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eco_mark
So custard had an old potterton fuego super backboiler on gravity HW pumped CH, and as part of a phased change over to other heat sources has put in a thermal store and converted to fully pumped.
BB used to have two 28mm pipes for HW and two 22mm for CH. The 28's have been capped and 22's now feed into the thermal store, with the old CH pump remaining on those 22's and now acting as the boiler pump. CH now fed with new pump and new pipework from store to where the 22's where disconnected from old pump.
Problem they've got is that the boiler won't fire up consistently. Turn the cylinder stat up and the pump comes on but boiler doesn't fire. At seemingly random times it may come on for a minute or so but doesn't stay on and doesn't seem to be any pattern.
I've gone in and bled everywhere I can on the store-boiler pipework, including uncapping the 28's and bleeding, but no change. I've checked the wiring and that seems fine - when HW is required, and cylinder stat says store isn't hot enough, then live signal arrives at a terminal that both pump and boiler are wired into. Pump comes on, but boiler doesn't. Tried removing wires for pump just to see if only having signal received by boiler made a difference (stab in the dark) and it didn't. The fact the boiler will occasionally fire makes me think there isn't anything fundamentally wrong with the boiler (like a broken gas valve), just that some fault condition exists ...
Found installation manual for the boiler ([DLMURL]http://www.partsarena.com/baxi/System/DATA/Dx/DS1/installation/2050/I01-2050/I01-2050.htm[/DLMURL]) but the troubleshooting doesn't really help. I'm now just drawing a blank as I've not dealt with many gravity systems. Anyone have any reasons why a boiler would not consistently fire when giving a live signal? If it used to be gravity fed then I wouldn't think it would be fussy about flow rates, but what else could it be? Nearly given up on this, and told custard as much, but sure would be nice to surprise them with a fix
[Princess Leia voice] Help me UK Plumbing Forum, you're my only hope.
BB used to have two 28mm pipes for HW and two 22mm for CH. The 28's have been capped and 22's now feed into the thermal store, with the old CH pump remaining on those 22's and now acting as the boiler pump. CH now fed with new pump and new pipework from store to where the 22's where disconnected from old pump.
Problem they've got is that the boiler won't fire up consistently. Turn the cylinder stat up and the pump comes on but boiler doesn't fire. At seemingly random times it may come on for a minute or so but doesn't stay on and doesn't seem to be any pattern.
I've gone in and bled everywhere I can on the store-boiler pipework, including uncapping the 28's and bleeding, but no change. I've checked the wiring and that seems fine - when HW is required, and cylinder stat says store isn't hot enough, then live signal arrives at a terminal that both pump and boiler are wired into. Pump comes on, but boiler doesn't. Tried removing wires for pump just to see if only having signal received by boiler made a difference (stab in the dark) and it didn't. The fact the boiler will occasionally fire makes me think there isn't anything fundamentally wrong with the boiler (like a broken gas valve), just that some fault condition exists ...
Found installation manual for the boiler ([DLMURL]http://www.partsarena.com/baxi/System/DATA/Dx/DS1/installation/2050/I01-2050/I01-2050.htm[/DLMURL]) but the troubleshooting doesn't really help. I'm now just drawing a blank as I've not dealt with many gravity systems. Anyone have any reasons why a boiler would not consistently fire when giving a live signal? If it used to be gravity fed then I wouldn't think it would be fussy about flow rates, but what else could it be? Nearly given up on this, and told custard as much, but sure would be nice to surprise them with a fix
[Princess Leia voice] Help me UK Plumbing Forum, you're my only hope.
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