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Central Heating runs when just needing Hot Water

Postby ijefferyes » Tue Jan 06, 2009 8:38 pm


I have just recently had some changes made to the Central Heating in my house and I was wanting to check some behaviour.

I think the system I have is an indirect boiler system. There is a hot water tank in the airing cupboard and two cold water tanks in the loft.

Recently a new boiler and wireless Thermostat was fitted as my old boiler was past it's serviceable life time and was not sufficient for a new house extension.

The new boiler is a Remeha Broag Avante 18v and the Thermostat is made by Salus.

The way I have things set up is that on the old control the heating is permanently on and the hot water is on a timer. The wireless thermostat seems to correctly switch on and off the heating.

But, just recently over Christmas we had guests and we ran out of hot water. So I switched the hot water on for an hour. But, this appeared to also work the central heating as the radiators got hot, even though the thermostat was reporting that the room temperature had been reached. The pump in the airing cupboard

What I would like to know is whether I should expect the heating to come on when all I want is more hot water?

If not, what could be causing this problem?


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Postby plumbbob » Tue Jan 06, 2009 11:47 pm

No the heating should not come on when just the hot water is wanted. What is going to happen in the summer?

How is the heated water controlled plumbing wise? Do you have a three port valve or two two port valves or what?
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Postby Steve the gas » Wed Jan 07, 2009 6:25 am


Sounds like the motorised valve is fubar, put slider into manual position to check.

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