Combi boiler pressure when cold

[Truman]

I had a new combi boiler fitted last week and it was set to 1 bar exactly when cold. I've been using the heating and hot water on an evening and have been checking the pressure gauge on a morning. Over the course of a week the pressure has gradually increased each day and it now sits at 1.2 bar, with a boiler/internal system temp of an indicated 27 degrees (give or take a degree) which has been consistent each morning. The system has an integral filling loop which is closed and I'm sure it's not passing as the pressure stays constant throughout the daytime, as I check it when home from work and it's the same as it was on the morning.

So to me, it seems that having the heating on and using hot water on an evening is somehow gradually stepping up the pressure. With the heating on, it rises to 2 bar which I understand is OK, but each time the pressure falls back down overnight as the system cools, its falling back to a higher and higher level.

Are there any other factors affecting where the needle sits? How accurate are they? Nevertheless, it's the consistent gradual increase that bothers me, which seems to indicate a trend, compared to just fluctuating a bit each way.

 

[brum]

Hi there disconnect filling loop it should be disconnected anyway there is nothing to worry about your system is warmer now than when filled so pressure would slightly rise..brum

 

[Truman]

It's an integral filling loop, hard piped so it's not like a flexi hose that can be removed. It's the daily slight increase (a total of 0.2 bar over a week) that's the concern. I guess I'll keep an eye on it and if it continues to rise then there's a problem.