Expert advise required! The overflow tank from my emersion heater keeps overflowing - it mainly seems to happen when the central heating fires up. My plumber has replaced the ballcock but this has made no difference. He now says that it must be something to do with the boiler due to the fact it overflows when the boiler fires up for the central heating. It is a fairly new boiler (couple of years old I believe) and under contract with British Gas (not my choice, inherited contract when we moved in last year). My plumber did do some re-plumbing to my emersion heater when installing a shower for me, but he doesn't think this is the cause. Any ideas what the cause could be? Who would be the best serviceman to call? Another plumber but one who does boilers too? Any help would be welcome. Thanks
I assume you mean the header tank is overflowing ?, The immersion heater is the electrical element which is fitted to your hot water cylinder. There could be a number of reasons.
The pump might be set too high, and pumping water over the vent. Select hot water only and when the pump is running, check to see if hot water is coming from the vent into the tank. Hot water in a plastic tank isn’t a good combination, plastic overflows don’t like it either. This can be cured by turning the pump speed down, say to No.2 on a three speed pump. Although this could be just a stop gap measure.
There should only ever be a few inches of water in your header tank, so if when it’s cold, the tank is full, you need to reduce the level.
There could be other things, but if it keeps happening it’s best to get someone to look at it.
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Originally posted by ezpz: Expert advise required! The overflow tank from my emersion heater keeps overflowing - it mainly seems to happen when the central heating fires up. My plumber has replaced the ballcock but this has made no difference. He now says that it must be something to do with the boiler due to the fact it overflows when the boiler fires up for the central heating. It is a fairly new boiler (couple of years old I believe) and under contract with British Gas (not my choice, inherited contract when we moved in last year). My plumber did do some re-plumbing to my emersion heater when installing a shower for me, but he doesn't think this is the cause. Any ideas what the cause could be? Who would be the best serviceman to call? Another plumber but one who does boilers too? Any help would be welcome. Thanks
Hi it might be worth checking whether the expansion pipe outlet is below the water level in the tank. The expansion pipe is the one that curves over the top of the tank and turns down towards the interior. The water level in the tank should be below the outlet. Another possibiity is lagging or a badly placed cover bearing onto the ball valve in the tank causing water to run into it.
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