ferroli combi boiler

Postby ianbcr » Mon Jul 27, 2009 8:35 pm

hello chaps,i have a ferroli optima 901 combi boiler that looses pressure and drains the water out of the system to the outside drain.i had the automatic air vent & c/h safety valve changed last year,and the safety valve changed again this year by a plumber,if the system is running heating or water the pressure drops quite quick,ie a few hrs,if not in use it lasts a day or more,my Q is. is the problem still with these parts,the boiler is 10yrs old now and i dont want to throw money at it,i would sooner have it replaced.if i do would it be best to change to a condensing boiler,i have a 2 bed bungerlow with 5 convector rads with thermostats and a towel rail.the boiler sits in the loft.thanks for looking and advise.
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Simply Build It

Postby htg engineer » Tue Jul 28, 2009 5:11 pm

If it's definately losing the water to outside, it could be a few things.

1) The combi fill / filling loop is not fully closed, the system may be filling slowly until it reaches 3 bar then the PRV will open.

2) The PRV is passing, renew pressure relief valve.

3) The expansion vessel isn't taking up the expansion - check to see if the pressure rises to above 3 bar when the heating is on. You may be able to re-pressurise the vessl to 1 bar witha foot pump, if not it needs replacing.

4) The plate heat-ex is mixing the water, the water from the mains is topping up the heating side - water is discharged via PRV, when it gets to above 3 bar.

htg engineer
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Postby ianbcr » Tue Jul 28, 2009 11:05 pm

thanks htg,i can only think it will be your answer 2 as the pressure never rises,only falls slowley to zero when the boiler wont fire up.
Posts: 6
Joined: Mon Nov 03, 2008 7:06 pm

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