To insulate pipes or not to insulate pipes (hot water radiators)
I live in a 145+ year old house in NJ. I have 2 boilers in an uninsulated basement with 5 zones plus an indirect water heater, 4 zones are hot water radiators & 1 is radiant floor heat. There are about 14 big cast iron radiators in the house which is to say a lot of pipe running all around the basement of different sizes and material (mostly copper also black pipe, galvanized ?) The reason I mention all the zones is because each one has its own pump and different run of pipes to illustrate how much copper we are talking about. None of the pipes are insulated, at one time they had asbestos on them but was removed a few years back when the system was upgraded from 1 oil boiler to 2 natural gas. Also, when the heat is running, the basement is the warmest place in the house.
I have been getting mixed answers on whether it’s worth it to insulate the pipes or even if it is a good idea. I have been told it dries out the basement of moisture and preventing mold plus hot air rises to the rest of the house. Although I’m not buying the hot air theory for heating the house, maybe the drying out factor is needed??? But if it is, this doesn’t seem to be the best way to go about it, or is it? Am I losing that much heat through all those pipes going all over the basement?
Also if I should wrap them, with what?
Foam vs Fiberglass ?
Is one more cost effective? Better? Worth the cost?
Is buying this stuff at big box stores the best way to go or does plumbing supply places have better/cheaper alternatives ?
Thanks for any and all advice in advance.
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Replies
Dan,
You should:
(1) Insulate your heating pipes (because it makes no sense for your basement to be the warmest room in your house). You can use either pipe insulation from a Big Box store or insulation from a plumbing supply house; anything is better than nothing.
(2) Insulate your basement walls. For more information on this work, see How to Insulate a Basement Wall.
Anything is better than nothing, but if you are going to go to the trouble, I'd opt for a thicker wall than the stuff you can buy at the big box store. I had to order online to get significant wall thickness.
Just to fill in the theory behind Martin's recommendations:
1) If you could insulate the basement walls and floors to R-400, then all the heat lost from the pipes would have to go up into the house above, because it would have nowhere else to go. So there'd be no reason to insulate the pipes at that point. but if your basement walls are insulated about as well as your other walls, or less well, only a fraction of the heat lost from the pipes goes upstairs. To stop the loss, you can either superinsulate your walls, or put a much smaller amount of insulation on the pipes. Because the pipes are a much smaller area, you need less thickness and less area of insulation to get the same reduction in heat loss.
2) Boilers in basements do help dry them out, but unless something is wrong, your basement shouldn't be damp in the winter anyway.
Insulate the pipes , piping loss is LOSS . You should also eliminate some of those circulators probably and replace with a Delta t logic ECM circ or circs with zone valves . Different emitters have different characteristics and flowing the RIGHT amount of fluid dependent on the heat load at a given time has an energy conservation value that would make you cry . Now , finding a contractor with enough hydronic knowledge to put this in place is entirely another story . What county are you in ? I may know someone in your area and if in Monmouth or Ocean I might even be able to help .
Rich - I am in Monmouth county. I have no idea what you just said about circulators but I'm guessing some are more energy friendly than others? And I think some more work can be done to make things more efficient.
Ok, So I'm going to insulate the pipes - is one product better than the other? Foam vs. Fiberglass in those pre-made tubes? That's really the big question.
As far as insulating the basement, I think I have other issues to tackle before I can do that. Brick walls, the mortar in a lot of places isn't looking so good and in some it almost seems like it's sand. I don't know if that's what happens after 145 years or so, but I know that should be addressed. I should probably also mention if you dig outside after a foot of two you are digging in sand. So I'm not sure what this all means when it comes to insulating those old brick walls. Plus the floor is very old and moisture comes up through the old concrete, I'm thinking one of these days I'm going to have to have it busted it up and replaced - an expense I really don't want unless there is another way??? But I think all of this needs to be done before I insulate the basement - correct?
Yes, the basement wall and floor repairs should happen before insulating, but I'll suggest opening a new thread to ask about how to approach that.
You may think that heating the air and convection is the only factor, I urge you to consider the effects of radiation. Your pipes are radiating their heat to the basement walls and floor which are absorbing that radiation and conducting it away into the ground never to be seen again.
