pipe insulation question

[Eric Johnson]

This may be slightly off topic for this forum, but here goes anyway:

I've got one-inch copper supply and return lines running from my wood boiler to a heat exchanger on our gas-fired boiler. For about 20 feet (out of 100) the pipes run through a section of the basement up between the floor joists, a couple of inches from the subfloor. I'm getting to the point where I'm considering adding additional insulation to the system, and was wondering if it would make sense along this stretch. Currently they're not insulated at all, although other parts of the run are heavily insulated.

Any radiant heat lost from these pipes is sucked up by the framing and eventually moves into a tile floor, which is nice. Would it be more efficient to keep the heat in the pipes at this point?

 

[Rhone]

That's a good question.

It's easy if it were fossil fuel. In summer it's a double-edged sword you don't want uninsulated hot water pipes wasting heat to your house and having your AC wasting energy to remove it. All hot water pipes should be insulated. But you have a situation if you don't use the wood boiler in summer and these hot water pipes do nothing then, I'd vote not to insulate them. In winter any heat loss is recycled in heating the house and keeping the tile floor warm and cold tile floors stink.

 

[Eric Johnson]

Thanks. No need for AC where I live, and this line only circulates water between the wood boiler and the heat exchanger on the gas boiler, so even if we used the gas, there's no hot water moving through them when the wood boiler is idle.

 

[elkimmeg]

The theory is to get the most heat to the living space. Loosing it in a 100' run is counter productive. Depending on the temp of the fluid in the pipe as to which insulation to useEPI Engineered polystyrene ( Styrofoam base is good till 180 degrees then melts)
Rubber base armor flex is good till 200 degrees does not melt but will become brittle over time, Hotter than that Armor flex HT good for up to and maybe a little over 220 degrees then there is fiberglass wrap even better. In your climate R 5.0 about 1 " thick 3/4"= R4.2 3/8" equals R 3.3Armor-flex approximate insulation values

 

[Eric Johnson]

I hear you about losing heat through inefficiencies in the supply and return lines. I have a 35gpm circulator and every time that water goes around (100 feet out and 100 feet back), a percentage of my heat goes 'poof." Currently I've got the lines that run through unheated space sandwiched between R-13 fiberglass bats. In some places it's surrounded by the cheap styrofoam pipe insulantion first and then sandwiched between the bats. (Yes, the styro melts at 200 degrees). As my dad says, "you can never have enough insulation" but in your opinion is that sufficient for 1" copper carrying water ranging from 140-180 through unheated space?

None of the piping in the basement is insulated, but it's all running as described earlier, i.e., up between the floor joists near the subfloor. I thought about stapling some R-13 or R-19 fiberglass bats across the joists, which would at least keep the radiant heat between the insulation and the floor. Again, any thoughts on that?

 

[elkimmeg]

Lets put it this way Two years I finished over the top pf my garage for my daughter to stay( inlaw setup)
Every pipe was insulated hot and cold. Why cold water pipes condensate during summer, It quiets the running water noise.
plus it get the hot water to the fawcet faster and hotter I mean I insulated every length inside walls in the living space. and you know what it is quiter no vibrations either.

Insulatining the bays are a good idea at least it allows the heat to escape upward Wrapping it with fiberglass also works. Do not do that on cold water pipes when they do condensate you will trap the musk smell in the fiber glass. Actually your celler ceiling should be insulated to prevent cold exposure to your living space and prevent heat loss living to your basement. If pinched for money just do your supply lines first with Armor Flex. Btw the return side: factor this in, if the water returns to your boiler warmer,, it takes less heat to bring it back up to temp. What if this pipe insulation and ceiling insulation can save you a cord or more a year . That's a lot of work saved? Plus save your receits, you are entitled to a tax credit. The down side your basement just got colder. You will notice the difference right away.

 

[Eric Johnson]

OK, that makes sense. Thanks.

Are you saying that the Armor Flex beats sandwiching the lines going through the unheated space between layers of the R13 pink stuff (one above and one below?)

 

[elkimmeg]

Eric read my last post and plug in your values then you can calculate the value of ceiling insulation. To me if the pipes are inside the insulation jacket they are no longer exposed. It would not hurt to use 3/8" armor flex and bat fiberglass as well. Will get a lot quiter.
Do this place a thermo on the line entering the hom or starting the loop then get a reading when it leaves. then take the temp after insulation as it leaves see if there is a difference, Rember more heat will dissipate more to the living space so I do not know if an accurate annalisis can be drawn but it would be interesting