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Welcome to the forum. Although you can post in any forum, the USA forum is here in case of local regs or laws

J

jimmybwoy

Hi all, as you can see I'm a completely new member, and here because I have a problem with the above condensing boiler !
It's in a cottage i've purchased, and all seemed to be fine with it...the domestic hot water side of things works fine, but when filling the heating side of the system using the 2 x black plastic valves underneath, water absolutely gushes out of the boiler, I have removed the cover of the unit and established the large red cylinder on the R/H side of the unit is leaking badly (the pressure vessel), and I have attached a gauged schrader valve onto the small valve at the base and when I try and pump air in and I can hear it bubbling up inside (!) and also water leaks out of the valve when you press the valve-so I'm assuming the internal diaphragm has split, I have eyed it up and it looks relatively straight forward to replace, but....

Should the safety valve have stopped this of splitting in the first place and vented the water out (i've never actually seen the heating work myself, so this has happened under only mains water pressure), but when I viewed the house in the winter the house was very warm so I can only assume the boiler was all OK then....

Secondly I have read a little about this on the net and also on the expansion vessel itself their is advice to pre-pressurise the vessel with air, but a nearby merchants tells me they come pre-pressurised...so is it a simple case of unbolting the faulty vessel and bolting the new one on and opening up the water pipes on the underneath of the unit to allow water into the heating system (whilst venting a downstairs rad for air) to the manufacturers recommended pressure (1 bar ish iirc) .


On the plus side of this boiler, access to the unit looks really good 🙂

Any help would be much appreciated, I would pay a plumber but it's my first house and money is tight to say the least !

James
 
Last edited by a moderator:
Hi.

If water's coming out of the schrader valve you need a new one.
I presume the boiler's out of warranty, worth checking.
Get new exp' vessel check the pressure @ 1 bar is fine. Turn off electrics & isso valves heating, & drain, fit part, turn on isso valves & repressure system @1.25 bar, make sure cap on auto air vent is open to bleed air. Fire boiler on heating & dhw, top up if necessary.
The safety valve wouldn't stop the exp vessel diaphragm splitting.

One thing to check, how many radiators on system, if more than 12 might need another [external] exp vessel fitting.
If in doubt get a Gas Reg installer to do the job
 
Many thanks Aggis-most helpful. I've ordered the new expansion vessel today so should be fitting towards the end of the week.

One question, do I remove the red cap from the auto vent valve completely during the refill/bleeding stage ? Screw back on tightly after I'm confident all the air is out or leave slightly loose ?

Only 5 rads in the house, it's only a 2 bed victorian cottage so is a relatively small system.
 
Cap on auto air vent req's cracking open when filling then fire boiler on heating & dhw. You can leave the cap on the AAV open, unless it leaks, may need changing
 
Hi, can you help with an ariston aco MFFI ignition fault? Goes to so1/ so2 and ao1, the book is no help, gas is good, vale and supply good, can't find a solution,,, help!!! [email protected] @mikegriffin99
 

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