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Underfloor heating on a narrowboat

Hi, I am interested in fitting a wet underfloor heating system as a primary heat source in my boat, which is 58ft long. I have been advised that most of the heat will be lost downwards in the bilge, is this true or can the floor be sufficiently insulated without losing too much headroom? Also, is there a way of calculating the amount of heat needed and what centres the pipes should be set at? Many thanks, Isaac Davis

Asked by: Isaac Davis  | 3.56pm, Friday 4 February

WW says:

There have been several attempts at underfloor heating in narrowboats and widebeam barges. Some have used narrowbore plastic piping set into either a mesh framework, with tiling on top, or the pipes set into a suspended concrete floor, with covering above.
It would be feasable to fit a system, though you would probably need additional circulation pumps. A high proportion of heat would probably be lost, either through the bilge (even with insulation) or behind the cabin linings. You would also need to be careful of the choice of covering above the heating- wooden floors would not be that efficent at conducting the heat through, and carpeting even worse. Tiling would be best, but give a rather cold feel to the boat.
Alde sell a system for motorcaravans, however this would probably be very expensive for a narrowboat- and also they don't suggest it as the primary heating method. By fitting an underfloor system, it would become more difficult to add items such as heated towel rails (drying wet stuff being of prime importance on a narrowboat in the UK!).
Also fitting underfloor heating could be limited to the areas where furniture is not fixed- you might not get enough heat transfer in the remaining areas to avoid cold spots, or to distribute the heating output of your chosen boiler- you don't mention if you are looking at gas or various diesel units.
Fitting underfloor heating limits you layout, and would probably mean that changing the layout in the future would be difficult. also, you might find it hard to achieve the level of heating in, say, a bedroom, that you require, and could leave some areas more prone to damp, as you would have reduced air circulation.
An article on diesel heating in WW showed the amount of heat required (will add the reference for you), which isn't much- however, the losses and inefficiencies of underfloor heating means a greater input would be required.
There is another dimension to add- convector panels ("radiators"), blow-air matrix units and finrads are popular on narrowboats, as they work. They are also liked by the second-hand market. Leaks can also be identified and dealt with- underfloor heating could pose problems if leaks occured, that would be harder to both spot, and rectify.l For this reason, they are unpopular with buyers, on the boats that ahve had them fitted.
So, not meaning to be depressive, but it is probably cheaper, more effective and better for the value of the boat, to stick with something more conviient. Look in next months WW for an example of some striking designer radiators in the boat review of Oak. The additons of fan-assisted finrad/matrix units (see the Alde catalogue) can assist with good air circulation and are almost silent.
If you do go ahead, then you would need to consult your chosen heating unit manufacturer, as any warrenty might be void if they are fitted to an udnerfloor system, which is not approved by the manufacturer.
If you want anything more specific, then please let us know.

Mark Langley  | 4.29PM, Friday 4 February

The diesel article "The burning question" can be found at

Mark Langley  | 4.31PM, Friday 4 February

Readers say:

Hello Isaac, we do not know how old your message is, but any how have a look at oir website www.yfh.nl. You will find all the info for in floor heating on our site. We are succesfully producing and installing our systems worldwide for ten years now. If you do need more info, please do not hesitate to contact us. Best regards Bram van Hanegem, Managing Director, YACHT FLOOR HEATING BV

Yacht Floor Heating  | 7.57AM, Sunday 24 February

I'm considering underfoot heating in a new build narrowboat.
It would be a supplementary heat source, primarily in the saloon, where one spends most of the time sitting and relaxing. In my experience of narrowboats, only 50 years on and off, cold feet while relaxing is uncomfortable.
We have UFH in our barn conversion and it's great. The tubes are fitted into 25mm pre-routed boards made by Osma, previously ThermoBoard, and all connections made accessible in channels similarly, connections could be made at the side of the floor, similar to conventional rads. I expect the UFH to make the saloon more comfortable. Insulation of 25mm king span is sufficient in my experience and can be fitted between supports to avoid the loss of headroom.
Pipes can be fitted into any board, preferably water resisting ply board on a boat.
Good luck.

Rob Pendleton  | 8.36AM, Wednesday 2 September

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