Ferroli 701 heating probs / over pressurises

7 Mar 2006
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United Kingdom
I recently bled the towel radiator in upstairs bathroom.
Since doing this I have had system pressure loss problems. There does not appear to be any leaks, apart from the pressure relief as the system over pressures.
System fired up OK on first occurence after having bled radiator then repressurised via fill loop.(1.2bar)
System now over pressures (3bar +) after starting at 1.2 bar. Subsequently as system cools overnight pressure drops below 1.0 bar and fails to start in the morning.I presume this pressure loss is due to loss of water from the system via pressure relief valve.
I have to repressurise system to get the heating to run, but next morning the same problem occurs. Could the Expansion Vessel need repressurising?
Any answers as to the reason/s for this problem.
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Having read other posts on this forum I am going to attempt to check and ,if necessary, repressurise the expansion vessel.

Can this be done without draining the entire heating system (boiler and radiators) ?

BTW Ferroli Optima 701 is 8yrs old.
See "Boiler Pressure Problems" in the FAQ section. I think it answers that!
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Can this be done without draining the entire heating system (boiler and radiators) ?

Fair question, the FAQ answer isn't clear. Altering it now.

You only have to drain ENOUGH water to drop the pressure to zero but water MUST be allowed to escape while you're pumping the pressure vessel up. ALternatively pump a bit then let some water out to drop the boiler pressure gauge pressure to zero again, then check the air pressure you've pumped to and pump a bit more if necessary and so on.
Cheers ChrisR.

I have read several different pressures for the PV in combi boilers, ranging from 0.7 -1.0 bar. I understand the pressure required in the PV for the Ferroli Optima 701 is 10psi (0.7bar).
Do I make up the remaining pressure in the system by using the fill loop?

I'm really dreading doing this job in case I find a broken PV. :cry:
It isn't that critical. Found a combi recently whose pressure vessel precharge had been 2.5 bar for a couple of years!

Don't confuse the two pressures. The PV has a PREcharge, that's the pressure of the air inside it, of say 0.7 bar. When you pump it up you arrange that there's no resistance so the PV is FULL of air at 0.7. There's a rubber diaphragm separating it from the water in the system. When you let the water in the other side, via the filling loop, the air squashes. The P gauge on the boiler is the water pressure.
As you fill with the P gauge saying over the 0.7, the air in the PV gets squashed.

I've tried to explain it all in the FAQ section but it gets a bit longwinded.

Not the end of the world if the pressure vessel is dead, but it's not all that common so don't worry!
Reassuring words ChrisR.

I am about to carry out the repressuring, I will get back to let you know how it goes.

Thanks for your help.
:( No joy........

What I thought to be the valve for repressurising the PV does not look like a Schreader type valve (like those on car tyres).
The valve connector on the foot pump (just purchased from Argos this a.m.) did not fit over the short (25cm) brass tube that sticks out at the top of the unit. This brass tube is positioned just to the left of the vent cowl. I made a small adjustment to the valve connector so that it fits over the brass tube. Upon depressing the foot pump I was unable to get any air into the PV (no pressure reading was evident when the footpump was connected, any pressure reading was from withing the footpump hose).

Could the small tube described not be the valve I need to be looking for?

How do I get air into the PV?
Can't identify the model; is it a Ferroli Fer Falcon, G.C. NO: 47-26701 by any chance? Is there a name?

If so the valve should be at about 7 o'clock on the big round red pressure vessel which is right at the back, and may be hard to get to.
Pressure for that should be 0.8 - 1.0 bar (12 - 15 psi)
Model is a Ferroli Optima 701 (a face lift version of the 700)

I'll have another look for the valve.

Heating is on at the moment and is over pressuring again.

Don't think I'll be able to do much before the weekend.

Found the valve :D The PV is at the rear of the unit near the top. Valve is at 1 o'clock on the right (it does look a little tricky to get to but, I'm sure I'll manage)
Over ridden the timer and allowing system to cool.
I could have this sorted by tonight.

Thanks for your help.
Heating is on at the moment and is over pressuring again.

Let some air into a radiator then, it'll serve until you can do the job properly.

Drained some water from system via d/stairs rad. until press. gauge read 0, removed dust cap from air valve on PV , secured footpump to valve, pumped up to 10psi, drained more water from radiator until pres. gauge read 0, pumped up PV to 10psi. charged system to 1.2bar via fill loop, set heating to run and waited..... Observed pres. gauge.........system has been running for 45mins and has not exceeded 1.8bar....all appears well. Fingers crossed we (that's you, other posters and I) have fixed the problem.

Many, many thanks to all who helped. :D :cool:

Tried this on a Domina 80 N worked a treat and fixed the leaking safety valve I recommend trying this if you have a leaking safety valve. The last one cost a fortune to fix. All you need is bike or car pump with pressure gauge. The valve BTW is on top of the pressure vessel.

Cheers very helpful posts

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