System main venting and operating pressure problems

jalubarsky

Hello All - Just was told about this site and wanted to ask for guidance and validation of my plan of action.
Background: New house for us vintage 1940. Steam heat has 3 mains 2 1/2" cast iron pipe, approx. 50', 60', and 70' lengths. Relatively new boiler Burnham IN6PVNI-M2. First problem is main venting.
1st main (60') has vent which just failed open (this got me thinking about my system) and I urgently replaced it with a Gorton #1. It replaced a Dole #1C. This has worked with no problems.
2nd Main (50') has a Hoffman No. 4 Quick Vent.
3rd Main is most interesting because there is no main vent. I wondered how stupid could the designer have been but then realized that when a new radiator was added (15 yrs ago) for a powder room I think they removed the vent and tapped into the original vent location. A realize this is a major problem because this long 70' main takes a long time to get that last powder room radiator to fully vent (around 30 mins approx.!!!
My First Priority Actions:
1. 3rd main is biggest problem. Add a Groton No. 2 where the powder room taps in so this main can at least have some decent venting.
2. Must get a pro to reconnect the powder room riser.
3. Replace the Hoffman and Groton No 1 vents with Groton number 2's to increase capacity.

2nd problem is operating pressure.
I have read that my pressuretrol settings should be around .5 psi and 1 differential.
From attached pic you can see my settings are 5 psi and 1 differential.
My concern is my pressure seems to start at about 5 psi and climbs to 10 during a long heat cycle.
I also notice that my boiler cycles on and off quickly at times. I think it senses low water even though the water starts in the middle of the viewing glass.

My conclusions: I know my main venting is a problem and I have to solve this now.
My confusion is around the pressure. Is my pressure too high? Is it just my settings or are there other potential causes? I did check my water quality by releasing water from my three valves and the water was rusty at first then much clearer after maybe 20 seconds.
I will attach a three pics to show my pressure readings, my boiler main connections.
I am open to suggestions. Thanks.

Captain Who

1st thing I notice is that the pressuretrol is an older mercury switch type and the pigtail is oriented so that if it expands due to heat it will throw the mercury switch off. You need to rotate the pigtail 90deg relative to the pressuretrol. Those pressures are way too high but I guess you are going by the 30psi gauge with internal syphon which is notorious for plugging up and giving false readings. According to the settings the cut-out should be 5psi and the cut-in should be maybe like 4psi. I don't know how far you can dial it down but you want cut-out 1.5psi and cut-in of 0.5psi as you said.

Captain Who

You will need to set up a Tee on the pressuretrol with a 0-3psi gauge sharing the same pigtail.

Jamie Hall

Pressure is way too high. Fotunately you have one of the lovely old pressuretrols, so you can fix it easily. The left hand scale is OK There is a crew above the right hand scale. Turn that screw until the marker is just below the 2. Still a little higher than ideal but much better than what you have now.

You may want to take the pigtail off and make sure tat it, the opening into the pressurestat, and the opening into the boiler are really clear.

You will want to add/change the vents as you have suggested.

You may also want to add a 0 - 3 psi gauge,so that you can see what the system is really doing. You don't really need to though -- the movement of that mercury switch will give you a pretty good idea.

KC_Jones

Agree with above and would add that you need WAY more venting than you are planning. Rule of thumb is 1 Gorton #2 for every 20' of 2" pipe. Recently 2 1/2" came up (as you say you have) and it has been suggested 1 Gorton #2 for every 12' of 2 1/2" main. So in your case that would be 4 on your 50' main 5 on your 60' main and 6 on your 70' main...if they are 2 1/2" pipe. If you had 2" main that would be 3, 3 and 4 respectively. Are you positive you have 2 1/2" main? 2" pipe measures 2 3/8" OD 2 1/2" pipe measures 2 7/8" OD And will reiterate that pressure setting is way too high and I wouldn't trust those 30 psi gauges to measure anything no matter how clean they are.

Captain Who

Ouch......15 Gorton #2 @ $83.16ea = $1247.40. One has to wonder what the payback period is in years on that.

KC_Jones

83? go to supplyhouse.com way less than 83 68 if you buy more than 5.
http://www.supplyhouse.com/Gorton-G2-Gorton-No-2-Straight-Air-Eliminator-3524000-p
Also to add the OP states 30 minutes to get one radiator hot at the end so if that time is cut to even 10 minutes (I bet with proper venting at least that fast) that is 20 minutes of run time not being wasted every time the boiler fires. That would add up very very quickly.

Captain Who

That is better since it brings it down to $1034. I've been pricing this out myself and wondering if there was some cheaper alternative and how to determine what the payback period is without actually making the purchase.

