Main air vent possibly failed - Vent Rite 77 replacement

jefftk3 · January 7

Hi folks,

I moved in to a house this fall with steam heat. Gas fired single pipe system, Independence PIN6SNI-ME2 boiler.

I have one main air vent (Vent Rite #77) near the end of the main loop before dropping down to the wet return.

I noticed a few days ago that the main vent seemed to be venting for longer than I recall seeing before. In one case it was spewing out a plume of wet steam / water vapor. Last night I sat and watched an entire cycle of turn-on to turn-off, while it didn't spew a cloud of water vapor that time it did vent out for a solid half hour before the thermostat stopped calling, then the vent began sucking air back in shortly after. While its not impossible I've missed this before, I think it is new/recent behavior.

When I tap on the vent it rattles a bit - which I think seems to indicate its not completely seized/clogged. I suppose it could still be partially clogged.

The main question I have is: Would this Durst A833 air vent be a compatible replacement for Vent Rite 77?

https://www.lowes.com/pd/Durst-Silver-Hydronic-Baseboard-Heater-Accessory-3-4-in-x-1-2-in-Straight-Quick-Vent-Steam-Compatible-Large-Fixed-Vent-Easy-Installation/3535250

This seems to be readily available, which if its not as good as a Vent Rite I could at least use for a temporary fix before I can get a new Vent Rite or better part.

Beyond that - is there any other possible explanation I should look for that would explain this behavior besides the main vent failing?

I discovered this behavior in part because I was keeping a close watch on things after I noticed the heating cycles changed from a pretty steady ~2.5 hour cadence with +-1 deg temp swing, to more like 5 hours with more overshoot. Some changes in behavior there could maybe be related to outdoor temp changes, and me moving the temp sensor for the thermostat a bit. I also noticed the (VXT-24) water feeder had fed some more water recently than I was expecting (granted this is my first season with this system, so I still don't really know what to expect). I also had one case where my cat knocked the temp sensor on the cold floor, causing the system to run for a prolonged time in the early morning - wondering if that could have stressed things and instigated a failure.

p.s. using a Nest Gen3 thermostat (came with the house), with just "Time to Temp" and "True Radiant" features enabled, but not using any other fancy learning/scheduling/setback features.

ethicalpaul · January 7

No, don't buy that vent. You can get a Maid O Mist #1 or a Gorton #1 to replace it, assuming that it gave enough venting. Here's a link to supplyhouse.com

Steamhead · January 7

@jefftk3 , before recommending a vent, we need to know how long your steam main is, what size pipe it is, and whether or not it is the only main in the system.

jefftk3 · January 7

I thought that is the answer I would get after reading various posts about vents 😂

I should have added, there is sadly not a lot of clearance around the main vent. My main water line goes right next to it, and a hot water pipe is also probably a 1/4inch or less from the top/side of the current vent-rite 77.

I think the Gorton or Maid O Mist will not fit without redoing some piping of either water lines or vent.

The Durst vent looks similar in size/shape to the vent rite, so I think it has a chance of fitting. Since its cheap, and it looks like I can get it locally today, I'm thinking I could swap it in, then swap in a new vent-rite when it comes in. But I'm just not sure if there are some other relevant specs I need to make sure match.

If I can find detailed measurements for the gorton or MoM, I can try to check more thoroughly if there is a chance they will fit when I get home.

ethicalpaul · January 7

You know, I shouldn't have been so quick to condemn the Durst. I thought it was one of the big-box stores' no-name ones, but apparently Durst makes a decent amount of hydronic products so maybe it would be OK. Can't hurt to try it if you watch it.

Steamhead · January 7

That Durst vent comes from China. It's not very durable. Don't waste your money.

If space is limited, one can usually use some pipe nipples and fittings to move the vent location to one with more room.

jefftk3 · January 7

@Steamhead, I'll have to get measurements later for main run length - a very rough estimate base on floorplan is it may be around 60 ft going around the basement. So far as size of pipe… I'll have to measure that as well, might be 3inch, but that is based on recollection with my non-plumber experience.

jefftk3 · January 7

VideoCapture_20250107-143307.jpg

Here is a photo of the vent - it is nearly touching the copper water line.

I do understand what you're saying about using some nipples / fittings to move around the vent - will take that in to consideration, I might prefer to get a local professional involved if going that route.

