Replacing Black Heat Pipe

mpmcgrath8

I am replacing black heat pipe in my basement. Right now there is 1 1/2 black pipe supply and return lines that branch of to 3/4" pipe for various radiators. There are 3 radiators on the loop. My question is can I use smaller feed and return lines for example 1" copper to feed these radiators instead of 1 1/2 ? I am pretty sure the system was used originally used for steam and is oversized.

Thanks

kcopp

hard to know for sure unless we see a couple pictures of the set up.

Snowmelt

Kc is right we need more info, the best info you can give us is, how many btu's does each radiater put out. Then we can determine pipe size.

Gordy

You have to know how many btus the rads have to produce to off set the heat loss of the room they serve. If the rads were at one time steam they may be under sized already from converting to hot water. Steam rads have higher output do to higher temps using steam vs water. Unless of course there were up grades to the structure envelope to lower heat loss.

That being said pipe sizing down also increases head for the circulator. So it's not a simple answer because there can be unintended consequence.

1 1/4" pipe Carries 145k btus
1" pipe carries 75k btus
3/4" pipe carries 42k btus
These are capacities with standard hydronic flow rates between 2-4 FPS.

wmtandson

Gordy said:

You have to know how many btus the rads have to produce to off set the heat loss of the room they serve.

1 1/4" pipe Carries 145k btus
1" pipe carries 75k btus
3/4" pipe carries 42k btus
These are capacities with standard hydronic flow rates between 2-4 FPS.

Someone please explain to me .
How my 3/4 " copper pipe supplies heat to my house thru loops that cover each floor from a 110,000 but boiler

Gordy

A little more info?

How many zones?

Hot water or steam?

Paul48

Well..... First the water is heated in the boiler, then.........Nah, just kiddin'. We'd need to know exactly how it's piped and pumped. It may not be right, and still heat adequately. It may be able to be improved.

Gordy

If each zone is 3/4" copper loops then they would be able to carry 42k each loop. Assuming you have say only 2 zones that's 84 k or 3 zones that's 126 k. Also assuming that each loop is using the full 42k due to ample emitters on each loop, or zone. Also assuming that the 110k is the gross input of the ci boiler then you would only have around 88k doe available for actual heat load. If a condensing boiler then maybe 92 k available to heat load.

Then there is also the assumption your boiler is twice as big as it needs to be, and your using only 1/2 of the available output because some knuckle head who installed it never did a heat loss calculation, and just threw in a boiler same size as existing one previously because it worked.

Snowmelt

Nice job explaining Gordy.