Adding ASHP to thermal store.

Air Source Heat Pumps (ASHPs)

Last Post by bontwoody 8 months ago

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Roohairy

(@roohairy)

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Joined: 8 months ago

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Topic starter 16/11/2024 3:23 pm

I have a new heating system design with thermal store to take advantage of heat produced by log burner and oil fired raeburn. The thermal store is prepared foe ASHP with a coil. The store is designed to run at 45 degrees with appropriate radiators. I'm happy with the design, but I don't understand why coil has been included for the ashp when the log burner, raeburn are both just open circuit. This additional coil is causing problems......

Can I run the ashp on common circuit as well?

I can't ask designer why he specified this, we have parted ways but not because of technical issues.

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bontwoody

(@bontwoody)

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16/11/2024 3:44 pm

Might it be because the designer assumed the ASHP would be using antifreeze?

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Roohairy

(@roohairy)

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Joined: 8 months ago

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Topic starter 16/11/2024 6:59 pm

@bontwoody could be but the whole thermal store will be treated water, not potable. HW will be DHW.

I know it's needed for solar because of the higher pressures, but can't figure out why for ASHP - I was reading through specs for ASHP for pipe sizings as I need to finalise and order tank when I realised they are OK with common thermal store - as far as I can see.

Need to order tank, there is a significant saving to be made if I drop the extra coil, due to design problems.

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bontwoody

(@bontwoody)

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17/11/2024 6:11 pm

@roohairy I plumbed (!) for a thermal store in my last house and was advised to have a splarge pipe rather than a coil in it for the heat pump. I hadnt realised that the whole of the store would then need to have antifreeze in it and the cost of that. In the end I used the solar thermal coil instead which got me out of a hole at the time.

Nowadays I would probably use the splarge pipe and omit the antifreeze using anti freeze valves (or nothing depending on your attitude to risk). In your position I think thats what I would now do if ordering a thermal store.