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# Main Venting (enough?), Rusty Water in radiator vents

Member Posts: 18
This is my 1st time posting to this site but I’ve read many of the steam heat discussions and Dan’s We Got Steam Heat book which have helped me improve our steam system considerably so thank you to all of you who are so generous in sharing your expertise and time.

We have a 2 story, 100 year old colonial in central NJ with a one pipe parallel flow gas boiler system. Overall, the system is running ok but there are a couple of tuning/problem questions I’d like to ask about. I’ve included information about the boiler, piping, etc. at the bottom of this note and attached some pictures. Thanks in advance for your help.

Main Venting

The first question is whether there is enough main venting. The main is 35 ft of 2” Inch pipe with a Gorton # 2 located on the dry return (picture attached). NBP, main, runouts are all insulated (the picture of NBP was taken before I completely insulated them).

I did a timing test that was recommended in one of the discussions where you turn the burner off for 1 hour in between the tests (I think the 1 hour off was to simulate a 1 CPH tstat setup, which is what my tstat is setup for). I did 3 runs with the burner off for 1 hr. in between each run. It took 4 minutes for steam to reach the Gorton in the 1st run and 4.5 min. for it to reach the vent in the 2nd and 3rd runs. This seems on the slow side based on other discussions I’ve read.

I’ve seen frequent references to a rule of thumb of 1 Gorton #2 per 20 ft. of 2” main.

I’ve also attempted to use the Gill/Pajek venting capacity chart to do the math. Using 0.23 cf per foot x 35’ I come up with a total volume of 8.05 cf of air for the main. At 2 oz, the Gorton #2 vents 1.750 cf per minute giving a total of 4.025 minutes to vent my main. This approximates the results of my 3 timing tests. So theoretically adding a 2nd Gorton #2 would reduce the venting time from roughly 4 minutes to 2 minutes. Please correct me if I got the math wrong.

Given all the above, it seems I’d get a significant benefit by adding a 2nd Gorton. Do you agree? Can you point me to a picture of how you’d setup the plumbing to add the 2nd vent?

Radiator Vent Problem

I’ve been trying to balance the radiators throughout the house. I had Heat Timer Varivalve vents but recently replaced all of them with Jacobson MaidOMist vents (based on many comments here about the difficulties in balancing radiators with Varivalves and having had a couple of them fail). Two of these MoM’s recently got stuck open and when I took them off and shook them rusty water drops came out. Is the rusty water in a vent normal? I also pulled a couple of vents that are working and they also had rusty water drops. The water in the boiler sight glass is clear. I drained some water from both of the valves (the one under the sight glass and the one under the LWCO) – about a quart of rusty water came out from each valve before it turned clear. I tested the PH of the drained water using my pool test strips and it looks to be about 9. The water level in the sight glass does not bounce at all when the boiler’s running and none of the vents are hissing/spitting. Occasionally, I hear some low level gurgling in one or two radiators, but not the ones with the failed vents (I haven’t checked the pitch yet on the gurgling rads but I will).

Wet Steam?

The distance from the boiler water line to the bottom of the NBP header is only 23” which is an inch short of the minimum 24”. I called the boiler manufacturer for their take on the impact and they didn’t seem to think the inch short was a major issue. I tried an experiment draining an inch of water to get the minimum 24” and re-ran the main vent timing tests mentioned above. I got the same timing results so it seems that being an inch short isn’t impacting the main venting rate. Could this be causing the rusty water in the vents?

System Information
• Boiler: Union Steam GSA-150, 150,000 BTU’s, Net steam output – 392 sq. ft., Installed – 2015
• Piping: NBP – 2 ½” (mfg. minimum), Main – 2“, Dry Return – 1 ½“, main vent nipple – ¾”,
• Tstat: Honeywell RTH7600D (programmed for 1 CPH)

## Comments

• Member Posts: 7,597
edited March 2023
Did you try the test with no vent at all? You can see how fast the steam arrives with no vent at all. The air will exit the 2" pipe thru the 3/4" tee fitting with no restriction that way. It may take only 1 minute. Or it may take 1 minute and 20 seconds. What ever that time is, then that what you want the vents to do. Or close to it. Lets say from turning on the boiler to making steam and getting it to the vent location with only a pipe nipple in the tee opening, it takes 1 minute 20 seconds. And with your Gorton #2 it takes 4 minutes 30 seconds. Then adding a second will shorten the time to to possibly 2 minutes 45 seconds. Adding a third might get you to 1 minute 40 seconds. At that point I would be satisfied. Because adding a 4th vent will only get you another 10 to 15 seconds. Not worth the effort at that point.

