Pipe heaters for plastic pipes

[Bene505]

Anyone know if there's a way to heat plastic pipes? The fresh water lines to our bathrooms run behind cabinets and behind the well-insulated fridge. They are also attached to the outer hull 2 feet above the water line. We are at a dock with 120v, 30 amp service (and another 30amps if I want to pay for it).

Although I'm heating the cabin all winter, the pipes are going to freeze unless I do something. I'm trying to aviod draining the pipes and applying antifreeze, since we are using the boat all winter.

I could have a blower force air into the spaces behind things, but I'm thinking that a small wire the followed the pipes would provide the little bit of heat needed to keep the pipes from freezing. I'd also need a thermostat(s) placed in the tightest spot(s) where heat build-up would be the greatest.

Is there anything on the market that does this already? If not, does anyone see a problem with the approach? I could build the thermostat circuit so it would turn on below 40 degrees F. I could use wire of the correct thickness for the length I need, to produce the watts I want - perhaps in combination with a step-down transformer to lower the volts and allow a thicker wire. I just want to make sure I don't melt the pipes.

Any clues here?

Regards,
Brad

[bjung]

These heaters are readily availlable, in differrent lengths, at your local hardware/ plumbing store. I have used one in an uninsulated building over winter, works great.
You have to be able to attach it to the pipe to ensure good contact, and possibly insulate around it.

Bernd
PSC 31

P.S. Just make sure to follow installation instructions. I remember the warning label being quite extensive, but had no problems.

[sailingdog]

Why not just install a goldenrod heater in that area.

[Bene505]

Originally Posted by bjung

These heaters are readily availlable, in differrent lengths, at your local hardware/ plumbing store. I have used one in an uninsulated building over winter, works great.
You have to be able to attach it to the pipe to ensure good contact, and possibly insulate around it.

Bernd
PSC 31

P.S. Just make sure to follow installation instructions. I remember the warning label being quite extensive, but had no problems.

Thanks Bernd. I'll ask at the hardware store to see what they have.

Originally Posted by sailingdog

Why not just install a goldenrod heater in that area.

The pipes run around the boat on both sides over much of the length. I'd need about 70 feet of coverage. Not sure how many goldenrod heaters I'd need. I'll look into it. Thanks!

.

Some more thoughts on the homegrown solution, in case I go that way

1) 12v. If I made it a 12v system, I could use it as my dump load for the wind generator. That would help to keep moisture down in the places that breed mold and mildew. Granted, that's more in the closets than around the pipes, but it would help. 12 volts also means less chance of a nasty shock and the use of bigger wires - to spread the heating area a bit more. The downside is that I'll have to use a transformer to get down to 12v. I could keep it at 12v AC (not rectified) when using shore power and use 12v DC when using it as a dump load.

2) 20 gauge wire has a resistance of about 1 ohm per 100 feet. For a 120volt system, that would mean 120 watts spread around all the piping. Seems really easy but I'd want some ground fault detection if using 120 volts. So that's another vote for using 12 volts.

3) If using DC, I'd want to use a twisted pair of wires, otherwise I'd be making a big (perhaps weak) electromagnet out of the boat. Maybe not a big effect, but there might be a long term effect because we have an iron keel.

Regards,
Brad

[Faster]

Ordinary wire will not provide enough R for what you want to do.. it will essentially be a dead short across your AC breaker. You'll need thermostatic heat tracing wire, used all the time in industry but we always were tracing steel or SS pipe/tube. There may well be low temp versions for plastic pipe.

Will you have access to actually run/install it properly?

[j34035]

There is a product called self regulating heat tape. This product is made for this application useally in industrial applications. You wrap your pipe with this special tape that includes conductors and then terminate it to 120v and it will maintain the design temperature as long as it has power. Google "self regulating heat tape" and you will see vendors there. We use it for freeze protetction on process water lines that are exposed to the elements and it works well.
DD

[Bene505]

Originally Posted by j34035

There is a product called self regulating heat tape. This product is made for this application useally in industrial applications. You wrap your pipe with this special tape that includes conductors and then terminate it to 120v and it will maintain the design temperature as long as it has power. Google "self regulating heat tape" and you will see vendors there. We use it for freeze protetction on process water lines that are exposed to the elements and it works well.
DD

+1 That's exactly what I need.

When wintering onthe hard, I spend $100 on antifreeze each year -- that's for 4 water tanks, 4 bathrooms, 1 water heater, 1 expansion tank and a transom shower. I'd rather have some left over than fall short when I'm doing the work.

After checking eBay today, for about $100 I can winterize the pipes and fixtures with 100 feet of "self regulating heat tape". That will work whenever we are doing in-water storage, which I'm planning to be 2 out of every 3 years. (On the hard, electricity is not as easy to come by.)

For pllastic pipes, one of the listing mentioned wrapping the pipe in aluminum foil first. Then I gather that standard practice is to insulate the pipe. Not sure I need that second step. A few watts per foot ought to do the trick without any insulation other than being out of the wind.

Regards,
Brad

[j34035]

Let us know how it works out!
DD

[scottyt]

i second the self regulating heat tape, in fact i was going to mention it. the good thing about self regulating stuff is only the section that gets below 34 turns on. ie if you get one cold spot that is only part that turns on, vrs the ones with a thermostat if the thermo does not get cold it does not turn on, or the whole thing turns on.

[Bene505]

I looked at the route I will have to take with the self regulating heat tape. There are sections that run sandwiched between the hull and marine plywood, with no airspace around it.

Is the self regulating heat tape safe for such an area? I did a test on the regular heat tape -- placed it on a table under a blanket. It got really hot. (I knew it would.) Can I do the same test with the self regulating heat tape?

By the way, I did the antifreeze thing, although less than I really want. I need a few more gallons to get a good concentration. Cold weather is on the way and I don't want to risk waiting delivery delay.

Regards,
Brad