WB 240 Combi - pressure issue

[smirge]

Hi all,

I've checked the heating FAQ's but am still not entirely sure what to do about my present situation, and would really appreciate any advice from someone who knows what they're talking about.

I've been losing pressure more quickly than is normal from my Worcester 240 combi for a good while now, but haven't had any great issue just letting a bit more pressure in with the tap when it gets a bit low. The boiler's carried on functioning okay, as have the radiators.

British Gas came to fix a new Smart Meter last week outside the house, and my pilot light went out while they had the gas off. As my ignition has gone and it's quite an old boiler, I got them back to re-light it today for free. At the point they started, pressure was just above zero - the engineer opened the tap and let it rise to about 1, which I didn't obviously question.

However now the pilot's back on and the boiler is heating the house again, pressure is climbing and climbing - it went past 3 earlier and I couldn't hear a pressure relief valve kicking in, so I turned it off out of panic. It hadn't been past 2 bar in living memory.

The pressure duly dropped down to about 1.5 over the next couple of hours, so I stuck the heating on again (house has been freezing for several days now so in a bit of a rush to get warm to say the least). It duly climbed past 3 over the next 15 minutes or so, so I turned it off again.

Is there anything a complete heating ignoramus can do to relieve the pressure a bit manually? The manual and servicing guide I found online weren't overly clear. The boiler is and looks ancient, so I'm a bit wary to just leave the pressure climbing on the premise it will hopefully get let out automatically.

I do know that history tells me if I just leave it alone then it'll probably drop over the next 7 days, but I'm really not up for being cold that long

Any thoughts, chaps?

Thanks a lot.

 

[MANDATE]

I think you have expansion vessel problem.
Most likely lost some of its 'air' charge. This results in the volume of air being reduced, which results in higher pressures than normal.
The PRV will have opened at 3 bar and discharged water outside.
The PRV will also have automatically have closed and left sediment trapped on the sealing face, leaving you with a small leak so you then lose pressure but over a longer time period.
Sounds like you should
release water pressure to zero
Ensure water side is open to atmosphere
Check expansion vessel pressure and pressurise to 0.8 bar
Close water side to atmosphere.
Clean or replace PRV
Pressurise water side to 1.0 bar.

So loss of pressure is due to;
PRV opening due to faulty expansion vessel (air loss/holed diaphragm)
Faulty PRV
Any other leak in the system

 

[smirge]

Hi Mandate,

Thanks a lot for your detailed response and feedback.

After a bit of investigation, the PRV is working okay. The pressure dropped to 0.5 after the first night so I stuck the heating on and it climbed to 3, but then started dropping back to 2 over the next hour or so.

I think I'm going to keep tabs on it over the next few days and get it looked it if the pressure keeps climbing to 3 every time the heating comes on; will let him know your thoughts if so!

 

[Agile]

It does sound like an EXV issue. May need repressurising or replacing.

Presumably you don't get the boiler serviced regularly?

Tony

 

[smirge]

Hi Tony,

It was last serviced over a year ago, but no longer than two years which is why this surprised me. I guess there's no harm in having it looked at, just a slightly unexpected expense given before British Gas' visit, it was functioning alright.

 

[Agile]

You cannot blame Brit Gas for faults on your boiler.

You say the ignition does not work. It seems you are aware of a fault on your boiler but have not bothered to get it fixed?

You coincidentally became aware of the pressure issues which as advised are likely to be with the EXV.

Tony

 

[smirge]

Neither am I blaming British Gas for the fault - just stating that the visit alerted me to some issues I wasn't previously aware of, or being inconvenienced by.

I haven't not been bothering to get it fixed, as I wasn't aware anything needed fixing til now; barring an occasional need to manually increase the pressure, it hasn't been causing me any significant bother.

To reiterate, I see no harm in having it looked at now - it simply just amounts to an unexpected expense. I will look at my options.

 

[Agile]

If the EXV can be repressurised than that's not a major job.

Difficult to know what the ignition problem is nut they are not usually major. How did BG relight the boiler?

I would expect to deal with both issues within our diagnostic fee in most cases within our normal area.

Tony

 

[smirge]

They re-lit the boiler with a match. If this isn't likely to be an overly expensive fix, as you describe, then that's certainly good news.

 

[Agile]

You are very lucky they did that!

Since its a fault with your boiler they were perfectly within their corporate rights to just say your boiler needs a repair!

You were lucky, many would not have done that. Some would even say it was not a safe thing to do or they were not gas registered to open up boilers!

Tony

 

[smirge]

Yep, however this is part of a long running complaint that British Gas have been handling for me, out of which I've thus far been awarded £200+ compensation (their offer - not my request), so I'd imagine they were probably more keen than usual to make amends.

NB I imagine you'll remind me that this isn't British Gas's responsibility again, but the complaints handler has repeatedly indicated that 'if it was working okay before we came and wasn't after, then it's our responsibility to sort it, and at no cost to you' so I guess that's what they've been trying to do!

 

[Agile]

Clearly the ignition was not working before. Its just that with the pilot light already on you were unaware of the problem.

Meter fixers are usually contract staff and would be totally unaware of any previous dealings you have had with BG. Its very rare for BG to be dealing with meters themselves.

I think that you were just lucky to have had a very helpful fellow on the day!

Tony

 

[smirge]

Well, I did speak to a supervisor from engineering on his mobile before the engineers came over, and explained the situation in full - he indicated he'd send the right kind of support for the described problem, so there we are I guess..