main venting -- 2 mains that are uneven lengths -- and producing uneven heat

JamesC in Stamford CT

Hello again,



Boy, I must say the people on this board are great. It is really nice to find people who are excited about steam systems.



I recently replaced an old aging Dole main vent with a Gorton #2. I figured that would be my fist step before I start troubleshooting for the other reasons that my heating is uneven. It has helped a lot -- I now get some steam to the last radiator on the main, but that radiator is still 2/3rds cold unless the call for heat stays on for a long time. But before I start tinkering with radiator air vents, or insulating where the main goes by the garage door, or checking for ponding, pigtail cleaning, firing rate, et.c, etc., I want to work through whether my main venting is OK.



So I measured every length of pipe in my system and worked out the drawing below. The smaller main with a Hoffman #4 fills (relatively) quickly and the rooms in that side of the house are always hot. The rooms in the other side of the house are never hot, and the radiators take much more time to get going. And wouldn't you know it, the one room I really want the warmest, is the last radiator of the longest main. Based on the many prior postings I've read on this subject, it seems that my longer main is way under-vented with the single Gorton #2 that I just installed.



Here are the lengths of the mains:



Shorter main, all approx 2 1/4" outside diam steel pipe (I am not sure how to convert to actual inside diam)

8 ft

4 ft

8 ft

19 ft

9 ft

Total: 48 feet, vented with Hoffman #4



Longer main:

6 ft

10 ft

20 ft

23 ft

6 ft

Total 65 ft, 2 1/4" outside diam steel pipe

plus: 16 ft, 2" outside diam steel pipe

So, 81 feet vented with one Gorton #2



So, for the longer main, the first 65 feet of length is a bigger diameter, I suppose for counterflow. The last 16 feet are smaller, as they have a wet return. Well, actually, probably not a fully wet return. When the return finally gets back near to the boiler, it is 32" above the basement floor. The water level when the boiler is cold is about 36" above the floor. The installer put the boiler on blocks trying to elevate it a bit, but I am not sure that is really an issue or not.



Can someone help me asses whether I need more main venting?



As I said, there may be many reason for the uneven heat. But if I can get the main venting sized appropriately, then I will work on the rest. If any of the following is important, the boiler is about 7 years old and here are some stats:



Peerless ECT-03-120 SPT

Gross output 144,000 BTU/HR water

142,000 BTU/HR steam

446 Net sf steam

IBR 107,000 BTU/HR steam

Rating 125,000 BTU/HR

Max Steam 15 psi

Max water 30 psi

Max water temp 250 degrees F

Min relief valve cap 144 lb/hr

BobC

More venting

The 2-1/4" OD is 2" pipe.



I would assume you need about 1 Gorton #2 for each 40 ft so it looks like you need one Gorton #2 where the Dole 4A is and one more Gorton #2 added to the existing Gorton (total of 2 for that main).



You want to get the air out of the mains very fast and then vent the radiators relatively slowly. The radiators want to be vented by their size in general,m faster venting for larger radiators. Hoffman !A's and Ventrite #1's are nice because they are adjustable over at least a 4:1 range at 2oz of pressure.



Bob

JamesC in Stamford CT

Hoffman #4 or Gorton #2? see diagram

Thanks BobC for the vent advice. So I will order another Gorton #2 and make an antler at the end of the 81 foot long main.



But the 48 foot long main has only a Hoffman #4. That vent seems operational. Would you be able to tell me if the Hoffman undersized?



I am beginning to think that, if the Hoffman #4 is undersized or maybe partly clogged, that maybe all the radiators on that main might be forced to serve as the main vent -- which would be why they heat up faster than the radiators on the longer vent. I will have to test the temperature at the hoffman and see if it gets hot at the same time as my new Gorton #2 to test my theory.