I guess Heat Timer Varivalves are not a viable replacement functionality wise to the Gorton #1's and #2's?

At 2.0oz/in2:

Gorton #1: 0.540cfm (~$22.99 ea, $42.57/cfm)
Heat Timer Varivalve (straight): 1.080cfm (~$18.55 ea, $17.17/cfm)
Gorton #2: 1.750cfm (~$71.95 ea, $41.11/cfm)

I must admit I'm not sure I like the fact that they do not have a float like the Gortons do. If the system were inadvertently flooded the floats might protect you. I don't know which is more reliable.

KC_Jones

If they system gets big enough I think some of the pros have gone to steam traps as a main vent to cut costs. I don't think those varivalves are designed to be used as main vents. And I have read way more posts on here complaining about the varivalves than Gortons, but everyone has their preferences.

Captain Who

Why would venting air on the main be any different from venting air on the radiator? Not arguing just wondering. Do you recall generally what the complaints were with the varivalves?

I will tell you that in my experience they haven't been all that bad but when I test the ones that are starting to make noise that I have thrown into my cardboard box labeled "questionable" I find that they close at a wide range of temps: from around 130 F to 184 F. The 184 F is one that I just removed from a radiator because it was hissing a bit much I thought. I tested the new one and it closed nicely at 160 F. I have been told by the company that they "start to close" at around 155 F. From now on, I test all the ones I remove and test the new ones too and assign a serial # to each one to track their history. These vents can get expensive!!

KC_Jones

One obvious one would be the heat exposure. Don't know if it really matters, but a main vent is always going to get hit with steam and a lot of it. Most of my radiators don't heat all the way across during a cycle so are they actually seeing steam or just hot air? Honestly I don't know, but if the radiator is stone cold on that end I doubt it is seeing steam. Does that factor into vent design? I don't know. Does it affect longevity? I really can't answer that either. I generally work from what the manufacturer states main vent vs. rad vent. I figure they designed it they know more than I do about it. I am a designer by trade so that could be a factor in my opinion. I got into a similar discussion on another forum about PVC pipe for air lines. Sure the PVC is rated for the operating pressure of that system, but the manufacturer explicitly states do not use on air. Just because something CAN be used doesn't necessarily mean it SHOULD be used. I agree with you...not arguing just wondering. Maybe someone with more experience than us can answer?

Captain Who

Thanks KC. Maybe I will email the mfg and ask them about it. I'll point them to this thread and ask them if they care to comment.

The savings per cfm is pretty huge at around 58%. They are easy to test too. Remove from radiator or main, submerge whole assy in a large pot or kettle of water, raise temp slowly while blowing through a hose. Simple really.

Again, though I may have hit on it when I said they don't have a float. I know my system got flooded once by accident when someone accidentally left the manual filler ball valve open a crack. Water was coming out of the radiators which had varivalves on them but I don't really remember much coming out of the Gortons in the basement.

I believe radiator vents may get cycled more often actually since they are not insulated. Not sure about that. Varivalves have a phosphor bronze bellows, Gortons have a bimetal curved element.

nicholas bonham-carter

Definitely more main venting is needed, for the system to get steam to all the rads at the same time.
you will be able to reduce your run-times by reducing your pressure, and increasing your venting.
is there a payback period for comfort?
Would you put plywood circles on the wheels of your car because they were cheaper than rubber tires?--NBC

Captain Who

Thanks NBC. Are you saying that we wouldn't be as comfortable with the equivalent cfm venting capacity of Varivalves as main vents as we would with Gortons?

Or are you saying that they are not functionally equivalent in some way?

This has been driving me somewhat crazy the last few years lol. I'm totally on the same page on the reduced pressure and run times.

jalubarsky

Thank you everyone for your comments. I did measure my mains. As KC Jones suggested my pipes measure 2 3/8 OD so I do have 2 inch not 2 1/2 - guess that is the good news meaning I can add less venting.
I did take apart the pig tail and pressuretrol to clean it and there was some corrosion. After taking the Pressuretrol off to clean it where the pipe meets the Pressuretrol I am concerned whether I maintained the correct calibration.
Are there any suggestions on how to make sure it is calibrated correctly?

Captain Who

PS: The manufacturer seems to imply that they can be used for main venting, since they had an independent lab test them vs Hoffman 4A and 75, and Gorton #2, and found that at 1" WC (very low pressure, around 1/2oz), they vented just as much as a Gorton #2 (around 0.8cfm). That's in contrast to what Gill and Pajek measured but they only went as low as 1oz:

Gorton 2 1.100 cfm
Heat Timer 0.660cfm
Gorton 1 0.330 cfm

http://cdn.heat-timer.com/wp-content/uploads/2013/01/VariValve_Lit.pdf

Captain Who

jalubarsky said:

Are there any suggestions on how to make sure it is calibrated correctly?

