Heat pumps are underfloor heating

[John Hardy]

I'm extending some of the work I'll do myself, but the architect suggested underfloor heating and potentially putting in an air-sourced heat pump. 

 

I'm open to it, but he suggested a company (which probably gets a kickback). I've researched grants, but I remain unconvinced, especially as the ones I looked at are just heat and not cool. 

 

The home was built in 2001, but does anyone have experience with heat pumps and any help knowing if it's worth it and what I need to factor in? 

[JohnMo]

Two ways to operate a heat pump with under floor heating.

 

1. Sized very closely to the heat demand, set up weather compensation and the let the heat pump run unconstrained by thermostats. It will then feed as little or much heat to the floor as required. Not a fan of any thermostats (may be one), so no actuators needed on manifold no mixer or pump.

 

2. The other way is to batch charge floor, you need a decent depth of screed and heat losses from house need to be low.

 

Most situations the first way to run is best. Basically run long period at a low flow temp.

 

You just heat the floor, you can also cool it.

 

All depends on what you end having to pay after your £7500 grant. But I just did a self install without grants.

 

You want plenty of insulation in any floor with UFH to lower the downwards heat losses.

[joth]

38 minutes ago, John Hardy said:

I'm extending some of the work I'll do myself, but the architect suggested underfloor heating and potentially putting in an air-sourced heat pump. 

 

I'm open to it, but he suggested a company (which probably gets a kickback). I've researched grants, but I remain unconvinced, especially as the ones I looked at are just heat and not cool. 

 

The home was built in 2001, but does anyone have experience with heat pumps and any help knowing if it's worth it and what I need to factor in? 

It's not clear, are you proposing to replace your existing heating (gas boiler?) with a heat pump, or just use the heat pump for the UFH in the extension?

 

You'll only get the grant if the ASHP can provide all heating and hot water for the whole property. Not just the extension. And if doing the whole property, the extension is the easy bit. The big ticket items are installing/upgrading heat-pump ready hot water cylinder and radiators.

 

[Dave Jones]

BEfore you do anything you need heat loss calculation for your building. 

 

This will tell you if your on a hiding to nothing.

[RobLe]

2 hours ago, John Hardy said:

especially as the ones I looked at are just heat and not cool. 

I'm pretty sure that to get the grant, you must swap out a fossil fuel heater entirely with an ASHP, and the ASHP must be heating only. 

Many of them can be retrospectively altered to include cooling, as almost all ASHP have built in reversing valves in order to defrost more effectively (than using a heater internally) - so it's a firmware change, or a dongle added on to "authorise" cooling.

I can understand the mcs intention behind disallowing cooling - but I think cooling is a significant personal benefit of a heatpump over a conventional gas boiler, so it would encourage ASHP uptake for a little extra electricity use in summer.  

[JohnMo]

26 minutes ago, RobLe said:

swap out a fossil fuel heater entirely

Yes

26 minutes ago, RobLe said:

and the ASHP must be heating only.

No stipulations about that any more.

 

[MR10]

22 minutes ago, RobLe said:

the ASHP must be heating only. 

I haven't seen any mention of cooling been excluded, any links to where this is stated? 

[JohnMo]

4 minutes ago, MR10 said:

I haven't seen any mention of cooling been excluded, any links to where this is stated? 

It's not, but many years ago it did. 

[John Hardy]

On 28/06/2024 at 12:28, Dave Jones said:

BEfore you do anything you need heat loss calculation for your building. 

 

This will tell you if your on a hiding to nothing.

Yes a very good point, I've looked at manual calculations, we got double glazing in which we know had a massive impact, but to be honest, I'm not 100% on the type and thickness of insulation in walls, roof, and floor.  I'm considering talking to a domestic energy assessor 

[John Hardy]

On 28/06/2024 at 11:26, joth said:

It's not clear, are you proposing to replace your existing heating (gas boiler?) with a heat pump, or just use the heat pump for the UFH in the extension?

 

You'll only get the grant if the ASHP can provide all heating and hot water for the whole property. Not just the extension. And if doing the whole property, the extension is the easy bit. The big ticket items are installing/upgrading heat-pump ready hot water cylinder and radiators.

 

Sorry - to be clear I'm looking at the full system - to be eligible for the grants, but don;t know if its a false economy - because of the retrofitting. The initial consideration came from the new underfloor heating we're getting. I've got a good Worcester boiler, well maintained but its almost 10 years old.  

[John Hardy]

On 28/06/2024 at 13:18, RobLe said:

I'm pretty sure that to get the grant, you must swap out a fossil fuel heater entirely with an ASHP, and the ASHP must be heating only. 

Many of them can be retrospectively altered to include cooling, as almost all ASHP have built in reversing valves in order to defrost more effectively (than using a heater internally) - so it's a firmware change, or a dongle added on to "authorise" cooling.

I can understand the mcs intention behind disallowing cooling - but I think cooling is a significant personal benefit of a heatpump over a conventional gas boiler, so it would encourage ASHP uptake for a little extra electricity use in summer.  

Yes, 100%; I'm also looking at an aircon solution as an option and trying to go down the best route. I;d had a quote from eons air source heat pump but it was heating only, better going to a local guy for pricing - but I also got in to the air sourced vs. ground sourced, ha - its always the plumbing that's the most difficult part.