Heating a Crawl Space Frozen Pipes

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mkgrady

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I have a customer that has had frozen pipes in her crawl space and I'm stumped on a good way to keep the pipes from freezing. She has the problem when the temps drop down near zero for any length of time. It doesn't happen that often. The plumber says the fix is not to use heat tape because some of the freezing is happening in the room walls above. The

Her house is all electric heat. She has a house with a full basement below the main house and a 4' tall crawl space where a 8' by 12' bathroom/laundry room addition was built years later. The water lines below the room run across the bottom of the floor joists. There is a board type insulation below the floor and pipes to separate the cold crawl space from the pipes and the room above.

The main basement is unusually cold and I would guess it's because there is no furnace or boiler down there. I guess the crawl space is even colder. There is a 3'x3' opening from the basement to the crawl space that was cut through the foundation wall to build the addition. My customer is a little old lady so I won't be telling her to go inside the crawl to do anything.

My first thought was to put a 30" strip of baseboard heat (500 watts) on the addition foundation wall closest to the pipes. IF that is a good idea, Im stumped on how to control the heater. I could install a thermostat on the baseboard buy I'm concerned it will never shut off. A line voltage wall thermostat would be impossible to reach without going into the crawl space, and again I'm concerned it will try to heat the whole basement. I would hate to have to tell he to turn the circuit on when it gets down near zero. I'm stumped.
 
Probably least expensive is to crack open faucet just a little when it is extremely cold out.

Another option is a hot water recirculating system that uses the cold water line as a return line, this will waste heat from hot water system if left running year round, but will give hot water at fixtures pretty much immediately. Also means you won't necessarily get cold water immediately at the fixture though.
 
Place a 1500W heater in the space and plug it into a thermostat control cube plug (not sure actual term) that only activates when it drops to 35 degrees. This could eliminate the concern of constant draw. I use a thermocube in garage at work that has a strobe light plug into it. When it gets too cold in there, the strobe light flashes and I know to check the space. The garage has our domestic water supply and fire suppression riser. Makes for a real cheap alarm strobe system.
 
Forget what the plumber said and put heat tape and insulation on the available pipe. Copper pipe is sufficiently conductive that the warmth will work its way up the pipe into the wall cavity. We have a hot water heater next to a slop sink in the basement. The hot water travels up and around to get to the sink, a total distance of 10-12 feet. The pipe is UNinsulated, but if you put your hand on the line going into the sink hot water faucet, it is noticeably warm, just from the conducted heat, no water flowing.
 
I think the solution to this problem is more than just electrical.

If I'm visualizing this correctly, you're proposing a strip heater on the opposite side of the board-type insulation as the pipes? How would the heat reach the pipes?

Were you to install heat tape (and pipe insulation!) on the pipes in the crawl space, some of that heat will be carried upstairs by convection.
(everybody knows that heated air rises, but heated water also rises)

Is the crawl space ventilated to the outdoors? Heating the whole basement might be the least of your concerns.

Is the crawl space insulated from the outdoors? Maybe the answer's removing the insulation board from the crawl-space ceiling and putting it on the walls.

Is some of the freezing is happening in exterior walls on the first story? Putting water pipes in exterior walls in Massachusetts is just begging for trouble.

Closing off the 3x3-foot doorway -- even with only a canvas flap -- would prevent much of the newly-installed heat from escaping into the basement. But even an unheated basement and crawl space should remain above freezing if they're adequately insulated from the outdoors.

Has this been a problem since the day the addition was erected, or is it a recent problem? Have you looked for other causes, such as a raccoon clawing through the siding in order to nest in the joist spaces, and admitting frigid air in the process? (seen it)
 
I think I would look into heat tape. It is not a perfect fix but it works. It is something though that has to be replaced periodically.