Steamhead · January 7

Forget the Gorton or Maid-o-Mist #1. Remove the nipple under the present vent, screw in a 3/4"x1/2" bushing and install a Gorton #2. There's plenty of room, and the #2 has its own short nipple. This will vent the main much, much more quickly, increasing comfort and reducing the boiler's run-time. OK, it's more expensive, but worth it.

There's a whole neighborhood in Baltimore called Radnor-Winston where most of the houses have long mains like yours. We put Gorton #2 vents on those mains and that cures all the uneven-heat problems.

jefftk3 · January 7

Ok - thanks for the suggestion. I was about to ask if the Gorton #2 really vents more than the #1, but I see on their site that it says the #2 vents the equivalent of four #1's, despite having a 1/2in fitting rather than 3/4.

While I'd like to think I'm relatively handy, playing around with piping is on the lower end of my confidence scale.

If I end up proceeding with doing any of this myself, do you have any recommendations for what to use when reconnecting things? i.e. in terms of teflon tape vs pipe dope, or…?

I think I have some Hercules Megatape 3.5mil tape at home. If you were to recommend pipe dope, I have no experience with pipe dope at all, so not sure which specific type/brand to get.

delcrossv · January 7

Tape is fine.

ethicalpaul · January 7

Yeah the #2 definitely vents a lot, it is also very large physically. I have no idea why they don't use the same 1/2" - 3/4" combo fitting that the #1 uses, but they don't

EBEBRATT-Ed · January 7

I would also keep tabs on how much water is being added as adding too much water is not a good thing.

Also, how is the water line when it is steaming? It should be relatively stable moving slowly up and down 3/4"-1" is ok.

If you get a lot of fast movement or see water coming down from the top gauge glass connection that isn't good.

Steam pressure should not exceed 1 1/2-2 psi…the lower the better.

109A_5 · January 7

If for some reason you need more room for the new vent you can offset it to the right if there is room there with two elbows and an extra nipple or two, one longer.

jefftk3 · January 7

I just did my best to measure the main run in the basement - I came up with about 68 ft. It feeds a total of 5 radiators on the first floor and 6 on the 2nd floor. The two vertical headers off the boiler are 2 3/8 inch OD pipe, and the main pipes are 3.5in OD.

I just installed the Durst A883 vent, just because I was able to get it today to try. I tried watching for a whole heating cycle, granted I may have gotten briefly distracted, but I never saw it really vent and then shut, unless it was really subtle…

In the mean time I may try to clean the vent rite 77 I removed. It has some scale, but doesn't look too bad (I think?)

jefftk3 · January 7

Regarding water level, and pressure:

The water feeder has fed 10 gallons since the start of season (including when I drained about ~2gal). It seems like it feeds 2 gallons at a time. I have been watching it and noticed it had fed a few times in closer proximity than before, so I was getting suspicious (granted, temperature has been dropping along with some windy days).

Here is a photo of pressuretrol settings. I think the water in sight glass fluctuates within 3/4 - 1in, so it doesn't seem like its surging from what I understand.

I have a question about the pressure gauge next to the sight glass - should I see anything on that? I don't think I've ever seen the needle move. I assumed it should show me what pressure the boiler is actually at.

109A_5 · January 8

Hello jefftk3,

If your system is sized correctly you will never see that gauge move. If you want to see a gauge move you would probably have to add a low pressure gauge maybe 0 to 3 PSI or less depending on your actual pressure. For example my system runs at less than 2 inches of Water Column (or 1.16 Oz).

You could probably soak that vent in vinegar to clean it, however your system may benefit by a main vent that has a higher vent rate.

jefftk3 · January 8

Ah - thanks for the info. I was always curious about the gauge.

I did just boil the vent rite 77 I removed in vinegar/water. Some scale did indeed come off, however even while picking it out of the boiling solution and shaking it a bit it still rattles. I was expecting the boiling solution would cause the valve to shut, but it didn't seem to. I think either I'm misunderstanding something, or that confirms that the vent has failed.

Steamhead · January 8

It's shot. Get a Gorton #2.

Regarding the Durst, did the steam ever actually reach it?

jefftk3 · January 8

"Regarding the Durst, did the steam ever actually reach it? "

Not sure - that is still unclear to me. 2nd heating cycle since installing it just finished. Boiler ran for about 1 hour. Wasn't convinced of hearing any air leaving it while boiler was running, or coming back in once boiler was off. I did hear some radiators venting back in once boiler shut off.

