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Thread: Hot Water heat - Glycol? Other closed-system option?

  1. #1

    Default Hot Water heat - Glycol? Other closed-system option?

    We purchased a vacation home on Houghton Lake, Michigan that has a Hot Water baseboard heat system. Since we will not live there full-time and may only visit a couple of times during the winter, we're not too thrilled with having to leave the heat "ON" all winter.

    We've been told we should never drain the hot water heat system because it's too difficult for the average homeowner to recharge. I'm probably less than average and am not seeking extra work for myself.

    We'd also like to turn the well pump off when we leave (it's a 300 foot deep well), but since we have to leave the heat on, that's not an option.

    If we could choose to do what we'd like, we would empty the hot water heater and heat system, drain supply lines, anti-freeze all drains and toilets, etc, and turn all of the power off.

    A friend said he thought hot water heat systems could be charged with glycol and that it would then be a freeze proof "closed system." Can anyone point me in the right direction if we can convert the system to a closed-loop, non-freezing system?

    The furnace is new, the heat is transferred through older baseboards, and all of the water is routed through a softener.

    Any other closed-system options or suggestions? Thank you.

    Richard

    Arcadenut@aol.com

  2. #2
    DIY scratch-pad engineer leejosepho's Avatar
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    Do a web search for "radiant heat" and see what some engineers, installers or other technicians might advise. Here is one company with some friendly folks:
    http://www.radiantec.com/

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    Like an engineer alternety's Avatar
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    From what you said about the well and softner, it sounds like you are running water through the heating system. Is it really a boiler and isolated water circulating through the system? Your heating system should already be a closed system. All you need is antifreeze of the correct type. You should know the material used in the boiler heat exchanger to pick antifreeze.

    You should never use the water from the heating system as consumable water.

    Never use automobile antifreeze.

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    In the Trades Bob NH's Avatar
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    You can use propylene glycol, sometimes called "R/V Antifreeze".

    If you have electricity in the place you could protect it to just maybe 20 F and then use electric heat to keep it above that. Houghton Lake gets pretty cold; probably -20 and occasionally to -30 F. I'm from near Gladwin so have lived through those winters.

    But how are you going to deal with the water softener and the water supply to the furnace? I would consider using electric heat to keep the whole thing above freezing. I would also put in an alarm with a phone dialer to call me if the power goes off for a long time and the temperature goes down too far. You might also want to have a local look in if there is a problem with power loss.

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    Like an engineer alternety's Avatar
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    RV antifreeze does not have the addatives used in boilers and heating systems. It is not generally heated either so I am not sure how any other possible components of the RV fluid would feel about that. I would not do that if it were mine. Even after having to pay for 30 gallons of the correct stuff. Yes that is a lot, and no this is not the diluted stuff.

    Also, glycol carries less heat and is harder to pump. This will probably not be an issue unless heat capacity or pump capacity is currently right at the limit for operation. It would also be a good idea to flush the system with a cleaner before going to antifreeze. You should check the chemistry each year and put more of the antifreeze manufacturer's additives in if necessary.
    Last edited by alternety; 11-11-2007 at 08:03 PM.

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    Jack of all trades frenchie's Avatar
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    I caretake a place on Fire Island. Now, me, I'm paranoid - so when I close up for the winter, I drain everything.

    I didn't find it complicated to refill in the spring, just time-consuming, because the place has 7 heating zones, plus 3 indirect tanks, and a heat exchanger for the pool... it takes a while to bleed the air out of 11 zones.

    Not rocket science - just a hassle.
    Master Plumber Mark:

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  7. #7

    Default Hot Water Heat - Glycol questions

    Thank you to everyone for your replies. I'd like to clarify, just to make certain my request is clear. I have a few questions.

    Here's a photo of the system:
    http://s83.photobucket.com/albums/j3...current=38.jpg



    The first item involves the hot water heat. The system is, indeed, a closed system, but it uses water and as needed it gets it from the well (on-demand). I suspect the small tank next to the furnace (about two gallons) is the "water make-up" system.

    If the efficiency is decreased, that's fine. Again, we'll probably only be there a few days during each winter and can use the natural gas fireplace for cool spring or fall days.

    What I am hoping might be an option is this:

    To ELIMINATE the water source, so that the system is filled with a fluid, is completely sealed and closed, and that it never needs additional fluid (water or anti-freeze).

    Is this realistic? Does the heat come from steam? I have never had this type of heat.

