PDA

View Full Version : Ot How to prevent pipes from freezing?



plunger
07-15-2014, 03:10 AM
I live in s africa and where I live the temperature on a bitterly cold night drops to 8 degrees celcius. However we have had an unusually cold winter and a friend asked me how to prevent pipes from bursting. I know alot of you guys must experience this as you live in a cold climate.My friend lives on the highveld (600km away)and I, as a plumber could not answer his question because the last time the temp dropped below freezing in Durban was during the ice age.
I would also like to ask if anyone has a clever solution to the problem of a geyser being far from the kitchen sink and it taking a long time for the water to get hot at the sink that it becomes an irritation.
Thanks Eugene

The Artful Bodger
07-15-2014, 03:22 AM
Hi Plunger, we have a generally temperate climate here but the temperature does go below freezing some nights of the year. Low enough to burst exposed pipes and damage unprotected engine blocks in cars and trucks.

The usual protection for water pipes is to insulate them with about 20mm thick felt and they are quite safe if buried. The vehicles are protected with antifreeze in the coolant.

We also insulate the hot water pipes between the water heater and the sink. As far as I know the only solution for the delay in getting hot water to the kitchen sink is to install an under-sink water heater.

elf
07-15-2014, 04:06 AM
Simplest solution is to just leave the water running at a trickle when the temperature drops. We usually do this when the temperature will drop below -5C. Increase the flow when the temperature is lower.

Baz
07-15-2014, 04:59 AM
How odd to find people don't know! but I guess you know methods of keeping cool that we never have a need for.
Insulation choice may depend on your local rodent and other bug problems. In a country with no traditional need supplies might be rare but the simplest will be old blanket cut into 4 in strips and wrapped in overlapping turns along the pipe. A cheap all synthetic one is best to avoid mould and bug activity. In the UK a custom fluffy hessian product was used but has been surplanted by expensive foam plastic that comes in a preformed tube with a slit along it for ease of fitting. Bubble wrap might be available locally but won't be quite as good.
Electric heating wire/tape is also used.
For hot water at a distance the technique used to be a loop of pipe from top of tank returning to bottom of tank that would self circulate if some sense was used in the layout. Short spurs take off to the hot taps. In the UK new regualtions have all but outlawed this without expensive temperature regualtors.

PStechPaul
07-15-2014, 05:25 AM
I have heating tape on much of my plumbing and where properly installed, it has worked quite well even this winter when nighttime temperatures often went to near and below 0 F and during the day sometimes didn't rise above 15 or 20. But in some places the heating tape and insulation were not properly installed (by a contractor who didn't know what he was doing), so I found that leaving the water run as a trickle did the trick. There were also times when winter storms knocked out power for a couple of days, so it's good to have an alternate plan. I think I measured the power for the heat tapes and they were like 50 to 200 watts, depending on length ( 6 ft to 25 ft or so), and most have thermostats that turn them on only below about 35 F. But one of the heat tapes installed by the contractor causes the cold water in the kitchen sink to run hot for a while, even in the summer.

ikdor
07-15-2014, 07:16 AM
For the geyser:
- get an electric under sink boiler
- get a geyser with a small boiler inside, so it doesn't waste time heating up the heat exchanger
- use thinner pipe from boiler to sink to move the water faster
- and I guess you could use that new plastic pipe, as it has a lower thermal mass

Igor

J Tiers
07-15-2014, 08:49 AM
It takes a surprisingly long time for the pipes to freeze. But without much in the way of house insulation, it may be faster.

Obviously nothing is going to freeze until below 0C. A few degrees below freezing will not freeze pipes in a house if you can stand living in it..... But if the floors are raised, and there is a "crawl space" under the floor with pipes in that, I can see more of a problem. Then the usual solution here is to close the vents for that area. If that area is very open, insulate the pipes, and block airflow.

Still, with any sensible amount of regular water use/water flow, it takes many degrees of frost to freeze pipes that are not outside in the open.

We have an outside tap that is not a "frost-free" type, and it has never frozen despite not having any protection or insulation. Temps here go to -15C every winter. There is enough heat in the pipe from the warmer basement to keep it from freezing. Last winter it was colder, and we did insulate it, but probably did not have to.

