ASHP and Sunamp

[doyled]

Hi All,

 

New here and following reading some good threads on ASHP and Sunamp I wanted to detail my situation and see what people would advise.

 

I am based in South London and in a 4 storey Victorian townhouse. I'm keen to reduce my use of fossil fuels and have been working with a company (Evergreen) to take up the GHG voucher scheme and switch to using an ASHP.

 

I\m trying something interesting (and ironic) by looking to place the ASHP in the location of the old 'coal hole' that would be used to store coal when that was the only energy source. These are bunkers under the front steps but separate to the house structure, which kept moisture away from the main building. My existing steps have blown Yorkstone and are a patchwork quilt of bad concrete additions over the years. I'd get new steps fabricated from steel and then have a contractor dress them with masonry/tiles etc to resemble the existing steps to retain look. The ASHP would then be connected into the kitchen and could then directly feed new underfloor insulation (100mm piping gap I hope) and the main heating circult together with upgraded radiators.

 

From the attached image the ASHP (A Midea single fan 12kW unit - MHC-V12) would be in red, with the new exposed coal hole area under the green line. This would enable good airflow for the unit.

 

The issue is around cylinder location. My OH is not keen on being cold and our current compact combi boiler works well. As we are looking to develop the kitchen to get better layout and more storage the prospect of having to give up storage for a 250 litre cylinder has not gone down at all well. I've then considered whether I could use a horizontal cylinder under the steps down into the kitchen (pictured) and a 210 litre unit would fit snugly under them, however I have been advised online that a horizontal cylinder is not compatible with ASHP's and has lower 'stratification' than a vertical cylinder, affecting it's efficiency. So likely a non-starter there either.

 

So I was recommended to look at Sunamp. I have seen them before and didn't realise they could be 'charged' with water from an ASHP. A 250 litre equivalent model is a little over 1m high and would fit nicely under the kitchen steps area and has various piping options. As there is just 2 of us in the house presently we could even go for a smaller capacity Sunamp unit and change to a bigger unit over time if we chose. On an Agile/overnight tariff the ASHP could charge the Sunamp (or use electricity on some models) to give us DHW in the morning and keep some for later in day if required etc.

 

I have some questions though:

 

1) The installer has calculated a flow temperature of 45 degrees for a MCS SCOP of 4.1 for heating and 1.75 for hot water. The Sunamp's however seem to require 58 degrees or so (I believe) so would likely require more like 65 degrees or so from the ASHP. Does an ASHP have ability to 'flex' the temperature output to a higher temperature if required for purpose such as a Sunamp?

 

2) Sunamp seem to have tie-in's to Daikin and Samsung, but would their ASHP compatble units (the UniQ HW +iLTHP models) work with any ASHP that meets the input temperature requirement?

 

2) Another option could be to have a smaller capacity vertical tank like 120 litres or so, plus a Sunamp for 'backup' DHW e.g for a bath. 120 litres would be fine for 2 people I think (2 x showers per day). Is this a possible option at all? To run a Sunamp and a cylinder in series?

 

The key issue I am overcoming is storage. Though the house has a large square footage the actual usable storage is quite limited. Sacrificing more internal storage for a large cylinder is the issue I'm trying to negate.

 

Any and all advice gratefully received! Including telling me I'm doing the wrong thing etc....

 

Thanks,

 

David.

[Dan F]

On 15/09/2021 at 08:10, doyled said:

2) Sunamp seem to have tie-in's to Daikin and Samsung, but would their ASHP compatble units (the UniQ HW +iLTHP models) work with any ASHP that meets the input temperature requirement?

 

When I considered Sunamp they only recommended using it with specific heat pumps that had been tested by them.  This didn't seem terrible, but when I realised they that they used different ASHP-specific hardware that was a big no for me!