After draining down to remove a radiator, and refilling system, CH ok but no hot water,told that there is an air lock in the pipe from the back boiler to the hot water tank, help

scril, September 2008

i had the same problem a couple of days ago. central heating working but no hot water from the taps.
After some troubleshooting, i decided to bleed the rads in the house. The Ground floor rads had no air in them and were fine, but the ones upstairs, closest to the boiler tank had air in them.
As soon as i let the air out, the boiler tank in my bedroom started to feel hot, indicating that the inside coil was receiving hot water.
So in this instance, there appears to have been too much air trapped between the bath radiator and the boiler tank, which was stopping the hot water from reaching the boiler tank.
Have a go at bleeding your rads first, before undertaking anything more complicated or labour intensive.

Istak, October 2015

changed a rad and drained system on old baxi boiler water hot but no heating pump and stat working but ch not getting hot

cm, March 2013

Gary, Tony thanks,
There is no header tank in the attic, and no motorised valves. The hot water pipes run straight from the back boiler to the tank.I have tried redraining and refilling with no luck,also have taken out the thermostat to try and blast the air lock ,all to no avail. Anyting else you can think of?

Scril, September 2008

Could be gravity fed.If so you may have to turn up the boiler stat and try and boil it out.If you have drained the system make sure the small header tank in the loft has refilled as this will stop the water from heating if it is dry.

Tony S, September 2008

depends on ur system s-plan or y-plan ie one flow pipe from boiler to motorised valve or seperate flow pipe from boiler straigh to hot water tank ? if motorised valve then its probs the valve with as a lever to operate manually which will confirm if every thing else is working ok ie air lock or not

gary, September 2008