Or you could just tell her to crack a faucet or two open when it is especially cold as one of the other posters suggested.
 
petersonra said:
Or you could just tell her to crack a faucet or two open when it is especially cold as one of the other posters suggested.
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Most the time they want to throw as little money as possible at it, and don't want their utility bills to increase either. Letting a little water run when it is extreme cold is probably going to spend the least amount of $$ overall. It don't take much of a stream at all to keep it from freezing. Water wasted and heat from water heater that is wasted is going to be less than a service call from the plumber even if you have to let it run slow for a whole month.
 
Drain the water use it only in the 3 seasons.
Cut the chase open insulate the pipes on that outer wall, leave the chase open to surrounding temp.
Cut the floor/ drill in the pipe chase put a heater below.
 
190208-1044 EST

Several commets.

Some general things first.

If you are in an area where a basement can be dug, then have a complete basement, no cral spaces, or slab floors on base earth. When Robert S McNamara was first a Whiz Kid he built a home in our neighborhood as a slab on earth. He was a numbers man, not an engineer, and thought this was efficient. Many years ago a friend of my wife bought that house. After a few years they had to have a basement built under the house to provide adequate storage space. We have clay loam soil. Hard to hand dig, but no problem for machinery. A basement in our are is a very low cost space to build.

The small anount of money saved by building a crawl space instead of it being full basemsnt height is not justified over the long term.

If you are in an area where natural gas is relatively inexpensive, then don't use straight electric heat. In my area natural gas is 1/5 the cost of electricity per BTU. My real total cost of electricity is about $0.16/kWH. I can't see a heat pump here being better than natural gas as a source of energy.

To the specific subject.

Do the pipes freeze, break, and require replacement? If so that is very costly. Are they copper, galvanized, or plastic?

A circulating hot water piping system is a good solution. No motor required. The piping is laid out as, one large loop. The loop starts at the hot outlet of the hot water tank, and returns to the drain tap at the bottom of the tank. This scheme probably has been used for over 100 years. By convection it automatically circulates hot water thru the loop. My dad installed such a system 90 years ago in a home he built. Over time mineral deposits accumulate in the loop and have to be cleared out.

What about the cold water pipe? In a warm basement this will be somewhat warmed. But a circulating pump will be required. Whether there is enough self heating will determine whether heat tape is required.

To a large extent this is a thermal problem. If the pipes are plastic and will never break, then you might do very little. If the pipes are likely to break, then means must be applied to solve the problem. You might want to do some temperature recording. If you install some electric heating, then that might be controlled by an outside thermostat set to possibly 35 to 40 F.

Suggestions by others can be useful. Insulation is important.

.
 
zbang said:
Heat trace and pipe insulation. No need to heat the entire space.
Click to expand...

It's hard to heat a crawl space anyway. There is required ventilation because of the exposed earth flooring and moisture. If you were to seal it up so you could heat it then you would probably have a moisture problem.
 
gadfly56 said:
Forget what the plumber said and put heat tape and insulation on the available pipe. ....
Click to expand...

drcampbell said:
... Is the crawl space insulated from the outdoors? Maybe the answer's removing the insulation board from the crawl-space ceiling and putting it on the walls.

Is some of the freezing is happening in exterior walls on the first story? Putting water pipes in exterior walls in Massachusetts is just begging for trouble. ...
Click to expand...

Having spent a lot of years in the Great North, Gadfly and Dr. Campbell have it - none of the answers are cheap.

  • Move the pipes from the out side walls.
  • Add insulation between the outside and the warm areas.
  • Heat trace (and insulation ) work fine. But the trace is a forever cost.
  • Remote thermostats are available. I put one in a crawl space for freeze protection (domestic water, DWV, hot water baseboard). Sensor was an rtd 50 feet away from the control unit. Used 3w thermostat wire to the sensor. 2w output went to went to the baseboard valve. You would have to get either a line voltage output or use a relay.

Bite the bullet. Move the pipes where ever you can. Then spend money on the insulation. These are one time costs.

