Boiler pressure increase

[ron de ron]

I have a new combi boiler (Vaillant ecoTEC plus 832), 3 months old. It worked perfectly, until bathroom fitters installed a new radiator:

The fitter refilled the system after installation of the new radiator and set the pressure at 1.6B. Heating is off, hot water was not run at all, he pressure is unchanged, and I'm happy. However, a few days later I take a single shower and the pressure goes up to 1.8B - and stays there. Moreover, two days later the pressure goes further up to 1.9B, despite the fact that warm water had not been run at all since that single shower (no one is effectively living in the property). I don't understand, is this normal?!? Why would the pressure go up (and stay there!) if there is no heating on or hot water use at all?! Do I have to get a heating engineer in?

Many thanks!!!

 

[Elkato531]

Pressure will go up a bit when the boiler is running as the water is trying to expand as it heats up. The pressure can rise on a cold system if the filling loop is still attached and not closed properly or because of an internal leak on the hot water heat exchanger (very unlikely on a new boiler). It could be that there is air in the system and this is expanding due to the temperature. It could be that the water went into the system cold and has now warmed up to summer room temperature causing a pressure increase. I'd make sure all the rads are vented, then set the pressure to about 1.2 and observe for a few days.

 

[ron de ron]

Many thanks Elkato531! The fitters bled (vented?) the radiators, but I will do it again to see what happens. What I gather from your message is that this pressure increase isn't normal, so if bleeding the radiators won't help I should get a heating engineer around? Many thanks again for your kind help with this.

 

[ianmcd]

why would you get a heating engineer round for what you describe ? you are looking for a problem that does not exist

 

[ron de ron]

Well, I do think I have a problem: the pressure in the system continuously increases, despite heating system is off, and I have not run a drop of hot water for a week now.

The pressure is getting worse, now it's at 2bar. Once again: pressure was set at 1.6bar, no change in pressure for 4 days, then I take one single shower (last Tuesday), pressure goes up to 1.8bar (last Wednesday), then it goes up to 1.9bar (last Thursday), and now it is 2bar (last Sunday, i.e. yesterday). (again: no hot water has been used since that shower on last Tuesday) It's almost 0.5bar increase in pressure in less than a week while the boiler is completely unused!
1) I bled the radiators now (only one of them had some tiny amount of air), the pressure has not changed, it is staying 2bar.
2) I checked the two valves under the boiler, which are used to refill the system, they are both as closed as they could be.

I've been reading around like crazy: can it be that when the bathroom fitters drained the system, then the pressure in the Expansion Vessel changed and that's why the pressure in the heating system increases? So maybe the Expansion Vessel needs re-pressurizing? Any advice would be much appreciated! Thank you!!!

 

[Elkato531]

The pressure is within the normal operating range. Monitor it by all means but the boiler is happy with the pressure it has. It will tell you when it isn't. Get an RGI in to look if you wish for your own peace of mind but don't be surprised if they find nothing untoward.

 

[ron de ron]

Well, I'm expecting a new born in a few days and with a baby any boiler problem is a major event. What I am afraid of is that when not a drop of hot water is generated and the pressure increases by 0.4b, then when I move in, start to use hot water properly and the heating system is full on too, the pressure will probably go through the roof (i.e. 3b) in no time.

But many thanks for your comments, I really appreciate your kind help!

 

[Agile]

You were told here to set it at 1.2bar.

But for some reason put it at 1.6 bar.

Bleed out some water until it falls to 1.2 bar cold.

Tony

 

[ron de ron]

Hi Tony, the bathroom fitter (plumber) set it to 1.6bar, not me. I will set it to 1.2bar when I go back to the house (yesterday I didn't have the time), but it's not really the level of pressure which worries me, but the change in pressure: in a week the pressure went up by 0.4bar despite the fact that the boiler was not generating a drop of hot water, so the system is as cold as it can get.

 

[DP]

Ron, forget the boiler, prepare for the new arrival.
Let the pressure fluctuate- if it goes to 3 bar, boiler will dump excess pressure to then indicate a fault code saying low pressure. No doubt is a little strange that you are seeing different pressure at different times, but be aware pump when running will effect pressure reading

With Ian regarding you worrying needlessly

 

[Bunnyman]

As above leave it alone ignore Tony and worry about your arrival. The pressure can move 0.5 if pumps running, your probably viewing at different temps and pump running sequence,,,

 

[Dan Robinson]

Always makes me chuckle how people panic about boiler failures with babies on the way. The baby doesn't give a monkey's.
Especially in August

 

[dilalio]

OP: call your GP, not your RGI... The problem you have is called 'Expecting Father Syndrome'
Good luck and congrats

 

[ron de ron]

many thanks for all your comments! ok, i'll try not to worry about the boiler... (difficult) thanks again!