Combi Boiler Pressure

dougzz

I have to top-up my system every 10 to 12 weeks. I try to top it up to a little over 1 bar, as the green zone of the pressure gauge goes from just under 1 to about 3, and the installation guy said 1.25 was about perfect. This seems a little too frequent to me, but I cannot find a leak. It's a 2 story property and the pipework circulates between the floors, coming down to the ground floor rads, and up to the 1st floor rads. I listen for drips, search for water marks, nothing, I've lifted floorboards in places and searched with a torch, touching pipe joints for dampness and can't find anything.
I've also noticed that when the heating is on, the pressure gauge typically goes from 1 bar to 2 bars as the system gets hot, whilst I'd expect heat to increase the pressure that seams a lot. Last bit of info is if you turn on the hot tap, the pressure gauge will drop back about 1/3 of a bar, and then jump back as tap is turned off.
Does this all seem normal, any suggestions if not?

cyclonebri1

It's a little too often for my liking, 2/3 times per year has been the norm for me.

1 area I would check is all the rad valves, they aren't all rated for the higher pressure of a combi system and as such can weep.
Problem is the water evaporates due to the heat so you see no leaks;)
Check the gland nut is tight on each end of each rad, (the hex head under the stem of each valve.