Pipe Insulation

Brad White_200

Hi Peter- I ran some more numbers for you based on 2-inch pipe:

Bare pipe with 215F steam inside. Surface temp. 214.9. Loss to a 70 degree space would be 219.8 BTUH per SF if bare pipe.

Add 1/2" insulation: Surface temp. = 102.8F. Loss is 62 BTUH per SF. which is 28.2% of bare pipe.

Use 1" insulation: Surface temp. = 86.2F. Loss is 30.3 BTUH per SF. which is 13.8% of bare pipe.

Use 1-1/2" insulation (your condition as described, adding another inch over what you have): Surface temp. = 80.7F. Loss is 23.22 BTUH per SF. which is 10.6% of bare pipe and 17.6% better than what you have now with 1/2".

Use 2" insulation: Surface temp. = 78.0F. Loss is 19.68 BTUH per SF. which is 9% of bare pipe. This last entry is what most energy codes prescribe by the way. You MIGHT try 3"x1.5" insulation if you can find it at a good price.

Peter Means

Adding more pipe insulation

Home owner questions:

1. Last year I insulated my mains and risers with 1/2 thick fiberglass. I now realize I should have used 1-2 inch think stuff. Rather than replace it, what do you think of wrapping it with some Reflectix, Reflective Insulation, (that bubble foil stuff)? Any better ideas?

2. I'm going to do the returns this year, as the main vents are at the end of these runs, and not at the ends of the mains. I think I'll be okay with the 1/2 fiberglass there (HD sells only 1/2 so it's easy for me to get).

3. I didn't insulate the hartford loop or the equalizer yet. Should I do these? i'm guessing so.

Thanks in advance.--Peter

JohnNY

I think...

...you should leave it alone.
What you've already done is going to make a big difference.


But, others may disagree.

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Brad White_201

Not exactly disagreeing but

you, Peter, may find yourself in a better position than you think. You can "nest" insulation of say 1" thickness over the 1/2" you have.

Say you have 2" pipe insulated with 2x1/2" insulation. The OD is practically the same as 3" pipe so buy 3"x1" insulation. Apply the second layer staggered (deliberately covering, not aligning) the joints of the first layer. Tucking in a nice blanket.

John is right in that the first half-inch has taken your bare pipe heat loss down to (my charts are not here now so a guess), about 35% of what it was and a full inch itself will take it down to about 16% of bare pipe losses. Adding that extra inch will take your 65% reduction closer to 90 percent. I will verify this tomorrow but personally, I would do it, even a little at a time. Big pipes first.

Peter Means_2

Thanks!--Peter