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New hot water cylinder future proofed for heat pump?

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Active Member Member
22 kWhs
Joined: 11 months ago
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Hi Forums

I plan to change an old hotwater cylinder now, for a modern un-vented one, with immersion heater I can use with an Eddie and my PV system.

I currently have a reasonably new mains gas system boiler for heating and hotwater.

I plan in next few years to extend and insulate house and hope to fit ASHP at that time when property requirements are known.

Will a cylinder advertised as made to work with ASHP, work with current gas boiler? I assume it will make no difference to cylinder operation if boiler flow temp is set lower, but a plumber I talked to said they where all incompatible...


Help much appreciated

This topic was modified 11 months ago by Pen-y-Bryn

Prominent Member Contributor
2681 kWhs
Joined: 2 years ago
Posts: 382

Hi, @Pen-y-Bryn I had exactly the same situation as you and went for a Mixergy Unvented cylinder. It has a conventional heating coil and immersion heater but also has ports to add a heat exchanger for a future heat pump.

In the end I bit the bullet and took out the gas combi and fitted an ASHP before fitting the cylinder, but my original plan was to do as you are considering. I have plumbed things so I can add the heat exchanger but at present just heat my water via an Eddi. I thought I would monitor things to see if it was worth adding the exchanger.

All th details are in my blog, the address is in my signature.

This post was modified 11 months ago by bontwoody

House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
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