You can do all the math you want, but until you try it in real time, you won't really know.
Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
• Member Posts: 18
I did try it without the vent and got similar timings to with the vent. But I judged the times on when I saw white vapor coming out of the nipple and because the math says the timings should be much faster I assumed I was incorrectly judging the timings. What is the best way to tell when steam is coming out of the nipple?
• Member Posts: 983
The pressure gauge shows about 3psig. What are your pressuretrol settings? Do you know at what pressure the pressuretrol actually operates at for cut out and cut in?

• Member Posts: 18
Differential wheel set to 1, cut in set to 0.5. What I’ve observed though is burner doesn’t turn off until pressure’s almost 3 psi - then it takes about 5 minutes or so for pressure to drop enough to start back up. During normal operation, the pressure doesn’t move off 0. The only time burner cycles on pressure is on very cold days (single digits) or if I bump stat up 3 or 4 degrees. I’ll add ptrol pictures shortly.
• Member Posts: 18

• Member Posts: 2,668
and what about your pigtail?
has it been checked for free breathing back into the boiler,
so your Ptrol can see the boiler pressure???

the first picture of your sightglass looks like some dirty water,
then the next couple shows cleaner water,
dirty water makes for a dirty violent boil, which makes for wet steam,

I see the skim port plug still looks like factory installed,
has that been out, and nipple added, and some proper skimming done?
again, dirty water, especially the top oiley layer, makes for wet steam.
known to beat dead horses
• Member Posts: 18
The pigtail is cleaned every year as part of annual maintenance done by company that installed boiler. The picture of sight glass with dirty water was taken a couple of years ago before I fully insulated the NBP. I thought there might be a need to see the piping without all the insulation. The pictures with clear water are current. Sorry for the confusion. The water in the sight glass does not bounce/surge at all when the boilers running and no noticeable sounds from boiler. Would it surge/bounce if the water was oily or too dirty? They drain water and add SteamClean every year as part of their maintenance.

The boiler was skimmed after it was installed and then once or twice more during annual maintenance but not in the last 4-5 years. Is the rusty water in the rad vents abnormal? If the pitch is off on a rad, could it cause this?
• Member Posts: 15,344
Check your pressure gauge by installing a temp gauge on the boiler drain valve with a garden hose fitting. If the boiler gauge is accurate try lowering the pressure control setting if you are positive the pigtail is clean.

If your boiler gauge is right you can only try to lower the cut in setting or install a new pressure control or vaporstat. The high pressure is probably pushing water into the vents.

The quality of the pressure controls is not what they used to be
• Member Posts: 2,668
well, yeah, the rads should pitch to drain back to the supply valves,
and the valves should be wide open, so no water is held back,
post a picture of a valve connected to the rad, and of one of your rusty vents,
if rad vents are too fast they'll hold water up in there,
I don't know for SteamClean, but too much additive can be bad also,
You say no surging or bouncing, but,
are you seeing moisture at all in the top of that sightglass?
known to beat dead horses
• Member Posts: 527
More than likely you are getting some water in the vents just from those rare occasions as you mentioned where you turn the temp up 3 or 4 degrees or have the extremely cold day. In those cases it appears you are reaching 3+psi and cycling on pressure. If you have one or two radiators that are consistently the culprits after cleaning or replacing the valves you could go a month purposely avoiding the higher pressure situation by not doing setbacks and maybe if really cold weather is approaching go to a 2 CPH setting on your thermostat. If the vent stays clean then you know just avoiding the higher pressure maybe all you need to avoid your vent problem. There are ways to do that. You could do a quicker test by doing the opposite, starting with clean vents and purposely cranking up the temperature to get the boiler to cycle on pressure a few times.

As far as an antler for your main vents here is one example. I would in your case suggest putting two 90's together so you can put a slight pitch on your antler.

• Member Posts: 18
@dabrakeman Thank you. I'll try what you suggest re: the vents, and thanks for the antler picture.
@EBEBRATT- thank you for the pressure gauge suggestion - will try it this weekend
@neilc - I haven't seen moisture in sight glass but will check more closely when I do the pressure gauge test. thank you
• Member Posts: 983
Wait a minute. I just looked at the photo more closely. The gauge and the ptrol are on the same pigtail. How is the pigtail cleaned? Are you sure it is clear all the way to the ptrol? It seems pretty illogical for the gauge to read 3 psig and the ptrol to not cut out, unless someone has messed around with the internals or its just "broken".
• Member Posts: 18
Thanks for the question - you made me realize I actually don't know how it's cleaned or if it's clear. I assumed it was being done as part of my annual boiler maintenance but I've never watched closely enough to know if they are. I'm going to speak to the maintenance folks tomorrow. Just to clarify, the ptrol is cutting out just before it reaches 3 psig. But with the differential set at 1 and the cutout set at 0.5, it should be cutting out at 1.5psig? Is that how it should work?
• Member Posts: 527
My ptrol was similar and with clean pigtail all way through. They are not that accurate and as pointed out getting a vaporstat is probably the best way to go for more accurate low pressure control. I decided with some good advise from this forum to tweak mine to the point that now it does cut out at just under 2psi (vs the 3.5psi it was achieving at lowest settings previously) yet still cuts back in reliably. Details are contained herein:
https://forum.heatinghelp.com/discussion/comment/1717578#Comment_1717578

