Plumbing question: best pipe insulation?

[NetWareHead]

I have hot water pipes in the basement I would like to insulate because they sweat and additionally I would like to conserve energy. These are hot water pipes both from the water heater and from the boiler (baseboard heating).

I stopped at home depot and learned that I have 3 choices: polyethylene foam, rubber and fiberglass insulation. As far as the R value is concerned, the plumbing expert said fiberglass is the best and polyethylene us the lowest. I plan to wrap all hot water pipes and seal them with tape. Anything I should watch out for or avoid? My other concern is that if the pipe still sweats while wrapped in insulation, would this lead to mold or something similar? What would you guys suggest?

 

[pcgeek11]

Hot water pipes don't usually sweat. Usually the cold water pipes do.

 

[DrPizza]

Hot water pipes don't usually sweat. Usually the cold water pipes do.

Yep, the sweating is from condensation. Water condenses out of the air on surfaces that are colder than the air. That generally won't apply to the hot water pipes.

 

[NetWareHead]

Hot water pipes will condense when the water within cools down to a cold temp. I don't really care about the condensation that much, but to me it indicates that the pipe has cooled down. That means I have to run the hot water tap and waste water down the drain until it gets hot again. Or it means that boiler has that much more water to heat when the circulator starts.

I'd like to insulate all hot water pipes in the basement (both boiler and water heater) but I just want to make sure that if there is any condensation, it won't react negatively with the insulation. Additionally, I'd like to pick a good insulation that will save me some energy down the road.

 

[who?]

If you poke a hole in the bottom of the insulation it shouldn't leak too much heat because heat rises. If the insulation keeps the pipe too warm to sweat, no problem.

 

[who?]

Once water has replaced the air in fiberglass insulation it won't insulate well.

 

[yh125d]

Hot water pipes will condense when the water within cools down to a cold temp. I don't really care about the condensation that much, but to me it indicates that the pipe has cooled down. That means I have to run the hot water tap and waste water down the drain until it gets hot again. Or it means that boiler has that much more water to heat when the circulator starts.

I'd like to insulate all hot water pipes in the basement (both boiler and water heater) but I just want to make sure that if there is any condensation, it won't react negatively with the insulation. Additionally, I'd like to pick a good insulation that will save me some energy down the road.

But if the hot water pipes aren't flowing, which would cause them to cool down, they're only going to cool to ambient, which shouldn't cause condensation

Are you positive there isn't something else going on? If you're really getting condensation on hot water pipes, I think you may have a humidity problem

 

[DrPizza]

I'm not saying not to insulate them. Though, I'm not convinced that it really saves that much energy in a typical household. That's because hot water use tends to have fairly long periods between use. E.g., you use it in the morning, then for 8 hours, it's unused. No reasonable amount of insulation is going to keep it from cooling to ambient temperature over those 8 hours. Ditto overnight; no use.

Nonetheless, people use the word "sweating" for pipes. If they think it means a little bit of water comes through the pipe, they're wrong. 100% of the water from "sweating" pipes is water that condensed out of the air. The water condenses out of the air when it encounters a temperature which is below the dew point of the air. If the dew point is equal to the ambient room temperature, then your humidity is 100%. A 100% humidity level in your basement would indicate that you need a dehumidifier. Your hot water pipes will not cool to below the temperature of the room. So, if the room is 70 degrees, the coldest those hot water pipes (in normal situations - you could, of course, turn off the hot water heater, drain it, then start running water through it, essentially turning them into cold water pipes) is 70 degrees. That's how physics works - they won't cool to a temperature below that of their environment. And, if the dew point is even one or two degrees cooler, water will not condense out of the air onto that surface.

The most important point to insulate though is the first couple of feet from the hot water heater.

 

[velillen]

I did all my hot and cold water piping in my crawl space just since it was easy. I used the tubular rubber insulation. Itll work just fine for the temps seen by the home hot water pipes. Hell we use 1" thick stuff for temps up to 270 degrees at work (though i will say i dont agree with it).

Sure it wont help keep it hot for an hour or anything. But it keeps it warm at least. The main reason i did it was my sink and shower are quite aways from the hot water. So even taking a 15 minute break i would have ot run the water again for a minute or two to get back to hot water. The insulation helped quite a bit. But i went ahead and got a hot water circ pump which does wonders. Instant hot water in the mornings and when i am home. I have it set ot run for 15 minutes (shortest time it can) every 30 minutes and always have hot water now.


As for what you want....skip the shit at home depot and lowes. Most of it is either over priced or just sucks. We use Armaflex (armaflex-nh to be exact) at work but it can be hard to source. You want something you can seal up to stop the condensation. The armaflex you need glue and you glue it shut and glue the seams. I know they make (well other companies) stuff with peel strips with adhesive already applied and i have heard it works ok. The armaflex with glue when sealed properly will keep any ice/condensation from forming on piping down below freezing. Always pisses us off when someone pokes a hole in the refrigerant lines and we have a softball sized ball of ice coming out of it.

As for what you want....thickest you can get thatll fit. 1" would be preferred. Just remember most plumping is copper yet most rubber tube insulation is measure in IPS. IPS isnt exactly the same as copper pipe sizes so i would measure the O.D. of your copper pipe ot know what size you need for IPS.

 

[Red Squirrel]

For condensation you'll want something with a vapor barrier as well. The condensation happens when the air is humid so when it hits the cold pipe it condenses, much like when air hits the cold coil of the AC unit and condenses into the pan. Except in the AC unit you want that to happen since that's how humidity is removed. Technically your pipes are acting as a dehumidifier, except since the water is not being collected and removed it just ends up evaporating back anyway.

I have a pipe that passes over my electrical panel and condenses if it's very humid in the basement, I should look at fixing that lol. Well it's not directly over the panel so the water would miss it, but still too close to comfort.

 

[highland145]

Sure it wont help keep it hot for an hour or anything. But it keeps it warm at least. The main reason i did it was my sink and shower are quite aways from the hot water. So even taking a 15 minute break i would have ot run the water again for a minute or two to get back to hot water. The insulation helped quite a bit. But i went ahead and got a hot water circ pump which does wonders. Instant hot water in the mornings and when i am home. I have it set ot run for 15 minutes (shortest time it can) every 30 minutes and always have hot water now.

That's really the only way to make sure you have hot water other than an on demand near by. wonder what that'll do to the power bill?

 

[velillen]

That's really the only way to make sure you have hot water other than an on demand near by. wonder what that'll do to the power bill?

I barely noticed a difference in the powerbill when I installed it. If I remember right when I set it up I used a kill a watt and it used like 25w when on. Since its only on for like 3 hours total a day that's not bad at all.

 

[yh125d]

I barely noticed a difference in the powerbill when I installed it. If I remember right when I set it up I used a kill a watt and it used like 25w when on. Since its only on for like 3 hours total a day that's not bad at all.

I'd think the heater running more often would probably use more than the pump, but unless it's a huge house I could still see it being not more than a blip on the bill