Slow boiler pressure loss

[Harry Bloomfield]

Towards the end of May I topped it back up to 1.1 degrees. This is a digital display, and the temperature read 26.

I went away for the week, and when I came back, the pressure had dropped to 1.0, and the temp read 23 (presumably because we hadn't used hot water for a while) and so I thought the cycle was starting again.

Pressure can vary with the temperature of the water in the system, best just leave it alone, and stop worrying about it, unless you confirm you have a definite pressure loss - by the boiler refusing to come on.

 

[Johntheo5]

Alright, thought I would give you all an update on this.

So as you know, I was consistently losing 0.1 bar every five to seven days. It did this for about three months.

Towards the end of May I topped it back up to 1.1 degrees. This is a digital display, and the temperature read 26.

I went away for the week, and when I came back, the pressure had dropped to 1.0, and the temp read 23 (presumably because we hadn't used hot water for a while) and so I thought the cycle was starting again.

However, when we were back to normal usage of the hot water, the pressure went back to 1.1 and stayed there, with the boiler temperature at cold reading between 27 and 31.

I was doing these readings at the end of the day before the kids baths, the hot water hasn't been used since the morning showers.

The pressure stayed at 1.1 for eleven days, so I thought it was finally sorted.

Then last Friday the boiler pressure went up to 1.2 and it's stayed that way all this week, but obviously it's been a bit warmer out and the boiler temp was reading between 31 and 34 degrees.

So I was thinking that maybe I had air in the system and it took a few months for it all to get out via the aav, and that's why I was seeing those pressure drops.

I put the increase in pressure down to the recent hot weather.

However, I've just looked now, the boiler temp is 33 and the pressure is 1.3 so it's fine up again!

Have I just got a really sensitive pressure gauge and can this recent weather allow for that, or is it likely that I've still got air knocking around in my system that's playing havoc with the readings, or something more sinister?

You could scarcely calculate the change in pressure with a 5C difference in "cold" conditions. The pressure will only rise from 1.5bar to 1.6bar (actually 1.59bar) with system contents of 80L and a 10L EV with precharge and filling pressures of 1.0/1.5bar even if the temperatures were 15C & 30C to give those two pressures.