Ok to leave gaps in insulation on mains to add heat to a room?

bipbap

I have steam mains running along the ceiling of my basement. I’ve insulated them with 1” fiberglass but in the finished room of the basement which is a guest space I was going to remove a few 3’ sections of insulation to provide a bit more heat to
that room.  It’s not a super cold space overall but could use a bit more heat.

Is this OK? 

I wasn’t sure if having sections of pipe insulated and then some uninsulated would cause any issues or problems since the steam would be passing through warmer and cooler sections of pipe.  Could this cause issues with overall system function or hammering?

Here are some photos of the space, I was going to remove like 6’ of the insulation near the couch.

Its a one-pipe gas steam system if helpful.

Thanks for any advice!

pedmec

You should be fine. If taking that much insulation makes that much of a difference that you can't heat the rest of the house you got bigger problems.

An ideal way would be to use the condensate return if possible as its already done its job and is just high temperature condensate.

AdmiralYoda

Shouldn't be too big of a problem, especially if this space is used on a regular basis.

If it is used rarely a space heater might suite you better, something like an oil filled radiator type. Or even a small permanent electric, oil filled section of baseboard on its own thermostat to handle the room.

Jamie Hall

It won't hurt much, though it will slow steam getting to the radiators some. But -- have you considered how much heat you really will get? A 2 inch steam main has an EDR of about 0.5 per foot of length. That will produce about 120 BTUh per foot. That's about what a 35 watt light bulb will produce, or perhaps half that of a flat screen TV. Is it worth it?

ChrisJ

Jamie Hall said:

It won't hurt much, though it will slow steam getting to the radiators some. But -- have you considered how much heat you really will get? A 2 inch steam main has an EDR of about 0.5 per foot of length. That will produce about 120 BTUh per foot. That's about what a 35 watt light bulb will produce, or perhaps half that of a flat screen TV. Is it worth it?

If that's the case the time it'll slow the steam down should be completely unnoticeable.
That would give that entire length of pipe an output of about 3,600 maybe 4K btu/h completely bare, no?

Jamie Hall

That's about right. The slowdown -- which shouldn't be all that much -- comes from heating the pipe, not the room, at that spot.

bipbap

I didn’t realize it was so little heat.
They are 3” pipes hut when they used to be uninsulated it was super hot down there.

The bottom line though is that it needs heat and we use the space most of the time.

Is it more efficient then to uncover pipes or to
get a space heater?

The whole room is a long 12x35’ room with low 7’ ceilings.
I just figured to uncover some pipes and use that heat, I figured the space heater would cost more and I don’t love the risk of using them.

ChrisJ

It's more efficient to use a space heater.
However.

It's very likely cheaper to leave some insulation off the piping though.  Electric is far from cheap regardless of efficiency.

You probably do not need much heat down there.   Leave what you have and see how it goes 

jhewings

If you need more heat you could consider a ceiling mounted radiator. Or one lower if you can get the condensate to a wet return. Or even a hot water loop.

pedmec

according to multiple sources its closer to 212 and 256 btu's per foot depending on the ambient air and steam pressure.

dabrakeman

I would agree with Jamie's numbers on equivalent EDR. If you take a typical section of an old style 2 column radiator the sections measure ~2"x3". This is a 7.9" perimeter which is equivalent to a round diameter of 2.5". That is pretty close to STD 2" pipe OD of 2.375". EDR charts for radiators are measured from the ground so one section of a 15" high 2 column radiator would have about the same surface area as 2ft of 2" pipe. The one section mentioned would have an EDR of ~1.0 and thus the 1ft of 2" pipe an EDR of ~0.5.

If that basement room had 30' of pipe going around it then maybe could get 15 EDR equivalence. However, could also say that pipe would heat up earlier than all the main house radiators and heat to100% fill every cycle and thus actively radiate longer per cycle and to a higher degree of its capacity than an equivalent standing radiator vented to heat at same rates as radiators in rest of house. At that point the math appears to be too much work for me but I can see how it might heat up the room more than just the equivalent EDR would suggest.

bipbap

Ok thanks all.

I’m going to take some insulation off and see how it goes.
It won’t cause hammering to have sections of uninsulated mixed in, right?

ChrisJ

bipbap said:

Ok thanks all.

I’m going to take some insulation off and see how it goes.
It won’t cause hammering to have sections of uninsulated mixed in, right?

No it'll be fine

pedmec

the engineering toolbox gives you the output for bare metal pipe