2 pipe steam system - supply size to new radiator

josephc

In our new addition I am adding a radiator to our existing 2 pipe steam system. The available tap I have on the main is 1 inch. According to art of steam its max capacity is 56 EDR. The radiator I have is 63 EDR. Is this going to be a problem for radiator to function or is it close enough? I plan to insulate the 1 inch supply as radiator will be around 16ft from the main.

Thanks for any advice.
Joe

Jamie Hall

Probably close enough -- the radiator output may be slightly low. However, do insulate the runout and do give it plenty of pitch.

josephc

Pitch from supply main to the riser? Or from trap to return? What are recommended pitches? 1/4 inch per foot? The 1 pipe system section of art of steam calls out 1/2 inch per foot so assume less ok for 2 pipe?

Jamie Hall

josephc said:

Pitch from supply main to the riser? Or from trap to return? What are recommended pitches? 1/4 inch per foot? The 1 pipe system section of art of steam calls out 1/2 inch per foot so assume less ok for 2 pipe?

Both supply and return need to pitch. Less would be OK for two pipe (that is, closer the quarter inch) but I'd go with the half inch if I could. The problem is condensate in that small main conflicting with the steam demand of the radiator. Give the poor thing a chance!

JohnNY

Since steam will compress, I'm going to assume it would be ok to increase your supply branch to 1-¼" immediately after its 1" connection to the main. Do this carefully with either an eccentric coupling or with a concentric reducing coupling or elbow on vertical pipe. I know it's not ideal, but if anyone thinks I'm wrong I'd like to know why.

josephc

Radiator all installed. Pitch was kind of restricted by the geometry but got around 1/4 inch per foot. Getting plenty of heat. Only issue I have is that when steam starts to go to the radiator there is some banging in the supply line that is brief but there. I could feel the line getting hot and as it got closer to the radiator end there is some gurgling and banging indicating water hung up there. I will insulate the pipe to see if that helps. The megapress fittings were used for some connections.

josephc

the supply connection comes off the main towards the end of one leg. About 6-7 ft past this connection the main ends with a thermostatic trap (milvaco h100) which ties to the wet return.

Fred

Looks like maybe a little pitch in the wrong direction right at the end of the run-out right after that megapress connection where the pipe turns up to the radiator. May hold a little water there.

Jamie Hall

josephc said:

the supply connection comes off the main towards the end of one leg. About 6-7 ft past this connection the main ends with a thermostatic trap (milvaco h100) which ties to the wet return.

That's called a crossover trap, and allows air in the main to return to the main vents near the boiler. You don't need any other venting on that main.

josephc

Fred said:

Looks like maybe a little pitch in the wrong direction right at the end of the run-out right after that megapress connection where the pipe turns up to the radiator. May hold a little water there.

yes from the 90 el to the megapress tee it is pretty level; maybe should have been a 45 el. I'm going to insulate the line and see if that helps; though the water seems to be there following the off/cooldown period rather than while steam is flowing.

josephc

I insulated the runout but that did not improve the banging. I added a Gorton #1 to the supply run out to see if that gets the steam to that location faster and possibly get the noise over with faster or reduce the formation of condensate. It seems like the vent helps but it didn't solve 100%. Slightly less bang and over with a little quicker.

I'm not sure if the water is originating from start up and the steam condensing some as it warms the pipes pushing it along with the steam making its way down main to the last radiator runout or if its water from steam condensing at shutdown and left there to meet the steam.

There is a crossover at the end of main that connects to dry return which drops down into the wet return; is that crossover supposed to remove any condensate that forms or that was left in lines when boiler off and lines are cooling or just air? If it is not functioning could that be causing the condensing in supply and banging in the run out? There isn't any banging in the main.

Jamie Hall

If there is a crossover trap, it should be functioning -- but not to remove condensate. To remove air. Make sure that it is functioning, and then take all the vents on the main associated with it off and plug them. However, also make sure that that dry return is thoroughly vented -- not only does it take the air from the main through the crossover, but from all the radiators which return into it.

Also make sure that there is a drip from the low end of that dry return -- whichever it is -- to your wet returns.

josephc

I have a Gorton #2 as the main vent on the dry return at the boiler location. When you say to remove any vents that are on the steam main (other than crossovers) are you referring to the one I installed on the runout at the supply to the new radiator? There aren't any vents on the steam main itself except for the crossover traps at the end of each leg of main.

The dry returns do end at a vertical leg to the wet return. And the crossover traps from the mains tie into the dry return at those locations.

KC_Jones

If it's banging you have a pitch problem that needs addressed. You can try all kinds of stuff, but until you get the pitch correct it won't go away.

Also with 2 pipe you should not have a vent on that supply pipe, that's really no different than the people that put rad vents on 2 pipe radiators.

EBEBRATT-Ed

The supply coming off the main. I would have taken the 45 off and put a 90 in it's place. The would have started the supply out lower and you could have had more pitch.

Check your supply piping pitch with a level. If you have a low spot and can't re pitch, you could cut a tee into the low spot and drip it into a wet return or any return if you use a trap

josephc

EBEBRATT-Ed said:

The supply coming off the main. I would have taken the 45 off and put a 90 in it's place. The would have started the supply out lower and you could have had more pitch.

Check your supply piping pitch with a level. If you have a low spot and can't re pitch, you could cut a tee into the low spot and drip it into a wet return or any return if you use a trap

the tee and 45 are original piping so difficult to remove; that's why the plumber put the 90 where it is. The pitch from the radiator to the main is pretty much as much as it can be when working with the two pints, the distance and the fact that the main house beam cuts across the path.

josephc

KC_Jones said:

If it's banging you have a pitch problem that needs addressed. You can try all kinds of stuff, but until you get the pitch correct it won't go away.

Also with 2 pipe you should not have a vent on that supply pipe, that's really no different than the people that put rad vents on 2 pipe radiators.

with regards to the vent on the supply - I believe I read this done in the art of steam for getting the steam to go to a far point in the system quicker so to get that radiator warming sooner than others. I can move it to the discharge side of the trap instead if that would make a difference.

EBEBRATT-Ed

That 45 can be easily removed by someone that knows how. You giving up about 3" of pitch

josephc

Yes I looked at it and it would drop the line down giving me ability to pitch more. I also looked at art of steam again and the addition of a vent on riser looks like its only on 2pipe systems with wet returns.

Pitch currently 1/4 to 1/8 per inch even though I asked the plumber to be 1/4 to 1/2 inch per foot.