That's where the 0-3psi gauge comes in. I recently bought this one for myself and it is working fine so far:

http://www.amazon.com/gp/product/B00H9ZWLZG/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

nicholas bonham-carter

Who paid the independent testing lab?--NBC

Captain Who

nicholas bonham-carter said:

Who paid the independent testing lab?--NBC

The pdf I gave link to just says:

Laboratory Results
• All studies and tests were conducted by an independent
testing lab. Heat-Timer Corp. DID NOT technically or
financially subsidize these studies.

Fred

Jalubarsky, if you have a 0 - 3PSI pressure gauge on your boiler, you can turn your thermostat up about 4 or 5 degress so that the boiler has a fairly long run time and watch the pressure gauge to see when the boiler burner shuts down on pressure. It should shut down within a few ounces of the Pressuretrol setting and start back up within a few ounces of the Pressuretrol Cut-in Setting. Pressuretrols aren't accurate down to the ounce. If it is off significantly, following is the procedure to recalibrate the Pressuretrol:
- Inside the Pressuretrol, right below the micro switch, there is a pivot arm. At the end of that arm you will see a screw pin that is activated by the diaphragm at the bottom of the Pressuretrol. If you look very carefully at that screw pin, you will see it actually has a tiny (I mean tiny) hex head on it. It takes a .050 hex wrench and you can turn it clockwise (Towards the bottom of the Pressuretrol to decrease the Cut-out pressure or counter clockwise to increase the cut-out pressure (which none of us want to do but who knows, your Pressuretrol may be really screwed up!). Turn the power to the unit off first. You may find the first attempt to turn that screw a little bit stubborn (relatively speaking) because it has some Locktite on it but it does turn. Don't turn too much, a fraction of a turn goes a long way towards getting it adjusted where you want it (maybe 1/32 inch turn to start with). You may need to play with it to get it exactly where you want cut out to be.

Jamie Hall

The mercury pressuretrols, such as this one, don't have a calibration screw -- and don't need one. However, they are sensitive to being installed exactly level, so you will want to check that.

Fred

You are right Jamie! I should have looked at the Picture before I posted. He does need to turn that Pigtail 90 degrees so that it doesn't tilt side to side during expansion and contraction.

BobC

As long as it's level when hot he may be ok as is, best to check it to be sure.

Bob

Fred

If the expansion and contraction were that predictable and consistent, the "Best Practice" for using a pigtail on a mercury switch of any kind wouldn't be to mount the pigtail at a 90 degree to the face of the switch so that it can expand/contract from front to back rather than side to side. And beside that, it only takes a few seconds to turn that pigtail and have it done right and not questionable.

jalubarsky

After reading the many insightful comments more questions arise. If you noticed in my original pictures my 0 - 30 psi gauge reads 7. This is when the boiler was off for a while. Can I assume this reading should be zero which means my gauge is not calibrated accurately? If yes my gauge is now topping out at about 10.5psi which would mean 3 1/2 peak. I did lower my cut out setting to under 2 which did reduce my peak from about 12 to 10.5.
Considering these gauges are cheap is my best move to replace it or just add the 0 - 3 psi gauge and forget about the 0- 30 or do both?

KC_Jones

Put the low pressure gauge on and leave the 0-30 alone. The high pressure gauge isn't much use and as you say it is messed up. In many places the 30 psi is required by code so it's best to just leave it. I wouldn't trust anything it is telling you right now.

jalubarsky

Makes sense and sounds like a good plan. Sorry but maybe another dumb question. Does it matter if I just add a T fitting a nipple and then the 0 - 3psi gauge so it is mounted horizontally or should I also put a 90 elbow in so the meter is vertical?

KC_Jones

I would mount it vertically it isn't much more effort or money to do so. As long as the gauge is above the pigtail you are fine.

Captain Who

@‌ jalubarsky -

Not that that gauge is important right now, but later on if you want to fix it, we discussed that in an old thread here:

http://forum.heatinghelp.com/discussion/comment/1047697/#Comment_1047697

Basically, there is a very small pinhole that gets blocked with crud (happens constantly!) and then what happens is that the blocked off chamber of air next to the pressure sensing diaphragm heats up from the boiler and gives a false reading which will not go back to 0 until maybe the whole assy cools off. It is reacting to the temperature now and not the pressure. You have to clean it out. It really should be mounted above the waterline in my opinion.