Hi all,
Got a C-plan setup (gravity-fed DHW, tank-stat + 2-port valve and pumped CH.) There's a working back boiler on the lounge's open fire and I've got something a bit wierd going on. (Or maybe its normal.)
Now, by 'working', I mean if you set a roaring fire, after an hour or so you can get all sorts of gurgling noises coming from the chimney breast followed by a mass exit of water out of the vented primary coil circuit (DHW tank in attic). Water gets pushed up into one of the black plastic tanks above the copper tank, which then overflows and ****es water out onto the conservatory roof via white PTFE pipes. Nice feature.
I assume this is all ok (anyone?) Anyway, the rest of the system is working fine, except for one other strange observation...
With the tank-stat NOT calling for heat (light off on RF control box), I can set the DHW on the 2-ch controller to fully OFF such that the 2-port valve on the gravity-fed DHW return stays closed. That light will then stay off for many hours, even overnight. So the tank lagging is working. However, without fail, if you activate the boiler for CH, that tank stat is calling for heat within about 30mins.
I think I know where the heat is going... within about 10mins of firing the boiler/pump for CH, the area of the chimney breast where the pipes go for the back boiler feels warm to the touch. After a while the plaster feels really warm.
So I can only conclude that the CH pump is somehow pushing heated water into the back boiler tank and that a lot of heat is going up the chimney. I can't figure out how this back boiler has been plumbed in. All I know is house was a self-build around 25years ago and the guy who built it says he can't remember there being a back-boiler??!
Anyone got an idea what's going on here and what I might want to do about it (if anything)? I just want it all to be safe and as efficient as possible!
Got a C-plan setup (gravity-fed DHW, tank-stat + 2-port valve and pumped CH.) There's a working back boiler on the lounge's open fire and I've got something a bit wierd going on. (Or maybe its normal.)
Now, by 'working', I mean if you set a roaring fire, after an hour or so you can get all sorts of gurgling noises coming from the chimney breast followed by a mass exit of water out of the vented primary coil circuit (DHW tank in attic). Water gets pushed up into one of the black plastic tanks above the copper tank, which then overflows and ****es water out onto the conservatory roof via white PTFE pipes. Nice feature.
I assume this is all ok (anyone?) Anyway, the rest of the system is working fine, except for one other strange observation...
With the tank-stat NOT calling for heat (light off on RF control box), I can set the DHW on the 2-ch controller to fully OFF such that the 2-port valve on the gravity-fed DHW return stays closed. That light will then stay off for many hours, even overnight. So the tank lagging is working. However, without fail, if you activate the boiler for CH, that tank stat is calling for heat within about 30mins.
I think I know where the heat is going... within about 10mins of firing the boiler/pump for CH, the area of the chimney breast where the pipes go for the back boiler feels warm to the touch. After a while the plaster feels really warm.
So I can only conclude that the CH pump is somehow pushing heated water into the back boiler tank and that a lot of heat is going up the chimney. I can't figure out how this back boiler has been plumbed in. All I know is house was a self-build around 25years ago and the guy who built it says he can't remember there being a back-boiler??!
Anyone got an idea what's going on here and what I might want to do about it (if anything)? I just want it all to be safe and as efficient as possible!
