cold zone in steam heat

Bob W._3

A Ventrite No. 11 is really small; a Gorton C would vent 4.5 times as much air. Try larger vents and insulating the runout. See if you can figure out the model of the main vents as well. They are probably too small.

karl_3

cold zone in steam heat system

One leg of my steam system does not heat past the basement ceiling. Two radiators are on the leg. Both have new pressure valves. All other radiators in the house work fine. Last year I had the system cleaned with a chemical cleaner and I repeated the cleaning process several more times after the mechanic finished his cleaning. The above radiators worked a little but not well at that time.

This leg is not insulated. The supply pipe size drops from 1.5 In to a 1in as it goes through the floor. Do I need to replace the pipe in this leg? If so do I use the larger size pipe? If it just needs cleaning, what more can be done to clean it?

karl_3

cold zone in steam heat system

One leg of my steam system does not heat past the basement ceiling. Two radiators are on the leg. Both have new pressure valves. All other radiators in the house work fine. Last year I had the system cleaned with a chemical cleaner and I repeated the cleaning process several more times after the mechanic finished his cleaning. The above radiators worked a little but not well at that time.

This leg is not insulated. The supply pipe size drops from 1.5 In to a 1in as it goes through the floor. Do I need to replace the pipe in this leg? If so do I use the larger size pipe? If it just needs cleaning, what more can be done to clean it?

Bob W._3

The "leg" you refer to, is that a main or a runout to a riser? Post a picture or two and post the diameter and length and someone will give you a hand. Is the leg vented in the basement (does it have a main vent - if so, what kind)? It also sounds like you need to insulate as the steam could be condensing in the uninsulated pipe before getting to the radiators. Also, what kind and model of vents did you put on the radiators?

karl_3

Thanks for the reply. The leg is a runoff that goes to a riser to the first floor and another to the second floor. There is a main vent just past the runoffs and just before the return. The return pipe size is 1.25in, while the riser supply pipes are 1". The uninsulated portion of the main is 15 feet.The riser pipe goes to the second floor on an outside brick wall, and no sign of any insulation ever, (in fact there is a great cold draft down the chase) In addition the second floor riser must have at least 10 elbows according to where it comes through the floor. The first floor runoff however is a short 6' from the main and it turns cold just as it goes though the floor.

Bob Schultz

Slope

I had the same problem with one of my radiators. The pitch of the main going towards the floor was pitched down when it should have been pitched up. I think it was creating an air block so the steam couldn't pass. I fixed the pitch and it is now working. When you replaced the valves did you add length to your feed pipe? Sometime that will push the pipe down and create the wrong pitch. Check your pitch, that maybe the problem. Just a thought.
Ted

Bob W._3

karl, what kind of vents on the rads? or is this a system with traps only? Check the pitch on the runout, as someone suggested, and insulate it. If it needs further venting, try some vents like Gorton C's.

karl_3

That I know of there are no traps--at least I don't know how to recognize one if I see it. The vents are #11, and all are new. The main vents are larger but I can't remember the number. The pitch might be a problem, but it hasn't changed in 100 years that I can tell from the present hanging. All mains run down in pitch from the boiler, which I believe is appropriate for a harford loop system. The first floor runoff riser does go up in a slow pitch from the main--which is has to in order to get through the floor.

karl_3

Thanks Bob, I did not know the difference. I only got what my plumber told me to get, and I was never convinced that he really understood what to do.

I will try it. Any other thoughts? Especially about moving the radiator on the first floor, and putting both on a single runoff of a larger pipe that would be inside the house (rather than in the wall) and could be insulated?

Bob W._3

Do it in increments. Change the vents and insulate the runouts you can get too. That may be all you need. What about those main vents? Any numbers or names on them?

karl_3

Main line vent is a hoffman #4A as best I can see it. I will try to increase the vent size first to see if it works.

Steamhead (in transit)

How long is the steam main

and what pipe size is it? Those 4A vents are tiny, I remove a lot of them. Also, is that the only steam main in the house? If not, what are the lengths and diameters of the others?

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karl_3

The boiler is basically in the middle of the house, with one main leg that goes 35' or so in each direction. At the end of each leg, (1.5" pipe) is a vent--both seem to be identical but I can't see any marks on the other main leg vent. Off of the leg we are talking about there are four runouts. The two at the very end of the main are the two that don't work. I do have insulation on the main up to the point where the second runout is (about 12' from the boiler) but no insulation from the second runout to the third and fourth runouts which are those at the end of the main line that don't work. I could insulate the main, but the real cold area is in the riser from the third runout and it goes through the brick/plaster wall to the second floor, following a waste/vent pipe. I haven't a clue how I would insulate that.

What size vent should I try on the main? the 4A connects directly to a .75" pipe and doesn't seem tiny compared to the radiator vents. Does the lower number indicate a larger vent size or a smaller vent size?

Bob W._3

You have between .4 and .5 cu. ft. in that 35' main. Use a Gorton No. 1; they are physically smaller than the 4A's but will vent a lot more.

karl_3

Thanks, I will try it. Meanwhile I have removed the Ventrite #11 from both rads and they are starting to get warm. I don't think I need to leave the vents out long, but in 10 degree weather it is nice to get some warmth in the rads, and it does seem to prove the point of needing more vent.

karl_3

Bob W._3

Theres the proof. Just don't forget to put them back on:)