4 mains, 3 vents

Shalom

I have two boilers and two pairs of mains, one for each floor. When I bought the house only the longer mains (to the front of the house) were vented; the rears weren't. The vents were those cone-shaped jobs, and they were installed directly on a tee in the return pipe.



At some point I had one boiler replaced, and while they were doing that I asked them to tune-up the systems as well. As part of that, they yanked out those main vents, and replaced them with new ones that are sort of disk-shaped (I just went down and checked, they're labeled "Gorton Air Eliminator No. 1 V") with a nipple maybe six inches long between them and the tee, just like it shows in the book. They also installed one on the rear main for the 2nd floor boiler.



Unfortunately, they did not put one on the rear main for the 1st floor system. There is a tee used where an elbow would have been logical, which may have once upon a time have had a vent on the top leg, but there's a plug in there now, and it won't unscrew, no way no how. They even tried to shift it with a huge pipe wrench, longer than anything I own, and it wouldn't budge. I tried some PB Blaster and let it soak for a couple days, and still nothing. I'm don't want to put too much torque on this because I'm afraid I'll break  the pipes (otherwise I'd just shove a length of pipe over the wrench handle and lean on it). Nor am I anxious to use a torch if I can get away with some other method.



So I  got to thinking. The vent I bought (yeah it's a $9 special from the Orange Apron, I figure it's not optimal but it's got to be better than a plug, right?) has 3/4" thread on the bottom to match the tee, I also bought a nipple and a junction so it wasn't sitting right on the Tee, and I was gonna screw that in there if I could only get the plug out. But they also sell vents with smaller thread size like the ones for radiators, except that it comes straight out the bottom.



So could I drill a hole in the plug,  tap it for whatever thread that is, and screw the vent right into the plug? It wouldn't be on a nipple, but should still work given that the steam/condensate in the return line would have to make a right angle turn to get to the vent.



Also, I've been seeing people asking what size vent to use, so I'll ask the same. The rear main is about 15 feet from the end of the manifold to the last radiator (which for some odd reason has copper pipe going to it; the rest of the system is cast iron. Don't ask me whose bright idea that was, it was like that when I bought the house.) then there's a U-turn, and it's another 20 feet back to where the pipe turns downward to go to the boiler, and that's where that plug is. The pipe going out is 1-1/2" and that coming back is 1". I think the changeover to the smaller pipe is right by the take-off for the last radiator. So what size vent would be useful there, assuming I can either get the plug out or the hole tapped in it?



Thanks.

Hap_Hazzard

Vents

That sounds like the right location for a main vent. The pipe that runs down to the wet return is called a drip line, and they usually put the vents at the tops of the drip lines. That's not necessarily the best place for it though. There's really no need to vent the air from a dry return, so the best place is really just after the last runout or riser comes off, so if there's a convenient way to add a vent there, that's another option.



The thread size on those radiator vents is 1/8" NPT. I know it looks a hell of lot bigger than 1/8 of an inch, but the N in NPT stands for "nominal," which means that's just what they call it.



That vent you got at the big box store is probably a USAV 883, with the 3/4" male and 1/2" female threads. It's made to be used as a main vent but it doesn't have nearly the venting capacity of a Gorton #1. If they carry the Maid-o-Mist radiator vents, look for a Maid-o-Mist D. That has the same port size as a Gorton D, which is the same as the Gorton #1.



Rather than trying to drill and tap one of your main fittings, you can probably get the same result by just putting the D on the last radiator on that main, but if you find that it's getting hot before the other radiators on that main you might need to downsize it (or increase the venting on the other radiators), but I'm only suggesting this as a temporary fix to get you through the season.



If you want to get that plug out, heating the tee with a torch is your best bet. The penetrating oil never works because the threads are sealed with compound. That stuff hardens up over time and makes it really hard to break the threads loose. But when you heat a fitting, it expands at a rate proportional to its circumference, while the plug, being solid, expands at a rate proportional to its diameter, and if you apply the heat directly to the tee and heat it fast, it will also expand faster. Speed is really crucial here, because the tee is also screwed into some pretty big pipes which make great heat sinks, and the transfer is pretty efficient, so you should have a wrench on the plug before you stop heating.



