Heating intermittent

[Harry Bloomfield]

There is but it is now closed. The old boiler had a pump overrun but the new ones doesn't so it is not needed any more, I believe.

The idea of the bypass, is to short-circuit you heating system, so there is still some flow of water through the boiler, to help cool it, once all of the TRV's are satisfied, and closed. The bypass is pressure valve operated, if the pressure rises above a set level, it opens, allowing flow via the bypass. CountryFan may have in mind, that the bypass is sticking open, providing an easier route for the flow.

 

[charlieno]

Check for what @Harry Bloomfield mentioned then regards the microswitch, moving the lever does just that, moves the lever. Could also be a failure anywhere on that sequence, eg programmer, room thermostat

I am certain that the microswitch/programmer/room stat aren't the problem. They haven't be altered and I can tell the pump is on, boiler is on and the valve is open but heat just isn't getting round the system.

 

[charlieno]

The idea of the bypass, is to short-circuit you heating system, so there is still some flow of water through the boiler, to help cool it, once all of the TRV's are satisfied, and closed. The bypass is pressure valve operated, if the pressure rises above a set level, it opens, allowing flow via the bypass. CountryFan may have in mind, that the bypass is sticking open, providing an easier route for the flow.

The bypass is a simple loop with a tap on it - not a pressure bypass. The tap is closed.

 

[CountryFan]

The bypass is a simple loop with a tap on it - not a pressure bypass. The tap is closed.

So a gatevalve. Feel the pipe the other side of it and as @Harry Bloomfield says, you often need a bypass, depends on mi’s