When I was growing up in Minnesota, we regularly got temps as low as -38C, and the outside tap never froze there either. It was just on the side of the house, no special protection.

Guido
07-15-2014, 11:10 AM
http://www.supplyhouse.com/Grundfos-595916-UP15-10SU7P-TLC-Comfort-Hot-Water-Recirculation-Pump-3-4-NPT-115-V

Grundfos, timer controlled recirculating pump with thermostatic device. Plumbed atop hot water tank, the pump moves hot water to the furtherest point of use, with returns to the cold water line and controlled via the thermostat located at the furtherest point of use. Thermostat halts circulation until temps fall to below set point, then again allows hot water to replace cooled water.

Uses elecricity only while pumping, but wastes no water. Works like a charm. Cat's meow.

--G

davidh
07-15-2014, 01:21 PM
in many parts of the world, water is worth its weight in gold almost. . . . letting it drip during a cold period would waste a lot. using insulation on top of a well installed heat tape would certainly curtail the freezing. usually the elbows seem to freeze first.

here in the frozen northland, the neighbors tape and insulation system has allowed running water even when temps stayed below - 25 for a week or more at a time. heat tape on a cheap timer.

kendall
07-15-2014, 01:25 PM
I for one, would be happy if the coldest I saw was 8c!
Personally, I prefer staying away from insulation wrapped around the pipe itself. Insulation on the pipe will slow freezing, but not eliminate it. When it freezes any heat applied to thaw them has to go through the insulation, and if pipes are damaged, it makes it harder to repair. I prefer running the pipes through a box, preferably insulated with a vent at each end. When it's cold a small fan at one vent will pull warm air through and prevent freezing, or if frozen a hair dryer blowing in will thaw them out quickly. Installing a thermostat that operates a fan or heat source would make it completely automatic.
Sounds like I went overboard, but when I bought the house, every single pipe was split from freezing, and last year I shoveled 2+ feet of snow off my house and shed roofs multiple times.

If possible, change over to PEX tubing for water lines as well, it takes longer to freeze than metal or PVC and since it's able to expand, it handles freezing better without damage than either.

Best way to get near instant hot at the sink is to install a small heater there, will also eliminate 1/2 the water line freeze issue.

flylo
07-15-2014, 03:41 PM
I think foam pipe tubes would be the easiest & let the water drip on cold nights. These come in 6' lengths with different size holes for different size pipes & a slit to slide them on. I know there are better, more difficult & expensive ways but I believe these will work great. Also use spray foam where you can't get the tubes.

Paul Alciatore
07-15-2014, 05:16 PM
I lived in a travel trailer in Iowa for about 16 winters. My water supply was a drinking water grade hose that ran about 15 feet across the bare ground. Leaving the water dripping was not an option for two reasons: cost and with a slow flow, my drain pipe would freeze. Here is how I kept it flowing on all but a handfull of days in those 16 winters where the temperature was often below freezing and sometimes below -20 F.

1. Start with hose or pipe.
2. Wrap a layer of the cheap fiberglass insulation that comes in 3" or 4" wide rolls. Throw out the thin plastic that comes with it. This is to keep the hose from melting and would not be needed with metal pipe. But use it with any type of plastic pipe.
3. Add heat tape. Wrap it in a slow helix (1-3 turns per foot) around the fiberglass insulation. Do not use heat tape with a thermostat as it can shut off when needed the most. If you must use one with a thermostat, put the thermostat OUTSIDE of the insulation and not up against a heated wall or floor.
4. Add two layers of the foam insulation sold for pipes. You may be able to buy this insulation in a split tube form. If so, install them with the open sides on opposite sides of the hose or pipe to avoid cold air leaks.
5. COMPLETELY wrap the foam insulation with a good grade of duct tape. Leave NO GAPS. Completely covered, end to end.
6. Seal the ends against the outside air. Duct tape is usually good for this.

With this technique, my hose only froze on really cold days (-25 F / -30 C or colder) or when the heat tape or power failed.

Paul Alciatore
07-15-2014, 05:19 PM
Snow covering the pipes or the openings that allow cold air to reach them is cheap and GOOD insulation. I often shoveled snow ONTO my water hose.


