Uninsulated steam main is heating up basement. Is that so bad?

CoachBoilermaker · January 26

Oil boiler & single pipe steam heat.
60' steam main is uninsulated and mostly hidden behind drywall. Basement had laundry room, but we rarely go down there. I did seal up a big basement door draft.

The main is heating up basement. Is that so bad? Won't heat rise to main floor thru the floors anyway? Also, prevents pipe freeze in basement? House only has 6 radiators, so if all steam goes to rads, boiler might short cycle without main acting as large radiator? I don't want to break drywall, insulate main, and then create a new problem. Don't mess with it?

WillekesEaves · January 26

You'll lose some heat out the walls and the windows in the basement and the band joist, but it's up to you. You could make sure that the near piping is good and insulated, cause that gets real hot. There are statements in these forums about early condensation and wet steam, etc. Basically water appearing before the lines start to run downhill (condensate return). My uninsulated steam main is about as long as yours and a one pipe. 226k BTU newer boiler in a 2200 sqft living space, 2 floors. My basement was so hot that heat would come blasting up the stairwell like an open sauna door. It was ridiculous. I insulated a lot of it and have more work to do on all the joints and smaller runs, but yeah if your problems aren't that bad then don't bother. My basement is very dry and view that as a plus also.

If all your rads are hot, and you're comfortable, I'd say forget it. You ain't working for the Pope. Others may differ with my opinion. Your mileage may vary.

skimmer · January 26

I leave a portion of my main uninsulated on purpose to provide additional heat to a basement living area. I like it. Plus my boiler is a little bit oversized.

ethicalpaul · January 26

it’s not so bad.

There is a belief out there that an uninsulated main causes too much condensate and/or will hasten main corrosion, somehow causing balance problems, wet steam, and cancer, but it seems false to me.

After all the main already carries ALL the condensate every time the boiler runs. The main can’t tell the difference between water that it condensed vs water the radiators condensed.

Hap_Hazzard · January 26

To me, the answer depends on who is there to enjoy the heat.

When I moved into my house, the mains weren't insulated, and the basement got HOT! The colder it was outside, the hotter the basement got. I used to think it would be fun to dump a few yards of sand on the floor and host a beach party down there. The previous owner had cut holes in the floor and installed vents in hopes that the hot air would rise and help heat the rest of the house, but as far as I could tell, the effect was negligible.

If your basement is as hot as mine, I hope somebody's enjoying it, but if you're just using it for storage like I do, you're wasting energy.

In addition to temperature, you might want to consider what it's doing to the humidity. Anything that could be damaged by dry conditions is at risk during heating season. In the summertime, that same basement will probably be cool and damp, and things like furniture and musical instruments can be damaged by the recurring dry/damp cycles.

CoachBoilermaker · January 27

https://forum.heatinghelp.com/discussion/comment/1838039#Comment_1838039

The basement is not overly hot. More like normal 68 room temperature. The basement exit door is drafty. If it was extremely hot like that, I'd be more inclined to insulate the main.

In the summer, tankless coil basement is overly hot.

109A_5 · January 27

My main and run-outs are about 98% insulated. My basement is presently 50 degrees and it is 25 Degrees outside now. Its usually in the mid 50s but I think with the single digit weather we just had it cooled things down a bit. On one overnight when it was 1 degree out the pipes did NOT freeze.

I have been toying with the idea of putting a radiator next to the workbench.

clammy · January 27

I'm not going to get into a debate over this but i believe Erin posted a whole article written by dan on the subject but what does he know being he has seen more of old junk them most of us but we all can believe Paul being he has done all the experiments on his own system so i would image there's zero insulation on his steam piping and by some miracle of physics his basement is not over heated and everybody else loves a hot basement and cool home not.

My answer is if your basement over hot and home is cool maybe insulate your pipes and or lower the air infiltration and insulate your your rim joists and rafter ends to lessen thermal migration . your could also make sure your main vents and radiator vents are properly sized and in proper working order and if ya still have issues maybe paul can tell you what to do next like add glass piping to ensure your boilers making dry steam or possibly not flush and wand your boiler every few years or yearly ? Or ya do and listen to the guys who try to make living at this way before paul even knew or cared about a air vent or main venting was nor even heard of this web site ? Choose your poison .Erin has posted a article written by the Dan the man himself who educated just about everybody on steam and paided it forward ,who's first round of seminars for TLAOSH i attended in jersey ,don't even know how long ago being i was the shops to go guy for steam and i was a no nothing kid but i knew how to read instruction and follow them , possibly you should read the article and then think about which path you take being there's those who walk the walk and drag the knuckles and those who push the own theories as word of god but are not out there doing it for a living . I try not to interject to much but when i see suggestion that go against basic common sense and laws of thermodynamic and in some areas energy codes well i gotta say something . But guess everybody including the nys doe and federal doe suggesting and the enforcing insulation of heating pipes ( NYS) Well you can explain pauls theories to them as they stick a failed inspection sticker a on your door ,i dont think there gonna buy that theory but you can try . I would like to make it clear i have no malice toward pauls or others opinions hats off your a diyer and you have done it yourself excellent . But i feel that on some subjects especially when it comes to details like insulation that posting that its not necessary well i know when i smell bull or stepped into it.

