Drained central heating and using Hot Water?

28 Jul 2009
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United Kingdom

Had a look around the forum but could not find anything on this problem I have.

I was replacing the radiators in my house for some new ones as the old ones were only single and did not give off much heat and have drained down the system without any problems and started the work. I left the system down as was planning on doing this over a few weekends as there is no rush as its still warm. To my suprise when the hot water came on the pump seems to make a horrible noise which sounds like a problem when there is no water in it. I obviously turned it straight off away but thought I would be ok to have the central heating down but the hot water on.

Any ideas or am I just being stupid :oops: and can't have heating empty and hot water on?

I have open vent system with the little tank in the loft and a Grundfos pump (normal red one)

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no, the CH water is what warms the coil in the hot water tank. You might still be able to have hot water if you have an imersion heater though.
Thanks for that, did not realise. Learn something everyday!! :)

Thanks for speedy response. Tank does have imersion heater but think it does not work as the on switch had tape on it when I moved in and a plumber mentioned to me that it was common for these to go and often people don't bother to replace.
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a lot are also taped over by homeowners to stop kids/accidental turn ons, if youve got the old type electic meter it will be easy enough to tell by how fast it spins when on/off.
Thanks will try it, guessed it might be that expensive on the electric!!! :LOL:

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