I’m told that many heat pumps nowadays can reach water- heating temps of around 65deg required to ‘charge’ a heat battery, ie to bring about the ‘melting’ of the phase-change material in the battery. Does anyone have experience of this? Understand it would push down the COP. (We have no space for a water cylinder. )
Are you sure you need a phase change device? See
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That puts a different view on things- I’ll look into this, it sounds convincing. Was going to book in an ASHP survey/quote with hHeat Geek, but I could try this new cylinder with our existing combi boiler…thanks. Is its main advantage that it uses already-tepid/warm water to be heated by the the coil?
As far as I’m concerned its main advantage is its size. Which advantage is “main” to you is really a personal choice. However, it is a long time since a DHW cylinder has been designed from basics rather than as an evolutionary step from what was already there, so it does have several advantages.
Is this Heat Geek Mini Store a solution for overcoming the issue of having to run the tap for a while until the water is hot enough for washing in the kitchen sink, the shower and the bathroom washbasin? I’m thinking that this might be possible to install this in the space I have beside the bath/Shower right next to the bathroom washbasin and directly above the kitchen sink?
I already have a Tepeo Boiler connected to the HWC as well as have Solar Thermal Panels connected to the HWC
Short answer: yes
Long answer: it depends.
I had contemplated putting one of these in the kitchen cupboard vacated by my boiler but Mrs G has found another use for it. If you have room for multiple hot water storage then you can seriously reduce pipe runs and their associated heat losses but the cost of doing so is quite high.
Recently I have read of several Passivhaus’s that have water heating at the tap to avoid storage losses and associated space heat gains.
Returning to the MiniStore: can there be any advantage to using the MiniStore with a gas boiler? - I’m guessing not, assuming a modern, reasonably efficient condensing boiler. However, I’d like to find a way of domestically-using the 60% of our rooftop-PV output that currently goes into the grid ( for a pittance of 3p/kWhr), which a cylinder set-up would allow.
Before I had a heat pump or as much solar as I have now I had stopped using gas to heat the DHW. I had a condensing system boiler, so there was a cylinder already. I used “Octopus Go” and “Agile Octopus” cheap rates to heat the water via the immersion. I achieved about the same price that gas would have given (assuming 85% system efficiency for the gas) but had a clean conscience regarding CO2 emissions.
I subsequently got an Eddi solar diverter but due to the high hot water use in winter still needed to rely on overnight top up. You don’t get much solar in winter.
You’re specifically asking about a MiniStore and I have a 200l cylinder so my experience may not be particularly useful to you.
Now I have an EV charger compatible with Intelligent Octopus and export via Outgoing Octopus, so it is more profitable to export all my solar and heat water overnight at the off peak rate. I still have the Eddi ready for when tariffs change but currently it is just an expensive timer.
I pay 7p/kWh for electricity and with a hot water COP of about 2.5 pay less to heat than using gas.
Export is at 15p/kWh.
If this post makes anyone want to change to Octopus, just ask me to share my referral link to get a credit from them when you sign up.
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You may have moved on to the ministore now, but in case it’s still useful @Dom is charging his Sunamp from his heat pump and I’m sure would be very happy to talk about how it’s going.
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