J
JJone
Ok so was at a job yesterday, customer said boiling water had been discharging from his header tank for the past 4 months. I took a look, got everything up and running, stayed for a good half hour everything seemed to be working perfectly and just as I was about to leave boom the pump started to struggle and would make the most awful intermittent grinding sound and stop for a second or so then continue pumping with a lot of noise and the discharge would begin and last for a few mins. The boiler would also switch off, but doesn't lock out. The motorised valves stay open.
Went back today, changed the pump. Fired it up, again all was well then the discharge started again after about 45 mins and lasted for a few mins and the boiler stopped firing but didn't lock out. The new pump runs fine even when it's discharging and continues to pump after the boiler stops firing so the old pump was WORD REMOVED, but this problem still exists. The boiler won't fire up again until the system has cooled right down.
I noticed this only occurs when the hot water only is on, when both hw and ch are on together it doesn't do it. So I think it may be overheating? But when the ch is on it can disperse it obviously. There is a bypass rad in the upstairs bathroom and this was warm when I just had hw on but I'm unsure if it was still warm from when I had the ch on initially so need to see from a cold start.
When everything is working initially the flow on the coil heats up and the return is a lower temperature as it should be but then this suddenly switches and the return becomes very hot and the flow cools- that's when the discharge starts. The feed is tee'd into the vent that comes off the coil flow, I can see it used to feed separately into the coil return as it is blanked. The cylinder never gets anywhere near the 65 the stat is set at.
Initially I thought cylinder stat could be goosed and telling the boiler to shut off but surely it would shut the hw motorised valve? Which it doesn't. So is it the boiler stat? Or can anybody think of anything else?
It is an oil fired warmflow external heat only boiler. The pump, ch and hw motorised valves are all inside the casing. Both motorised valves and now the pump work perfectly. It was completely new heating pipework installed but they've obviously changed things about with the feed in the cylinder cupboard, it was installed 10 years ago, this problem has only been occurring the past few months.
Any help would be greatly appreciated, thanks
Went back today, changed the pump. Fired it up, again all was well then the discharge started again after about 45 mins and lasted for a few mins and the boiler stopped firing but didn't lock out. The new pump runs fine even when it's discharging and continues to pump after the boiler stops firing so the old pump was WORD REMOVED, but this problem still exists. The boiler won't fire up again until the system has cooled right down.
I noticed this only occurs when the hot water only is on, when both hw and ch are on together it doesn't do it. So I think it may be overheating? But when the ch is on it can disperse it obviously. There is a bypass rad in the upstairs bathroom and this was warm when I just had hw on but I'm unsure if it was still warm from when I had the ch on initially so need to see from a cold start.
When everything is working initially the flow on the coil heats up and the return is a lower temperature as it should be but then this suddenly switches and the return becomes very hot and the flow cools- that's when the discharge starts. The feed is tee'd into the vent that comes off the coil flow, I can see it used to feed separately into the coil return as it is blanked. The cylinder never gets anywhere near the 65 the stat is set at.
Initially I thought cylinder stat could be goosed and telling the boiler to shut off but surely it would shut the hw motorised valve? Which it doesn't. So is it the boiler stat? Or can anybody think of anything else?
It is an oil fired warmflow external heat only boiler. The pump, ch and hw motorised valves are all inside the casing. Both motorised valves and now the pump work perfectly. It was completely new heating pipework installed but they've obviously changed things about with the feed in the cylinder cupboard, it was installed 10 years ago, this problem has only been occurring the past few months.
Any help would be greatly appreciated, thanks
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