Worcester Combi pressure loss

[sophiejazz]

We've recently installed new pipework and fitted 4 new radiators as well as pipework for 2 towel rails yet to be fitted. After pumping the system to 2 bar there is a rapid decrease to 1 bar or less. We've partially bled the radiators (still air trapped in the system - it's taking time to bleed) and checked all pipe fittings. There doesn't appear to be any leaks on the pipework or radiator valves. What could be the problem? The gas fitter says that symptoms indicate an open pipe and that it is not a problem with the boiler. However the plumber suggests it might be the schrader valve. There has been no service or valve test of the combi.

 

[looneyfitter]

Have you checked the pressure in the expansion vessel with NO pressure in the system? If you have a leak then i doubt you would only loose pressure down to 1 bar.

Is there any sign of water from the blow off? Does the pressure rise rapidly when you top it up??

 

[sophiejazz]

The gas fitter hasn't checked the expansion as he didn't have a foot pump.

The pressure does rise rapidly when the loop valve is open. No sign of water from the blow off.

Sorry, the pressure does drop virtually to zero within 15 minutes.

 

[looneyfitter]

sounds like the expansion requires pressurising. If you remove the black cap and push the valve, do you get water out of it at all?

 

[sophiejazz]

Found it!!! The plumber who put the new pipes in had put a short length on, under floorboards not up, and hadn't fitted the connector properly. Fortunately our new plumber knows what he's about and has a good sense of hearing.

 

[looneyfitter]

good old fashioned broom handle to the floor trick eh lol