Saunier Duval F30E - can't repressurise

alanrowell

I have one of these (yes I know it's crap but I didn't install it) and the pressure has dropped so that the boiler does not run. Tried using the integrated filling loop but there was no water flow and the pressure stayed at 0.4 bar.

Did some research and replaced the Filling Valve which also contains a non-return valve but this made no difference.

So what else could it be? Could it be that the combination of pressure within the boiler plus the spring pressure from the non-return valve is too much for my mains water pressure? Or am I just unlucky in fill valves?

DevCoder

Are you sure the diaphragm in the expansion vessel hasn't failed?

alanrowell

I could understand that if the expansion chamber was leaking then the pressure would drop but I'm trying to get the pressure up.

keystone

alanrowell wrote: »

Tried using the integrated filling loop but there was no water flow and the pressure stayed at 0.4 bar.

Theres a pretty good clue here that the problem lies somewhere between the water source and the filling valve really.
Understatement of the bleeding obvious I know - sorry.

Could it be that the combination of pressure within the boiler plus the spring pressure from the non-return valve is too much for my mains water pressure?

Unlikely - but have you measured it? are all valves upstream open?

Or am I just unlucky in fill valves?

Who knows?

Sounds like you may need to find yourself an SD accredited service man local to you i.e. someone who knows the animal.

Cheers

keystone

Ohh - possible lightbulb moment. Didn't leave a plastic blank in the inlet did you?

Cheers

Canucklehead

You could try replacing the fillingcock

You have replaced the RPZ.

alanrowell

keystone wrote: »

Theres a pretty good clue here that the problem lies somewhere between the water source and the filling valve really.
Understatement of the bleeding obvious I know - sorry.

Unlikely - but have you measured it? are all valves upstream open?

Who knows?

Sounds like you may need to find yourself an SD accredited service man local to you i.e. someone who knows the animal.

Cheers

Latest update - drained the boiler totally, then started refilling. Reached 0.4 Bar then stopped. Drained again, repeated with the old RPZ, same result. Also checked the fillingcock and there's definitely a good flow of water through it. There is water getting into the boiler - just not enough of it.

Another thought - could the air not be venting from the boiler when filling?

Nathanlgd

I have this exact same problem with the exact same boiler! - I'm desperate to find a solution (I'm not a plumber). Please help!

keystone

Nathanlgd wrote: »

I have this exact same problem with the exact same boiler! - I'm desperate to find a solution (I'm not a plumber). Please help!

Same advice. Find yourself a local SD accredited tech who knows the beast to look at it for you.

Cheers

alanrowell

Turned out to be a blocked water pressure sensor. Once cleaned out everything worked.