Unfreeze and Shut Main Water Shutoff valve

Old 01-26-21, 08:36 PM
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Unfreeze and Shut Main Water Shutoff valve


Due to CoVid reasons, we have been unable to return to our new Flagstaff home to shut off the water. Our neighbor told us today that, upon checking, no water comes out of the faucets, Our assumption is that water has frozen, in spite of our having left the home heating system running at 50*F. Various neighbors who have lived in our subdivision for years have observed that heavy snow accumulation, such as what Flagstaff had yesterday, plugs the heater air intakes in the roof, causing the gas furnace to temporarily shut down and water to freeze in the pipes. Once the snow has melted and restores air supply, the furnace resumes its operation. This gives us a couple, maybe three, days to take action.

The best suggestion we have heard is the one thing we would have done in the first place had we been there: turn off the main water supply and open the faucets to drain the lines. This same action is now required to minimize burst pipes and water flooding inside the house as the frozen water lines thaw.

My questions are:

1. Is this truly the best suggestion at this point?
2. If the water in the lines is frozen then the water shutoff valve may also be frozen and prevent the valve from being shut off. Is this a good assumption? If so, how do we thaw the main shutoff valve.in order the start draining water from the lines?

Thanks very much, in advance, for your advice.


Old 01-27-21, 02:29 AM
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I am not from a warm climate so I have no idea how deep your water lines are but here in MI water lines are installed 4-5' deep and even in the worst of winter they wont freeze due to warmth of the earth. Yes there are exceptions to that as you always see burst water mains in winter.

Typ lines will freeze inside a house where they are exposed to the elements or not insulated well.

If you have a frozen line Id be looking at where it enters the house.

Old 01-27-21, 05:24 AM
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It's hard to advise specifics without knowing more about your home. With vacations homes I always turn off the water and relieve the pressure in the system when I leave, no matter the house's location.

Yes, having someone shutoff the main water valve is a VERY good idea since you have no idea what's going on inside the home. If pipes burst you don't want water to be leaking in the house for months unnoticed. Thawing the main valve is done with... heat. Plain and simple. Heat it up to thaw it out.
Old 01-27-21, 08:51 AM
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I have been able to find a plumber who's willing to drive out, but only if the heater's working. If the heater was only out for short period (no metrics on that) and comes back on, he says the water may have thawed out by the time he gets there. Otherwise, call the HVAC guy first.
As this may have turned into an HVAC situation, I'll pause here and post a question in HVAC.

Thanks for responses!. The lines are probably no more than 2' deep, IIRC.
Old 01-27-21, 03:09 PM
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I too would start just by shutting off the main water valve and opening a sink faucet. With the water main shut off, you'll limit any damage to the water in the pipes - and hopefully most will just go down the sink.

Just because they froze doesn't mean there is a break - but if there is, you definitely don't want to come home to hundreds of gallons of water flowing out.

I don't know that I'd necessarily have a plumber out right away - I'd ask the neighbors to stop by and check it if it's not too much trouble. Then figure out what may or may not be wrong when you can.
Old 01-30-21, 06:12 AM
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Just a quick update.

This situation started when our neighbor found out the water had frozen in the pipes, likely due to the furnace shutting off when the snow had piled up and plugged the air intake vent. Which triggered my first post about how to unfreeze water already in the lines.

The call to the plumber gave me the correct solution sequence: 1. clear the snow, 2. manually or automatically restart the furnace system and 3. open a faucet. All of which our neighbor's son did and after a few hours, the water was flowing again. I called the plumber back and thanked him for the advice. I thanked the neighbor for saving our pipes and possibly our carpet, as well.

Once everything was back to normal, we didn't take any more chances. We shut off the water main valve. This way, we're ready for more snow!

Thanks to everyone who generously chimed in and set me on the right direction. I've never failed to get good advice from this forum.
Old 01-30-21, 12:11 PM
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Good neighbors. Thanks for letting us know how you made out.
Old 01-30-21, 05:42 PM
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I think I'd get the fresh air intake for the furnace off the roof too. This story about your problem and the neighbor's problem tells me for sure the roof is no place for that intake especially when you are away for extended periods.

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