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Calorifier Problem

We have an unpleasant smell from our calorifier which gets worse when water is hot. There are no obvious leaks and bilges are dry. Water pump runs intermittently when water is very hot - presume that is normal venting? - but the real issue if the 'poo' smell which spreads throughout the under-bed area and into the wardrobe causing clothes to smell offensive. Help!!

Asked by: Barbara Wilson  | 5.53am, Wednesday 7 August

WW says:

Sorry to hear that you are having a nasty time with your hot water tank. It is unusual to get a "poo" smell from a calorifier, but here are some general suggestions as to what might be the cause...
Firstly, I assume that the smell is from the calorifier, and not from a toilet holding tank which is getting warmed by hot water pipes (either domestic pipes or the calorifier-engine flow and return pipes). I have know some holding tanks being warmed in this way- and plastic tanks often are permeable to certain smells!
Assuming it is directly the calorifier, check where the pressure relief valve is venting to. You are right that an intermittent running of the pump is due to water being discharged from the pressure relief valve. Often this goes directly overboard or into the engine bilge.
It might be worth checking that these hoses are actually clean and have not filled with any mould/biofilm (or oil, in the case of hoses into the engine bilge).
If the PRV is leaking elsewhere (which can be a litre or two a day of water venting off- possibly more) then you should have noticed it before.
It is worth carefully inspecting the insulation of the calorifier, and all the dead space around it. It is not unknown for rats and mice to work their way through tank insulation, eating it- and it could be possible that a creature has departed this earth, while taking up residence in the insulation- which might cause the smell.
Also, check that there is no leakage from any type of toilet (or shower) anywhere around the calorifier, as this can led to a build-up of smells when heated. However, this is unlikely, as you have not spotted any leaks. However, older leaks (that have sunk into the wood, for instance) can stink for ages, especially when heated.
I am assuming that the water coming out of the tap is wholesome and doesn't smell? At least once a year, preferably more often, a full disinfection of the water system is recommended, as well as more frequent disinfection of hosepipes used to fill tanks. However, once heated to about 71C for more than 30 minutes, the calorifier would be thermally disinfected anyway.
Please let me know if any of this is helpful! This is a really tricky one to identify- if we can be of more help, please let us know, or email me directly; mark.langley@waterwaysworld.com
I am sure other people may have suggestions as well... its certainly interesting, but I feel for you

Mark Langley  | 9.12AM, Wednesday 7 August

Readers say:

Thank you. All food for thought. I think perhaps a proper inspection is required to get to the bottom of the problem. Appreciate your help.

Barbara Wilson  | 6.46PM, Wednesday 7 August

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