I have recently drained, flushed (using mains) and refilled by sealed heating system. However, the boiler keeps cutting out due to there being insufficient return water to the boiler. The boiler starts, the flow gets red hot, the boiler cuts out. This then repeats every few minutes. I have felt the return and it is cold indicating a blockage of some kind. But how can I figure out if it is an airlock causing the problem or if the pipe is blocked with something else?
Airlock or other blockage in the CH system?
- Thread starter kurtuk
- Start date
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If it was okay prior to draining I'd say it's a fairly safe bet it's just an air lock.
Manually open any motorised valves. make sure all auto air vents open, vent pump at bleed screw and make sure pump is free, bleed any manual air vents and try again.
You might have to try turning boiler on several times to try and push any air out. Finally have a look at the frequently asked questions, there is most likely something of use in there.
P.S i'd check to see if your pump is actually spinning when it should be.
Best of luck
Manually open any motorised valves. make sure all auto air vents open, vent pump at bleed screw and make sure pump is free, bleed any manual air vents and try again.
You might have to try turning boiler on several times to try and push any air out. Finally have a look at the frequently asked questions, there is most likely something of use in there.
P.S i'd check to see if your pump is actually spinning when it should be.
Best of luck
I have done all of the above and still no luck. When I am draining the system, I connect a hose to the return to the boiler and only a trickle of water comes out. Is this evidence of an air lock or does this signify a physical blockage?
have you definitely filled it. you say it's a sealed system, what is your pressure gauge reading. are you gettin water at the manual air vents. are any auto air vents open? On a sealed system its unusual to have any blockages that would prevent the system fillingor draining. Perhaps if you could elaborate on the type of system you've got?
The trickle of water when draining could be indicative of a number of things. 1. No water in system. 2. no system pressure and you need to let air into system to allow to drain-eg open an air vent. 3. faulty drain cock-usually rubber washer has become lodged in body
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The system is powered by a Vaillant 428 ecotec boiler. I have 2 manifolds for underfloor heating - ground and first floor - 4 towel rails on and 2 small radiators on the second floor.
I have recently had the system power flushed so I know the system is clean however the engineer that did the power flushing did show me a small lump of concrete that was on the system. The house is a new-build (2004) and this must have been there from installation. I fear that my problem may be caused by a similar lump still in the system that didnt come out during the flushing. The engineer will not come back to sort out the system as he says that he has spent enough time on it already and I refuse to pay him any more to complete the job that he should have done in the first place - hence the reason that I am trying to sort it out myself.
The pressure shows between 1.5 bar and 2.0 bar when it is full, depending on how I have set it.
After I fill the system, I bleed all radiators and towel rails until water comes out. The auto-air vents also hiss signifying the release of air. I also check the pumps for air.
I have recently had the system power flushed so I know the system is clean however the engineer that did the power flushing did show me a small lump of concrete that was on the system. The house is a new-build (2004) and this must have been there from installation. I fear that my problem may be caused by a similar lump still in the system that didnt come out during the flushing. The engineer will not come back to sort out the system as he says that he has spent enough time on it already and I refuse to pay him any more to complete the job that he should have done in the first place - hence the reason that I am trying to sort it out myself.
The pressure shows between 1.5 bar and 2.0 bar when it is full, depending on how I have set it.
After I fill the system, I bleed all radiators and towel rails until water comes out. The auto-air vents also hiss signifying the release of air. I also check the pumps for air.
Kurtuk, how are you getting on with this? Was just wandering why you had this flushed in the first place. Was the boiler cutting out on overheat prior to the flush? Is the boiler showing any fault codes? I'll see if i Interest anyone in the Comb' Chamber in having a gander.
Couple of final questions.
1. Does the boiler have isolation valves underneath and are they fully open.
2. Has anyone checked any filters there may be on the flow and return to the boiler? These may have become blocked especially if the dirty water was flushed through them
3. The drain off point you referred to. Was this on the boiler or external?
Couple of final questions.
1. Does the boiler have isolation valves underneath and are they fully open.
2. Has anyone checked any filters there may be on the flow and return to the boiler? These may have become blocked especially if the dirty water was flushed through them
3. The drain off point you referred to. Was this on the boiler or external?
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