you break even, if ever?

[saveasteading]

8 hours ago, TerryE said:

How many years before you break even, if ever?

Gut feeling....5 years.

But It is more about elegance and the loss of a part of the wall.

[Conor]

Said this a few times before, but if you can, install UFH in every room, including upstairs. It's the simplest and most cost effective solution (assuming run as a single zone.) if you don't need it, it's not taking up space and only cost a small amount of money.

 

We did the for every room except one... And turns out to be too cold in winter and we need to use an electric oil heater.

[Dave Jones]

waste of time upstairs really, shouldn't be a need for heat in bedrooms with a well built insulated and air tight house.

[G and J]

38 minutes ago, Dave Jones said:

waste of time upstairs really, shouldn't be a need for heat in bedrooms with a well built insulated and air tight house.

As most self builders only self build once, it comes down to a leap of faith.  
 

Air tight I get, because if my ‘91 built house wasn’t a wind tunnel it would be very cosy, but U values are harder to invest in and trust, emotionally.

[sharpener]

On 17/09/2024 at 10:15, saveasteading said:

I've seen some aluminium skirting that the pipes click into. This seems tidy and easy enough to do and is my current plan for upper rooms.

Anybody tried it?

 

Looked at several systems at the NEC last year. For bedrooms with 2 or more external walls it was difficult to get enough surface area to replace the rads on an oil boiler let alone an HP. Expensive, the straight runs are OK but the corners and end fittings up the cost considerably.

[saveasteading]

43 minutes ago, sharpener said:

difficult to get enough surface area to replace the rads 

I'm thinking of the intermediate amount of heat between @ProDave saying we need none, and plumbers speccing big rads.

[ringi]

On 01/10/2024 at 13:25, sharpener said:

 

Looked at several systems at the NEC last year. For bedrooms with 2 or more external walls it was difficult to get enough surface area to replace the rads on an oil boiler let alone an HP. Expensive, the straight runs are OK but the corners and end fittings up the cost considerably.

 

You can install double height skirting in these few rooms, or add a radiator as well as the skirting.  Remember if you make any effort with airtightless the normaly calculated heatlose will be max more then true heatlose.

[ringi]

I am thinking of designing UFH as zoned, but not installing any room thermostats or activators.  Just have a 13 amp socket near manifold for use if I need to later put in a few wireless overheat prevention room stats.

 

Party I may wish to overheat the living room area of our banaglow on cheap rate electricity, but that is 3/4 of floor area so limiting our bedroom will not force use of buffer tank.

[JohnMo]

If you running WC it's pretty difficult to overheat any part of the house. Unless you're curve is way out.

 

Local rooms overheating via solar gain pretty much self manage anyway, delta T between floor and room decreases and output from floor stops. No controls needed.

 

2 hours ago, ringi said:

may wish to overheat the living room area of our banaglow on cheap rate electricity

You can use your floor to buffer loads of heat and it really has very little impact house temp (to a point). Thicker the screed the easier and least fluctuation on house temp.

 

With gas boiler I routinely heated whole house floor for 6 hours and lived of the heat for the next 18 hrs, about 1/2 Deg house fluctuation. Heat pump isn't powerful enough, to do that on a cold day.