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Heating/hot water

Are there any rules or regulations or reasons why I can not fit a small LPG domestic combi boiler in my narrow boat. David

Asked by: David Anderson  | 1.27pm, Thursday 16 June

WW says:

In principle, there is no reason that you cannot instal a combi boiler, provider the manufacturer has warrantied it for installed on marine craft. If they do not allow it to be installed and will not warranty the boiler, then it is not type approved and cannot be installed. Some manufacturers will, but most won't.
You also need to be able to safely accomodate the flue- you must use the manufacturers fitting and terminal ends- and also the maximum (and more importantly, minimum) lengths of flue- which can be difficult to fit in a boat.
If the boiler is not room-sealed (as some models aren't) then installation is much more difficult- read the BSS guide. To pass the flue spillage test, may require a much longer flue than can be accomodated. A room sealed unit would not have those issues.
Also, the gas input loading would mean that, to avoid pressure drop, you would have to fit a sizeable diameter pipework to the boiler- and the marine GasSafe engineer that you use to fit such a boiler should be able to advise.
However, even the smallest domestic combi unit is vastly overpowered for use on a narrowboat- a narrowboat needs a maximum of around 5KW to heat it- and actually a lot less- around 2.8KW constantly for a 60ft narrowboat, maintaining an interior temprature of 21dec C when its -1C outside...
This means that the boiler will be constantly cycling- which doesn't do it much good, as it will be lighting, burning and shutting down within a very short time.
Also, it would require a constant pure sine wave 230V supply operating- and the consumption when pumping on heating cycle is quite high, compared to a extra-low voltage (12 or 24 V) diesel heating system, for example. This would mean a landline or inverter running constantly.
So, you might be able to fit one, given the above constraints- but think why they are almost unheard of on boats- if they were easy, simple and effective, they would be far more utilised. I have come across two boats (one narrow, one widebeam) with them fitted and the owners were not happy with them on both occasions- it had cost them a lot to maintain (due to the short-cycling)- one was planning to remove and fit a smaller caravan/marine LPG burner unit.

Mark Langley  | 9.42AM, Friday 17 June

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