Cold water tap turned on trips combi switch to start


18 Oct 2005
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United Kingdom
Had a new oil combi CH system installed a couple of months ago and as part of the system the plumber fitted an Adey MagnaClean Professional2 filter which has dripped ever since. He came to see it but couldn't find the problem which was pretty obvious since the pipes were hot and the drips were being evaporated.

Furthermore I have noticed that when the cold water taps are turned on then off again it trips the combi switch to fire-up. Same thing with the washing machine and toilet.

Plumber who fitted the system came and installed a Zilmet shock arrestor but that hasn't cured the problem.
Plumber now wants to install a PRV but I don't understand why since the pressure is showing 1.7bar!

Can someone please shed some light on the matter.
Thank you in anticipation.
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1. The 1.7 bar showing is likely to be the pressure within the heating system, not the pressure of the incoming cold mains water.
2. If the incoming pressure is 5 bar or more, a pressure reducing valve would be a good idea for other appliances as well as the boiler.
3. Leave the boiler / system off before the plumber's next visit, then he / she can see the leaking Magnaclean.

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