Tough job. Good luck. Let us know how it comes out
 
iceworm said:
Having spent a lot of years in the Great North, Gadfly and Dr. Campbell have it - none of the answers are cheap.

  • Move the pipes from the out side walls.
  • Add insulation between the outside and the warm areas.
  • Heat trace (and insulation ) work fine. But the trace is a forever cost.
  • Remote thermostats are available. I put one in a crawl space for freeze protection (domestic water, DWV, hot water baseboard). Sensor was an rtd 50 feet away from the control unit. Used 3w thermostat wire to the sensor. 2w output went to went to the baseboard valve. You would have to get either a line voltage output or use a relay.

Bite the bullet. Move the pipes where ever you can. Then spend money on the insulation. These are one time costs.

Tough job. Good luck. Let us know how it comes out
Click to expand...
You live where those options are more of a necessity. OP mentioned this only happens occasionally, might still be worthwhile to just let a small trickle of water run at those times if it doesn't happen very often.
 
growler said:
It's hard to heat a crawl space anyway. There is required ventilation because of the exposed earth flooring and moisture. If you were to seal it up so you could heat it then you would probably have a moisture problem.
Click to expand...
Truth.

For the crawl space I heated, it got two layers of 6mil poly and sealed around the edges.
 
kwired said:
You live where those options are more of a necessity. OP mentioned this only happens occasionally, might still be worthwhile to just let a small trickle of water run at those times if it doesn't happen very often.
Click to expand...

That's true. Minimal is good
 
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mkgrady said:
I have a customer that has had frozen pipes in her crawl space and I'm stumped on a good way to keep the pipes from freezing. She has the problem when the temps drop down near zero for any length of time. It doesn't happen that often. The plumber says the fix is not to use heat tape because some of the freezing is happening in the room walls above. The

Her house is all electric heat. She has a house with a full basement below the main house and a 4' tall crawl space where a 8' by 12' bathroom/laundry room addition was built years later. The water lines below the room run across the bottom of the floor joists. There is a board type insulation below the floor and pipes to separate the cold crawl space from the pipes and the room above.

The main basement is unusually cold and I would guess it's because there is no furnace or boiler down there. I guess the crawl space is even colder. There is a 3'x3' opening from the basement to the crawl space that was cut through the foundation wall to build the addition. My customer is a little old lady so I won't be telling her to go inside the crawl to do anything.

My first thought was to put a 30" strip of baseboard heat (500 watts) on the addition foundation wall closest to the pipes. IF that is a good idea, Im stumped on how to control the heater. I could install a thermostat on the baseboard buy I'm concerned it will never shut off. A line voltage wall thermostat would be impossible to reach without going into the crawl space, and again I'm concerned it will try to heat the whole basement. I would hate to have to tell he to turn the circuit on when it gets down near zero. I'm stumped.
Click to expand...

Since no one has ever mentioned-- it seems like no one has had to install this—a circulating hot water pump.
Here in Southern CA., we hardly experience freezing temps like most Eastern US states. The last time I've seen frozen pipes was about 30 years ago but it only lasted like 3 hours and only on my sprinklers.

I have installed a small circulating pump in my motor home. I only used it twice when I parked the RV in my mountain property in northern CA where freezing temp is the order of the day during winter months.

It's a small pump. . . a little bigger than a window washer that runs on battery. Battery is replenished by solar during the day.

Since my water heater uses propane for heating there is always available hot water for shower. So, I tapped into the cold water line going to the kitchen sink because it is the longest pipe run.

There is a circulating pump sold by Grainger that will do exactly the same thing I did above. This is a thing you will see in most high priced residences in Hollywood Hills. These people are lazy—they don't want to wait for the hot water to circulate when they jump in the shower.

With this circ pump it can provide instant hot water. This is also an alternative to instant hot water tank (tankless water heater) but it requires a dedicated 240 V circuit for the massive 2500-watt heater.

