Idea for Preventing Frozen Pipes in Unheated Crawl Space

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Old 12-24-05, 02:05 PM
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Question Idea for Preventing Frozen Pipes in Unheated Crawl Space

Happy Holidays to everyone!

Background: I purchased the mobile home next to me a few months back, the plan is to rent it for a few years and replace it with a nice home after that. Space under the home is unheated and poorly insulated (I just learned). A short time ago, we experienced 15 degree below zero weather and the water pipes froze in this unheated space. As no one is living in the mobile home yet, no water was running during the cold spell. The pipes are black plastic and wrapped with what appears to be R11 fiberglass insulation. It is clear that the previous owner had experienced this same problem as I found areas where the black plastic pipe had old jackets piled on it to supplement the fiberglass.
I'd like to come up with a safe, energy efficient way of ensuring that the pipes will not freeze under any and all circumstances.

Heat Tape: Although I understand heat tapes have undergone significant improvements over the last few decades, it still makes me a bit nervous about the risk of fire. I did locate a heat tape that recommends covering with 1/2" of fiberglass insulation when used on metal pipes, no insulation is recommended when used on black plastic. I expect that the 1/2" insulation when used on metal pipe is okay as the pipes will conduct heat, ensuring that no "hot spots" will form. I'm very concerned that at -30 degrees F, heat tape may have trouble preventing freezing (and will not be very energy efficient) on the exposed black plastic.

My Idea: My idea is to cable tie metal tubing or pipe (perhaps copper?) directly to the black plastic pipe. The heat tape will be inside the metal tubing (the tubing may have to be adapted to a larger metal enclosure which will contain the thermostat for the heat tape). The black plastic and metal pipe is then wrapped in fiberglass insulation. When freezing temperatures occur, the heat tape comes on, heat is more of less evenly distributed along the metal pipe, evenly heating the black plastic, until the thermostat turns it off. The fiberglass insulation around the two pipes minimizes heat loss. I like the idea that the heat tape is encased in a nonflammable material (the metal pipe). I also realize that care and/or some means of ensuring that the heat tape is not damaged when threaded into the metal pipe may be required.

Any feedback will be greatly appreciated!
 
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Old 12-24-05, 08:08 PM
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One point that many people don't think about is that when you insulate a pipe, that pipe will eventually freeze if there is no source of heat and it is below freezing around the pipe. Insulation alone will not do it.
As for heat tape, you must follow the manufacturer's instructions, which are rather specific on how tightly to turn the heating cable on the pipe and how to insulate the pipe. Typically, they require 1/2" of fiberglass insulation (which doesn't work if it gets wet) wrapped around the pipe. If you put on too much insulation, the cable will overheat and could shut off too quickly, creating a fire hazard.
Don't put regular heat tape in a pipe. That is too dangerous.
Google something like "heat tape in pipe". There is a heat tape that can be inserted inside a pipe. It is not cheap, but is a safe alternative.
 
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Old 12-25-05, 05:06 AM
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Are these the water lines original with the mobile home? Is so, it should be an easy fix.

Water lines in mobile homes are installed at the factory run along the heating ducts. Then, in whole, it's wrapped in insulation. If you have enough play that you can do this, it should help. Even if you have to rerun some of the lines, it might be worth it.

You said you have black water lines. While I'm not familiar with what those are specifically made of, I know the old grey polybutylene pipe, it would be a wise investment to replace anyway.
 
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Old 12-26-05, 01:10 PM
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Why not just keep the water running a little (at the farthest sink)? This plus some insulation wrapped around the pipe should be enough. You will pay more for water, but it probably will be less than cost of electricity and heat tape.
 
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Old 12-26-05, 06:08 PM
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Reply to Fixitron

Thanks for replying! I've been doing more reasearch and have found products from "easy heat" and "wrap-on" that appear to be safe and effective (although quite expensive) and may solve my problem with minimum fire risk. These products appear to adjust the amount of supplied heat based on the ambient temperature and can be covered with insulation when used with metal or plastic pipe. Thoughts and comments from all are welcome!

If these new products really work, it makes my idea probably not a great one- although having a conductive metal spread the heat over the length of the run still seems appealing to me. Does anyone know how these new heat tapes work??? Exactly how do they get heat only where needed - even if it's 20 feet down the line - without heating other areas that don't require additional heat? All I can think of is a variable resistance- i.e. local resistance of the cable decreases as the the temperature increases. If this is the case, cold areas will be more resistive and generate more heat until warmed. The descriptions of how these cables work are not consistent with this idea--- as I recall, they talk about multiple pathways turning on and off- the more pathways, the greater the resistance that generates more heat. This might be the technically equivalant to a resistance that depends on temperature, but it sounds a lot more complicated to acheive!

