Do I need more venting?

1887steam

I’m having trouble getting those farthest radiators to keep up with the rest of the building. Do I need additional venting on my main or riser or am I already maxed-out?

Boiler is located near front of an 85' building with shorter faster front riser located directly above the boiler (about 60': 35' x 2" pipe + 25' x 1-1/2" pipe). There is no vent on this straight shorter riser – It heats up very quickly with only the radiator vents at smallest openings. Distance to furthest radiator on 6th floor rear is about 240' from boiler (including figuring extra feet for fittings used).

The main, from boiler to rear riser & main vents is about 150' x 2 -1/2" pipe with one Gorton #2' and 4 Gorton #1’s venting the main just past the bottom of the riser (and another Gorton #1 venting a radiator just past the main vents). Steam runs in same direction as condensate in main to drain line at end of main.

The 2" riser heads up another 90' more or less vertical feet (again adding in for fittings) with a Gorton #2 at top of riser, but with steam rising & condensate draining in same 2" pipe.

Huge old American Standard A-5 (circa 1962) 260,000 Btuh boiler with 1082 EDR capacity. Connected load on front riser about 400 EDR (6 radiators) and about 410 on rear (8 radiators). Vaporstat cut-out at 10 oz. and cut-in at 5 oz. No banging, hissing or spitting throughout the system.

I just added the two Gorton #2's on the main and riser and that seemed to help. Do I need more on the main or riser? I am almost getting steam to top of both risers at same time, but mostly all varivents closed except on furthest radiators on top floor which are fully open. Therefore I have little adjustability on the other vents and some lower floors are too hot.

You can see in the photos a bad piping job at the furthest radiators limited by no access to pipe below first fitting. I know I will have to change this at some point, but it isn’t much better on floors below which are heating faster, with vents at smallest openings. The steam is there in the riser to the vent, but it takes a while for these radiators to fill as other floors get too hot. I have put the thermostat on this top, coldest floor. I tried adding a second vent on the big radiator, (Gorton D below - tried both Gorton 1 then Varivalve above) piping it in through the tappings at the top. That certainly got the heat through there faster, but I started to think that might also make the radiator cool down faster because it wouldn’t trap heat in the upper part of the radiator, letting in too much cool air in when they open.

Any insights would be appreciated, Thanks.

BobC

Smaller radiator vents.

Heat Timer Varivents are very aggressive even at the low settings. Do you have any smaller vents, like the Hoffman 1A or Vent Rite #1, that you can try on the hot side of the building?



I suspect your thermostat is being satisfied before the steam finds it's way to all the radiators.By slowing those radiators down the steam will find the cool radiators a lot faster.



Also what is the steam pressure?



Bob

1887steam

smaller vents

I have a couple of Gorton 4's & 5's I could try, but I thought the Vari vents close down pretty well if the blow test is any indication.



I put the thermostat on this coldest floor, so it is not satisfied untill the radiators heat up. I tried putting it on a warmer floor but then it did cycle off before heat hit the top floor.



Vaporstat cut-out at 10 ounces, cut-in at 5. Thanks

Carl1979

2 vents on 1 radiator

sounds like that idea was working , your concern that they where not allowing heat to be trapped is not valid . there only purpose is to allow air out so the steam can get in .



One thing you might want to try it putting double faced insulating aluminum foil with a air pocket in it Behind those huge radiators not only does it help stop the radiant heat from going thru the wall. but it also forces it back thru the radiator and you may find it will help it get hot and stay hot easier and faster.

nicholas bonham-carter

more venting needed?

this is one good use for a low-pressure gauge, in that you can see the back-pressure of the air venting segment of early steaming. if all is adequately vented, the back-pressure would be 2 ounces. of course that does not tell you which main needs more venting, but it's a start.--nbc

BobC

Vent rates

The Hoffman 1A's are 0.026cfm at 1oz for setting #1, the Dole 1A's are 0.045cfm at setting #1, The Vent Rite #1 is off at setting 1 and 0.033cfm at 2, the Heat Timer Varivalve is 0.060cfm at low but rapidly goes up to 0.34cfm at mid setting.



Vent the hot radiators at a very slow rate and the cold one at a faster rate. Also is all the piping in the basement insulated?



Bob

1887steam

Tried the hoffman 1a's, but burning too much fuel.

Bob C.,

I bought a couple of the hoffman 1A's and that really helped to slow down the hot radiators and balance the system (using the #1 slowest setting), but still too slow to the 6th floor. I will try adding another Gorton G2 at the end of the "long main". Also thinking of the changing the second top vent on that last radiator from the varivalve to a Gorton 1.



Where did you find those vent rates - that was very helpful? I appreciate that your suggestion was for an adjustable vent, but once I am close, are there even slower but reliable vents than the hoffman 1a, even if not adjustable? Do you know the venting rate on the slowest Gorton #4?



It seems to achieve balance by slowing down radiators, the boiler is working longer to satisfy the thermostat and burning more fuel - Is this the tradeoff for balance? Are my vaporstat settings good? (cut-out 10 oz, cut-in 5 oz) with (by my calculation) a 3 oz drop from boiler to farthest radiator? Does my set back thermostat (only set back 2 degrees) really save any money - the boiler seems to work so long in the morning to heat up all those cold pipes & radiators?



Also (in answer to your question) every inch of steam pipe in boiler room, mains, & risers is insulated, but not return line in basement outside of boiler room where it never seems even warm.