Lining with closed-cell foam for floatation, insulation, and safety

  • 04 Dec 2019 17:50
    Reply # 8176628 on 8169104
    Anonymous wrote:

    The Poor Man's Webasto

    Len,
    Here is a cheap way of circulating heated air...

    Arne


    I like it. I would also note that the "Taylor paraffin heater" pulls cold air (and CO2) from the cabin floor and exhausts it thus pulling warmer air from higher up towards the floor. Good job.
  • 04 Dec 2019 17:30
    Reply # 8176506 on 8176044
    Anonymous wrote:

    Years ago I bought an 80% efficient furnace for my home...... It used a plastic pipe exhaust, and an aneroid sensor to turn the gas on once it sensed that the exhaust fan was functioning.   I was disgusted with the flue temp, which was around 150F, and seemed like a lot of wasted energy.

    150F is quite good, most heat driven flues require 200F to 250F and are less than 80% of course. The other half of a gas driven heater that is not measured and not a part of the efficiency rating, is the amount of heat lost through the flue when the unit is not running. A non-pilotlight operation with a exhaust flap can help but does not help the efficiency rating and so few manufactures bother.

      As a result I took an aluminum car radiatior, and installed it after the primary heat exchanger, in a way that the fan drew the air through it also, but I angled it in such a way that the condensed water could drain out, and I attached a drain line to it.   The result was that the temp at the stack now runs about 10 deg above room temperature.   I'd call that very efficient..... and used it for over 20 years in that configuration.   It's amazing how much water condenses out.

    The furnace manufacture would not be allowed to do this. their lawyers and insurance and maybe regulations in some of the places they want to sell, won't let them.

         I prefer unvented catalytic heaters, and have switched over to them, as humidity is something I need in this climate in winter.   100% efficient, they wouldn't of course work on a boat.


    How do you supply them with air for burning?
  • 04 Dec 2019 17:05
    Reply # 8176300 on 8174956
    Anonymous wrote:

    Len wrote:

    [..] (dedicated air intake for heaters is dangerous in my opinion) [...]


    Will you please explain why you think this is dangerous? I expected that an external air intake for the combustion chamber would be a good idea -- for preventing cold drafts.


    All flues eventually gets holes in them. With outside air going into the burn chamber direct you are now pumping exhaust into your cabin (which being sealed will be at a lower air pressure than the flue gas). Contrary to popular belief... the cold drafts are actually a plus for someone who wants to stay healthy. The minimum required fresh air in a new house is one exchange per hour (one exchange means all the air in the living space is replaced in the hour). Note the word minimum, that is the amount that keeps biulding code people from getting sued. Of note, those who use rats for testing have found they need to replace the air the rats use with a 8 full air exchanges per hour to keep them healthy enough to test on. So I expect that 1 air exchange per hour is not keeping people healthy but it does keep them from dying. In a new "energy efficient" house, they use a heat exchanger that warms the incoming air from the exhaust air to help get around this. I suppose this is possible on a boat too but getting air movement that made sure all the air in the boat actually moves rather than just replacing a small local bit a air over and over would require ducting and fans etc. Is it really worth the space and time? The small space of the boat cabin is always collecting smelly as well as odorless but poisonous gases. Breathing even produces poisonous gas but so does cooking and the head. A working heater flue system is like a free exhaust fan. If you don't use it, you then need to provide your own "draft" for ventilation.

    Staying warm at the expense of ones health does not seem reasonable but being able to advertise a higher percent heat kept in the living space does sell that living space and system even when after bought the windows must be left open to keep from getting head aches.

    As a side note, all those steel box wood heaters that boast efficiency like 85% (note that legally 100% is 85% to allow the flue gas to be hot enough to "pull" so 85% is 85% of 85% or 72%) are tested in a sealed room and conditions that are not livable. That is the room they are tested in will reach very high temperatures. After the heater is installed in a house it will be used to keep people comfortable and when used that way will be about 10% efficient.

    Getting heat is not the whole thing, but having a healthy space is also a concern. This is why heating the body by radiation and direct contact (hot coffee or tea) is better than heating the air which has to be exchanged anyway.

    Sorry for such a wordy post...

  • 04 Dec 2019 16:28
    Reply # 8176049 on 8172574
    Anonymous wrote:

    I have one of these - a simple heat exchanger, a fan and a flue.

      although I think it's quite expensive. Luckily I found a used (as new) one for less than half the price. Shouldn't be too hard to make a DIY version, either.

    Yes it is quite expensive, even when converted to my own currency. should work reasonable well though. I am thinking the upside down bowl looks a lot like the one I got from the dollar store but the heat exchanger is more complex. I expect there are fins inside the flue as well as out but still DYI- able. The fan could be any computer brush-less model, though I would prefer one with a metal frame and blades. So with parts, time and effort for building and some profit, half price seems about right. I suspect the testing to be allowed to sell the unit is where the other half of the cost comes from. So maybe not as overpriced as it seems.

