FERROLI MODENA 102.......FLUCTUATING PRESSURE !!!

[aspley]

Hi Guys........I have a Ferroli Modena 102...it has just started to act in a strange way.

Pressure cold will show circa 1.5. When it fires up pressure will increase above 3, water will be expelled from the overflow pipe and the pressure will drop to below 1 and the boiler will understandably shut off. If I repressurise I will get the same cycle.

Any Ideas ???

 

[Burnerman]

The air pressure in the expansion vessel needs checking, and refilled to about 10 psi. This is best done when there is no pressure in the system.
If, when the air fill valve is pressed and water comes out, the EV is kaput.
John

 

[aspley]

The air pressure in the expansion vessel needs checking, and refilled to about 10 psi. This is best done when there is no pressure in the system.
If, when the air fill valve is pressed and water comes out, the EV is kaput.
John

Is this a DIY job Burnerman?? I guess not as it looks like a pressure guage is required!!

 

[Burnerman]

So long as the valve on the EV is accessible, its a simple enough job.
Boiler off, lose the pressure by bleeding off water at a rad valve.
When the pressure is at zero, check the air pressure in the EV using an accurate car tyre pressure gauge. If low, pump up with a foot pump to 10 psi, then check that the valve isn't leaking.
Repressurise your boiler up to 1 or 1.5 bar, set it going and see if the pressure only rises a bit with the CH on.
Job done! As before, if there is water at the EV valve, the internal diaphragm has split and its useless.
John

 

[aspley]

Thanks for that John, I'll give it a go. Happy New Year

 

[Burnerman]

Cheers mate hope it goes well, and all the best to you.
John