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Weirdness in hot water system.

Postby simonthepieman » Sun Dec 27, 2009 11:15 am

We have a direct supply gas fired boiler (I think) in our basement and our bathroom and kitchen are upstairs. Last week the hot water upstairs in the bathroom gave up the ghost - the pressure is fine but the temperature is tepid/intermittent. Bizarrely the kitchen hot water still works, as does the hot water in the basement loo basin. An airlock in the bathroom is not the problem as the pressure is fine. An emergency plumber looked at the boiler and thought it was fine, and announced that the shower mixer probably needed changing. We made an appointment for someone to come after New Year (at £80 an hour, not Christmas rate £140 an hour!) But a faulty shower mixer will not explain the intermittent nature of the hot flow throughout the bathroom - bath and basin as well as shower. Any ideas folks?
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Postby rosebery » Sun Dec 27, 2009 10:49 pm

First thing to do is cancel the appointment and arrange for a reasonably priced fellow who knows what he is doing. £ 80.00 an hour is theft particularly when the guy is either that incompetant or thinks that you are that stupid to believe that changing the shower mixer will affect what is happening at your taps!

First some questions:

Do you have a combi boiler? or;

Do you have a system boiler with an unvented sylinder for DHW storage? or;

Do you have a conventional boiler with HW cylinder in the airing cupboard and cold water storage in the roof? If you have a cylinder where is it situated relative to the bath/basin/shower concerned?

Your incoming cold mains will be colder than it was a few weeks ago. If you have a cold water storage tank in the roof that will also be colder Perversely the solution to this problem may lie in turning the DHW temperature down! This would reduce the temperature differential betwen hot and cold and make it easier for the system to cope. More when you are able to say exactly what system you have.

As regards the shower he probably thinks that the cartridge in the shower has failed so that its not mixing the water correctly. In that case its only the cartridge that needs changing not the whole mixer - unless that is what he is suggesting and he didn't explain himself properly. In any event I'm thinking its also more to do with differential temperature than anything else.

I'll look back for our reply.

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