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Contaminated hot water?

My narrowboat's hot water is heated by the engine (this may be usual; I don't know). There is a noticeable smell of diesel when the hot water is run, e.g. in the shower, which can't be right. Any thoughts please on cause(s) and solution(s)? Thanks.

Asked by: Paul Taylor  | 8.02pm, Sunday 19 August

WW says:

Having a calorifer (hot water tank) heated by a coil from the engines hot water is the most common primary water heating method on narrowboats.
It would be very unusual for the hot water to be contaminated by diesel directly, and it is very infrequent that the engine coolant would leak into the calorifier.
One possibilty that might occur, is that the pressure relief valve on the top of the calorifier might lead to a hose in the bilge, and that water can be sucked back into the calorifier, possibly from the engine bilge, which could explain the contamination.
Sometimes, the PRV hose is so long it leads into the bilge- it should be traceable from the top of the calorifier- or as a solitary connection to a single pipe, if a horizontal calorifier.- open the valve at the top, and you will see water come out- somewhere!
The pressure relief valve is designed to operate if the internal temperature raises the pressure too much- and often an amount of water is discharge when the calorifier heats up. However, some of the valve can fail, allowing water to enter.
Another possibility, though highly unlikely, is that one of the hot water pipes passes through the bilge, where it is absorbing oil through the pipe or a joint: though in most boats this shouldn't be able to happen!
It might be worth checking that the engine coolant is not leaking: though this might mean draining the engine cooling system and adding a dye such fluroscein to trace any leakage.
Do you have any diesel smell in the cold water at all (such as if you boil it in the kettle?). If so, this may mean a contamination of the water tank. This would mean a full clean and repaint/lining of the tank.
If all seems normal with the connections then let us know and we will try and think a bit deeper! A very unusual problem and one that I hope you can sort out quickly- not a nice thing!

Mark Langley  | 9.53PM, Sunday 19 August

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