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Gas Water Heater - Safe to drain baseboard loops but run domestic?

Raiborn
Raiborn Member Posts: 4
We sprung a leak on a baseboard pipe. I have the loop valves closed off, and the drain pipe is trickling out. I want to completely drain that loop, but I'm not sure that the trickling is effective - it may be leaking into the loop from the main supply. We're not planning to use the water heater for baseboard heating anymore, so I'm fine draining the entire thing.

BUT, it also heats our domestic water. I assume it's a unique line through the furnace? Is is safe to open the main drain and drain all the water because the domestic is coming in/going out from the side of the unit? or would that also drain and kill our domestic supply of hot water? And of course it would need to keep running to heat our domestic water. The baseboard loop would be empty, and the pump/thermostats would be turned off too. But would having that empty during heating (heating the domestic line - if it is unique) damage the unit?

I just want to get the water out of the leaking loop entirely, but it doesn't seem like opening the drain valve to that section is getting the job done.

Note: This is an OLD water heater (hence wanting to get it stopped since planning to replace at least the house heating loops)

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 10,317
    Need more information. Can you post some pictures??
    Zman
  • Jamie Hall
    Jamie Hall Member Posts: 17,095

    Need more information. Can you post some pictures??

    Indeed we do. From what I can interpret from what you have written, do I take it that the same unit is providing both the baseboard heat and the domestic hot water? And the domestic hot water has a separate inlet and outlet, perhaps on the side of the unit?

    If so, you cannot drain the baseboard loop and still run the unit. The water in the unit is the way heat is transferred to the domestic hot water, and without water in the unit it will overheat -- very quickly indeed -- and you really don't want that (yes, it would damage the unit. Probably burn the house down too while it was at it). If you were to manage things so that there was still water in the unit, but it was really cut off from the baseboard loop, you would still have to circulate that former baseboard loop water through the unit.

    And so... if my guess is right -- and we really do need more information, because I could be interpreting what you wrote quite wrongly -- it is time to get a proper hot water heater for you domestic hot water.

    In any event, do NOT drain the baseboard loop until we can figure out what you have here.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Raiborn
  • Raiborn
    Raiborn Member Posts: 4
    edited March 2017
    Okay, I'm back with some pictures. Just saw the last post as I went to post this one. There is a loop between the circulators and the outgoing line that returns some of the hot water directly back to the unit. Is that loop sufficient to keep it going with all the baseboard loops closed off/empty? My understanding is that the immediate return line is to keep the cold return water from shocking the system as it mixes with it in a line just below the circulators before going back into the unit. I haven't drained that short furnace return section or anything further in than the zone drain valves - it's gridlocked to that short furnace loop and is still hot via convection. The leaking zone return line is actually warm all the way back up to the closed fly valves (and thus the water trickling out from the closed leaking loop is slightly warm too).

    Is it possible that the fly valves are slowly letting some water through? Or that the main outgoing loop flow control valve is letting some out despite being closed as well? Or could all the air in the loop from the leak really slow the draining down that much?

    I found that leaving the drain lines open to drain keeps the water from gushing out the baseboard leak upstairs (flows through instead of leaking out), but closing the left drain valve starts up the leaking again (or at least last I left it closed). And reopening 20 min+ later would have a surge of drainage for a couple of seconds before going back to a trickle.

    Drains Returns_profile Domestics
  • Jamie Hall
    Jamie Hall Member Posts: 17,095
    This is not good. You absolutely must keep water in that boiler, and circulating; should the water level in the boiler become too low there is a very real risk of fire or explosion, unless the automatic shutoffs on the boiler work -- which I wouldn't count on, if it were mine.

    Whatever you do, do NOT open the main drain and let the water out.

    Honestly I cannot recommend that you keep operating the system. Turn it off and leave it off until you can either get someone to repair the leak, install a new, dedicated hot water heater or, if that is your plan, install a whole new boiler with tankless coil (which is what you have now) and repair the leak.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Raiborn
  • Raiborn
    Raiborn Member Posts: 4
    Okay, I'll probably kill the whole thing for now then :/

    If we switch to central air heating, what type of unit(s) would we be looking at for heating our domestic water?

    Thank you for the replies!
  • Jamie Hall
    Jamie Hall Member Posts: 17,095
    Well... I can't recommend central air heating if all you have is a leak. Fixing the leak is going to be a lot easier -- and cheaper. And hot water baseboards are, in my opinion, more comfortable. But -- that is just my opinion.

    On alternatives for hot water -- any number of possibilities. In my area I would stay away from electric anything, as electricity is pretty expensive. Then there are gas fired on-demand water heaters, which take up almost no space at all and work well if they are properly sized to the demand. They can be had for either LP or natural gas. Then there are both gas and oil fired storage tank hot water heaters; a very conventional solution, but perfectly good for all that.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Raiborn
    Raiborn Member Posts: 4
    Thank you! Servicemen came out to fix the pipe today. Definitely the easy short term solution :)

    -closed-