I have a 40 year old oil fired central heating system in a bungalow. The boiler is positioned in a cupboard outside along with an air handler. The house has underfloor hot air ventilation and a vented, direct DHW cylinder. It has recently had 2 radiators added and a new pump.
My feeling is that the system is pumping over and drawing air. Every time the pump starts I can hear air moving in the pipework in the loft and unless I isolate the DHW cylinder then virtually no heat gets to the rads. There are no motorised valves in the system, the boiler is controlled directly by a mechanical time clock and the only room thermostat controls the the air handler. Both new radiators are fitted with TRV's on their returns.
I have just traced the pipework this morning; the flow leaves the boiler rising to the loft, tee-ing off to the air handler, followed by 2 radiators along the way. It then tee's again dropping down to the DHW cylinder and rising further to the cistern. It is a combined F&E in 15mm. Firstly I was of the impression the first connection on the flow should be the expansion. Am I correct? To finish things off the circulating pump is on the return about 6" from the boiler.
To make things more interesting there is an AAV on a short stem off the flow inside the boiler cupboard. I was under the impression these had to be at the highest point in the system or else they can suck air in, not expel it. The plumber who installed the new rads obviously had some problems because at the other end of the loft from the cistern there is a 2m pipe tee'd off the return to one of the radiators which rises to the same height as the cistern and has a stop end (which I presume he cracked open to make some kind of makeshift expansion pipe / guiser!)
Should I be moving the pump to the flow or should I be moving the F&E to the first tee off the boiler? or should I be moving both.
Craig
My feeling is that the system is pumping over and drawing air. Every time the pump starts I can hear air moving in the pipework in the loft and unless I isolate the DHW cylinder then virtually no heat gets to the rads. There are no motorised valves in the system, the boiler is controlled directly by a mechanical time clock and the only room thermostat controls the the air handler. Both new radiators are fitted with TRV's on their returns.
I have just traced the pipework this morning; the flow leaves the boiler rising to the loft, tee-ing off to the air handler, followed by 2 radiators along the way. It then tee's again dropping down to the DHW cylinder and rising further to the cistern. It is a combined F&E in 15mm. Firstly I was of the impression the first connection on the flow should be the expansion. Am I correct? To finish things off the circulating pump is on the return about 6" from the boiler.
To make things more interesting there is an AAV on a short stem off the flow inside the boiler cupboard. I was under the impression these had to be at the highest point in the system or else they can suck air in, not expel it. The plumber who installed the new rads obviously had some problems because at the other end of the loft from the cistern there is a 2m pipe tee'd off the return to one of the radiators which rises to the same height as the cistern and has a stop end (which I presume he cracked open to make some kind of makeshift expansion pipe / guiser!)
Should I be moving the pump to the flow or should I be moving the F&E to the first tee off the boiler? or should I be moving both.
Craig