As you slowly tweak the screw down you need to verify that the boiler will turn back on if it does indeed cycle on pressure. I thought I had mine down to 1.5psi at one point but a day later woke up to a cold house and had to inch it back up a bit. Been good for many years now as is.
• Member Posts: 983
The 0.5 is cut-in, like it says in the photo Add the differential and you get the 1.5 cut-out.
• Member Posts: 983

There's a tiny screw that threads into the vertical shaft (its in the middle of the pic near the little white dot that is a reflection of the flash on my camera) and is painted black to reveal if someone has changed the setting. Take a close look at the screw and the adjusting screw that moves the tab that shows the setting. If this looks disturbed, please comment and post a photo.

• Member Posts: 983
I can't tell from your photo if it has been disturbed and maybe repainted.
• Member Posts: 18
@SteamingatMohawk I spoke to the maintenance office and they said the pigtail is cleaned every annual maintenance but I didn't ask how. I see fresh thread sealant tape for the pressure gauge, ptrol, and the T that connects to the pigtail but the tape where the pigtail connects to the boiler looks old. Is the pigtail supposed to be removed to be cleaned thoroughly?

I also looked at the screw and adjusting tab in the ptrol. The black paint on the screw looks fresh and undisturbed to me. If I push up on the silver bar to simulate rising pressure, it does move up and depresses the pin above it.

@dabrakeman I'd like to re-calibrate the ptrol as suggested but I'd like to do it off the boiler as the video showed to avoid any significant down time if I get it really wrong. But that would probably mean I'd have to wait until the heating season's over and I'd really like to resolve this while I have some momentum. I have a low pressure gauge coming today to help with main vent tuning and I'm wondering if I should just bite the bullet and get a vaporstat to replace the ptrol and install both the low pressure gauge and the vaporstat on an 18" riser instead of the pigtail as has been suggested in other discussions. I could bench test the vaporstat off the boiler to be sure it's accurate and then disconnect the ptrol and connect the vaporstat. I'd leave the 0-30 gauge as is on the pigtail. What do you (and others) think?

@neilc I looked to see if there was any moisture in the top of the sight glass when the boiler's running. I didn't see any but will keep my eye on it. One thing I did notice a couple of times is that when the boiler first fires up there's a slight popping/crackling sound that sounds to me like it's coming from the water chamber. The sound stops after 2-3 minutes.
• Member Posts: 527
I would put your low pressure gage on first and verify pressures before doing anything else. Certainly one can't argue against buying a vaporstat and having the ptrol as backup. Just a matter of what you want to spend. If you did that you probably would not need to mess with the ptrol cal at all. It only took me 4 days to finish the calibration the trial and error method. Only about 10 minutes of standing, witnessing and adjusting each day during the normal morning recovery I was using at that time.
• Member Posts: 18
Ok, makes sense. Yesterday, in the process of trying to tweak the cut-in setting, I turned the screw too much and it came loose from the spring. After I re-attached it to spring and reset the cut in to 0.5, I bumped the tstat up so I could verify that ptrol was still working. It cut out when pressure reached 2 psi (previously it was not cutting out until almost 3 psig) and cut in at 0.5. I’m wondering if I could do the remaining cutout calibration from 2.0 down to 1.5 psi by just lowering the differential wheel from 1 to 0.5? Seems simpler than adjusting the screw but don’t know if it would have some unintended negative impact.
• Member Posts: 334
nj88142 said:

Ok, makes sense. Yesterday, in the process of trying to tweak the cut-in setting, I turned the screw too much and it came loose from the spring. After I re-attached it to spring and reset the cut in to 0.5, I bumped the tstat up so I could verify that ptrol was still working. It cut out when pressure reached 2 psi (previously it was not cutting out until almost 3 psig) and cut in at 0.5. I’m wondering if I could do the remaining cutout calibration from 2.0 down to 1.5 psi by just lowering the differential wheel from 1 to 0.5? Seems simpler than adjusting the screw but don’t know if it would have some unintended negative impact.

Set the differential wheel to 0.5? On my Ptrols, there is no 0.5. It is just 5 and you have to turn the wheel the other way to get there. Don't do that, it will raise you cut-out pressure way too high.

I've turned the differential down as low as it will go--to some unmarked amount less than 1. It doesn't hurt anything.

