Baxi Dou Tec Combi Boiler

[susanxx]

My friend has just had a radiator moved due to space restrictions, and a new one fitted. The plumber (retired) that did the job would appear to have re-pressurised the boiler to excess and the gauge is now bordering in the '3' zone instead of '1.5-2' area. The instructions do not give any help on de-pressurising and instruct you to call an engineer. Is this really the only option?

[Hymie]

I don’t have the service manual for this model, but normally there will be a pressure relief valve accessible once the outer cover is removed.

Normally it a round knob (often red in colour), by twisting in the required direction (and maintaining the torque) – the system will slowly depressurise. Once at the correct pressure, release the knob.

[susanxx]

thanks for that, are you saying that we need to removed the whole of the cabinet rather than just open the drop down front or is it something that can be accessed by looking underneath as the boiler is above a worktop and we can get head and hands underneath?

[Baldric]

If it's easier you can lower the pressure by opening a bleed valve on a radiator and running some water out, keep an eye on the gauge though!

[Hymie]

Baldric’s advice is probably better than mine, if you can have someone watch the pressure drop as the radiator is being bled.

Operation of the pressure relief valve can lead to debris being caught on the valve seal, resulting in a leaky valve.

[susanxx]

Thanks for the help, found the red valve and expelled a lot of water and got the gauge down, but now it keeps creeping back up again! Any thoughts as to the next move please?

[Hymie]

Oh dear, I looks like your plumber friend failed to fully shut off the re-fill valve.

On older boilers re-filling (pressurising) is achieved by the provision of an external loop – normally a braided flexible water pipe with a valve at each end. The loop is connected between the mains water supply and the boiler central heating circuit.

To make things neater, newer units have all this contained within the boiler. If you are lucky with an external loop fitted, you should see a small hand operated valve at one end of the braided pipe and an in-line screw valve operated by screwdriver at the other. Make sure that both valves are fully off and de-pressurise the system once again.

If the filling control valves are internal to the boiler, and you have the installation manual, this should show their location.

If poking about within a boiler with a screwdriver, make sure that the mains electrical power to the boiler is switched off.

[susanxx]

thanks for the help Hymie, I'll try to find the valves tomorrow. Its unfortunate that my friend is always trying to save money and pays peanuts in this instance she really did get a monkey!

[susanxx]

I have tried looking for a braided loop but can only find something that looks like a miniature version of a periscope with a black cap on each end which currently are closed. I tried unscrewing them but nothing appeared to happen when I did. They are connected together by a small piece of copper pipe and I did look at the instructions including the installation ones and I believe I have identified the correct ones. Any more help otherwise its a call out for the plumber.Thanks