Sub Floor heating

Discussion in 'Multihulls' started by saltifinch, Apr 1, 2016.

  1. Barry
    Joined: Mar 2002
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    Barry Senior Member

    We have owned hydronic diesel and forced air diesel heat.
    Espar, Webasto and others build both.
    Forced air is quick to feel the heat in a room. Certainly the floor is not warm instantly but it is the quickest
    Downside, is that you have to run the air through vents 3 - 4 inches in diameter minimum and perhaps on a boat that has already been built, might be difficult. Time to feel hot air coming out the ducts, maybe 3 minutes

    Hydronic, diesel, uses a loop usually, 3/4 to 1 inch hose, from the heater to a buss style heater, ie coil that the water runs through and a fan to blow air through it. Easier to run than forced air but slower to heat things up as you have to heat up all the water in the system before the fans turn on. Hurricane is the one we have now but I think that Espar, Webasto make them as well. Time to feel heat coming out the ducts, maybe 15 minutes

    I would think that running a bunch of water in pipes and waiting for the floor to heat up enough to feel the heat might take a long time before you feel the heat. Our Hurricane has a loop through the water heater that heats it as well so we have hot water for our sinks. The water heater is also electric so we can plug in to shore power to heat the water. The Hurricane has a circulating pump that will push the water through the system so you can get shore power heat.
     
  2. Barry
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    Barry Senior Member


    I could not find any mention of them being illegal in the ABYC 2009 standards. Can you tell me where you read that they are not legal?

    There are many pages written about the standards for propane appliances though but not an on demand water heater being offside with the regulations


    http://www.precisiontemp.com/showermate-m-550-marine-tankless-water-heater/
    A US company advertising an on demand hot water heater
     
  3. DGreenwood
    Joined: Aug 2004
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    DGreenwood Senior Member

    This is from Practical Sailor PS Adviser, and I agree with it 100%


    Tankless propane water heaters carry serious risk of causing carbon-monoxide poisoning or oxygen depletion when mounted in a tight or sealed space. Because a boat is more tightly sealed than a shoreside home, the carbon monoxide is more likely to become trapped. Multiple boater deaths have been attributed to tankless water heaters, and several brands have been recalled over the years—among them Wolter Water Heater, Paloma, and Rheem-Rudd—because they posed a carbon-monoxide poisoning hazard.

    That said, you will find tankless propane water heaters on some production boats, but it is buyer beware, in our opinion. Where you mount the heater, how it is installed, and how it is vented are of critical importance. We’ve heard of boat owners mounting them successfully in vented spaces such as cockpit lazarettes, galleys, and anchor lockers, and many install them with heat shields. For extra precaution, you could run the water heater on a propane system separate from your stove, and rig it with a water solenoid that opens when the propane solenoid opens so the propane won’t flow unless there is water flowing.

    If you decide to install the tankless water heater despite the risks, you should first be sure that your heater hasn’t been recalled. We also recommend investing in a quality carbon monoxide detector like the Fireboy/Xintex (PS, December 2005), and always keeping a hatch open in the shower when using the heater. Also, check out our recent blog on inspecting marine systems for propane leaks (Dec. 30, 2013). It wouldn’t hurt to look into your other water-heating options as well; you’ll find a good sampling of what’s available on the marine market in our December 2013 water-heater test.


    I don't think it is actually "illegal" but it should be. They are a little too risky for me and I won't install them or work on them.

    Stick with a diesel hydronic system. This means another tank, another fuel, and more weight. It is the price you pay for comfort and safety.

    By the way. diesel has more calories per volume than gasoline. Not even considering the losses due to conversion from internal combustion engine to generator to resistance coil. That makes for some pretty expensive hot water.
     
  4. gonzo
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    gonzo Senior Member

    If you have propane, which is denser than air, in the living compartment, the area would have to be treated like an engineroom. That is, a bilge blower needs to be run and all electrics should be spark proof. However, you could install the system either on deck or in a vented to the outside compartment.
     
  5. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    I think that's not entirely correct. You can have propane gas consumers in the lounge but the store, the bottle of propane, must be in a separate local, well-ventilated place. That is what is done in all vessels which have, for example, propane stoves in some local. There must be, of course, sensors and certain protections but never at all, as in an engine room.
     
  6. saltifinch
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    saltifinch Junior Member

    I need to find someone who has actually installed an RV water heater in their boat, vented to outside. I'm not sure how I would provide adequate protection for the outside facing parts. But I'm sure they're entirely legal as long as the actual propane burner is outside and the tank and line connections are all outside. Absolutely no risk that way.

    I want an RV heater style, because it can work on AC while at shore, and propane (much faster heating times than electric) while at anchor.
     
  7. saltifinch
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    saltifinch Junior Member

    Thought I might make a small drawing of how I could see this heating system work with a generator. Hopefully its self-explanatory.

    Honda Inverter ( 2000 watts max ) ( Runs 3.5 hours on 1 gallon at 1600 watts, 59dba)
    10 gallon electric water tank, 1500 watt power supply.

    Manifold produces separate water supply for sub-floor heating, and shower/sink.

    Generator runs outside, provides direct power to water heater, which is located in salon.

    The idea behind this system being that you can anchor for the evening, run the generator, heat the boat, have showers and cooking as needed. Generator can also have a separate link to power grid to charge batteries as necessary.

    Any problems/suggestions?
     

    Attached Files:

  8. saltifinch
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    saltifinch Junior Member

    The other solution is to use electric underfloor heating.

    https://www.warmlyyours.com/en-CA/floor-heating/environ-heating

    In a 15ft x 4ft area per hull (60 sq. ft), at 12watts per sq ft, that equals to 720 watts per hull. Or roughly 1500 watts. Which is almost the exact same wattage as used by the hot water heater.