So when insulating the pipes - does it matter with what?
Foam vs. Fiberglass
It's far better to insulate & air seal the foundation than it is to insulate the pipes, and it's sometimes easier too. But if you're not going to insulate the foundation, you DEFINITELY want to insulate the pipes.
The pipe insulation sold in box stores is overpriced & under performing, particularly when looking at the high-temp fiberglass insulation that would be appropriate for the iron plumbing. There are much better deals from online vendors, where you can get 1" wall thickness (R3.5-R4) for less than half the price of 1/2"- R2 goods from box stores. The cheap 3/8"-wall poly insulation for copper & PEX is only ~R2, and doesn't have the temperature ratings for high temp hydronic heating. If the radiant zone distribution plumbing is sufficiently low temp you MAY be able to use foamed poly pipe insulation, but get 3/4" wall R4-ish stuff at a minimum (again, available from online vendors or plumbing supply houses. Before buying any pipe insulation, look up the operating temperature range, or you'll be re-insulating the plumbing in short years.
I have no direct experience with them, but this vendor has reasonably priced pipe insulation (including the pre-formed bits for tees & ells) and will sell in onesie-twosie quantities rather than only by the case. You may be able to do better from a local plumbing supply place (or not), it just depends: http://www.statesupply.com/pipe/insulation/fiberglass
Dan,
1/2" or 1" wall fibreglass would be best . [email protected] . What town are you located in and are you east or West of route 35 ?
Basement temps warmer than the living space above do have benefits. Wood framing can often be kept dry enough in winter even with basement ceiling temps 10 degrees or more below the living space. But wood that has been thoroughly dried out can withstand longer exposure to excessive humidity, before becoming saturated and damaged, come Summer. Also a basement kept warm through the winter will already be warm come late spring when the humid weather arrives. Maintaining warm basement temps through the summer is one method of keeping basement humidity under control. With a cooler basement you may have to do more to control summer humidity.
The biggest advantage of a warm basement is comfort . People often complain about cold floors. A warm basement will produce warmer floors in the rooms above than anything short of radiant floor heat.
Rising warm air can carry heat from the basement to the rest of the house. If you don’t leave the basement door open or have grates in the floor little heat will move by this method. A long as the air at the basement ceiling is warmer than the air at the floor above heat will move through by conduction.
The heat lost from the radiator pipes isn’t truly lost until it leaves the building. Heat loss into the ground is surprisingly low. Neither a wood floor or a brick foundation wall are good insulators. I did a few rough calculations. With the basement noticeably warmer than the rooms above; Anywhere from a third to half of the heat lost from the pipes will be conducted though the floor to heat the living space. The remainder is lost through the foundation wall. Insulating the foundation wall could reduce this heat loss by 80 percent. If you insulate the pipes instead, it would be extraordinary if it reduced the basement temperature enough to reduce heat loss though the basement walls by 50%. There is likely significant heat directly from the boilers and flue, and once the basement temps are below the upstairs temps there will be heat coming down to the basement. Of course basement temps low enough to significantly reduce heat loss through basement walls will result in cold floor complaints by some.
So:
1: First insulate the basement walls. ( If the basement is the warmest room in the house it should be the best insulated as well)
2: If the basement is uncomfortably hot then add operable floor grates or insulate the pipes enough to achieve comfort.
Draping the wide plastic faced batts, made for insulating steel warehouses, down from the top of the walls can be a cheaper way to insulate a unfinished basement. I wouldn’t recommend it for a finished space the potential for condensation problems is fairly high if not detailed right.
Wrapping multiple parallel pipe runs with duct insulation can be more cost effective than insulating pipes individually.
Insulating the foundation can lead to greater frost damage to the brick foundation if moisture issues are making the bricks very wet.
I appreciate all the input, unfortunately until I fix other issues with the basement which may be a while (based on expense & time) insulating the basement isn't going to happen soon, which is why I wondered if it was worth it to do the pipes and if it would have any negative drawbacks.
Which turns out there might be moisture issues until I can do something about the very old porous cement but I'll deal with that - probably with a dehumidifier until I know what to do with the floor.
So, it looks like I will be insulating all those pipes.
Thanks.
And Rich I'll probably be reaching out to you through email.
I'll be here Dan