Question about insulating hot water heating system pipes

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Old 03-03-07, 03:14 AM
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Question about insulating hot water heating system pipes

My house has a hot water heating system with radiators.
About a month ago, a pipe which goes through in a crawlspace was bursted due to a cold weather (I live in Midwest and once in a while, the temperature is only a single digit or even below 0F). The pipe was insulated but I think it was not enough or too old. (I could not tell what kind of insulation previous owner used. House is really old...) The crawlspace is vented, so it gets really cold in there.

I have to redo a pipe insulation. I heard about heat tape but I have some concerns.

1. Is it safe to use for hot water heating system pipes? This pipe (copper pipe) gets really hot. The setting is around 180-190F.
2. Is it easy to install?
3. Do I really need to use "heat tape", or just regular tube pipe insulation is enough to prevent pipes from bursting?

I have some tube pipe insulation (from Home Depot, looks like a black rubber tube, wrap around type). I wonder if that can be used for this pipe.

Any advice and suggestion is appreciated!
 
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Old 03-03-07, 07:34 AM
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I can't advise on the heat tape, but am almost certain that you NEVER want to install a heat tape under any kind of insulation.

I will also say that in my opinion the FOAM pipe insulation they sell is barely worth the effort to install. I am basing this on the fact that if you wrap your hand around that insulation when it's installed on a heat pipe, you can feel it's warm on the outside. Yes, it's better than nothing, and it will stop cold water pipes from sweating pretty effectively. But it seems pretty useless at keeping heat IN.

I haven't tried the black RUBBER stuff you are talking about.

If you had an extreme situation, I'd take a look at the fiberglass stuff they sell. White covering, yellow fiberglas inside.

Was your heating system not running when this pipe froze ?

Are you using a wood burning appliance in the home that is preventing the boiler from operating ? If so, you might look into purchasing a timer that connects to your thermostat, and runs the boiler periodically in spite of the thermostat being satisfied. Keep a little bit of heat in the pipes and they won't freeze.
 
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Old 03-03-07, 07:51 AM
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Insulate the crawl space and close the vents in the crawl. I've used heat tape and insulated it, but the manufacturer was very specific about what insulation to use when insulating on top of heat tape so follow what they recommend.
 
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Old 03-03-07, 08:12 AM
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Originally Posted by sgthvac View Post
...the manufacturer was very specific about what insulation to use when insulating on top of heat tape so follow what they recommend...
Might wanna check local building codes too, just to be sure, I believe they would supercede any manufacturers recommendations...
 
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Old 03-03-07, 12:00 PM
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Thanks for all the suggestions!
It sounds like installing heat tape is a bit complicated.

The heating system was running ok when I had the first pipe burst, but wasn't running properly for the second burst...

Everything is fixed now and hot water is going through the pipe. Running a boiler periodically is a good idea, but sorry, I have no idea if it's possible for the boiler that I have (I'm totally new to a whole thing).

Currently I have a flexible black polyethylene pipe insulation. It's self seal. But I just checked the manufacturer's site and it is supposed to be used under 180F. My copper pipes may be too hot for that.

NJ Trooper- I would like to take a look at fiberglass insulation. I remember seeing them at Home Depot, the one you just wrap around the pipe (2-3 inch wide roll), right? The R-value seemed too low to me (it was like 4 or something). Do you have any recommendation for R-value? How thick the fiberglass should be? And it should be fine with HOT copper pipe?
I'd appreciate if you give me a brief instruction.

sgthva- The crawl space vent is closed. I read somewhere that vented crawl space's side wall should not be insulated. Insulation should be only toward the floor. Do you think it is fine to put some insulation on the side so cold air won't come in easily?

Thanks!
 
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Old 03-03-07, 12:30 PM
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The stuff I was thinking of isn't in the roll, but I've seen that too, never used it. No, this stuff is in like 3 or 4 foot straight sections, and I believe it's more commonly used on Steam piping. This stuff is like 3" outside diameter, with maybe 1" inside, so it's a pretty good amount of insulation.