I for one, would be happy if the coldest I saw was 8c!
Personally, I prefer staying away from insulation wrapped around the pipe itself. Insulation on the pipe will slow freezing, but not eliminate it. When it freezes any heat applied to thaw them has to go through the insulation, and if pipes are damaged, it makes it harder to repair. I prefer running the pipes through a box, preferably insulated with a vent at each end. When it's cold a small fan at one vent will pull warm air through and prevent freezing, or if frozen a hair dryer blowing in will thaw them out quickly. Installing a thermostat that operates a fan or heat source would make it completely automatic.
Sounds like I went overboard, but when I bought the house, every single pipe was split from freezing, and last year I shoveled 2+ feet of snow off my house and shed roofs multiple times.

If possible, change over to PEX tubing for water lines as well, it takes longer to freeze than metal or PVC and since it's able to expand, it handles freezing better without damage than either.

Best way to get near instant hot at the sink is to install a small heater there, will also eliminate 1/2 the water line freeze issue.

Paul Alciatore
07-15-2014, 05:31 PM
...<snip>...

When I was growing up in Minnesota, we regularly got temps as low as -38C, and the outside tap never froze there either. It was just on the side of the house, no special protection.

J, this may be deceptive. I observed that outdoor taps in the northern US states often were of a design that had the actual valve recessed well inside the wall, where they were protected by the house or building insulation. In effect, they were inside, not outside. The passage way from the valve to the outside end of the spigot sloped downward so any water would drain out and not freeze in there. They also had lawn spigots with the valve mechanism buried well below the surface and a slow leak to keep the vertical pipe drained.

In the south, where I was born and lived for the majority of my life outside spigots were much more unacceptable to freezing. I have plastic/foam covers for mine here in South Texas and they are needed even though the temperature only goes below freezing two or three times per winter and only for short periods. Otherwise I would be replacing faucets every few years.

My advise is not to assume that an outside faucet is safe. Unless you are completely sure, insulate it in winter.

davidwdyer
07-15-2014, 05:53 PM
It depends a lot on the construction of the house. If in the US, then there is one answer.

If he has pipes imbedded in clay block walls which are skim coated with concrete, then he has

to find a way to keep the rooms hot enough or let the water run a little.

The circulating idea sounds good, but maybe he doesn't have enough time to do it before the freeze.

J Tiers
07-15-2014, 09:40 PM
I am going to guess, no doubt rightly, that heat tape is not widely available in S.A. Pipe insulation ditto.

Essentially, if you can stand to live in the same space where the pipes are, even with a coat, there will be no issues.

If, as is perfectly possible in generally warm climates, the pipes are outside, then some insulation around them will be of definite assistance.

Pipes INSIDE in living quarters are usually safe unless nobody is home for an extended time, AND it does not go back above 0C for several days, AND there has been no heat for an extended time.

The reason for this is that it takes a good deal of heat removal to freeze water, which holds a lot of heat, the most of any common substance. Exposed pipes, with the frosty wind blowing past them, are obviously an issue. But inside, the heat has to escape from the pipes to the air, and then out of the house.

That takes a while, and if anyone is living there, running water from time to time, etc, the pipes won't freeze solid. They do not burst until they are solid.... a little ice around the edges doesn't do it, and gets melted when water out of the warmer buried supply pipes is drawn through.

It's worth considering, since the nuisance and expense is considerable if they DO burst. But going below 0C outside does not automatically freeze the pipes. Even at -10C it takes a while with any sort of reasonably tight house. "A while" being more than one day, in general.

As for the faucet/tap outside.... the one in Minnesota has been like that since the 1950s, and has never frozen... it is on the outside of the house, no recess, but gets warmed by air in the basement. It is also in the middle of the side of the house, not on a corner.

The one on the house here is likewise on the outside, no recess. No cover other than this past year. No freezing. I know about it since 1986, and the faucet wasn't new then.

kendall
07-15-2014, 09:58 PM
Snow covering the pipes or the openings that allow cold air to reach them is cheap and GOOD insulation. I often shoveled snow ONTO my water hose.