Another approach that works well is impact. If you have an air compressor, a good impact wrench and the right size square socket, you can probably rattle it right out. Sudden, repeated impact has a better chance of breaking the thread compound than grunting and groaning on a cheater pipe.



Back to your pipes, are they insulated? It's always difficult to balance a system when you're losing 40% of your heat through the pipes.

Shalom

The pipes are insulated. Even the returns. I know you don't have to insulate dry returns, but they're just the right height for me to bash my head on them, which I did regularly, so I put the insulation on more as padding than anything else.

As a belated follow up to this post: I wound up dismantling the pipes, starting at a union in the drip line, and replaced the entire Tee. (Took it to a real plumbing supply, not the Orange Apron, as they didn't have a Tee with a 3/4" side port and the rest 1"; before selling me the new Tee, he took the old one into the back room and tried to get that plug out... even he couldn't do it.)

The $9 special lasted a couple months, then the system got overfilled (valve wasn't tightly shut) and it acted like a water fountain for a few minutes. Never worked right after that, so I went back to the plumbing supply and got a real Gorton #1. Also replaced all the #C's and #D's that who-knows-who installed on the radiators with #5's and one #4 in the living room where the thermostat is, and it seems to be working better now.

Also, I recently acquired a combo pressure/temp gauge from the decommissioned, locomotive-sized oil burner at the local synagogue, and installed it on my boiler. I dunno if the pressure gauge works (it's rated 0-50PSI, so 1-1/2 pounds would barely lift the needle even if it isn't stuck), but the thermometer seems to work. I put that where the Gorton was, and moved that onto a side branch. Of course I don't "need" it, but it looks cool up there.

(Given that it has metric markings on it, it can't be anywhere near as old as this ancient boiler was.)

Got a question about steam pressure, but I'll start a new thread for that one.

Abracadabra

A single gorton #1 is probably not going to provide enough venting for your mains.

You should protect that gauge with a pigtail or create a trap using fittings. You don't want steam reaching the gauge.

ww

you should read Balancing Steam Systems using a venting capacity chart by Gerry Gill and Steve Pajek available on this site. this will go into detail on how to set up venting on mains, how to check how long it takes, how to do alot of the things you are looking for.

that gauge is in direct line for water hammer,clogged,etc..the vent should be at least 15 inches back away from the 3/4 inch hole..and pitched properly. like the above comment that number 1 is too small. If you read that what i mentioned you should know alot more on this..

i recently did this same thing you are referring to so if you need to know anything else if i know it i'll tell you.

Shalom

That #1 isn't the only main vent on the system; there's another one in the other leg. The rear leg (which this is) has three radiators on it (well two and a half, the one in the bathroom is really small) and the front leg has five.

I do have the Lost Art of Steam Heating on my shelf, and I looked in there when I bought those vents, I didn't just buy 'em at random. The system does seem to heat the house evenly as it stands, and the boiler doesn't shake like it used to do. Remember these radiators are all on one floor; the second floor has its own boiler.

The gauge isn't really in direct line for water hammer; that's why it's up there at the end of the nipple. That Tee is more of a street tee than a straight one; water coming in the side is steered downward. I put the gauge where the vent used to be, and moved the vent to the side, but I suppose there's no reason why I couldn't swap their positions, and have the gauge on the extension at the left side (well, except that the temperature probe that sticks out the bottom is too long to fit on the elbow, actually reaching below the side port of the upper Tee; I'd have to put it at the top of another nipple if I moved it).

I'm not sure I understand why steam shouldn't reach the gauge, though. I'm pretty sure it's designed for direct exposure to steam, given that the temperature markings go all the way to 260℉. If it was located after a trap, it would only ever see air, and would never get anywhere near that temperature. In any case, in its original installation, it was right in a boiler tube.

edit: the gauge appears to be an Ametek (US Gauge) PT1088. There's a guy on ebay selling that exact unit for $22.97.