Air lock in unvented cylinder

[tomy]

A friend of mine has called me about a problem in a cus house, I have not seen the set up so I am going on second hand info. All he has done is turned off the mains to alter pipes in the kitchen, now the water coming out of the hot taps is cold . From what he descibes it must be a mains unvented cylinder because when he turned off the cold water the hot stopped immediatly, he has described a normal looking cylinder and an expansion vessel and he said two pumps but he might have meant motorised valves, it sounds like this cylinder mixes hot and cold to give an even temp but it is just giving out cold water at the moment, cylinder feels hot , any ideas how to sort it out??????

 

[Nige F]

Thermal store possibly Range manufacture...one pump runs the c/h and other from boiler to store. Has he got the unvented cert.?

 

[ChrisR]

Pssssst he doesn't need it for a thermal store

But this guy is asking for clairvoyance

 

[tomy]

He is a kitchen fitter so no he hasne got a cert, but all he is doing is replacing the kitchen and so he had to turn off the water to take out the sink and now the hot water wont come through , so I assume it is an airlock , any ideas how to get the hot water working again???????

 

[Paul Barker]

Can't be an unvented cylinder because aftre you turn off supply water comes out until pressure inside reaches atmospheric pressure.

Always worth going the normal air lock route, force it out with mains water.

 

[tomy]

It is an unvented cylinder , its a heat store and we have sorted it out now , it was a faulty thermostatic hot water blending valve which apparently has been a bit dicky for a while but the cus didnt tell my kitchen fitting friend that so he thought he had done something to it. But all is well now

 

[ChrisR]

tomy glad you got it sorted.

Paul Megaflo's and similar do what you said but the ones with separate expansion vessels typically don't cos they're charged to say 3 bar. So the HW only carries on until the pressure drops to 3 bar - half a second!

 

[Paul Barker]

Thanks Chris, I've only fitted bubble tops.