Oddest experience I ever had with frozen pipes was a few years ago. The underground water line from pump to trailer froze in late December, we kept the pump shed heated for a couple days, hot enough that snow melted for a foot around it, never got the water going. So we bought a bale of straw, threw some down over the snow, ran copper line from the pump 50 feet, then threw more straw on top of it. We figured that was going to freeze again, but it would be easy enough to clear off and apply some heat to it.
Oddly, even though it was colder, -30F, for much longer stretches, that line never froze for the rest of the year. When we dug the old line up to replace it, it was just under 3ft deep, there were a couple splits and several bulges in it, we put the new line 6ft down, figure the next person to replace it is going to hate us.

goose
07-15-2014, 10:13 PM
It has to get really cold for a period of several days (20 degrees F or lower) for pipes to freeze to the point of bursting, AND the pipes have to be separate from the heated structure, such as outdoors, or in a part of the house outside of the insulation envelope.

In a place like South Africa preventing pipe freezing would be better treated as a reactive solution to the problem rather than a proactive solution. Example, put an electric space heater on in the crawl space if the temperature dips too low.

plunger
07-16-2014, 02:31 AM
Houses in S Africa are generally all brick and tiled roof .We have no basements and the pipe is mainly thin walled copper chased in the wall but mainly run in the roof. This freezing only happens inland and from tv reports ,can go as low as -10 degrees Celsius. But in the day its back above 8 degrees plus. If this was a common occurrence we would know what to do but I think the guys get caught by a surprise cold front and are unprepared.The tape idea was brought up on another s african forum. Funnily for a different purpose. The refrigeration guys use it in cooler rooms. Water in s africa is a scarce commodity and where I live we get taxed a sewer tax and is based on our water consumption

camdigger
07-16-2014, 03:32 AM
Where is the copper line in the wall? For best frost prevention, it should be in the warm side of the wall.

Is it possible to direct warm air through the chase?

Is PEX water pipe available and/or approved for domestic use there? BTW, PP pipe used in some countries is not as frost proof as PEX. FWIW, there is a story there....

PStechPaul
07-16-2014, 05:28 AM
One idea I was going to try is to use an electrically operated valve from a washing machine and connect it to an interval timer and/or a thermostat, so that it turns on the water for a short time, or when it gets below freezing. A combination of the two might be best, so it opens the valve only when cold enough, and then just for a little while. You could have the water drain into a bucket or the bathtub so that it won't be wasted. You can get the valves for free if you have access to a junkyard, and programmable timers are pretty cheap. If you like electronics, this would be a perfect application for a little Arduino or PIC project. You can use a thermistor to sense temperature and a SSR for the valve. If this becomes a more frequent problem, it might be a cool little "cottage industry" to make and sell these little devices.

plunger
07-16-2014, 06:46 AM
Paul I am electrically challenged but I like your way of thinking. I was wondering if one could have a simple box which accommodates a thermostat. If the temp drops below zero the 12v pump switches on and uses the cold as a return pipe to the geyser in the roof.I dont know if a pump would move water in a static system? If one had a series of non return valves strategically placed it may work and then you would not even need a third or return pipe. This should also solve my second question .I have to wait for 30 seconds before hot water gets to me. A waste of water and irritating. As a plumber I get asked this regularly and suggest a small geyser under the sink but its costly and also needs power. It would be interesting to hear the comments whether this is feasible or not

macona
07-16-2014, 12:11 PM
They make circulation pumps that keep the hot water circulating through the lines so they stay warm. You would have to add another line and make sure they are insulated to not waste energy with water circulating through uninsulated pipes. The pumps look like this:

http://www.nationalpumpsupply.com/armstrong-astro-230ci-r-flanged-rotated-cast-iron-circulating-pump-part-number-110223-315/?gclid=Cj0KEQjwxZieBRDegZuj9rzLt_ABEiQASqRd-uVgEssslH1-XcuU9UOtaf7DK4P1WDvHCHrt90qC57MaAo5_8P8HAQ

Baz
07-16-2014, 03:29 PM
You could link the circulation pump to a PIR in the bathroom so it come on when someone goes in and with a bit of luck has got the hot water into place in time. I'm not sure how this 'using the cold as a return' works.
Biggest problem is going to be availability of parts in SA. I'm wondering if central heating items are even available in the country but if they are a standard CH pump would be the cheapest owing to volume of the market. You probably have a bigger market for swimming pool kit than CH so maybe a small pool filter pump would do.
The flow pipe has to be normal size to ensure a good delivery at the tap but the return pipe could be microbore to be cheaper.

elf
07-21-2014, 07:42 PM
Draining the pipes during a cold spell would also be an inexpensive solution.