Thanks for any additional feedback. This is a great forum.

Ed in Cambridge VT -- I grew up in Moretown, VT - not far from Warren!

Originally Posted by fixitron
One point that many people don't think about is that when you insulate a pipe, that pipe will eventually freeze if there is no source of heat and it is below freezing around the pipe. Insulation alone will not do it.
As for heat tape, you must follow the manufacturer's instructions, which are rather specific on how tightly to turn the heating cable on the pipe and how to insulate the pipe. Typically, they require 1/2" of fiberglass insulation (which doesn't work if it gets wet) wrapped around the pipe. If you put on too much insulation, the cable will overheat and could shut off too quickly, creating a fire hazard.
Don't put regular heat tape in a pipe. That is too dangerous.
Google something like "heat tape in pipe". There is a heat tape that can be inserted inside a pipe. It is not cheap, but is a safe alternative.
 
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Old 12-26-05, 06:28 PM
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Reply to hankhill6018

Well, that's a really good question. I think these are the original water lines. Why they are not above the insulation that is suspended below the floor of the mobile home is a big mystery to me (ease of accessibility mabe????). I talked to other owners of mobile homes in the area today. In the mobile homes they own or previously owned, the supply line to the kitchen and baths are below the floor insulation and required heat tape to prevent freezing.

The black pipe I referred to is used for the supply line. I'm not certain of the exact name, but I think that it is polypropolene. It is commonly used for underground runs from the water source to the building, here in Vermont.


Originally Posted by hankhill6018
Are these the water lines original with the mobile home? Is so, it should be an easy fix.

Water lines in mobile homes are installed at the factory run along the heating ducts. Then, in whole, it's wrapped in insulation. If you have enough play that you can do this, it should help. Even if you have to rerun some of the lines, it might be worth it.

You said you have black water lines. While I'm not familiar with what those are specifically made of, I know the old grey polybutylene pipe, it would be a wise investment to replace anyway.
 
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Old 12-26-05, 06:49 PM
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Reply to cgar

Very valid point - except that it may not work reliably as we will be renting the mobile home for a few years until we can build a small house on the lot. We have been doing weekly rentals for several summer cottages on Lake Champlain since 1988, and have learned that "anything that can go wrong will go wrong" (our next door neighbor is a Murphy- really!).

So our goal is to have the mobile home set up in such away that no matter what the weather, water will not be a problem even if our tenants are away for the entire winter. We're basically looking for foolproof!

Originally Posted by cgar
Why not just keep the water running a little (at the farthest sink)? This plus some insulation wrapped around the pipe should be enough. You will pay more for water, but it probably will be less than cost of electricity and heat tape.
 
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Old 12-31-05, 08:14 PM
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Smile Hankhill6018 is right about the original water lines

The lines I have a problem with are the supply line from the well, and a line that appears toi be an add-on for the washing machine. Here's the note I send to hankhill-

"I tried to respond to your note again on the forum, but wasn't successful- I'll try to grab a copy of this and post it again.

With a better flashlight, a measuring tape, and some semi-serious crawling around, it was easy to see that you are correct about the water lines being above the insulation under the mobile home floor. The water line I was chasing was for the washing machine which was obviously an add-on. Unfortunate that it is located so far from the water source! So I'll need to prevent this from freezing and the incoming line and should be all set. Thanks for responding to my post!

Ed"

I've ordered some of the automatically temperature adjusting heat tape - it is UL and CSA listed and appears to be safe - I'm still interested in anyone's experience with this stuff! I found 2 brands "Easy heat" (freeze free, I think) and "Wrap-on" brand. Thanks for any additional info!

Ed


Originally Posted by hankhill6018
Are these the water lines original with the mobile home? Is so, it should be an easy fix.

Water lines in mobile homes are installed at the factory run along the heating ducts. Then, in whole, it's wrapped in insulation. If you have enough play that you can do this, it should help. Even if you have to rerun some of the lines, it might be worth it.

You said you have black water lines. While I'm not familiar with what those are specifically made of, I know the old grey polybutylene pipe, it would be a wise investment to replace anyway.
 
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