All this setup needs is a return line (from the sink) to where the hot water line goes into the heated tank. An electrician can easily do this without a plumber.

It plugs-in under the sink or you can install it next to the water heater . . . its draws small current you can use the dishwasher circuit.

All the best.
 
Last edited:
myspark said:
Since no one has ever mentioned-- it seems like no one has had to install this—a circulating hot water pump.
Here in Southern CA., we hardly experience freezing temps like most Eastern US states. The last time I've seen frozen pipes was about 30 years ago but it only lasted like 3 hours and only on my sprinklers.

I have installed a small circulating pump in my motor home. I only used it twice when I parked the RV in my mountain property in northern CA where freezing temp is the order of the day during winter months.

It's a small pump. . . a little bigger than a window washer that runs on battery. Battery is replenished by solar during the day.

Since my water heater uses propane for heating there is always available hot water for shower. So, I tapped into the cold water line going to the kitchen sink because it is the longest pipe run.

There is a circulating pump sold by Grainger that will do exactly the same thing I did above. This is a thing you will see in most high priced residences in Hollywood Hills. These people are lazy—they don't want to wait for the hot water to circulate when they jump in the shower.

With this circ pump it can provide instant hot water. This is also an alternative to instant hot water tank (tankless water heater) but it requires a dedicated 240 V circuit for the massive 2500-watt heater.

All this setup needs is a return line (from the sink) to where the hot water line goes into the heated tank. An electrician can easily do this without a plumber.

It plugs-in under the sink or you can install it next to the water heater . . . its draws small current you can use the dishwasher circuit.

All the best.
Click to expand...

I'm not sure I understand. The OP didn't mention whether it's the hot or cold line freezing. How would you make that work for the cold water line?
 
myspark said:
Since no one has ever mentioned-- it seems like no one has had to install this—a circulating hot water pump.
Here in Southern CA., we hardly experience freezing temps like most Eastern US states. The last time I've seen frozen pipes was about 30 years ago but it only lasted like 3 hours and only on my sprinklers.

I have installed a small circulating pump in my motor home. I only used it twice when I parked the RV in my mountain property in northern CA where freezing temp is the order of the day during winter months.

It's a small pump. . . a little bigger than a window washer that runs on battery. Battery is replenished by solar during the day.

Since my water heater uses propane for heating there is always available hot water for shower. So, I tapped into the cold water line going to the kitchen sink because it is the longest pipe run.

There is a circulating pump sold by Grainger that will do exactly the same thing I did above. This is a thing you will see in most high priced residences in Hollywood Hills. These people are lazy—they don't want to wait for the hot water to circulate when they jump in the shower.

With this circ pump it can provide instant hot water. This is also an alternative to instant hot water tank (tankless water heater) but it requires a dedicated 240 V circuit for the massive 2500-watt heater.

All this setup needs is a return line (from the sink) to where the hot water line goes into the heated tank. An electrician can easily do this without a plumber.

It plugs-in under the sink or you can install it next to the water heater . . . its draws small current you can use the dishwasher circuit.

All the best.
Click to expand...
Sorry dude, I mentioned it in post 2.:p

gadfly56 said:
I'm not sure I understand. The OP didn't mention whether it's the hot or cold line freezing. How would you make that work for the cold water line?
Click to expand...
You need a link probably with a check valve to prevent "mixing" when running faucets between hot and cold lines, probably near the sink. The cold water line becomes the return line for the loop. Can thermostatically control it so if return temp is above a certain level you shut down the pump, this would help lessen waste heat. One advantage is you get hot water faster, and such system is installed for that reason alone sometimes. One disadvantage is it will take longer to get incoming tap water temperature at the faucet.
 
Thanks for all the answers. Some good ideas here. I can answer many of the questions because I was just asked to put some heat down there by the plumber/heating contractor. Now I can at least go back with more options than I could come up with on my own.
 
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