1", 1.5", or 2" insulation on the pipes in unfinished basement and crawlspace?

agurkas

OK, so the inevitable time to insulate (and redo in some areas) the pipes has come.

Here are two questions:
1. For the unfinished basement do I do 1", 1.5" or spend $$$ on 2" thick fiberglass insulation? This unfinished basement connects by couple large openings to equally big 20X30 crawlspace. Which thickness fiberglass do I use for pipes in the crawlspace?
2. About 3/4 of pipes are insulated, but with crumbling 1/2 inch stuff. It is not asbestos, but is is plenty old, since it crumbles like compressed sand. No elbows are insulated. For the 2+-incher mains is it worth upgrading to thicker stuff? How about returns, which are mostly 1 1/4"?

ww

hello, I made this same inquiry and you can read the replies I got here on this site using the link below. Lot's of good stuff here to read.

http://forum.heatinghelp.com/discussion/148582/pipe-insulating-off-mains-to-radiators#latest

ww

don't forget if you look at the pipe insulating link in the post you measure the od of the pipe and then it tells you what size insulation to use which is smaller and the inside diameter. i've been told that the one inch thickness is good and advised over the 1/2 inch thickness.

Spence

Speaking of the value of more and more insulation, I heat my home with a mini-split heat pump with no auxiliary heat. The design degree for my area is 14. My house faces west, and on a 12 degree day last winter with a 25 mph wind gusting to 29 mph, the interior was 68 degrees (design for my area is 70).

Regarding the basement, if it is unheated and not living space, you should insulate the pipes. If it is the plan to convert to living space, you should insulate the basement walls.

agurkas

Finally was able to get into crawl space and do all the measuring.

So I basically have:
75' of 2 1/2" mains, 30' of 2 1/8", and 33' of 1" returns. Everything is wrapped in 1/2 inch stuff. Elbows not covered (as mentioned).

Big question is, if I ignore the cost of elbows, since I am doing them anyway in each scenario, is ROI high enough to make spending $500 to upgrade from 1/2" to 1" on 140' worth of mains? Especially if I am only going to use the steam heat only in 35F or colder days (which Boston does not have as many as say Maine).

To re-do insulation of my crawl space would cost me the same. So it is a toss up between me doing new vapor barrier and insulating walls with Polyiso or re-doing pipe insulation this year.

Fred

I think, in addition to the ROI, you have to consider design and comfort. The design of a steam system is that you facilitate getting the steam into the living spaces as effectively as possible so that those spaces stay comfortable for you and your family. That means moving the steam down those mains/risers quickly so that the steam can actually condense in the radiators and give off its heat and not in the pipes below the floor. Much of your steam is condensing in those pipes which means it takes longer to get the steam to the rads, creating more temp swings in the living area than is necessary or desirable. If it were me, I'd put at least 1" of insulation on those pipes. You will see fuel savings and maintain a more even temp in the house as a bonus.

agurkas

Good points. Which then leads to another question: energy code in MA specifies 2" insulation. Doing everything in 2" is over what I want to spend, but maybe I do 1" on 1" returns and do 2" on 2" supply mains?

Fred

2" on the mains would be great especially in the crawl space! The returns are fine with 1" as they only carry condensed water back to the boiler and there is no significant energy loss there.

agurkas

Then is it even worth upgrading current 1/2" insulation on the 1" returns?

ChrisJ

I can't remember the exact numbers but there is a chart floating around comparing cost vs value on pipe insulation. 1" thick was by far the best bang for the buck and it's not much more than 1/2". 2" if I recall is a lot more expensive than 1".

I did all of my piping in 1" but kind of wish I had done some of my crawlspace piping in 1.5" or 2" just because. I also did my returns in 1" because as I said, 1" isn't much more money than 1/2".

I bought all of mine from www.buyinsulationproducts.com

SWEI

Delta-T again -- 2" insulation makes plenty of sense on high temp process piping.

David Nadle

I think it was me that made that chart way back when. The chart only takes the material cost into consideration and not the labor to install. So even though I thought the difference between 1" and 1.5" was not large enough IMO to justify the extra material cost, as a percentage of the total installed cost it might be worth it to go for the 1.5". There is a heating efficiency code that specifies 1.5" for steam pipes 2" NPS or smaller.

I think whether its worth $500 depends on how long you expect to live in the house.