Replaced shower mixer, now rads hot when heating off

Postby Chubbaatwork » Tue Jun 09, 2009 1:46 pm

Any suggestions please?

2 weeks ago I had to strip down and repair a leaky hot and cold fill shower mixer in an upstairs en suite. Now 2 or 3 of the upstairs rads get hot/warm when the Central heating system is turned off. To service the shower I turned off the mains stop cock, drained cold water tank in the loft (could not get access to the isolation valve on the output of the cold tank) and closed off valve from the hot water tank in the upstairs airing cupboard. Central heating system is a "classic" gravity fed design (i think) with boiler in the kitchen and the pump for Central heating co-located in the airing cupboard with the hot water cylinder. Put the shower back together, all OK on that score, turned hot and cold water back on and now rads get hot, one in particular which is in the same en suite as the shower and nearest to hot cylinder. Checked CH programmer and themostat to confirm CH is off and Stat is set to lowest temp. However although programmer for CH was off, pump still seemed to be running!

Is likely that turning the water off and on when working on shower would interfer with hot water / heating? Thanks
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Simply Build It

Postby plumbbob » Tue Jun 09, 2009 9:11 pm

I can't really see there is any connection with changing the shower and the warm radiators. The heating and hot water are totally separate circuits and working on one cannot effect the other.

Having said that, is it possible you have altered a wrong valve?

Is the system definitely a gravity system, or is it fully pumped with zone valve(s)?
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