Combi pressure - temperature dependant?

Quick question, should the pressure on a combi system vary slightly with ambient temperature?

I had a leak on my heating system fixed by a plumber, to enable this to be done, I had to remove laminate flooring, before I re-fit it, I'd like to be sure there are no more leaks under the floor

After the system had been refilled, I ran it for a bit, bled any more air out of it, and ran it for a bit more. I then switched it off and filled the pressure up to a nats over 2 bar and watched it for two days, it didn't move at all. This morning however its moved slighly back towards 2 bar. Its perhaps a drop in the region of 0.05 to 0.1 of a bar. However today is much colder than yesterday, is this likely to be the reason for the small drop?

The boiler is located in the garage where it is subject to much cooler temperatures than the house

I have now dropped the pressure back to 1.5 bar and plan to run it for a few days and keep monitoring the pressure

How did you reduce the pressure from 2 bar to 1.5 bar?

newboy said:

How did you reduce the pressure from 2 bar to 1.5 bar?

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Through the valve on the bottom of the magnetic cleaner under the boiler, using a bucket

I wouldn't think combi gauges are that accurate so as to respond to a slight drop in ambient temp change. I would drop the system pressure to 1 bar. I do hope you checked the expansion vessel pre charge when the system was drained?

The pressure will vary about 0.3 bar between cold and hot if set up normally.

But the gauges usually have some hysteresis which is why an engineer will often tap the gauge ( but not on the glass ).

Tony

The pressure will vary about 0.3 bar between cold and hot if set up normally.

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The OP was referring to ambient air temp and not operating water temperatures, as I read it.