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Does anyone have any experience or reports of hybrid heat pump / gas boiler systems?
I am in a large old semi in a town and the gas boiler running the small-bore central heating will need replacing soon. I understand that heat pumps don't usually produce water hot enough to run the radiators as they are, and the disruption from replacing the whole system would be unacceptable. It is also pretty reliable, touch wood. The house is being progressively insulated and draught-proofed, but I can't imagine a heat pump ever being enough on its own.

Fitting a modern condensing boiler would be the simplest option (although the condensate disposal route would not be straightforward) but a heat pump as the primary stage could work...
https://www.daikin.co.uk/en_gb/product- ... svEALw_wcB seem to be promoting them.
I don't know whether the return water temperature at the boiler is too high for the heat pump to make a useful contribution in those circumstances. Some "hybrid" systems just seem to have a boiler to take over when air temp is too low for the heatpump.
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I've seen them. I don't know anyone with one but I'm very wary of such "best of both worlds" devices.

For me, you'd be better fitting an air-to-air heat pump and/or a storage heater or two, completely independent of your wet central heating.

I simply added my heatpump in parallel with the existing combi gas boiler but I don't use them together although I have tested them both working together and it still works and nothing bad happens. I do limit the the heating water temp from the gas boiler to 55 degrees and I have fitted a check valve to the output of the gas boiler heating circuit so the heatpump cannot force water backwards through the gas boiler heat exchanger. And I have a zone valve on the heatpump which prevents the gas boiler forcing water through the heatpump.

In the past winters, I ran the heatpump on the cheap rate, then switched from the heatpump to the gas boiler. This year with my cheap rate storage heater boost I have managed to so far keep the gas boiler switched off completely by running the heatpump on my battery bank during peak rate times.

I have to say Nowty Towers needs one hell of an operating manual which is still on the ToDo list in case of my demise.

nowty wrote: ↑Sun Dec 05, 2021 2:05 pm I have to say Nowty Towers needs one hell of an operating manual which is still on the ToDo list in case of my demise.

I'm the same, my wife keeps saying she wouldn't have a clue what to do with all the "systems"

I think it does raise a, perhaps, difficult issue. Whilst the systems - PV, wet, wind, that many of you have installed, how much depends on you as individuals ?

How easy would it be for a partner/family member to maintain ?

Doesn’t have to be a terminal situation , a dose of flu or COVID could be enough to incapacitate for a couple of weeks.

I think the principle of usability, effectiveness and robustness is proven. Is it time to start to develop systems for the non-expert ?

Fintray wrote: ↑Sun Dec 05, 2021 4:02 pm

nowty wrote: ↑Sun Dec 05, 2021 2:05 pm I have to say Nowty Towers needs one hell of an operating manual which is still on the ToDo list in case of my demise.

I'm the same, my wife keeps saying she wouldn't have a clue what to do with all the "systems"

Ditto

I try very hard to make everything “dead mans handle” so my input is more “optimising” rather than anything essential to keep the system running.

Eg if a very sunny summer day is forecast I might set the batteries to charge to 80% rather than 100% in the cheap period. While being left on the “wrong” setting is sub-optimal it isn’t a catastrophe.

Boiler cascade systems are nothing new and can be made to work with many varied heat sources, that's kind of what we have here at spiky-ville, wood stove-gasser-solar thermal.
It can be as simple as a few change-over and pipe/appliance stats.A plan of the logic is very helpfull when trying to work out a fault. Or it could be all apps and smart phones, nests and etc, in which case when it fails you are bazookered.

It's a shame the GOVT are short on neuron power with heat pump legislation, as a heat pump and a gasser could make good partners.

Desp

Stinsy wrote: ↑Sun Dec 05, 2021 1:39 pm I've seen them. I don't know anyone with one but I'm very wary of such "best of both worlds" devices.

For me, you'd be better fitting an air-to-air heat pump and/or a storage heater or two, completely independent of your wet central heating.

YUP, i'd prefer the ability to have a chance to have some heating rather than everything go down (well, power cuts excepted, y'know what I mean)

Mr Gus wrote: ↑Sun Dec 05, 2021 6:15 pm

Stinsy wrote: ↑Sun Dec 05, 2021 1:39 pm I've seen them. I don't know anyone with one but I'm very wary of such "best of both worlds" devices.
For me, you'd be better fitting an air-to-air heat pump and/or a storage heater or two, completely independent of your wet central heating.

YUP, i'd prefer the ability to have a chance to have some heating rather than everything go down (well, power cuts excepted, y'know what I mean)

I'm thinking of keeping the gas CH and having batteries to keep the house (CH) control and lighting working.
A heat pump would be a bonus and cut gas consumption in normal circumstances, but when the grid goes down (like flooding of a big sub-station) I would like to thnk that the battery would keep the background GCH and lights going.
Resilience!
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