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Winterize Forced Hot Water

New here and have a few questions.

I recently had a furnace fail and 3 top floor cast iron baseboards freeze and crack.

A plumber came, since there is only one zone he drained the system down below that level to allow heat to remain functional in the lower level.

The home will be vacant and won't sell anytime soon I'm sure. I would like to winterize the house then come back in spring and perform repairs. My questions are as follows.

Would it be easier to simply drain the heat system?

If not where exactly do you add the antifreeze?

Might it be easier to drain the system then add premixed antifreeze in order to ensure proper ratios?

Thanks in advance!


  • Jamie Hall
    Jamie Hall Member Posts: 23,442
    Hoo boy. Well, since you already have some cracked bits... and the building will be empty, there's something to be said for draining it completely. The key word here is completely. You will need to be quite certain that all the water is out of all the pipes and radiation and the boiler -- and all the other plumbing in the building as well, such as traps for sinks and toilets (or you can add antifreeze to them alone -- use antifreeze made for RVs as directed). I would drain things down, then use compressed air and blow through all the piping. Be aware of two things. First, if you miss some piping, or leave water somewhere, it will freeze and break something -- so when you go to restart, pressure check the system with air before you turn on the water! And fix the leaks. Second, once it's drained and shut down, you will not be able to restart until spring, when you have a spell of warmer weather during which to restart and fix any problems which turn up.

    Good luck.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • icesailor
    icesailor Member Posts: 7,265
    Part of the equation is the "Cast Iron Baseboards" on the third floor. Cast Iron Baseboards are not usually "series Looped" but are parallel piped. Either with one pipe fittings (Mono-Flow tees) or parallel direct or reverse returns. Series looped CI baseboards are a very bad idea. But if you are in the cellar, and it seems that every radiator in the house connects in the cellar to a larger main running around the cellar, you can just open the flow checks and drain the water out of the boiler and system. You MUST open all the flow checks or you will trap water in the system. If there are any new wet rotor circulators installed with IFC's (Internal Flow Checks), you will have to take them out.

    Don't worry about having small amounts of water trapped in the system. As long as the pipe isn't filled completely with water, the water/ice has room to expand and won't push outward but upward.

    The old dead guys that put that system in understood that "pitch" (to them) wasn't a musical term, and a "Low Point" (with a drain) isn't a bad time in your life. The systems were designed to be drained and safe from freezing. Try to avoid putting any kind of anti-freeze in an old system. I found it hard on systems that had it, its corrosive, and almost impossible to remove. I never had a broken pipe in an old house unless there was some really strange circumstance. That's why I finally came upon blowing them out with air. You can't because of the broken baseboards in the attic.

    Sounds like the house was for sale and the Real Estate Hen wasn't checking properly. They never walk up to the third floor to check the temperature, Besides, the thermostat was set to 40 degrees. Before she changed it to 55 degrees after she heard the water running.

    Much water damage?

    I once saw a house where the baseboard split on the third floor with the heat on and the house was unoccupied. The single woman owner went to the Caribbean for the winter. The fill valve was able to keep up with the leak. It pumped 170 degree water to the leak which caused a very humid and steamy house. The hot water flowed all the way to the cellar. The oil burner ran merrily away. The sheetrock ceilings fell down when they because saturated with moisture. All the oak floors and trim in the house turned black. The cellar filled up with water ruining the things stored on the floor. The water pump continued to run until the pressure switch on the pump shorted out from the high water mark. The oil was on automatic delivery. The oil ran out because of the high usage and the oil company filled the tank. The next automatic delivery didn't take any oil. The oil company tried to contact the non-existent caretaker. There was no Plumber of record. The woman came home from the Caribbean in April on a Friday night in April and found the mess. Total destruction. She checked herself into the hospital because she thought her anxiety attack was a heart attack.

    If your experience wasn't up to those standards, the owner was lucky. I've seen worse.
  • RobG
    RobG Member Posts: 1,850
    Don't forget to put RV anti-freeze in the toilets, sink and tub traps and dishwasher.
  • icesailor
    icesailor Member Posts: 7,265
    Pump the water out of the tank and bowl, and pour a cup of anti-freeze down the overflow. A cup of water in the lav and tub trap. If you use air to blow out the pipes, cycle the dishwasher and the washing machine. The air will blow all the air out of the solenoid valves. If there is an icemaker in the refrigerator, cycle the icemaker by the necessary ways. The air blows all the water out of the line and the solenoid.

    Oh yeah. A big wad of toilet paper stuck in the toilet bowl for the rats nests in the sewers. And be sure to ALWAYS leave the toilet bowl cover DOWN, so the rats don't get in the house and raise hell. And they will raise hell!!!.

    In the spring, close the low points and turn on the water.

    If you know it is a tight system with no issues, leave the low point drains and faucets closed. When you come back in the Spring, most tight houses still have pressure. Just open the valve or turn on the water pump.

    It always worked for me.

    If you have a very big crib that always gives you problems, connect the air compressor to anyplace and turn it on. If you get pressure at the faucets, and it doesn't run away, the system is tight. Turn on the water. Or walk around with the system pressurized and listen for air leaks. Leaking Faucets.
  • weiercd
    weiercd Member Posts: 2
    Thank you all very much for the responses. This has been very informative. I believe my plan will be to drain the heating system completely of water and attempt to blow out what I can.

    Is it ok to hook the compressor to the drain fitting and blow air in this way? Certain pressure number to have or avoid?

    Are there any reasons I should not drain the hot water heater? Or perhaps something different should be done with this?

    The long term plan is to come back in spring and make any necessary repairs. Thanks again.
  • icesailor
    icesailor Member Posts: 7,265
    Why do you want to drain the boiler of water. Then, you have to get the air out by purging and venting. You have to fill it back up with water to get rid of the air.