gas boiler wont fire

[pjmcke]

Hi, I have a mynute 14se gas boiler who refuses to ignite. Having had 2 leaking isolation valves (on the flow and return lines)which were replaced and lines refilled. The boiler now refuses to ignite. The h20 pressure is above the minimum of .5 bar but less than 1 bar. The flow sensor and switch for the circulating pump remains open. If I assist the sensor/switch and toggle the flow switch the unit fires up and central heating works .But once powered down again the boiler wont light again unless the flow switch is closed. Can anyone tell me what is the cause for this before an engineer callout is required.

 

[AnonymousImport]

If memory seves me correctly the flow switch in the mynute is a rubber diaphram. The diaphram must be torn and not moving the pin to make the micro switch.

If you drained the boiler to change the washers it probably happenrd then because ir was disturbed. It was probably on it's last legs anyway.

Gasman

 

[DP]

Open the valves

 

[AnonymousImport]

The blindingly obvious!

So obvious I didn't think of it, I thought it would be common sense.

Gasman

 

[pjmcke]

Thanks Gasman,


Will remove the flow switch and check for worn rubber seals. The only other item is that the boiler when on for serveral hours starts to make a rattleing noise again similar to an air lock. But can as of yet relieve this. The Rads are all hot, the auto air switch on the Pump was opened and also at the cylinder to remove any air . ( This is a sealed system). Any suggestions??

 

[oilman]

The rattling sounds like kettling, there is localised boiling in the heat exchanger. Add some boiler scilencer chemical to the system, or have the heat exchanger descaled.

 

[pjmcke]

Hi Gasman
The flow switch diaphram?. It it sealed somehow, as on removing the 4 screws, I cannot remove the face to reveal the diaphram.