I've got that poly foam insulation (that I don't like) on some of my piping. It hasn't really shown any signs of deterioration (one year) yet. My boiler occasionally gets up to about 190* or so.

Maybe you don't need to do ALL the piping in the thick stuff I mentioned, only the area (and to each side) that is subject to freezing the most. You might be able to get by with something less expensive for the rest of it, cuz as I recall that fiberglas stuff wasn't cheap. (cheaper than a plumber to fix the pipe every year though!)

On a side note, does your crawlspace have a "vapor barrier" on the ground or floor ? How damp is it in there ? Those will be things to consider when choosing insulation methods. You might wanna post your questions in another topic concerning insulation, etc ...
 
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Old 03-03-07, 01:26 PM
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I just wish to mention that insulation, contrary to what some people think, only prolongs what is inside of it to get either hot or cold. If there are long periods of time that the pipe is not pushing hot water through it, and the crawl space is cold, the pipe will freeze, no matter what. (In cases where equal outside cold and warm forces are acting on the insulation, the middle of the whole thing will get to the average temperature of the hot and cold combined. BUT...if you have static warm water, that then is no longer circulating in the pipe, but blowing cold wind in the crawl space, the cold will supercede the warm, and it will end up freezing)

If someone say were to (in essence) bypass the boiler thermostat by using electric space heater in the house and this warmed up the boiler thermostat in your ohouse, it would fool the boiler into thinking it does not need to run = bad. Even if the pipe were insulated.

Just wanted to point that out.

This scenario called me to 2 service calls so far this winter season and one resulted in massive ruptures in the whole hydronic system. For the other, we caught it in the nick of time and thawed out the crawl space by running the dryer in the basement and pointing ducting at the crawl space access window and running a fan to force the warm air back in there.
 
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Old 03-03-07, 03:18 PM
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Right... insulation can only slow the inevitable... but if it's cold enough out to freeze pipes in the crawlspace, that boiler should have been operating often.

Yer also correct about a space heater, that's why I asked about the wood burning stove too, but no answer on that.
 
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Old 03-03-07, 05:49 PM
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Pipe insulation

The fiberglass Trooper spoke of is my preference as well. It is semi-rigid & has a heavy white paper cover. It comes pre-split (usually) & has a flap on one side which will need to be taped or glued down. The also make plastic & metal elbows to cover the insulation on 90 turns. Not likely to find this stuff in a home center. You will have to go to a plumbing supply house or to a pipe insulation company.
 
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Old 03-03-07, 07:18 PM
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Grady, believe it or not, both our local HD and Low's carry it. I think they only have one or two sizes, and not a lot of it, but they do carry it. But, they don't carry the elbows and such...
 
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Old 03-03-07, 07:24 PM
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Home Centers

Wow, it is amazing that they carry it or have even heard of it. Not surprising that they don't have what you need to do the whole job.
 
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Old 03-04-07, 05:40 AM
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I don't know if HD or Lowes in my area carries that fiber glass insulation. We will see...

By the way, what can I use to tape them together? If I cannot find plastic/metal elbows, can I just bend the insulation and tape it tight or something?
 
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Old 03-04-07, 08:20 AM
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Fiberglass Pipe Insulation

This insulation cannot be bent around an elbow. In order to fit it around an elbow, the insulation needs to be cut at a 45 angle & the cut ends turned 180 to the original cut. This will give you a nice 90 turn. If you cannot find the metal or plastic ells, you can tape over the joint in the insulation with metal tape. Make sure to use the metal tape not ordinary cloth based duct tape. The foil stuff will last a lot longer.
 
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Old 03-04-07, 07:23 PM
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Thanks for all the info.
I could not find the semi-rigid pipe insulation, so I used the fiberglass pipe wrap and cover it with polyethylene one. I hope it will be sufficient...
 
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Old 03-04-07, 07:29 PM
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Pipe Insulation

The fiberglass pipe wrap is better than nothing but not by much.
 
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