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We have a warm air heating system driven by a heat pump.

This is fitted with a 98% efficient heat recovery heat exchanger.

If I use an electric fire, where 98% of the heat is recirculated, will I use more energy overall?

I would assume that the heat pump heater would turn off sooner due to the heat from the fire warming the place up.

Does this make sense?

The heat pump will generate significantly more heat than a regular electric fire for the same energy input.

clv101 wrote: ↑01 Dec 2022, 22:53 The heat pump will generate significantly more heat than a regular electric fire for the same energy input.

Of course, you are right.

The only reason for the electric fire is to provide a boost on cold days, as the heat pump is a little under-specced for our house.

(Actually, today I'm trying a 4kw portable butane heater as a boost to see how that changes things)

The firm who fitted the system to the house warned us of the need for occasional extra heating, based on their thermal modelling. The building wall area / volume ratio is too high to make a perfect eco house. Too much wall and glazing to be ultra thermally insulated.

The heat pump is an internal fridge-freezer sized unit designed for apartments, so was ideal for our 100 sq metre place.
The next size up would have needed the hardware to be installed outside, which we didn't want.

4 kw sounds a bit much for an eco house, or is it a heater with a MAXIMUM output of 4 kw, but used on the lowest setting of about 1.3 kw.
1.3 kw sounds a very reasonable cold weather supplement, and LPG is still a bit cheaper than electricity.

If the butane heater vents inside the house the heat pump will extract a lot of heat from condensing the water vapour from burning the butane. Make sure the drains on the heat pump are clear and connected to a drain pipe or collection vessel.

Make sure the drains on the heat pump are clear and connected to a drain pipe or collection vessel.

The heat pump certainly dumps out a ton of water when the fire is on ... nearly caught us out.

REPORT :

The butane fire works surprisingly well.

At the 4kw setting the house temp climbed from 17C to 21C in about 2 hours!

Warmest we have been in ages .. and it's a nice focal point in the living area.

When turned off the temp slowly subsides .. the heat pump target is 18.5C.

Additionally, we have just fitted our new electric blanket. This also is a life improver!

So our timetable is: heat pump off for much of the day, heat pump target at 18.5C for some of the day, heat pump + gas fire for late evening and then heating off overnight, with bed pre-warmed by an hour blast of electric blanket.