Sudden jump in boiler pressure

[nervous123]

Wonder if anyone can advise re a seemingly erratic fluctuation in boiler pressure.

Over the last few weeks, we observed our Vaillant EcoTec 630 (unvented sealed) boiler losing pressure about 0.2 bar each week. I top it up at the start of the week with the filling loop to cold pressure 1.0 ( = hot 1.4) and generally by the end of the week it is cold 0.8. A plumber advised to bleed the rads and there seemed to be a lot of air in some, but pressure still drops at same rate. (Incidentally, if this is caused by a leak somewhere, are the internal leak sealers from Wickes or B&Q any use?)

Yesterday afternoon I happened to bleed 1 rad while the system was still on. A lot of air came out, but when I checked the boiler, cold pressure was 0.7. I filled it with the loop as usual and then last night, about 7 hours later, I happened to be up and saw that the cold pressure was 1.8 (hot 2.2) !!

Concerned, I turned off system, drained about 400 ml from an upstairs rad and 1.1 litre from downstairs rad, to get cold pressure down to 1.4. When turned on again, hot pressure is 1.9.

So… any explanation for the above sudden ‘jump’? Anything to be concerned about?

 

[Chrisgy]

Pressure of 2.2 when hot would be ok, there's probably a small leak somewhere, more than likely from te rads you have to keep bleeding, check the valves and put a piece of tissue under them for a day see if there's any drips on it during that time. Failing that the leak sealer fluids are effective.

Also when you bleed a rad the pressure of the system will drop, don't know if you knew that or not

 

[nervous123]

Pressure of 2.2 when hot would be ok

But is there a reason why it's suddenly gone up so much more than usual?

Also when you bleed a rad the pressure of the system will drop, don't know if you knew that or not

Yes I did - that's why I filled it up again with the loop. My concern is that it still loses pressure gradually over the week. As I can't see any obvious drips guess I'll have to try the sealer. Incidentally, I don't think the plumbers put inhibitor in yet. Should I put that in before or after the sealer? Thanks for the help.

 

[JimH]

But is there a reason why it's suddenly gone up so much more than usual?

Check your fill-up valve - if it has a small plastic lever... sometimes they become slack and allow water from the mains to pass - you can tighten it with a small Philips screwdriver.

 

[Chrisgy]

The pressure rises when the water is warm or hot, that's normal

 

[fuzzy]

can you disconnect your filling loop?

 

[nervous123]

The pressure rises when the water is warm or hot, that's normal

I know that. Maybe I didn't make myself clear: I'm concerned that the pressure used to be: cold 1.0 - hot 1.4 and then suddenly last night jumped to cold 1.8 - hot 2.2

 

[nervous123]

Check your fill-up valve - if it has a small plastic lever... sometimes they become slack and allow water from the mains to pass - you can tighten it with a small Philips screwdriver.

When water passes into the boiler it is quite audible (a sort of hissing sound) - the sound stops entirely when the plastic lever is back in its original position, and the lever seems to be turned right to the end. BTW - not the tidiest of jobs - i have to contort my arm under the pipework to reach the fillup valve!/...doubt I'd get a screwdriver in, anyway....

 

[fuzzy]

that dont sound like a good install then, the filling loop is supposed to be disconnected

 

[JimH]

To put your mind at rest.. I wouldn't be too worried about a pressure under 2bar - monitor it - you must have a safety Pressure Relief Valve fitted, it'll dump any pressure over 3bar. Use the PRV to dump excess pressure.

 

[gasmarc]

never use the PRV to dump pressure unless you want to create more problems for yourself in the future, a new PRV for a vaillant can be £60 or more for some boiler

 

[JimH]

never use the PRV to dump pressure unless you want to create more problems for yourself in the future, a new PRV for a vaillant can be £60 or more for some boiler

It must be some PRV that costs £60, I think I'd be changing it out? Mine cost under £10.00 - never had a problem using it to dump a few PSI of pressure?

 

[Eddie Charlton]

agree with gasmarc. would not reduce pressure with PRV, hardly ever reseat and generally need replacing. costs can vary aswell

 

[SafeGasInstall]

Is it not part of the yearly service you all do to make sure prv works and if stack to replace as it's a SAFTY device end of the day. If left alone and no one check if is doing what is. Supposto do ,'then when pressure rise and prv not working who is going to be blamed for not checking it over ????

 

[Billy Bob Bob]

It must be some PRV that costs £60, I think I'd be changing it out? Mine cost under £10.00 - never had a problem using it to dump a few PSI of pressure?

am i reading this right jim h your a diyer and advising on this site filled with gsr engineers like me to use the prv to dump pressure?stop advising no disrespect or offence intended but you do not have a clue what your talking about i hope you dont have a worcester there will be lots of tears when that prv fails to seat

 

[tackleburger]

The filling loop on that boiler is built in and is not disconnectable by the user it does have two isolators though.

 

[tackleburger]

could be the filling loop is left open slightly and his mains pressure is 1.8 bar??

 

[WHPES]

Have you checked the expansion vessel pressure itself recently? (when no system pressure). These should usually have a pressure of 1 bar when not in service (will have it written on it).

 

[nervous123]

The filling loop on that boiler is built in and is not disconnectable by the user it does have two isolators though.

Are you sure you're not confusing my model with the equivalent Vaillant combi? So far as I can see, there is an external filling loop...

 

[JimH]

am i reading this right jim h your a diyer and advising on this site filled with gsr engineers like me to use the prv to dump pressure?stop advising no disrespect or offence intended but you do not have a clue what your talking about i hope you dont have a worcester there will be lots of tears when that prv fails to seat

Hello gas man, I take no offence - I worked for over 35 years in oil & gas, on & offshore, where safety is far, far more stringent than in the domestic homefront - pressures up to 10,000psi - how do you think we reduced rising pressure in a vessel before it reaches critical stage??? I'll leave you to think about it for a minute...
Granted I did get a little stuck with the small compact boiler I have, I could hardly access it - I could virtually walk inside the ones I worked on... all instrumentation accessible... all wiring guaranteed to be correct.
Seem's to me that many of you have little or no confidence in the safety equipment you install? It's rarely the PRV that fails (they are tested, hit thousands of times with overpressure until they fail), it's sludge, grit & often solder, trapped in the seat that allows pressure to pass. Now, if you know of a particular valve that is unsafe, and is likely to fail should you operate it... complain to Worcester.
Here's a question for all of you - why isn't there a pressure gauge fitted in the return line as a standard install... that is one on the intake & one on the return?