I suppose that could mean steam never reached it (what would that mean? some other problem?), or the vent shut/opened faster than I noticed, barely venting any air and leaving the radiators to do all the work. I could believe the latter, since I noticed at least one radiator seeming to vent more than I recall (although I'm not ruling out it could be bias since I'm suddenly watching everything more closely).

Also, FYI here is boiler info

Steamhead · January 8

@jefftk3 said: "I suppose that could mean steam never reached it (what would that mean? some other problem?)"

It means the vent is way too small for your system.

BobC · January 8

Durst ,alesd terrible rafiator air valves do I would assume theit main vents are of the same dubious quality. The big box stores are not the place to buy vents. Better to go to supplyhouse.com or Amazon and get Gorton ot Maid O mist main vents - Gorton #1 and MOM #1 are pretty much the same, Gorton #2 is alst 3x the capacity.

Bob

jefftk3 · January 8

I have another Vent Rite 77 on order, and found Amazon has a Gorton #1 available with quick shipping so I ordered one of those as well to see if it might actually fit without modification. At least with amazon I can return it easily if it doesn't work out. I imagine I could inevitably end up getting a Gorton #2 as has been suggested 😅

Could I simply use a shorter nipple to install the Gorton #1 if there is interference with nearby water lines? I thought I remember reading somewhere that the main vents should be XX inches above the main - but would have to go search for that again unless someone can offer any insight.

In seeing some other random posts, I'm becoming wary of some other things. Does around a one hour run time of the boiler sound excessive? I'm sure its widely variable on lots of factors. I'm not sure I've ever seen it cycle based on pressure from the pressuretrol, maybe once - typically whenever I see it shut off its because the thermostat stopped calling for heat. Its kicking on about every 3 hours, with temp swing from ~68.5 to ~71.5.

ethicalpaul · January 8

I remember reading somewhere that the main vents should be XX inches above the main - but would have to go search for that again unless someone can offer any insight.

People say this because they think that there's a massive wall of condensate that comes barreling down the steam main, but it's just not true (I've looked). You should be OK. In actually, condensate is a gentle trickle or stream.

The only time there is a massive wall of water barreling down the steam main is when the boiler is surging, and that is such an undesirable state that it should be priority one in fixing, regardless of any damage to main vents. It shouldn't be "fixed" by raising the main vent above the torrent.

jefftk3 · January 9

The Vent Rite 77 I had ordered came in today, didn't think it would get here so fast (from Zoro). I installed it in place of the Durst, and watched for one heating cycle. I never caught if/when it closed/opened, but I think it must have because I tapped on it periodically to try to check and at some point it no longer rattled while the boiler was running.

Venting noise out of a couple radiators was back to what I sort of remember, much less than when the Durst A883 was installed.

The Gorton #1 should arrive tomorrow, might install that at some point later and see how things perform.

I also cut apart the old VentRite 77 to see if there was any obvious sign of failure. I couldn't identify anything obvious, but I did also try to heat the float with a torch and the bottom never popped out and the solder holding it together started to reflow instead. (The tarnish, at least on the outside, is from boiling it in water/vinegar previously)

jefftk3 · January 9

What would be the risk/downside/symptom of too much venting or too large a vent on the end of the main?

The system had a Vent Rite 77 installed for who knows how long as the one main vent. So far as I could tell it appeared to be working OK. I don't take for granted, though, that just because that is how it was it must have been "correct"…

If I should go and install a Gorton #1 or #2, which I believe both have more venting capacity than the VentRite 77, is there something I should watch for that would be indicative of too much venting?

Steamhead · January 9

Nope.

Remember, when these systems were installed, they had coal-fired boilers. The steam came up only once a day, and much more slowly than we see with oil or gas. So a smaller vent was fine.

Nowadays steam comes up much faster, so we need to vent as fast as we can. You'll end up with a Gorton #2 on that main.

dabrakeman · January 9

On cycles where the pipes are already warm the larger main venting will help the mains fill faster saving you fuel. This is true up to a point. Can't vent any faster than the open pipe.

Main air vent possibly failed - Vent Rite 77 replacement

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