    One would have to make their warm drink first I am guessing  :)

  • 04 Dec 2019 16:23
    Reply # 8176044 on 8167053
    Anonymous wrote:
    Anonymous wrote:

    I meant a stove dedicated for heating. However, I have seen postings here showing a makeshift heater with a flue, occupying one of the two burners of a cooking stove. I fear that at least half of its energy escapes up that flue.

    If only half of it's energy escapes up the flue it would be a wonderful efficient heater. Most small heaters are not that good. (most large open fire heaters are not that good - masonry heaters aside)

    My needs are modest. I only make day-sails, these days, and then choose the fine days. During winter I often visit the boat and then light a little gas heater, which makes use of all the heat, and quickly brings up the temperature.  However, without a flue, this has no de-humidifying effect.

    quite the opposite in fact. Burning anything (like breathing) produces water (and CO2 of course).

    So a flue even with all it's losses, is still a plus, it acts as a forced vent removing unwanted moisture and poisonous gases. There must be a place for new air to enter of course and I would suggest not having the air inlet too close to the heater (dedicated air intake for heaters is dangerous in my opinion) so it can remove bad air from as much of the living space as possible. Warming of the body from a heater on a boat is best by radiation rather than warming the air.

    Any fancy ways of recovering heat before it exits, takes a lot of space and is not worth while. Make the heater small, run it hot and don't worry about loosing heat up the flue.




    Years ago I bought an 80% efficient furnace for my home...... It used a plastic pipe exhaust, and an aneroid sensor to turn the gas on once it sensed that the exhaust fan was functioning.   I was disgusted with the flue temp, which was around 150F, and seemed like a lot of wasted energy.  As a result I took an aluminum car radiatior, and installed it after the primary heat exchanger, in a way that the fan drew the air through it also, but I angled it in such a way that the condensed water could drain out, and I attached a drain line to it.   The result was that the temp at the stack now runs about 10 deg above room temperature.   I'd call that very efficient..... and used it for over 20 years in that configuration.   It's amazing how much water condenses out.


         I prefer unvented catalytic heaters, and have switched over to them, as humidity is something I need in this climate in winter.   100% efficient, they wouldn't of course work on a boat.


                                                                H.W.

  • 04 Dec 2019 13:47
    Reply # 8174956 on 8167053

    Len wrote:

    [..] (dedicated air intake for heaters is dangerous in my opinion) [...]


    Will you please explain why you think this is dangerous? I expected that an external air intake for the combustion chamber would be a good idea -- for preventing cold drafts.

  • 04 Dec 2019 07:25
    Reply # 8172600 on 8166168
    Here's a picture of Bill Churchouse's stove on Belgean, a Westerly Nomad (22') and Jester Challenge boat.  If he can do it, perhaps so can I.

    Looks interesting, any more info?

  • 04 Dec 2019 07:23
    Reply # 8172574 on 8148577

    I have one of these - a simple heat exchanger, a fan and a flue.

    Light, easily installed and removed (I have a one-burner stove) and only one moving part, which is cheaply and easily replaced. Uses very little electricity.

    I have made a small, dedicated inlet vent for this, because this heater circulates the air inside the boat. I think it's good to push in fresh air.

    I'm also planning a "flap" for pushing the warm air downward, or maybe a bit of aluminium pipe to push it down to the cabin sole.

    EDIT: although I think it's quite expensive. Luckily I found a used (as new) one for less than half the price. Shouldn't be too hard to make a DIY version, either.

    Last modified: 04 Dec 2019 07:35 | Anonymous member
  • 03 Dec 2019 22:19
    Reply # 8169104 on 8148577
    Anonymous member (Administrator)

    The Poor Man's Webasto

    Len,
    Here is a cheap way of circulating heated air...

    Arne

  • 03 Dec 2019 17:12
    Reply # 8167053 on 8166591
    Anonymous wrote:

    I meant a stove dedicated for heating. However, I have seen postings here showing a makeshift heater with a flue, occupying one of the two burners of a cooking stove. I fear that at least half of its energy escapes up that flue.

    If only half of it's energy escapes up the flue it would be a wonderful efficient heater. Most small heaters are not that good. (most large open fire heaters are not that good - masonry heaters aside)

    My needs are modest. I only make day-sails, these days, and then choose the fine days. During winter I often visit the boat and then light a little gas heater, which makes use of all the heat, and quickly brings up the temperature.  However, without a flue, this has no de-humidifying effect.

    quite the opposite in fact. Burning anything (like breathing) produces water (and CO2 of course).

    So a flue even with all it's losses, is still a plus, it acts as a forced vent removing unwanted moisture and poisonous gases. There must be a place for new air to enter of course and I would suggest not having the air inlet too close to the heater (dedicated air intake for heaters is dangerous in my opinion) so it can remove bad air from as much of the living space as possible. Warming of the body from a heater on a boat is best by radiation rather than warming the air.

    Any fancy ways of recovering heat before it exits, takes a lot of space and is not worth while. Make the heater small, run it hot and don't worry about loosing heat up the flue.



       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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