ASHP and Thermal Battery

[Sarah29]

Just seeing if anyone has done something similar or can tell me I'm barking up the wrong tree.

 

New build house in progress with wet UFH throughout, c.2000sqft 4-bed. Have been considering the best ASHP installs and what could be a good approach.

 

Considering a Daikin ASHP with Sunamp Thermino 300 for the UFH and hot water. Any shortfall dealt with by E7. Seems like a fairly straightforward setup and PV ready.

 

Has anyone done something similar or can offer any thoughts?

 

Would you expect any flow rate issues when concurrent showers are used etc?

 

Would I be correct saying the UFH circuit would still require the usual buffer tanks as this basically operates in the same way as usual? 

 

Thanks in advance for any comments.

[ProDave]

Why that choice of Sunamp model?

 

This https://midsummerwholesale.co.uk/buy/sunamp-heat-batteries/sunamp-ehw-ipv-12

 says input source is grid electricity or solar panels.  (solar panels will not do a lot in mid winter)

 

So it won't heat from the ASHP.  You would be fitting an ASHP just to heat the UFH?

 

A more conventional and cheaper system would be an ASHP heating the UFH and a hot water with an unvented cylinder (heat pump model with high capacity input coil) where you have the flexibility to heat the hot water by the heat pump or surplus PV energy.

 

Imho you want a compelling reason to choose a sun amp, such as your 2000sq ft house really does not have a suitable cupboard to house a big hot water tank?

[PeterW]

Thermino is £2400 above the price of the same 300 litre UVC (£900) . It also has a CoP of 1, so assuming 3000Kw of hot water per annum (standard value used) then your Thermino will require 3000KwH of electricity at best 20p/KWH off peak so around £600 PA, lifetime cost over 10 years of ~£10k

 

Same setup on UVC and ASHP at raw CoP of 2, then power cost is £300 PA, lifetime cost over 10 years of ~£5k

 

You can “over charge” a UVC to 95°C and double its delivery capacity at 42°C - you cannot do that with a Thermino so it really is a solution where unless you have no space then it’s not a very economic choice or one that makes sense if you are only using it off electricity and not a dual heat source, and even then the costs are significantly higher with no discernible benefit. 

[Dave Jones]

i looked at this and decided better off spending on a battery as you can be flexible with how you use the stored electric. Heat battery are 1 trick pony.

 

 

[sharpener]

51 minutes ago, Sarah29 said:

Just seeing if anyone has done something similar or can tell me I'm barking up the wrong tree.

 

New build house in progress with wet UFH throughout, c.2000sqft 4-bed. Have been considering the best ASHP installs and what could be a good approach.

 

Considering a Daikin ASHP with Sunamp Thermino 300 for the UFH and hot water. Any shortfall dealt with by E7. Seems like a fairly straightforward setup and PV ready.

 

Has anyone done something similar or can offer any thoughts?

 

Would you expect any flow rate issues when concurrent showers are used etc?

 

Would I be correct saying the UFH circuit would still require the usual buffer tanks as this basically operates in the same way as usual? 

 

Thanks in advance for any comments.

 

Presumably you are thinking of the Daikin-specific Sunamp this one. I think they tweak the phase-change mix to suit the attainable flow temp of the HP so you need to be sure your particular Daikin is compatible and find out what DHW temp you would get. AFAIR they all have 22mm tappings so concurrent showers would be no worse that with a cylinder. The water circuit in it is not large so would not serve as a buffer for the HP ir you need one.

 

I looked at these 2 yrs ago when Sunamp were also offering their phase-change products as a thermal store for the heating side. They discontinued them for this application and were unhelpful when I enquired if the DHW products could also be used in this way. There have been some horror stories about bursting units and subsequent warranty claims. I would avoid unless you are desperate for the space saving.

 

Edited April 5, 2023 by sharpener

[SteamyTea]

3 hours ago, PeterW said:

so assuming 3000Kw of hot water per annum (standard value used) then your Thermino will require 3000KwH of electricity at best 20p/KWH

If the sentence had been longer, then we could have had kw/h as well.

Edited April 5, 2023 by SteamyTea

[Nickfromwales]

2 hours ago, sharpener said:

I looked at these 2 yrs ago when Sunamp were also offering their phase-change products as a thermal store for the heating side. They discontinued them for this application and were unhelpful when I enquired if the DHW products could also be used in this way. There have been some horror stories about bursting units and subsequent warranty claims. I would avoid unless you are desperate for the space saving.

Yup. I have an ever-growing portfolio of “deceased” Sunamp units, which is a constant reminder of why I fit unvented cylinders. With an UVC you get;

 

1/3 of the price.

Lifetime warranty. Sunamp will insist your install is “non-standard” and try and palm you off with you stumping up the replacement cost. 

 

Site interchangeable immersion heater. Sunamp / Thermino has to be disconnected electrically, drained and all the plumbing disconnected, then hump 200kG of dead weight out of your house, palletise and return it to base, and wait for it to come back. Wash your hair with a kettle until it gets back to yours.

 

Local service & maintenance is pretty much on every street corner. Sunamp units need “specialist” installers and they all rely on SA for the technical info / design. Used to take an age for any kind of response, and that was usually just to say “we don’t deal with the public”. 
 

May be different now, but this used to be a major gripe from the clients I used to get sent to to repair / replace these things. 
 

UVC every single time for me, and I regret swaying towards these things for the time that I did.
 

Most recent one to go ‘pop’ was January 2023. Sunamp tried to wriggle off the hook stating the usual “it’s not covered by warranty as it’s a non-standard installation”. 
What these idiots forgot was that my company developed the design with them for this client, so it was all installed with them involved directly!!! Wasn’t long after I got involved that they ‘decided’ to replace the failed unit FOC. 🙄👎. 

[Sarah29]

All - thanks for your input on this. It's decided, I won't try and reinvent the wheel, seems the tech just isn't ready for anything more creative just yet. UVC and a monobloc ASHP it is! Now onto deciding on the most suitable ASHP make, am swaying towards Vaillant in this scenario, shall keep the research going.