Rod

Hoffman # 4

According to Gerry Gill's venting book, at one ounce of pressure a Hoffman #4 vents 0.060 cu ft/ min. A Hoffman #4A vents at  0.133.   A Gorton #2 vents 1.100 cu ft. and a Gorton #1 vents 0.330. It sounds like your radiators are doing all the work.

- Rod

Rod

Double Post

JamesC in Stamford CT

Photo of completed job - Now I have three Gorton # 2s!!!

Thanks everyone for all the helpful advice and encouragement. I am quickly learning a real lot about steam. Just wanted to post the photo results. I took the advice, and where I had put a single Gorton #2 at the end of the 81 foot main, I made it into an antler for two of them. And where I had the old Hoffamn #4 on the 48 foot main, with a new bushing I replaced it with one Gorton #2. Photos below.



Things are much better now on the 81 foot main, but I still have uneven heat. But I can trouble-shoot only one thing at a time. So, next I will replace the pigtail and add in a 3 psi gauge. And after that I deal with pitch. Then main insulation. Then radiator air vents. Then, I am not sure what, but my guess is that there will always be something.



Thanks everyone!

SteamRoller

Overhead space...

Question for those who know more than me:  Are these vents too close to the wood in the ceiling (joists or subfloor for the floor above)? I'm looking at replacing my main vent, and I have even less overhead space available.

Brad White

Ends of Mains

I hate to be the skunk at the garden party, but if those Gorton #2s are installed at the ends of the mains (any vent for that matter), they will bear the brunt of velocity-head. The full mass of any condensate propelled at steam velocities will enter those Gortons with force and shorten their lives. The condensate drop upstream of them is not enough to collect and divert the hydro train.



The ideal is a separate tee held back 15 inches from the end of the main. (The 15 inches is really semi-arbitrary, a 12 inch nipple and the fitting bosses make up this dimension). But you know what I mean.



If you MUST go off the end, route and elevate the vents remotely with a few elbows to limit the amount of momentum heading to those wonderful objects. I call this the "Antler" arrangement with its symmetrical counterpart known as the Menorah.



EDIT: I tried to post my detail but it would not stick. Steamhead's tag photo above is a good indication of an antler arrangement.  There are envious moose lurking on this site.

Steamhead

As long as there's enough room

to actually install the vent, you should be OK. 

STEAM DOCTOR

galvinized fittings

The fittings appear to be galvanized. It is recommend that galvanized fittings not be used on steam because the flacks will interfere with the vent operation

JamesC in Stamford CT

end of mains

Steamroller -- the Gortons are VERY tall. How tall? I did not measure, but I had to cut holes in the homasote ceiling and work in between joists.



Brad, thanks for the comment about the ends of mains. In both cases, for the 81 foot-long main and the 48 foot-long main, the Gorton #2s I installed are indeed at the very end of the main. So, yes, it probably would have been better to have them not at the very end, but this is the way the system was piped in 1930. I really had absolutely no room to elevate since I was already between joists and inches away from the bottom of the subflooring. So I will just have to keep an eye on them.



BN -- Since the fittings are a bit shiny, the flash of my camera makes them look galvanized. But They are not, just cheap and imported. Sigh, it's what my local plumbing supply house had -- but they're not galvanized. Thanks for thinking of that though.

SteamRoller

How tall is a gorton #2?

Hmm..  how tall is a Gorton #2?  They do look HUGE in the pictures...

STEAM DOCTOR

6 3/8"

6 3/8"

crash2009

Shortcut to find out pipe size

  James, if you ever need to find out what size pipe you are dealing with, and you will need to know when you insulate, just get up close to one of the fittings, an elbow or a T, the size is stamped on the side.  Older fittings sometimes need to be rubbed with a little spit or sandpaper for the stamp to show. 

Brad White

Or

a Pocket Rocket, available in the "Shop" department of this site. Invaluable, not just for heating but lolly columns and other cylindrical objects.

You can even measure the diameter of a cat's tail with it, something you may appreciate more than the cat does.