New Cabin Sole + Radiant Heat

[-scooter-]

Hello,

So I've been searching and reading a lot about laying hardwoods or alternatives in the cabin, but no one talks doing this with radiant heating. I liveaboard in Maine on a '76 Catalina 27, and while we have had a very mild winter, my heating system (electric fan style) is not really up to snuff. I really want to replace the floating carpet I have now, and also install a better heating system before next winter. Logically, radiant heating makes a lot of sense, as it saves a ton of space when compared to other systems. Has anyone done this? If so, what materials did you use?

So far, I've found this Flexiteek – The original synthetic teak decking material for boats and emailed to ask:
"...I don’t think that the radiant heat would be a problem, if a low heat, but I have never heard of it being used that way."

One company that will cut a custom radiant mat suggested contacting manufactures who make the standard marine ply with teak veneer, but he was adamant that traditional hardwood should not be used.

I thinking that insulating in a manner similar to this: The Frugal Mariner: Insulating your boat and installing a better heating system should keep me much warmer and decrease the electric bill next winter.

Any thought?

[Pyxis156]

We have radiant heat in our home and our living / dining rooms have hardwood floors. While it works well, we find that the heat is significantly less efficient going through wood than it is tile. Also, the logistics of implementing a radiant heat solution on a boat seems daunting, as you have to attach the heating tubing to the sole and you will also want to somehow back it with some sort of reflective foil on the hull side of the tubing as close to the tubing as possible in order to maximize the amount of heat going in the direction you want it to go... i.e., into the floor / living space of the boat, not into the bilge / hull of the boat. Remember that radiant heat is omnidirectional so you have the potential to "lose" most of your heat into parts of the boat that you do not want to heat if you do things incorrectly and that can lead to a very inefficient solution.

Just a few thoughts that come to mind. Good luck!

Steve
Tartan 3700 - Pyxis

[Sailmonkey]

The biggest problem I see with this is the limited amount of floor space available vs. the total BTU needed to keep the boat comfortable. I may be a nice supplement for comfort though.
these look like they could be just the ticket, but I would hesitate to install a floating laminate floor on something that heels. Just a thought, but maybe the under tile unit in epoxy under 1/8" teak and holly?

Radiant Floor Heating, Radiant Floor Heat - Electric Floor Heating By ThermoSoft

[Adelie]

I don't think a radiant floor would work well. There are 2 options for installation:

1. Wiring embedded in the flooring, on a boat that can be flooded. This type of system has gone out of favor in the housing industry because the heating elements would not last long enough, and replacement involved pulling up the flooring.

2. Hot/warm water tubing embedded in the flooring and fed by a boiler. The tubing is going to be 1" OD plus the thickness of the flooring so you are going to lose 1.5-2.5" of headroom on a boat that has limited headroom to begin with. Also you need to have a boiler installation, pumps etc. so the there won't be a space savings.

Improving your insulation is the place to start then think about alternative heating arrangements.


Edit: having just seen Sailmonkey's link, maybe embedded wiring is making a comeback in the housing market. Still, lots of wiring right over the bilge and it's water, the can only end badly.

[-scooter-]

Hi Pyxis and SM,

Thanks for the replies. Should have pointed this out, but the idea would be build up in this order: reflexive or similar, than closed cell foam, then radiant pad, then wood. All would have to adhere to the floor (I wouldn't consider a floating system). I have a bit more floor than most because of the dinette layout and would consider doing this down the starboard side quarter-berth as well. SM, thanks for pointing out the BTU issue, as this is a main concern. I'm wondering if the engineered products will allow more heat through than wood would?

[-scooter-]

Hi Adelie,

I appreciate your perspective. I had been looking at the electric wire systems, because as you point out, the other doesn't save any space. My impression had been that these systems were quite popular with homeowners and fairly bulletproof now, but I may have been swayed by good marketing. Most of these pads have a five year warranty, which given the current age of my boat, isn't all that long.

[red_sky]

I have been toying with this too, but as a temporary installation between underlay and carpet that I throw down for the winter. Something like this. I haven't tried it yet but if I get stuck here for another winter I definitely will. I've found the cabin sole is the most problematic issue of living in the ice.

[Pyxis156]

The primary factors of heat transmission are the thermal conductivity of the engineered material and the amount of airspace in the material itself. If the engineered material is wood or rubber / plastic based then it likely won't have great thermal conductivity, and if the design of the material permits air to be trapped in the material when it is created, it will also act as an insulator. That isn't to say it won't work, as we have the underfloor heat in all rooms of our house and it works fine under both the hardwood floor and the carpeted rooms... it just works harder in those rooms.

As far as the type of heat source, I hadn't even considered electric as it would drain a battery bank really fast though if you just use it when plugged in to shorepower it would be a possibility. I just assumed hydronic as the source and that does mean a fairly significant up-front cost for installing a hydronic heating system, though you could then use it for both the floor and to heat the air (via heat exchangers). We currently have a hydronic system (with heat exchangers) in our boat and love it, especially having hot water for showers and dishes and the like in addition to heating the boat.

Hope this helps,

Steve
Tartan 3700 - Pyxis

[nwdiver]

I run the hoses servicing the heat boxes (forward 2) for my hydronic heater under the deck of the salon and left them uninsulated, the good part was I removed the box for the salon and use about the same amount of fuel and have a warm deck and dry bilge.
In your boat I don’t think you could mount the heater unit. Mine is demand hot water and 6 station hydronic system. In a boat that size I would use a bulkhead mounted propane Dickenson Newport with a fan to move the heat around, that system keeps boats your size toasty in the PNW.

[Dockhead]

I wouldn't do it. You will either have very thick insulation under the radiant heat tubes, or you will lose much of your heat to the bilge. Because you will have to insulate more underneath to offset poor heat conductivity above.

I have hydronic heat on my boat with fan coils. The fan coils save space but are noisy and use a ton of electricity. I would probably bite the bullet and use radiators, despite the problem with finding space for them.

Another thing to keep in mind is that hydronic furnaces are dandy, but only when they work. They are not designed for heavy continuous use and can be a lot of trouble and expense to keep up. You might consider a simple drip fed diesel stove. On a boat that size, distribution of the heat is less of a problem.

[Antonkov]

I have been thinking about this idea too and researched it quite a bit.
The only installation I found is discussed and pictured here.

The main problems I see are, as was mentioned before, loss of the headroom and the total floor surface used (which may or may not be sufficient to deliver the required BTU).

As for the flooring material, there are so many choices, certain laminated hard floors have heat transfer rates close to tiles. And radiant heating is claimed to be working even through the carpets. So, conceptually, it should work, it is just needs to be properly calculated (area, temperature, flow rate, heat transfer).

I personally was thinking of it as a supplemental heat source, something that will help to level out the vertical temperature distribution.