    Any preferences/negatives to an electric underfloor heating system?
     
  9. Richard Woods
    Joined: Jun 2006
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    Richard Woods Woods Designs

    The simplest hot water system would be something like this

    http://www.amazon.com/Coleman-Portable-Water-Heater/dp/B00EHKPJMI

    Major manufacturers like Rinnai do not give a warranty for their propane units if used on boats. another major reason boatbuilders don't fit them. Of course you buy a portable one on ebay from China.

    Plumbing/heating and services take up a lot of space and you have to hide it all. So you need to think about it in advance, but I think you are still a long way from those details?

    Richard Woods
     
  10. Spiv
    Joined: Jun 2007
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    Spiv Ancient Mariner

    In my mind, floor heating is the most beautiful, cosy way to heat living areas. :cool::cool:
    I would live with the additional cost/weight/complexity in order to enjoy warm floors.
    Yes, it would take longer to heat, but it'd stays warm longer as well.
    I do not see the gen-set that has to be on for hours, as an option for the noise (both on your boat and the other cruisers at anchor).
    Small diesel heaters are used extensively on trucks, RV and boats in N.EU and N.America and are extremely efficient.
    The hydronic (water) option is normally used to feed radiators, but I often wandered how a small underfloor piping system could be made to work properly.

    I wandered about the possibility to, also, collect heat from all on board combustion engines, exhausts etc. so as not to waste any heat to the outside.
    A larger than normal hot water tank, even the use of a heating fluid heat-exchanger ( :confused::confused: ), could be used.

    I thought these floor heaters could be constructed sawing small plastic tubes under carpets, emptied, rolled and stored away in the summer.

    Any ideas on how to build this and if it would work?
     
  11. saltifinch
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    saltifinch Junior Member

    Perhaps a diesel heater may be more efficient. The trucks I work with use them to heat water, and they are extremely fast. And perhaps they're quieter as well.

    But as I mentioned, the Honda is only 59dba at 1600 rpm, about as loud as a dishwasher. And I intend to keep it inside a compartment, further reducing the noise.

    One way or another, fuel is going to get burned. The objective is not to be as cost effective as possible. Rather, I'm looking at creating an effective, safe, professional heating system. This heating system will be run 90% of the time on shore power, since it's an electric heater. The generator is simply to give it limited portable use while I'm not at a mooring slip.

    If I use a diesel heater, than all it can ever do is produce heat. But if I use a generator and electric water heater, than I can produce heat and electricity in every possible scenario.

    The other nice thing about this setup is that its completely out of sight. No wall heaters, no fans. Just turn on the switch, and feel the heat. In 30 minutes haha. These systems are designed to actually be left on all the time, otherwise they are inefficient and use much more power.

    The hoses through which the hot water runs is made of polyethylene, designed to last for decades. Considering you have hot water running through your boat, its not really a system you want to be rolling up every season, potentially degrading or damaging the hoses. These hoses are low pressure low heat and should never leaked. I've worked with high pressure hoses using boiling water, and if you bend them enough, or let pressure build up, that's when damage happens.

    The point is, they stay there all their life. You inlay them into a structure of either foam or plastic over top of a solid floor that won't flex, then over top of the hose/foam structure, you lay another floor. In houses this is often concrete. That should tell you how long the hoses will last. I would personally use some sort of vinyl interlocking flooring system. They're strong, easy to install, and easy to take apart.

    As Richard mentioned, any heating system takes up space and can become complicated. That's why as I was drawing this up, I was trying to envision where all this piping/wiring would go. A drawing is just a drawing, not a design.
     
  12. saltifinch
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    saltifinch Junior Member

    To be honest though, after spending a full day researching this, I feel an inboard diesel engine is a must. I can create heat and electricity all at once, very little energy wasted while off shore power. If I use a generator or outboards, I am only producing electricity, all heat is wasted. Maybe the extra weight of a diesel is not such a concern. It would save weight and money spent on a generator.
     
  13. Dinis Matias
    Joined: Mar 2013
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    Location: Richmond, BC, Canada

    Dinis Matias New Member

    Heating

    I lived aboard my Niagara 35 for 10 years in BC and 3 in the South Pacific.
    We had a Sigma balanced 2 stags system(now Dickenson).
    It work well for the salon, but the aft part of the cabin was always cold, it was prone to flare ups, dirtied to service, and din't work that well under sail. It was OK for existing aboard, but not for Living Aboard.

    For a LA, the first and more important step, is to fully insulate the hulls, bridge deck and ceilings, witch is a major undertaking, because the foam needs to be install as tight as possible, with no air pockets etc, it's very time consuming, is heavy (epoxy/skinning), and expensive.

    For heating, basically one is restricted to electrics at the dock, if the Hydro fails you freeze.
    Forced air, big diameter hoses, gets cooler the far end of the hose run and really not designed for 24/7.

    The Hurricane hydronic system, is design for marine use, 24/7, gives you hot water on demand, but is heavy and expensive. Thats my choice.

    On Vida Nova, we had the Paloma that came with the 1981 boat, it worked well, but I will not use one again.
     

  14. saltifinch
    Joined: Mar 2016
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    saltifinch Junior Member

    Perhaps both systems would be useful.

    For summer - Reverse cycle heater mounted in the salon to cool and heat as necessary (cool air will sink from salon to hulls ) (ocean temperatures around 9 Celsius in summer up here).

    For winter - Underfloor heating powered by electric water heater with heat exchanger, diesel engine acting as backup.
     
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