I moved into a new rented property about 3 weeks ago in the UK. I put on the heat, which is water-filled radiators supplied by an Electric Boiler, a Range Senator 6W, and a medium-sized water cylinder. I have never had this type of system only ever a gas/electric mix so I wasn't really sure how long it should take for the radiators to heat up!

It took about an hour and a half to get to kinda hot, like lukewarm. Is this right? The same with any hot water? and the tepid water only seems to last about 4 hours, shouldn't a boiler produce warm water into the pipers relatively quickly? and keep in the tank for a while?

I'm having no luck with landlord. They have sent out an electrician who didn't know anything about electrical heating systems. He said he thinks something it wrong as when its turned on the pipes leading from the boiler didn't warm up at all after 10 mins of being on and told me just to turn it off until it could be looked at. I am now waiting for a plumber, so who knows how long that could take?

To top it all off, I checked how much my electrical bill was for the first 2 weeks I was in the property. It was over £70! This cannot be right I'm not even warm and was putting it on for less than 1.5 hours a day. Is this normal for this type of system?

3 Answers 3


If everything was cold to begin with, and the boiler is heating both hot water cylinder and the radiators, it can take several hours before the cylinder is up to temperature. Since the cylinder is a massive heatsink, it holds down the water loop temperature until the water in the cylinder gets up to temperature.

Is there a control to select CH/CH+HW/HW? It'll be on a timer box that controls a diverter valve, probably hidden somewhere. If so, set it to HW only, and the tank should warm fully in about 2 hours. These systems should be set up with a thermostat on the HW cylinder that shuts off the diverter valve, which then would shut off the boiler it it were set to HW. You could set it to CH only, the radiators should warm up quickly then.

If there's no diverter valve, and the HW and radiator loops are run in parallel, you're going to find that the temperature that the radiators get up to is not very warm, as the boiler thermostat will be set to a value that is safe for the hot water - probably 40-50C. As such, the radiators don't output as much heat as you'd expect.

I've never been impressed with these "electric furnaces" or "electric boilers". While they're technically very efficient, they're far more expensive than gas to operate, and usually pretty limited in output - 6kW is about 20,000BTU, and I had a 36,000BTU boiler that struggled to maintain room temperature plus HW in a 2 bedroom single story building. They are unfortunately popular in rental properties, since they're usually pretty reliable, and the owner doesn't see the operating cost.


thanks for that I wish I understood it more!

I usually only am heating one or the other and either way the radiators take hours to heat, the pipes either side of the boiler don’t even warm up. I’m really hoping there is something wrong otherwise I don’t think I’m gonna be able to live there for long with those costs and not heating or hot water.

  • That should be a comment, not an answer. If it's taking a long time to warm up with only the radiators in circuit, maybe the boiler isn't producing the output it should. What are the status lights on the panel doing? As for cost, it's bound to be 2-3 times more than a high efficiency gas furnace would cost to run.
    – Phil G
    Dec 10, 2019 at 17:22

You really need the landlord/agent to provide instructions for the system as installed.

This may be connected to Economy 7 or 10 electricity tariffs, so they only or preferably heat up on cheaper off-peak electricity - you may have to wait until the following day to notice much benefit.

If it's connected only to peak rate electricity it'll cost a fortune to run and be comparatively unresponsive.

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