In the close to 40 years in the business i have to say now adays i'm at a point where i guess everybodies right so i must be wrong it seems much easier that way and i move on being they know best . i mark there number on my phone and do not pick it up no need to re hash what i was wrong about the other guy got it covered i assume being he was correct right but why you calling me instead of the guy w the answers ? huh

One final note if ya dont need insulation then why did they install it on the piping when the system was installed and now 50 or 70 years later it is not needed . Logic answers only please not theories . Please remember all fuels where much cheaper then as was labor so why not just heat the basement ? They had reason and knew why but not all new theories run a true . Events over time always repeats the same mistakes different generation to commit .

peace and good luck clammy

Mad Dog_2 · January 27

Insulation is the icing on the cake. It's nice on the mains and radiator/riser branches, but don't dare insulate my boiler header & piping. Mad Dog

CoachBoilermaker · January 27

https://forum.heatinghelp.com/discussion/comment/1838171#Comment_1838171

I agree with everything you said. But my mains are behind finished drywall, so it's a big project to open up walls. If they were exposed, I'd insulate and see.

My house is not cold, and all rads get heat. My main question really is whether the heat is truly wasted if heat rises from basement anyway.

CoachBoilermaker · January 27

https://forum.heatinghelp.com/discussion/comment/1838175#Comment_1838175

Why not?

ethicalpaul · January 27

I do have most of my main insulated, because I didn't want or need that much heat in my basement.

maybe paul can tell you what to do next like add glass piping to ensure your boilers making dry steam or possibly not flush and wand your boiler every few years or yearly ? Or ya do and listen to the guys who try to make living at this way before paul even knew or cared about a air vent or main venting was nor even heard of this web site ?

@clammy I respect you a lot but I wish you would tone down the personal attacks which hurt my feelings, and instead focus on a discussion of how insulating the mains can do the things that some people claim.

One final note if ya dont need insulation then why did they install it on the piping when the system was installed and now 50 or 70 years later it is not needed . Logic answers only please not theories

I can't say why they did it because I can't see any reason behind it. I think it's other people's task, if they wish to, to explain what exactly the insulation is doing that I can't see. I am easily convinced by facts and observable results!

You have a good point, they didn't even insulate the walls, so why insulate the pipe, right?

hot_rod · January 27

hot goes to cold, and the rate is based on the temperature difference.

If you have a lot of exposed concrete foundation wall and un or poorly insulated rim joists? And infiltration? You are heating the heating the great outdoors to some extent.

At the very least I would seal up the rim joist leakage, seal off drafts that are raising the heating load of the conditioned space.

Hap_Hazzard · January 27

If your basement is 68°, don't insulate or you'll have to install a radiator. If your mains are all behind walls, that's probably insulation enough, but you might be losing heat to the outdoors on outside walls. If that's the case I'd say insulate the walls, not the pipes.

CoachBoilermaker · January 29

https://forum.heatinghelp.com/discussion/comment/1838217#Comment_1838217

There is not much remediation I can do. Basement is finished. Foundation and rim joist is hidden behind drywall. I saw the basement door to outside had huge drafts, so I added door sweep and foam strips. I think that's all I can do.

I was also told that you do not want airtight basement since oil boiler needs fresh air or else risk CO poisoning. I have CO detector next to boiler, which does not have fresh air intake duct.

CoachBoilermaker · January 29

https://forum.heatinghelp.com/discussion/comment/1838300#Comment_1838300

On 2nd thought, basement is probably like 75. Single main is a large square. I think the main in the laundry room was left exposed to be a radiator for that room.

I'm probably not going to mess with the walls. Too big a project for uncertain returns.

Long Beach Ed · January 29

Certainly a bare main condenses a lot more water than an insulated one does. It's like adding another radiator in line with the main.

That will produce more condensate and less dry steam at the end of the main, which can affect the performance of your heating system depending on pipe configuration,sizing and system loads.

If the system performs well without insulation, and the boiler has the additional capacity for the EDR of the piping and you don't mind some added fuel expense, go for it.

CoachBoilermaker · January 30

https://forum.heatinghelp.com/discussion/comment/1838834#Comment_1838834

Boiler is very very old and probably oversized. There are only 6 radiators in the house. There are no balance issues. All rads get fully hot. The system works fine, in general.

In fact, insulating the main could overwhelm the radiators?

Jamie Hall · January 30

No, it wouldn't overwhelm the radiators. It might produce shorter boiler cycles, though.

But… that heat from those mains isn't waste heat. It's useful heat for the basement. It would only be considered waste if the basement were warmer than you needed or wanted it to be.

On your smaller system, the other real (and usually forgotten) advantage of insulating the mains is that it results in getting the steam to the ends of lines more quicly.

vaylie · January 30

This topic came at a good time because I'm in a similar situation. Half-finished basement with electric baseboard heat. Currently I don't use the baseboard heat at all with my boiler keeping the space at a toasty 65F.

If I were to insulate my pipes and rely on baseboard heating to keep my basement warm (let's say 55F), does this save costs at all? I'm in MA so electricity is pretty expensive around 34c/kwH.

ethicalpaul · January 30

It's very hard to say, but in your shoes I would be very loathe to spend money on insulation for the privilege of paying .34/kWh

ethicalpaul · January 30

https://forum.heatinghelp.com/discussion/comment/1838834#Comment_1838834

You're right, it is like adding another radiator to the main. Let's explore that. Imagine a small-mid house with a 2" perimeter main like 50-60 feet long. It has like 8 radiator runout tees coming off of it. Let's say 250 sq ft of steam. The main is insulated. It works great.

Now add a new runout at the beginning of the main feeding roughly a 25 EDR radiator in the basement (at the ceiling of course). This is from memory so correct me if I'm wrong @KC_Jones

That amount of steam use and additional condensate (I would hardly call that "a lot more water") is equivalent to what would result from removing the insulation from the entire main. Removing insulation is even less disruptive, because the additional condensate is spread over the entire length of the main. Remember, a straight pipe is a pretty poor radiator.

It does not affect the performance of the system. It does not reduce dry steam. It does not add wet steam. It simply adds heat into the basement.

Uninsulated steam main is heating up basement. Is that so bad?

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