    If these systems are capable of using an anti-freeze, does it ever need a recharge or additional fluid if there are no leaks?

    Now for specific questions to the replies:

    Frenchie: If the system really can be drained and refilled with ease, how do you ensure nothing is left in this intricate system?

    Bob NH: It's the water supply to the furnace that I'm trying to eliminate (if possible). Again, I know nothing about these systems.

    I'd like to avoid anything electric. I've found electric heat sources to be too costly to use and would prefer to simply shut EVERYTHING off after draining water lines (except the heating system if it is charged with anti-freeze). I would also ensure the water softener is addressed.

    Again, thanks to everyone for the suggestions.

    Richard

  8. #8
    Like an engineer alternety's Avatar
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    If it is a closed system, and not steam, there should be almost no makeup water.

    The little tank is an expansion tank to absorb pressure changes as the closed system water is heated and cooled.

    The way you want it is the way it should work now. If you are using any significant amount of make-up water there is a leak.

  9. #9
    In the Trades Bob NH's Avatar
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    The small tank on the heating system is an expansion tank to allow the water to expand a bit when it gets hot without causing pressure that would rupture the boiler. It has a bladder with air on one side and the boiler circuit on the water side.

    You need water makeup if you get a leak, because if it loses water the system could overheat and damage the boiler.

    You might operate the boiler to keep the place above freezing during the winter. That, along with an alarm system and an arrangement with a local caretaker might solve the problem.

    I would set up a thermostat system to operate the boiler only when the temperature is below about 40 F, and shut it down completely when it is warmer than that or when it is above 35 F outside. By completely shutting down the boiler when it is safely above freezing you will not lose a lot of heat up the stack.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    My boiler (and I'm sure some others) has a built-in anti-freeze protection. Even if it is not being asked to provide heat, if it senses it could be damaged by freezing, it will turn itself on to maintain some minimum temperature. this sort of thing is probably only available on newer, computer controlled boilers, though.
    Jim DeBruycker
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    Like an engineer alternety's Avatar
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    I believe my boiler also protects itself from freezing. But it could not operate zone valves or the circulation pumps so the rest of the system could freeze.

    Regarding loss of water. Your boiler should have a protection device to shut it down if it runs out of water. Information only; won't help you problem.
    Last edited by alternety; 11-12-2007 at 05:26 PM.

  12. #12
    Jack of all trades frenchie's Avatar
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    I blew out all the lines with a compressor. It took hours - but like I said, that house has a huge / complicated system.

    I worry about small / slow / un-noticed leak, leading to small infusions of makeup water so that I end up with a "freezable" solution in the system.

    I also worry about power outages - we had three, the winter we kept the house open & I stayed there. I know it's not electric, but it still needs power to operate the electronics, pumps, etc... If you keep it running, I think Bob's suggestions of a local caretaker's a good one, if you keep it running.

    FWIW, others who leave their houses open there, leave the thermostat set to 55 - for the margin of safety - if the power goes out, you have a day or so grace before the house & pipes cool down to freezing.
    Master Plumber Mark:

    there is nothing better than the
    manly smell of WD 40 in the air
    while banging away on brass with a chisel and hammer...

    it smells like......victory......

    do not hit your thumb...
    __________________
    Just so everyone's clear: I'm the POODLE in the picture ("french", get it?) The hot woman is my wife.

  13. #13

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    LeBlanc,
    I agree with what the others have said about antifreeze the only thing I would add is that glycol will break down with time and become corosive and needs to be changed every 5 or so years maybe 10 with light use. About the boiler supply line. are you sure thats not feeding a tankless coil to provide you with hot water ? any good plumber should be able to do what you ask

    Lou

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    In the Trades Bob NH's Avatar
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    Referenceing the Photo: The picture is not clear but that appears to be an unusual connection on the Temperature/Pressure port of the hot water heater. If the Temperature/Pressure relief valve is not permitted to discharge freely then you have a serious hazard.

  15. #15
    Jack of all trades frenchie's Avatar
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    Good eye, Bob...

    Richard - the pipes in question, are right above that damp spot on the floor in the picture. Is that all one assembly, or just look that way because one's in front of the other?

    A picture of same area, from a slightly different angle, would clear thing up.
    Master Plumber Mark:

    there is nothing better than the
    manly smell of WD 40 in the air
    while banging away on brass with a chisel and hammer...

    it smells like......victory......

    do not hit your thumb...
    __________________
    Just so everyone's clear: I'm the POODLE in the picture ("french", get it?) The hot woman is my wife.

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