Grant Vortex 26e rapid loss of pressure at random intervals

[Goochster]

Hi I'm new here.

I have a couple of questions that I'm hoping someone might be able to help me with.

I have a 2 year old Grant Vortex 26e boiler that runs on oil. To be honest I've had intermittent faults with it from day one but at the moment the main problem I have is that it seems to lose pressure at random intervals going from 1 bar down to zero rapidly within a few hours. This can happen after a few months, weeks or in one case this weekend it happened overnight. Each time it happens I have to turn the 2 relevant switches on the boiler to put the pressure up to 1 bar and off we go again.

I do have some radiators in the house that have faulty valves that were leaking slightly. These have been switched off to try and isolate the problem as I'm aware that these leaks could affect the pressure over time, but I'm sure not overnight. To be honest this really hasn't made any difference as when I lose pressure on our boiler it happens at a rapid rate of knots.

Another really weird thing I noticed and again this is completely random, is that on occasion when running the hot water, a bath for example, I can actually watch the pressure gradually dropping down to zero and I have to stop running the hot tap before the pressure reaches zero. It will then slowly recover itself back to 1 bar. At other times the pressure doesn't change when running the hot water.

I'm completely baffled by it. I have had a visit from my regular plumber who isolated the leaking valves on some of the radiators. He recommended replacing all the radiator valves in the house with better ones as the existing ones are cheap ones, and also chemically flushing the system. He also mentioned that there could be a leak in the pipework under the floor.

Carrying out the valve changes and the chemical flush would be extremely expensive for me and I'm not sure how it would solve the main problem as it's not the gradual tiny leak from the faulty valves that seems to be the main culprit as they have already been isolated. Yes it could be a leak in the pipework under the floor but how would that explain the random rapid loss of pressure? Surely the pressure loss would be consistent with the leak? I personally would think its a problem from within the boiler itself from monitoring it on a daily basis and having to live the problem.

Has anyone else come across anything like this? Any help would be gratefully received!

 

[oilhead]

There are many possible causes for this happening and some basic checks you can make your self, like checking for discharge from the pressure relief valve. You have already identified leaking valves. To prove the boiler, isolate the heating system with the valves that should have been fitted to the flow and return, and see what happens to the pressure.

 

[Goochster]

Hi Oilhead

Thanks for your reply. I think I may have sounded more knowledgeable than I actually am about this boiler. These are just my observations.

I'm afraid your reply has baffled me a bit.

Where will I find the pressure relief valve? I've looked in the manual. It does mention it but doesn't actually point it out with a diagram or where it is. If I can find it I'll check for a leak.

To prove the boiler, isolate the heating system with the valves that should have been fitted to the flow and return, and see what happens to the pressure.

Again I'm a bit baffled. Could you possibly explain this again in noddy terms for someone who isn't that knowledgeable?

Many thanks.

 

[oilhead]

The pressure relief will terminate outside through the wall in a copper pipe turned back on itself. If you find evidence of a leak, then you would need to find a competent person to rectify it for you. Did your 'plumber' make any other suggestions?

 

[Goochster]

Thanks, I'll take a look.

The plumber has so far only mentioned replacing all the radiator valves and doing a chemical flush.

Thanks for your help so far. It's very much appreciated.

 

[Goochster]

Hi Oilhead

I placed small dry container below the copper overflow pipe outside and discovered that a small amount of water is collecting when the boiler fires up.

Do you think I might have a faulty pressure relief valve? Could this be what is causing the sporadic and rapid pressure loss?

 

[oilhead]

Could be faulty, more likely to be a fault with the pressure vessel. This needs looking at by a competent person.

 

[Goochster]

Yep you're right. I spoke to the plumber and he asked me to attach a foot pump to the vessel. As soon as I did water sprayed out of it. It looks like its done for!

Thanks for all your help Oilhead! Top man!

 

[oilhead]

For what they cost, whilst changing the vessel, have the PRV changed. If it has been passing, you can't rely on the integrity of the seat

 

[Goochster]

Thanks Oilhead. I'm going to get that done too.