Digital Showers and lower temperature hot water
HiÂ
I am in the process of getting a heat pump. At present I have a Mira Platinum low pressure pumped digital shower, and assumed all I had to do was replace it with the high pressure version. When looking at this option I read the spec for the unit which stated the hot water operating temp. range was 55-65 degrees. As I want to store water in the range 48-50 degrees I emailed Mira customer services to ask if it would work ok.
The reply was vague, offhand and unhelpful "Don't know we haven't tested it at that temp, may work my not or not work as well as it could/should, any issues will invalidate your warranty" so not a lot of help there.
Any heat pump owner using something similar, does it work ok, I assumed anyone using a combi gas boiler would not be heating water to around 60 degrees so it should work? Â
I had a Aqualisa digital pumped shower prior to having the ASHP installed’. It had to be stripped out because the ASHP system is a closed mains pressure system and consequently cannot have a pumped/power shower.  Swapped it for a non pumped shower.Â
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Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.
2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.
Surely you could keep a vented DHW cylinder and existing cold water tanks. Also, why can't the ASHP primaries have a header tank like my gas central heating system?
That may be possible, I don,t know but why would you want the worst of both worlds? poor hot water pressure to taps & showers especially upstairs with a big imbalance between mains pressure cold and gravity fed hot and a pair of tanks sitting in the attic, when you can have high pressure hot & cold supply and a large tank of stored water?
@somerpark Mains water pressure isn’t necessarily high pressure. Minimum service level is around 1 bar. It may not be the case that there is a large pressure imbalance between hot and cold supplies.  A pumped thermostatic shower overcomes these issues and it is likely that it would be incompatible with an unvented cylinder.Â
@ianmk13 I though mains pressure of 1 bar and above was considered high pressure. and I have been using a pumped digital shower because I have a vented DHW cylinder at present with the associated cold tank and CH header tank in the attic. The pump only overcomes the issue with the shower, my upstairs bathroom hot tap has a 2 metre head, 0.2 bar and my cold tap is mains pressure in my case about 1.5 bar. The heat pump as far as I know only works with an unvented cylinder at mains pressure so it is not an option to stick with my current setup which I would not choose for my situation if it was possible. So the pumped shower has to go.
Posted by: @somerparkHi Did you swap it for a another digital unit and is it working ok?
Â
No. I swapped it for a non-digital, unpumped shower, and the cold water storage tank was removed. A power shower is not compatible with an unvented closed system. (As explained by my installer.)
Â
Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.
2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.
Posted by: @ianmk13Surely you could keep a vented DHW cylinder and existing cold water tanks. Also, why can't the ASHP primaries have a header tank like my gas central heating system?
How will you heat the water in the retained vented DHW cylinder? Because you won't be using the ASHP.
Â
Retrofitted 11.2kw Mitsubishi Ecodan to new radiators commissioned November 2021.
14 x 500w Monocrystalline solar panels.
2 ESS Smile G3 10.1 batteries.
ESS Smile G3 5kw inverter.
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