I have a suspicion of a fault and solution and would welcome any comments either supportive or critical. I have looked through the forums and do not see this, but I apologise if it is already covered.
Background. I am DIYer: At sisters house, a leaking lock shield needed replacing on an upstairs rad so decision to replace this as well as fit TRV. Partial drain off, rad removed, cleaned, refitted, filled. Pump off when rads refilled.
Problem: Heat did not get past pump; air lock diagnosed, ‘usual’ tricks applied (bled pump, rads, rechecked header, no good.
Called qualified engineer, confirmed air lock, disabled thermostat on boiler for a short time (less than a minute) to increase heat and ‘boil’ pressure through. Successful, heating working better than it has done for months apparently….
Learned/surmised air had been entering the pump persistently. I suspect it is the layout of the installation at fault.
The hot output exits the boiler low down, and travels vertically up, takes a 90 degree turn to horizontal to the pump, then a short horizontal run to a 90 degree turn downwards on the vertical. The pump bleed screw is facing me. I suspect this upturned ‘U’ bend arrangement allows air to be caught in the upper half of the pump, and the bleed vale being only half way up as it were, will not get all air out. I think there is space to loosen the pump and rotate it such that the bleed screw is at the very top of this U bend. Does this make sense?
System:
Gravity fed system – 2 storey house.
Header tank & Valve fine.
Boiler Glow Worm Hideaway; floor mounted in kitchen (ground floor).
Problem: Repeated / persistent air in pump.
Background. I am DIYer: At sisters house, a leaking lock shield needed replacing on an upstairs rad so decision to replace this as well as fit TRV. Partial drain off, rad removed, cleaned, refitted, filled. Pump off when rads refilled.
Problem: Heat did not get past pump; air lock diagnosed, ‘usual’ tricks applied (bled pump, rads, rechecked header, no good.
Called qualified engineer, confirmed air lock, disabled thermostat on boiler for a short time (less than a minute) to increase heat and ‘boil’ pressure through. Successful, heating working better than it has done for months apparently….
Learned/surmised air had been entering the pump persistently. I suspect it is the layout of the installation at fault.
The hot output exits the boiler low down, and travels vertically up, takes a 90 degree turn to horizontal to the pump, then a short horizontal run to a 90 degree turn downwards on the vertical. The pump bleed screw is facing me. I suspect this upturned ‘U’ bend arrangement allows air to be caught in the upper half of the pump, and the bleed vale being only half way up as it were, will not get all air out. I think there is space to loosen the pump and rotate it such that the bleed screw is at the very top of this U bend. Does this make sense?
System:
Gravity fed system – 2 storey house.
Header tank & Valve fine.
Boiler Glow Worm Hideaway; floor mounted in kitchen (ground floor).
Problem: Repeated / persistent air in pump.
