My central heating system has three 2 port valves. One for water and one for each heating zone. HZ2 is a 15mm two pipe system. HZ1 is the original single pipe 3/4 inch system with cast iron rads. All valves move correctly and all the programmers and thermostats seem in order. However when HZ1 is switched on, hot water from the boiler seems to feed past the valve to the hw cylinder. I can see that the valve is closed but the pipe gets hot both sides of the valve and the water in the cylinder rises above the temperature permitted by the cylinderstat. Oddly, this only happens with HZ1 and not with HZ2. There is just the one pump. Could it be something to do with the fact that HZ1 is a high water capacity circuit and exerts more pressure on the closed hot water valve so that there is some seepage through? The system has been installed for 8yrs but I have only noticed the problem recently when we switched on HZ1 during the recent cold spell. Normally we heat the most-used rooms on HZ2 only. When only the water circuit is on, the cylinderstat works fine, controlling the valve appropriately. Many thanks.
Leaky 2 port Tower valve?
- Thread starter BBL
- Start date
Thanks Pete. I was coming to that conclusion too but after the good talking to I gave it yesterday, it now seems to be behaving itself! Will give it one more chance!
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