Paul Alciatore
07-22-2014, 05:00 AM
"It has to get really cold for a period of several days (20 degrees F or lower) for pipes to freeze to the point of bursting,...". That is just not true. First, water reaches it's maximum volume just a few degrees below freezing and then starts to expand again. So 28 or 30 degrees F is enough to produce a maximum expansive effect. Second, exposed pipes can freeze in just an hour or two if the water is not flowing. If you rely on your advise, you will be replacing those pipes quite often.

Now, depending on the type of pipe, it may not burst at all. Some plastics will expand and some heavy metal pipes can resist the pressure. Often the cracks and leaks occur at fittings and valves. You may have just been lucky.




It has to get really cold for a period of several days (20 degrees F or lower) for pipes to freeze to the point of bursting, AND the pipes have to be separate from the heated structure, such as outdoors, or in a part of the house outside of the insulation envelope.

In a place like South Africa preventing pipe freezing would be better treated as a reactive solution to the problem rather than a proactive solution. Example, put an electric space heater on in the crawl space if the temperature dips too low.

PStechPaul
07-22-2014, 06:21 AM
One thing that can help delay the formation of ice and resultant increase in pressure is the heat of melting. Water has some interesting properties:
http://www.engineeringtoolbox.com/water-thermal-properties-d_162.html

Also look at the phase diagrams for water, which seems to show that it can remain liquid as low as -20 C at 200MPa:
http://www1.lsbu.ac.uk/water/phase.html

and http://www.chemix-chemistry-software.com/school/phase-diagram-water.html
http://www.chemix-chemistry-software.com/images/scrshpic/phase-diagram-water.gif

and
http://upload.wikimedia.org/wikipedia/commons/0/08/Phase_diagram_of_water.svg

http://upload.wikimedia.org/wikipedia/commons/0/08/Phase_diagram_of_water.svg

J Tiers
07-22-2014, 08:45 AM
"It has to get really cold for a period of several days (20 degrees F or lower) for pipes to freeze to the point of bursting,...". That is just not true. First, water reaches it's maximum volume just a few degrees below freezing and then starts to expand again. So 28 or 30 degrees F is enough to produce a maximum expansive effect. Second, exposed pipes can freeze in just an hour or two if the water is not flowing. If you rely on your advise, you will be replacing those pipes quite often.


"Exposed pipes".

Well, sure.....

And a good stiff wind helps a lot, since it keeps bringing new cold air to replace the warmed air at the pipe.

We are talking about pipes IN A HOUSE. If the house is at all livable, pipes inside (or slightly outside) will not freeze.... The Minnesota house didn't have a particularly warm basement, but warm enough to keep the faucet unfrozen at -25C or more,by conduction, and maybe some convection of water in the pipe. Water just above freezing has the maximum density, and will tend to flow away if there is any way for circulation to occur, as with the horizontal pipe to that faucet.

Pipes UNDER the house in an open crawl space are "outside", and the area should be closed in. If not, the floors will be pretty cold too....

If the house is vacant, and unheated, it WILL STILL take several days to freeze up pipes inside, since the wind etc cannot get in. The house must be brought to sub-freezing temps first, then the surroundings of the pipes are cold enough for freezing to occur. How fast depends on what temp it all starts at. If it has been "soaking" at 2C for days, freezing will be faster than if there is a "cold snap" from a higher temp.

But since water holds a lot of heat, and freezing gives up a lot of heat, the rate of freezing depends on the ability of heat to flow out through the immediate surroundings and the rest of the house. Unless you open the windows, that's not particularly fast.

With a new house, lightweight "engineered" wood, thin, light drywall, etc, it will be faster due to the low thermal mass. In an older house, with plaster walls, maybe a brick exterior wall, all that mass has to be cooled to sub-freezing before the pipes can "see" freezing temps.

camdigger
07-22-2014, 12:36 PM
If the temperature stays close to freezing, it may be enough to install a return line and a circulation pump on the cold water line. Keeping the water moving is half the trick.

A circulation pump will also resolve the hot water issue. Simply plumb the return line into the hot water tank drain with a tee. My house has this, but I use convection to circulate as the hot water tank is in the basement.

If you have the option, you could run the hot and cold lines next to each other in the chase.