Pressure drops after fitting new radiators

[Tim10]

I fitted 6 new radiators last weekend, but after refilling the system the pressure has dropped from 1.5 bar to 1.2 bar since last Sunday. I have carefully checked all the joints that I’ve made into the new radiators and there are no signs of any leaks whatsoever. All joints appear bone dry to the touch and there’s no visible signs of any leaks. Before carrying out this work I would on the odd occasion need to top the system up, but no more than a few times each year. If pressure keeps been lost at this rate I’ll be topping up virtually every week. So a few questions I have are:

1. Is this normal on refilling a pressurised system after completely draining down, possibly caused by air bubbles in the system working their way out (where water can’t get out) or other similar explanation meaning it should settle down after a short while?

2. Could I have a small leak(s) that maybe aren’t severe enough to be detected but enough to cause a pressure drop?

3. If there are any minute leaks anywhere in the system, is it advisable to try Fernox F4 leak sealer? I’ve read mixed reports on this. If I use this is it best to leave it in the system permanently or to drain down after a few days or a week of it circulating to remove it from the system?

The system is a Worcester Bosh Greenstar 28i Junior condensing combi boiler.

Thanks in advance for your help.

Tim

 

[kevplumb]

not much of a drop it could well be a little air getting out

there is an auto vent on the boiler

 

[Mark Br]

Fernox F4 really is a last resort. As Kevplumb says probably just a little settlement of air in the system.

 

[Tim10]

Thanks for the replies.

That sounds like a reasonable explanation, I hope that is what’s happening! I think I might put the inhibiter in at the weekend and see how it settles down, topping up where necessary. I seem to remember when the boiler was first fitted 4 years ago it needed regular topping up for a while, but not after each time I’ve drained the system since for minor alterations apart from now.

Cheers

Tim

 

[ChrisR]

Dissolved air tends to separate out inside theboiler (like bubbles in a kettle). That then getsout of the system at the auto air vent. It's pretty normal.