During a freeze, what is better - keep running water or block/drain (Texas specific)?

Factual Questions
1

This question is in relation to the houses in southern Texas (Houston area) and a repeat of the freak freeze event.

So houses here like mine, have PVC lines buried about a foot deep, run from the curb to the side of the house to an isolation valve. The pipes then rise through the house wall, go to the attic and are piped to different end use points. The pipe material inside the House is CPVC. The pipes in the attic are insulated using the foam insulation sold at hardware stores. There is no heat tracing of any kind. (This is the typical in the southern texas area where freezes are 100 year events).

So during the last freeze, I was really worried about things freezing and kept most of our water (hot and cold) running at furthest points and a few at intermediate points. The water heater is gas powered and kept running happily.

A lot of houses though had pipes burst in the attic and thereby flood their houses. Some claim that their pipes burst despite them running water continuously, although I doubt that.

So, in preparation of such an event in the future, I was wondering if the strategy of letting water run is the best or can an isolation valve be installed (buried to avoid leaks) and a drain to effectively drain all lines in the attic ? Also cab the water heater be drained and turned off ? Any other solutions ?

2

Generally up north where we worry about such more often, we just set a few sinks trickling.

Do the hot water pipes also run up into the attic? If so I guess you could leave hot water trickling also.

You could drain the hot water heater but that is a fair amount of work and probably just as wasteful as the trickling.

A gas hot water heater should have cut off valves for the cold water supply and the gas. It should have an electric cut-off or at least a breaker also.

  • Close the cold water supply valve and turn off the electric to it.
  • Then at the bottom of the tank will be a small hose bib that you attach a hose to and drain the water.
  • Open the highest faucets in the house to get as much water out of the hot water pipes as possible.

When you go to restart everything, again make sure the faucets are open as you now need to purge a lot of air.

3

In my experience, it can be very tricky to make sure that all sections of pipes are actually drained. I would just leave the water trickling.

4

I have seen the same, but the home pipes up North have better insulation per local codes. And you probably don’t lose power either, which probably keeps the attic a little warm.

Also the water pressure goes down significantly during such events. In some places the main water lines develop leaks since they are probably not buried enough.

5

Following Superstorm Sandy we were without power for 11 days and during it had a Nor’Easter drop a lot of snow. I stuck to the trickle concept, but also no pipes in the attic helps a lot. To me, a northerner, that sounds horrifically dumb. But you have a very different climate than NJ.

Moving water tends to not freeze, but it isn’t perfect.

I drained my outside hose bibs every year but I also put a shop vacc on them to finish the job. To me that is the best way to be pretty sure the exposed pipes won’t freeze.

6

Definitely, flowing water is safest. Up here in chilly Canada, this is the usual solution where the furnace stops running - power fail, ran out of oil, etc. (In remote cabins with water supplied by a tank, sometimes they use antifreeze in the lines after draining them to help dilute any low spots that did not drain)

The big problem, as alluded to above, is what to do if the water supply stops - ie. the city system fails, or the pipe from the street into your house freezes. if both happen at once, no furnace, no water - drain the pipes.

Obviously, if you have a gas/oil furnace and electric stove, and the electricity is live, use the stove to try to keep the house warm. Keep water trickling if the house is getting close to freezing in any location where there are pipes. If the pipes are cold in the basement, for example, make sure the laundry room sink is trickling too.

If the water stops running, drain the pipes. TURN OFF THE HOT WATER HEATER. The last thing you want is to burn out the tank trying to heat an empty tank. The tank should hav a faucet at the low point that allows the tank to be drained - it usually has a garden hose thread… beats using a bucket. (Of course, this depends if the outage is going to be an house or a week…)

Open the highest and lowest taps in the house, let the water drain. Then - turn these off. Otherwise, if/when the water supply resumes you will get a gush of water, and it may happen when you are not home.

I find it amazing that pipes would run through an uninsulated space, as even Texas gets the occasional freeze. At the very least, wrap these pipes in insulation if you can.

I assume beefing up the house insulation will make a difference in your air conditioning bill, not just your heating bill.

7

One reason this can happen is that dripping faucets doesn’t mean the water moves throughout all the pipes. Pipes go all around your house. The pipe for the kitchen faucet might come straight from the street to the faucet. Dripping helps keep those specific pipes from freezing, but won’t necessarily mean the water in all other pipes will continually flow. If the attic pipes were for an attic-mounted water heater, then having the cold water dripping won’t prevent the pipes to the water heater from freezing. So when you think about dripping faucets to prevent freezing pipes, make sure you have several faucets dripping in strategic locations so that all the water in all the pipes in your house is affected.

8

This blows my mind. A foot deep for your primary water supply??

9

There’s no way that you can drain a water heater by turning the water off.
The hot water exits from the top…

10

Maybe a few inches more than that. The frost depth in our area is less than 5 inches.

11

This attitude (especially on the part of builders) drove me nuts when i lived around there.

Houston typically sees sub-32 degree weather at a minimum a couple of times every winter and it’s more common in the suburbs. Yet each time there’s a chilly forecast you hear the refrain about watching out for plants, pipes and pets.

If they constructed buildings properly for the climate there’d be a problem only rarely. But the county/city/state lets developers get away with shit.

12

@beowulff - The water heaters are in the attic, on the second floor. Do you think a block valve with a drain connection where the main line comes into the house will help in draining ?

13

True as long as the vacuum relief valve or anti-siphon hole is still intact. That should be a safe assumption, but people do dumb things, and little-used valves and holes can be blocked by mineral build-up. If the heater is in the attic or an upper floor, it can siphon itself empty if there’s no vacuum relief.

14

I don’t think it’s possible no matter what safety device is broken…
If water started to syphon out of the tank, it would be replaced with water from the inlet. If there was no water in the inlet, as soon as the tank started to fill with air, the syphon would be broken.

ETA:
I suppose it is barely within the realm of possibility that if the inlet side had negative pressure, that could cause the tank to drain, but that would be an “end of civilization as we know it” scenario.

15

Ah, I see what you mean. I wasn’t thinking about it correctly, and you’re right it can’t empty through the outflow.

But now that you mention the inlet, couldn’t it happen that way if the water supply is turned off and you drain the rest of the pipes? Opening a faucet on the 1st floor would drain the tank in the attic if there’s no working backflow prevention device.

16

Yeah, you go a little bit north (Dallas), and things are built differently. Frozen pipes are virtually unheard of, except in situations like February, where the interior of the house isn’t being heated any more.

In Houston terms, you could drop everything by about 10-12 degrees from what you see there and be in the ballpark of a Dallas winter, so about as often as you see 40 degree temps, we see freezes, and as often as you see freezes, we see temps in the 20s.

17

Arkansas - we wrapped pipes under grandmother’s house in heating tape. They were turned on/off with a timer. We didn’t turn them off if the daytime temp was below freezing.

My grandmother’s house had been moved and setup on blocks. We closed it in but the wind still blew through the crawlspace. She had her toilet freeze and crack one winter.

Heating tape. You can buy it at most hardware stores.

18

Not a good option for South Texas, because we lose power when there is a snow storm.

19

If you want to drain the heater, open a hot water tap, and then drain spigot on the tank.
It should drain easily (unless the tank is really full of sediment, in which case the water will just trickle out…).

20

Beowulff, I am fairly familiar with house plumbing. If there are some recommendations for installing extrra vents and drains, I am open to do so.