And I've also taken the spring that becomes disconnected out completely. (It does practically nothing at its lowest setting.) But if you try that, you have to be careful that the boiler cuts back in after a cut-out. It all depends on how that calibration screw is set. (You can check it when you get your low pressure gauge; you want the cut-in to occur before the pressure gets to zero.)
• Member Posts: 527
Well, I too thought 1 was the lowest setting but if you can turn it further certainly turn the white wheel as low as it will go and see where you are at before messing with the screw. If you are cutting out at 2.0psi consistently and still consistently cutting back in then you are probably fine. Up to you to how much you want to keep tweaking for the 1.5psi. I tried just because I am kind of that way... Ended up somewhere between 1.5psi and 2.0. Make sure it has cut out and back in a few times off the ptrol successfully before deciding you are good. Sometimes it works once and then not the next when get that close to the edge.
• Member Posts: 18

My apologies for taking so long to respond but a few unexpected things came up and I wanted to do my heating “homework” before responding. I installed a low pressure gauge (Kodiak Controls 0-3 PSI) and tweaked the ptrol cut-out and cut-in settings until I got them as close to 1.5/0.5 cut-out/cut-in as I could using the cut-out dial and cut-in tab. They are now consistently at 1.7 psi and 0.5. I can get the cut-out down to 1.5 but then the cut-in moves down to 0.3 – not sure if it’s worth any further effort. I replaced the rad vent that had stuck open after accumulating rusty water. I also calculated the EDR for all the radiators (spreadsheet attached). It totals 365 sq. ft. and the boiler’s Net AHRI Output: Steam is 392 sq.ft. If I’m correctly understanding the boiler sizing discussions I’ve read, my boiler is sized pretty well - ?

I’ve watched several heating cycles since installing the low pressure gauge and adjusting the ptrol. The timings in the cycle below are pretty typical. The outside temp was 48 degrees and I bumped the tstat up 1 degree to force a run.

• 3 minutes from the time the header was too hot to touch until the main vent closed. Pressure during this interval hovered around 0 on the gauge. The lowest marking after 0 on the gauge is 0.15 psi (2.4 oz) so I’m guessing the pressure at this point was 1 oz. or less.
• after another 3 minutes all the runouts/risers were too hot to touch
• after another 19 minutes, pressure had risen to 0.15 psi (2.4 oz)
• after another 1 minute, pressure had risen to 0.20 psi (3.2 oz)
• after another 3 minutes, room temp where the tstat is located had risen 1 degree and tstat shut burner off. Pressure was still 0.20 psi at this point.
• Total duration from the time header was too hot to touch until tstat room temp had risen 1 degree was 29 minutes.

Are these timings and pressures good? I have a feeling that the total cycle duration could be shortened by some additional radiator balancing but before I do that I want to be sure that the main venting is reasonably good and the best it can be without tapping another hole in the dry return. As I mentioned earlier in this discussion, the timing tests I did with and without the main vent installed took about the same time which indicates a 2nd Gorton (on an antler) wouldn’t help but the math (if I did it correctly) and the rule of thumb I’ve seen here (1 Gorton #2 per 20 ft. of 2” main) seem to indicate otherwise. I’ve read a number of posts where @Nicholas Bonham-Carter suggested a way to tell if you need more main venting by using the low pressure readings I now have available to me. I’d like to try it but I didn’t bookmark the postings and don’t remember the process he suggested.

• Member Posts: 5,617
edited March 2023

Those timings and pressures are among the best we ever hear about on this forum IMO, you are in good shape.

I can get the cut-out down to 1.5 but then the cut-in moves down to 0.3

That would be good, but honestly, given what you have shared, your pressuretrol will never or very rarely activate, maybe after a big setback, that's it. And that's a good thing.

PS: the good thing about these tests is the outside temperature doesn't matter hardly at all

NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
• Member Posts: 18
edited March 2023

That's good news - thank you! I see you're in NJ. Do you know any steam pros that would service Union County? I didn't see any in the Contractor locator.

@neilc, @EBEBRATT-Ed , @dabrakeman - thank you for all your help - it made all the difference!

• Member Posts: 5,617
edited March 2023

There are many in the contractor locator for 07033, a random zip in Union county that I tried…maybe try again? They may not be located in Union but they almost certainly cover it

Looking in there I can vouch for @JohnNY which I think is Toro in NJ and also @EzzyT which is Travis. That's not to speak negatively of several other contractors here in NJ who are active on this forum—I just am not familiar with their service areas

NJ Steam Homeowner. See my sight glass boiler videos: https://bit.ly/3sZW1el
• Member Posts: 18

Thank you

• Member Posts: 1,290

@nj88142 the best way to reach me is at 2018878856