Baxi Boiler 105 he - pressure rising issue

[fishboy1976]

Hi all,
looking for some advice. My pressure on the system rises to 3 bars every time the heating kicks in. then the release valve goes and dumps water outside (a very small trickle). there is no similar effect from the hot water however.

I have just disconnected the filling loop and each time the boiler loses all pressure (as well as spraying my walls! there is a tap fitted to the cold mains end of the loop but seeming nothing to keep the boiler end of things pressurized on removal of the loop (from what i read i am not sure this is normal)
i therefore cannot test if the continual rise in pressure when i activate the central heating is due to a faulty filling loop valve (this has recently begun to drip water at a very slow rate too)

or is it something more sinister like the expansion vessel? i know this may similarly generate the same symptoms. as it only happens maybe 30-40 seconds after the heating comes on i wondered if this was more likely the cause?

My boiler instructions state that replacing this requires the removal of the boiler from the wall and full disconnection of gas and water(that sounds extremely expensive before the cost of parts)

would hate to call some one out to find it was a £4 tap i could of bought from a diy shop!

any advice as to which is more likely?

Thanks

 

[ChrisOxford]

I have just disconnected the filling loop and each time the boiler loses all pressure (as well as spraying my walls! there is a tap fitted to the cold mains end of the loop but seeming nothing to keep the boiler end of things pressurized on removal of the loop (from what i read i am not sure this is normal)
i therefore cannot test if the continual rise in pressure when i activate the central heating is due to a faulty filling loop valve (this has recently begun to drip water at a very slow rate too)

There should be a NON-RETURN VALVE on the boiler side, see http://www.screwfix.com/p/combi-straight-filling-loop/46605 These often fail, and the temptation is then to just leave the loop permanently in place, which is a bad idea (and contravenes the Manufacturer's Instructions, and water regs, I think.

Have you checked that the EV is pressurised (to about 0.5Bar) and not full of water?

C.

 

[finnkiwi]

I was just about to post a new topic, when I noticed your post. We have a very similar issue with our boiler (Themaclassic F24E Plus, about 5-6 years old) to what you described. Hope it's okay to jump on your post and seek advice together!?

Our boiler has been fine in the previous winters and is always fine when the heating is not on. When we turn on the heating, the pressure rises to 2.0 and then crashes and turns itself off (after about 10-15 mins). This has happened a few times in the last couple of weeks when we have attempted to put the heating on.

In addition, the boiler has been dripping water for about a year. We have a bucket underneath it and it fills up about 10cm in a week.

We had a Heat Care engineer (through a Groupon voucher) come in to do a general check up a couple of weeks ago.
- In regards to the raising pressure, he recommended we pump a bit of air into a valve at the top area of the boiler (e.g. using a bicycle pump).
- Re: water dripping, he identified we need to replace the 'reduced pressure zone valve' in the bottom area of the boiler.

In regards to pumping air to the valve with a bicycle pump, this sounds a little strange!! And we haven't done it yet, and are not sure whether to do so.

Any thoughts or advice?

 

[ChrisOxford]

I was just about to post a new topic, when I noticed your post. We have a very similar issue with our boiler (Themaclassic F24E Plus, about 5-6 years old) to what you described. Hope it's okay to jump on your post and seek advice together!?

Please start a new post, or else everything will get seriously muddled

 

[fishboy1976]

Hi again,
thnaks for the posts so far guys.

i have no idea what EV means sorry so you gonna need to explain that befoe i can answer your question (sorry)

the plus news is that the screwfix link is spot on what's on my system.

there is a constant drip coming from the black tap (on the mains side of the setup.

presumably you are saying the other end has a valve that shouldnt let water back through it? if so it has deffo failed with it in place i took of the flexible hose and it went off like a geyser!

 

[pipshady]

EV is refering to expansion vessel, and it is a possibility the diaphragm within it has perforated, i have checked this by touching the side that has the schroeder valve fitted to it, if this is the same heat as the opposite side then the expansion vessel has probably failed. it is also possible that vessel has lost its air pressure charge

onto the filling loop issue a check valve/ non return can fail, it sounds like it has! and if the isolation valve on the other side is slightly open it can cause it to constantly fill the system , however you would find this would happen constantly, not just when you turn the heating on, incidently, ChrisOxford is right, it DOES contravene water regs to have a filling loop permanently connected to the mains.

 

[fishboy1976]

the problem with the EV is that to access it the instructions for my boiler state disconnection from the mains for water and gas and removing the boiler from the wall.

i am not sure i can access it any other way to check it's heat level.

from what you are saying though and from what i have read i suspect that the EV is the issue.

Bought a new tap valve to replace the one currently leaking. get the feeling i might replace the whole filling loop now. and then can leave the loop itself off as advised (and legally obliged)

it's been on since being fitted - presumed the coboys who put it in knew what they were doing! wnt make that mistake again.

so if the EV isnt perforated, but only lost it's pressure it wont need replacing? Any idea of the approx cost of the part and fitting - bearing in mind the disconnection/reconnection issue

 

[pipshady]

cost will vary a fair bit, you are correct in saying its a boiler off the wall job though!, so its a few hours work, i remember SSE (Southern Electric) charged 60 an hour labour plus parts at retail price when i worked for them, BG were the same, I d say take 60 per hour labour and check retail prices of labour and you ll get a ball park figure