Boiler Pressure - Filling loop fault or normal?

[everson]

Hello all,

I recently had my annual combi boiler service on Jan 5th . Upon finishing my boiler guy asked me how often do I fill up and I showed him a I keepa log and he mentioned that I should keep it no higher than 1 , as people usually think topping up more saves on tool ups, I explained I was aware of this and never go above 1-1.2 bar. He then mentioned that as he was topping it up it and turned it back on it went over 2bar and he had to release the pressure via the radiator. I assume he mentioned this just to be fully transparent.
But I did notice within a a day or two my pressure was below one. Thinking nothing of it I said to myself I'll top it up in a few days, typical life , days turned into a couple weeks (i.e today) as I noticed it had dropped further. So doing the usual topp up I noticed when opening the valves, water comes out from both ends, is this normal (please see video attached).

View: https://youtu.be/xn8c1_8GUp0?si=1dtXJDyIhLuMCAM2


Thanks any help appreciated as I want to top it up but worry I'm gna introduce some type of double pressure.

 

[Chuck]

What you show is to be expected. The pressure on the supply-side (left) will be much higher (more than 2 bar) than the pressure on the right hand boiler-side (approx 1 bar when filling).

Once you have topped up the system water to 1.0–1.2 bar, see what happens to it when the heating is operating. The pressure should rise as the system heats up but should always stay well within the 'green' area on the boiler pressure gauge.

(I assume you know you should top up after the boiler has been off for long enough for the water in the radiators, etc. to have cooled to room temperature.)

 

[everson]

Hello chuck,

Thanks for getting back to me, and clarifying this is normal. Yes I was aware of filling the system 'cold' if you. Whislt I have you wondering if you could shed some light on this is normal. So I Re-pressurised the system back up to 1.2bar and left the boiler off whilst I went out on a job for 2.5 hours (please see video prt 1:

View: https://youtu.be/J2MRv52oRG0?si=_YUbdN7chesiYJjq
)

But upon return I have noticed the left loop closes to the guage is leaking a small amount, is this normal. In addition my heating has auto come on (I set it this way) but wanted to know if pressure that the boiler is showing is too high or not? Please video prt 2:

View: https://youtu.be/qJHYqd2gTOY?si=qvLG_XD_RLXbv_GB


Thanks any insight would be appreciated

 

[Gasmk1]

Why have you taken off the loop it’s supposed to stay on on that boiler

 

[everson]

Well my filling loop is a small copper pipe. I took it off because I am pretty sure my manual states it should not be left on (would need to double check) and then I happened to notice the leak / drip. Currently it is at about 80-100ml since yesterday. So just trying to find out if this is normal or not.

 

[Gasmk1]

If loops is removed there would be two caps to attach to the open ends. Think you may find that the removal of filling loop will be if it’s external to the boiler

 

[Chuck]

The valves should be drip-tight but they often aren't after a few years of use, which is why the instructions say to disconnect the filling-loop to prevent the boiler over-filling. As @Gasmk1 says, there should be a couple of screw-caps to seal the open ports when the fill-loop is not in place.

Personally, I'd be worried about the amount the pressure is rising in the boiler. Assuming the CH (radiator) water temperature is set to something like 60 or 65°C having the pressure rise to 2.5 bar (as reported in the 2nd video) in normal operation seems a bit high. I'd want to check that the expansion vessel is correctly sized for the system and is working correctly and has the correct amount of air in it. If the expansion vessel has not been performing correctly, water may have been dripping out of the pressure relieve vent pipe so the integrity of the PRV needs to be checked by a suitably qualified engineer.