More venting needed? Where?

underdog32

On my 2 pipe system I have one main vent. The vent was old. I think it was a float type and not working. I visibly saw steam escaping, and water spitting out of it. I went to my local plumbing supply shop and the guy sold me a gorton #1, which is awfully small compared to what was there. I was hesitant there, but he assured me that it was big enough, but now I'm having second thoughts.

This is what was there:


Since I installed the gorton, my boiler went from running like 30-40 minutes every 2-3 hours to 20 minutes (consistent) every hour. Some radiators take a long time to heat up (but they did before too). I'm thinking the steam is moving slower because of the smaller vent, causing the house to heat, but not "overheat" because the rads aren't fully up to temp, so the heat doesn't last as long as it did yesterday and the boiler turns on again sooner.

So I ordered a bigmouth which will be here in a few days to replace the gorton 1, but I'm wondering, is it enough? I read some stuff about old coal systems not needing as many vents, and when the boilers were upgraded to gas people didn't upgrade the vents to match the new requirements.

Should I try to install a few more vents, and if so where? Are more vents at the end of the line enough, or should they be added throughout the dry return pipes? Would adding vents after F&T traps leading to the wet returns help with overall system venting?

EdTheHeaterMan

No vent after traps. Bigmouth in place of the Gordon #1
if you still need more venting, then you can put a Tee there and add a second vent in the same location. Remember, it worked before with the old vent before it failed. Don't try to reinvent the wheel. Just get as much venting as you can where the old dead men designed it.

Steamhead

That's a Trane vacuum vent, and it is supposed to close when steam reaches it. Is this a 2-pipe system, as in two pipes connected to each radiator? Is this the only place on the system where there is a vent?

underdog32

Steamhead said:

That's a Trane vacuum vent, and it is supposed to close when steam reaches it. Is this a 2-pipe system, as in two pipes connected to each radiator? Is this the only place on the system where there is a vent?

Yes, two pipe, and this is the only vent, aside from a single vent on the single radiator that i believe to be performing the worst.

Steamhead

You might have some trap issues. Where are you located?

underdog32

Steamhead said:

You might have some trap issues. Where are you located?

I'm in Northeast PA, Wilkes-Barre area. I changed 2 radiator traps yesterday and ordered a new cage/cover for a trane b1 on the slow filling radiator, and I've been insualating pipes for the last couple of days as well. I'm not sure how to tell if the traps are working or not. Two days ago, all my return pipes were hot to the touch during the longer cycles, but I read that flash steam can make them hot so that isn't an indicator of a failed trap.

Today they only get slightly warm at the trap.

Over the last 3 days I:
Insulated 90% of the pipes
Changed 2 steam traps
Changed the float vent i mentioned (and subsequently changed it back until the big mouth comes)
Turned on a bunch of radiators that were previously turned off

Things that changed in the system due to this:
Colder dry return pipes
Shorter, more frequent boiler cycles
A bucket trap that i installed that was rattling is no longer rattling
Radiators don't get fully hot

I'm not sure if the previous owners ever used or maintained the steam system. I feel like they got enamored with the forced air heating system and just neglected the steam system, though the boiler was at least serviced last year.

Jamie Hall

Flash steam really applies only to higher pressure systems, not residential. If the returns are steam hot, you have leaking traps. However, if they are hot like hot water hot, you're probably OK.

Unless your pressure is high, you'll do better to keep that Trane vent. Much better. Or replace it, if you must, with a Gorton #2, which has a float in it. The Big Mouth may spit water in that location. And take the vent off the radiator which is performing worst; if it then doesn't heat, it's probably the trap although the return may have a problem in pitch. The only reliable way to check whether the main venting on these systems is big enough is to check the operating pressure. When the boiler fires, the pressure should rise to a few ounces -- perhaps as many as 2 or 3 ounces per square inch. That's OUNCES, not pounds. And should hold there pretty steady until the radiators are full. It if does that, you have adequate venting. If it keeps rising, you need more -- in this system, at the same location.

underdog32

Jamie Hall said:

Flash steam really applies only to higher pressure systems, not residential. If the returns are steam hot, you have leaking traps. However, if they are hot like hot water hot, you're probably OK.

Unless your pressure is high, you'll do better to keep that Trane vent. Much better. Or replace it, if you must, with a Gorton #2, which has a float in it. The Big Mouth may spit water in that location. And take the vent off the radiator which is performing worst; if it then doesn't heat, it's probably the trap although the return may have a problem in pitch. The only reliable way to check whether the main venting on these systems is big enough is to check the operating pressure. When the boiler fires, the pressure should rise to a few ounces -- perhaps as many as 2 or 3 ounces per square inch. That's OUNCES, not pounds. And should hold there pretty steady until the radiators are full. It if does that, you have adequate venting. If it keeps rising, you need more -- in this system, at the same location.

The highest I've ever seen the pressure gauge go is about 1psi. My pressuretrol is set to .5 with a +1 differential. I've never seen it cycle on pressure. It turns on with the t-stat, and stays on until temp is reached.

Right now the house is getting to temp (68) before the radiators are even fully hot, which I suppose should be a good thing, but I feel like the radiators should get hot and continue to radiate heat for a while otherwise most of the energy is getting lost because the radiators don't really radiate.

I know they all heat up if given enough time. When I set the temp to 73 to test things all of them get hot.

I don't think keeping the trane vent is an option. I'm pretty sure it's malfunctioning.

After these two vents, it's possible that my only problem is an oversized boiler. I need to measure the radiators today and figure that out.

ethicalpaul

My opinion is that the Gorton (and MoM) #1 vent way above their weight class. Time from "boiling start" to "steam arrives at vent" for the #1 and your Big Mouth when you get it, and I bet they are only seconds apart.

I had bad luck with my Big Mouth-- it was slow to close, and then it stopped closing, so I took it out of service.

If you can recover from a few degrees setback without cycling on pressure I'd say your boiler is sized pretty good.

Jamie Hall

And at the pressures you are seeing, it is very likely that your venting is entirely adequate.

On the radiators not getting hot all the way -- they don't need to. In fact, on most shorter runs, they won't. It is useful, though, if they get more or less the same amount of hot in various places. You're not losing energy that way at all -- as the radiators cool, all that heat is convected (not radiated) into the space. This is why the system should turn off the boiler before it actually reaches the set temperature -- otherwise the remaining heat in the radiators will cause the temperature to overshoot. Further consider this: if you are above design temperature -- say a cloudy 40 degree day -- the heat loss from the structure is low, and so the heat from the radiators needs to be correspondingly low. You don't want them going full song!