Sub Floor heating

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

  1. pool
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    pool Junior Member

    The Chris White Atlantic cats have them, if I recall correctly. Seem to work well, and Alwoplast would likely not use a system that's illegal in US or CE markets.
     
  2. Richard Woods
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    Richard Woods Woods Designs

    Instant water heaters have not been legal on boats in the EU or US for years. I fitted one in my Eclipse 15 years ago and the gas installer refused to sign off on any of his work until it was taken out. So I did, he then capped the hose ,signed it off and then I put it back in. I talked to a US builder about it recently. He said "we tell the owners to fit them themselves, we cannot".

    I assume that is what Alwoplast says as well

    Richard Woods
     
  3. saltifinch
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    saltifinch Junior Member

    From what I've just researched, I don't believe an on-demand system is necessary. Hot water enters a manifold, where a thermostat adjusts the temperature to the proper heat for the low pressure/low heat hose running underneath the floor. These hoses are suspended in a foam/metal grid in order to support and radiate heat under another layer of flooring. The hose is expected to last for decades, and all connections are made at the accessible manifold. Separate connections can be made for showers and sinks which would naturally use higher heat/pressure.

    My challenge now is to find a hot water tank that runs on electric/propane, so I can heat the boat in any situation. I know my RV had one, but it was obviously vented to the outside air. Since I am running outboards on my boat, I don't really have capacity to use a heat exchanger. Perhaps a diesel heater is the only solution
     
  4. saltifinch
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    saltifinch Junior Member

    I suppose a better question to ask you Richard is.... how do people heat their boats/water when they're not moored? Or maybe another way to ask that is... Do people even do that? When it comes to sailboat life, you're my expert
     
  5. Skyak
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    Skyak Senior Member

    I have been giving theoretical answers because I figured you wanted to talk about what can be achieved in comfort and high efficiency. Then half way through you say you want simple and reliable and I think WELL THEN JUST ASK RICHARD DO AS HE SAYS!
     
  6. rasorinc
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    rasorinc Senior Member

  7. saltifinch
    Joined: Mar 2016
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    saltifinch Junior Member

    Thanks for linking those heaters Rasorinc. But those are for use in recreational vehicles, I've used them myself actually. I need to find out if installing such a thing is legal on boats. And if so, how to install on a boat. I'm not sure how they hold up in a salty extreme weather environment, such as one finds on a sailboat.

    Syak, I was simply trying to get some insight from Richard. He has been a leader in multihull building and living, and he deserves respect and credit for that.
    But in no way was I giving up on the idea. I want my boat to be legal and professionally built, and I love using new technology. But I have been having difficulty finding the technology I am looking for, at least with a marine application. Sometimes hearing an explanation of a proven method can inspire a new idea, or a refinement of an old one.
     
  8. saltifinch
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    saltifinch Junior Member

    Also, I must be not understanding the concept of a heat pump. Water in the Pacific Northwest is only about 5-10 degrees Celsius year round. How exactly is that a "heat source"
     
  9. gonzo
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    gonzo Senior Member

    A heat source is anything above absolute zero. The higher the temperature, the more efficient it will be. However, 5-10 is pretty good.
     
  10. saltifinch
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    saltifinch Junior Member

    Unfortunately, 0-5 Celsius is also the ambient air temperature in winter where I live. So there's not any heat to be gained.
     
  11. saltifinch
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    saltifinch Junior Member

    I think the answer I've come to is,

    When you're sailing, you don't heat the boat. When you moor for the night, you plug in and heat the boat. When you're moored for the winter, you're not sailing, so you plug in and heat the boat.

    Just curious about when anchoring somewhere up north. Or a crew member gets cold. Just a small portable heater in one of the bunks work best? I suppose a generator on board could solve the problem.
     
  12. Stumble
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    Stumble Senior Member

    I think I would rather have a diesel powered hot water heater than propane. You already have diesel anyway, and there's that whole not blowing up the boat thing.
     
  13. saltifinch
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    saltifinch Junior Member

    Again, I won't have diesels, I will have outboards. Plus, have you ever owned a diesel truck? I do, and it takes 20 minutes just to get up to operating temperature, meaning an incredible amount of fuel is going just to heat. I hope I'm using my engines mainly for maneuvering inside harbors. If that's taking me more than 30 minutes, I might be doing something wrong. And that's why I go with outboards.

    Less weight
    Less maintenance
    Less cost
    Less fumes

    But getting back on track..... Is my thinking correct? Is a generator the solution to heating when you're out on anchor? I just read a Honda 2000Watt Inverter Generator can run 8 hours on a gallon of fuel at 1/4 power. Let's see a diesel do 1/2 of that.
     
  14. Steve W
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    Steve W Senior Member

    Every Gemini I have seen has had an on demand propane water heater, I seriously doubt that they are all owner installed, there are over 1000 of the things out there. Who is the governing authority who outlaws these heaters?
     

  15. gonzo
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    gonzo Senior Member

    You are confusing heat with temperature. Anything above absolute zero has heat that can be extracted from it. Water at 5-10 degrees is a very good source of heat. Because heat pumps are transferring heat, they have efficiency of more than one. It is like a fuel pump. It pumps energy, which will become heat to run the engine, but it transfers more energy than it uses to run.
     
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