Log in
Article search:

Q & A

Lpg Water Heater on New Self Fit out

I'm currently looking into getting a Sailaway built and doing the fit out myself (obviously getting a qualified professional to fit the gas). Ideally we'd like an Lpg instant water heater, though there seems to be lots of conflicting information out there as to what is suitable. As far as I can find out it seems that all new boats must have a room sealed water heater which means the Morco F11. Though there may be a problem with the flue height unless I use the angled version and have it going out the rear bulkhead. Does anyone have experience of this or are there any other water heaters that would be suitable? I've found the Widney Slimtronic which also looks like it might do the job....
Is there any source for information on instant water heating for canal boats?

Asked by: Matthew Booth  | 4.20pm, Tuesday 22 April

WW says:

One easy way to overcome the flue height is to mount the instantaneous water heater much lower on the bulkhead than most people fit them. This gives a longer flue length inside the boat without the large bridge clobbering external flue seen on many boats.
Some people have tried LPG versions on combi boilers, but these tent to be far too powerful for all but the very largest craft. They also need a good 230V constant power supply.
Gas appliances have to be type-approved to be fitted on boats, or they will fall foul of the BSS, which is why gas fridges cannot be fitted new- as the manufacturers don't approve their use aboard boats.
Most boaters use calorifiers heated from the engine, with a second coil from the central heating system, if fitted, as this make use of the waste heat from the engine and only needs 30 to 60 ,minutes of cruising to heat enough water for a couple of good showers.
Instant gas water heaters are good for boats that aren't going to cruise much, as trying to heat just a calorifier from a (diesel) central heating boiler is not very effective- and doesn't do much for the heaters longevity! However, instant gas water heaters MUST be professionally serviced every year.
There is an alternative unit- made by Truma, called the Boatboiler. A gas burner (and backup 230V heater element) heat either 10 or 14 litres of water to 70C, which gives a good length of shower. The unit is room sealed, requires minimum 12V power, the boiler can be fitted under a bunk or sink unit, is very well insulated, efficient and the flue can be roof or cabin side mounted. I have seen them in good use both on Narrowboats and also grp cruisers. The unit on gas takes around 40mins to come up to temperature and then thermostatically holds it there, though you can choose the temperature that you want the water heated to. It is certainly worth a look as an alternative. They are also more discrete, as they can be tucked away out of sight.
You could combine both a calorifier off the engine and an alternative heat source, as long as one heat source cannot flow into another (for example, from a calorifier through an instantaneous gas water heater) as this could lead to steam formation and serious risk of scalding. However, with careful planning, and use of a Y valve, you could have two separate supplies of hot water, one to use cruising, one to use when tied up, that prevent the double-heating scenario.
Let us know if we can be of any further help.

Mark Langley  | 9.27AM, Wednesday 23 April

Readers say:

Many thanks for the info Mark. I've been in touch with Widney and found out that their water heater is not approved to use on boats, so the only one is the Morco F11.
As we'll be living aboard, I don't really like the idea of having to run the engine every day even at the times when we're not moving around just to get hot water so I think we're going to with the Morco rather than a Calorifier, and a further spot of research, I've found that the horizontal flue only needs a minimum of 10cm as opposed to the vertical flue needing 60cm - so its going on the rear bulkhead and facing backwards. If its in the top corner then this should give at least 50cm clearance to the door and I'll mount it as low as I can in case it works out we need to switch to the vertical
In the future if i feel like we're wasting potential heat when cruising then we'll fit a calorifier and Y valve.
Many thanks for your input.
Kind Regards, Matthew.

Matthew Booth  | 10.15AM, Friday 25 April

I am a fully qualified Gassafe registered engineer with 30 years experience with all Morco Boilers.Firstly you cannot fit a Widney Water Heater as Widney have not put this appliance through the approved boat safety scheme and must only be fitted in a caravan.If you intend to go vertical flue for a Morco F11 water heater it required a 240 volt supply the pipe work may have to be increased to 22mm. and the flue length MUST NOT BE REDUCED to less than the minimum flue height as in the manufactures instructions.A possible alternative is made by ALDE LTD. but at the present time a small radiator would have to be incorporated in the system as they only do a combination system at present,and are very expensive.The advantage with the Alde Boiler is that the flue is only a few inches above the roof. My gassafe registration number is 163635 if you would like to check my credentials and you may contact me via the details on their web site
Hope that this information has been useful to boaters

David Gilbert Briggs  | 1.55PM, Tuesday 2 June

Where in the boat safety scheme does it say you can not fit a widney slimtronic?...what exactly do you mean by put this appliance through the approved boat safety scheme?
I was unaware that the BSS test appliances
The Slimtronic is perfectly acceptable for installation on boats and as it is one of only two balanced flue models far safer than most of the other models commonly installed

Emily Green  | 2.47AM, Saturday 4 February

You must log in to post an answer.