I have a problem that try as I might I can't solve. It all started when I changed a rumbling UPS for a new UPS2 pump. After 40 minutes I can hear some gurgles of air / gas entering two radiators. This carries on for a few minutes and then stops. I bleed this off and the same thing happens the next time the heating is on. We have an S plan system, independant heating and hot water valves so the boiler is a system one. I do see minor air bubbles appearing from the cold feed in the f/e tank but they are really small, covering only a patch of one squire inch. I think the 40 minutes timescale might be related to this happening when the hot water cylinder gets hot enough and the hot water value closes. This then cause any trapped air to be more easily distributed to the radiators. I've been bleeding the system many times. So I have tried:
All radiators taken off an manually flushed - very little sediment.
I have circulated x400 for 3 days.
I have attempted to descale the Baxi Platinum He24 boiler with X800 left overnight in the heat exchanger. I didn't want to do this hot as it's an aluminium heat exchanger. The boiler does not sound very noisy so I have doubts about kettling.
The system is definitely not pumping over into the open f/e expansion tank.
I have changed the pump speed which makes no difference.
I have pressure tested the system for leaks and have maintained a steady 1 bar for 12 hours. This was done with part water in the system.
The water leaves the boiler at 65c and returns at 50c.
The pump is definitely round the correct way as the boiler has a flow switch which is working.
The pump is on the flow, 3 metres from the boiler with the cold feed and vent just before it on the inlet side. The cold feed / vent pipes are combined via an air separator, vent on top, cold feed 1 inch from vent.
The system is dosed with 1.5 litres of X100. The system has 10 radiators.
All radiators get hot ok so I can't think that there is any blockage around the pipe work.
The f/e tank has a head of about 3 metres to the top of the boiler so I guess there is about 0.3 bar in the system at this point.
I have thought of increasing the system pressure by raising the f/e tank but I can only achieve 1 metre of height which will only change the pressure slightly.
Is there any way of definitely checking whether my system is kettling and therefore creating air?
Any suggesting would be extremely gratefully received a I have run out of all ideas apart from converting to a sealed system.
All radiators taken off an manually flushed - very little sediment.
I have circulated x400 for 3 days.
I have attempted to descale the Baxi Platinum He24 boiler with X800 left overnight in the heat exchanger. I didn't want to do this hot as it's an aluminium heat exchanger. The boiler does not sound very noisy so I have doubts about kettling.
The system is definitely not pumping over into the open f/e expansion tank.
I have changed the pump speed which makes no difference.
I have pressure tested the system for leaks and have maintained a steady 1 bar for 12 hours. This was done with part water in the system.
The water leaves the boiler at 65c and returns at 50c.
The pump is definitely round the correct way as the boiler has a flow switch which is working.
The pump is on the flow, 3 metres from the boiler with the cold feed and vent just before it on the inlet side. The cold feed / vent pipes are combined via an air separator, vent on top, cold feed 1 inch from vent.
The system is dosed with 1.5 litres of X100. The system has 10 radiators.
All radiators get hot ok so I can't think that there is any blockage around the pipe work.
The f/e tank has a head of about 3 metres to the top of the boiler so I guess there is about 0.3 bar in the system at this point.
I have thought of increasing the system pressure by raising the f/e tank but I can only achieve 1 metre of height which will only change the pressure slightly.
Is there any way of definitely checking whether my system is kettling and therefore creating air?
Any suggesting would be extremely gratefully received a I have run out of all ideas apart from converting to a sealed system.
