Heat pump cylinder without the heat pump...

[Antonb182]

Recently I was given a 14kw heat pump and associated cylinder. Now, we're putting up an outbuilding, it's 100sqm with walls at 0.1 and ceilings at 0.11 (sips build with superfoil). Obviously, the heat pump is going to be massive overkill to provide heating and DHW. However, I was wondering if anyone has just used the CYLINDER from a heat pump as an immersion heater for the DHW without connecting up the heat pump? It'd save me buying a new immersion heater at £1500, and I like the idea of using something I already have if at all possible. Any thoughts on whether this is possible? The heat pump is the puhz-hw140vha2 and the cylinder is ehpt25x-ukhcw. Any thoughts or ideas would be hugely welcome 

 

[JohnMo]

2 minutes ago, Antonb182 said:

wondering if anyone has just used the CYLINDER from a heat pump as an immersion heater for the DHW without connecting up the heat pump?

Basically nothing wrong with that. Have heated mine a few times just via the immersion.

[PhilT]

you say "It'd save me buying a new immersion heater at £1500" - sounds like you are asking if you could use the heat pump only for heating hot water "without connecting up the heat pump" (to the rads/UFH?). Sorry if misunderstood.

[ProDave]

But a 100 square metre building will need some heating, unless you never plan to use it in the winter.  So why not use the heat pump you have?  What else are you going to use?

[JohnMo]

1 minute ago, ProDave said:

But a 100 square metre building will need some heating, unless you never plan to use it in the winter.  So why not use the heat pump you have?  What else are you going to use?

Just do UFH throughout in a thick screed, then you have 20 to 30T of concrete to buffer against and batch charge the floor for a few hours a day. Big heat pumps also usually have a good turndown ratio.

 

Only thing to watch is you have enough flow rate, so add a 2 port buffer and secondary pump as per drawing. 

 

[Antonb182]

On 05/05/2024 at 09:58, ProDave said:

But a 100 square metre building will need some heating, unless you never plan to use it in the winter.  So why not use the heat pump you have?  What else are you going to use?

Only 2 of the rooms are going to need heating over the winter and the requirement (can't find it at the time of writing) is so small that even a 4kw ASHP would be overkill. My thought was to use an aircon system instead then it can also be used for cooling in the summer. I realise this might seem counter-intuitive to save 1500 on a boiler, to then spend it on aircon, but it would definitely make the space more adaptable year round. 

 

I do plan on looping in the UFH as a "just in case" option for future, but the a/c puts out about 1200 BTU's, which should be more than enough to make each space comfortable even in the middle of winter.  

[Dave Jones]

On 03/05/2024 at 20:25, Antonb182 said:

Recently I was given a 14kw heat pump and associated cylinder. Now, we're putting up an outbuilding, it's 100sqm with walls at 0.1 and ceilings at 0.11 (sips build with superfoil). Obviously, the heat pump is going to be massive overkill to provide heating and DHW. However, I was wondering if anyone has just used the CYLINDER from a heat pump as an immersion heater for the DHW without connecting up the heat pump? It'd save me buying a new immersion heater at £1500, and I like the idea of using something I already have if at all possible. Any thoughts on whether this is possible? The heat pump is the puhz-hw140vha2 and the cylinder is ehpt25x-ukhcw. Any thoughts or ideas would be hugely welcome 

 

 

yes. The eddi solar diverter does exactly that.

[JohnMo]

47 minutes ago, Antonb182 said:

Only 2 of the rooms are going to need heating over the winter and the requirement

Are you sure, the reason I say that, is our house at zero only need a couple kW, it's 195m2. If I don't heat does it get cold, yes. It's fine at an average temperature of 9-10 without heat. But then it's gets less comfortable. So heat is required.

 

The 2 rooms heated will be cooled by heat transfer to the rest of the house, so by default the whole house will get heated.

 

I would 

Either A2A heat pump or

 

Install UFH, in thick screed.  Use ASHP to batch charge floor and use as a storage heater. Heating time anything from 3 to 4 hours upto 8hrs depends on outside temp and flow temp. Heat DHW via ASHP. 5 to 6kW ASHP (or check the turn down on the one you have) will provide the heat to house on cheap rate electric. Or do similar via a Willis heater at 3 to 4 times the cost. If your heat pump does cooling cool the floor in summer 

[Gary68]

Its an Ecodan, flick DIP switch SW2-4 to on, reboot system, cooling now available in heating menu select flow temp and away to go.

Edited June 27 by Gary68