Back boiler thermostat and not heating one radiator

yamaha4life

Hi all,

The house im living in has oil heating and open fire with back boiler.

The oil heating heats all the radiators they thermostat for that is set to 70 afaik but the radiators never feel that hot. Its an old house so its hard to heat so they could do with being hotter really.

The back boiler heats all the radiators bar one which is annoying why would this happen?

The radiators the back boiler heats do be roasting compared to when the oil is heating them.

The pipe thermostat is set to 50 on the back boiler but sometimes it doesn't kick in and ill have to manually wind it down until it starts, when it kicks in if i wind it back up it wont click off until just under 80. Is this normal? Or should the pipe thermostat be changed? The pipes do be banging!

Ive spoke to the landlord about it and the plumber came and his solution was to set the pipe thermostat to 40 which did stop the banging etc but the radiators may aswell be off they barely got luke warm all night at that setting.

John.G

The pipestat should only have a hysteresis (difference between cut in/cut out) of 6 to 10C, if you just turn it up or down slowly until you hear a click, then immediately turn it in the opposite direction you should hear another click 6 to 10C "later". what may be happening to yours is that the stove isn't for some reason able to get the circulation going by gravity, if the water in the stove is 10C higher or so than the stat setting then it should click off very fast.
How far away from the stove is the stat located?.

yamaha4life

Its right beside the fire in press under water tank, the plumber bleed the pump but made no difference to this particular problem seems fine once it starts pumping, the radiators that doesn't warm up is annoying as its in a bedroom thats used

John.G

The best way to test that stat IMO is to unclip it from the pipe, let it for 5 minutes or so and if the room temp is say 20C or so then the stat should switch on/off when moving it by 6C to 10C around this point, there must be something amiss if the pipes were/are banging.(see rad problem)

If the stove can heat all the rads then the OF boiler should have no difficulty in doing likewise, check the boiler setpoint and set it ~ 70C.

Re cold rad, suggest shutting both rad valves, get a dish/bucket, open one rad valve fully, open rad vent fully and vent air then approx 2 or 3 litres of water. shut this rad valve and repeat with the other one. This problem may also be a reason for the stove not circulating by gravity to switch the stat/pump on.

Also, the simple one, ensure water in the feed and expansion tank.

yamaha4life

Hi thanks for the reply, its the Backboiler having trouble heating the one rad it works fine off OF boiler but the radiators arent as hot as the fire. Ill check the stuff you mentioned tomorrow as ive the fire on at the moment.

yamaha4life

I closed the out on rad and took 3 liters of water out of it seems too have made difference which is great, the OF thermostat is set at 75 on boiler the thermostat doesn't seem to be attached properly? The header tank is full.

John.G

The OF boiler thermostat is normally in a pocket on top of the boiler but some also I think have a pipe stat on the boiler outlet for circulating pump overrun.