Installed Vent-Rite's and now the boiler short cycles?

JimmyNJ

I replaced a bunch of maid-o-mist #4 vents with on some rads with the Vent-Rite #1 vent. With the maid-o-mist vents on I never had any problem where the boiler would cut out before the thermostat was satisfied....in fact, the 0-5 PSI gauge barely even moved much during the heating cycle. This morning when I turned the heat up by 2 degrees I realized that the boiler would stop before the thermostat was satisfied and then start up a minute or so right after it stopped. So I went downstairs and saw that the 0-5 PSI gauge was actually moving a lot more than ever before - I took a picture of my pressuretrol and cut in/cut out settings (the cut/in setting is as close to 0.5 as I can get so that the boiler actually fires up when the thermostat calls for heat - I have tried to bottom it out but then the boiler never does anything. The cut/out wheel is at 1 (I think!!) It's hard to see exactly where the differential "marker" is for that wheel. The vent-rite vents are on settings ranging from between 3-4 and one of the rads has it closer to 6 (a bigger one that is in a colder room). Does anyone have an explanation for why all of the sudden the boiler heating pressure seem to be higher and why the boiler is short cycling? Should I tinker with any of the settings on the pressuretrol or should I tinker with the settings on the vent-rites? (maybe set them to a higher venting setting?). Any insight would be much appreciated!! And sorry if the answer is obvious when looking at the pressuretrol settings....I'm just confused why this started to happen just because I changed air vents.

KC_Jones

How much main venting do you have?

JimmyNJ

Hi KC,

I have one Gordon #1 the section of main that is 11 feet long and one Gordon #2 on the section of main that runs 33 feet. It's a 2" main pipe I think. I know I could probably add some more main venting on that longer run.....but I'm just stumped "why" I'm running into this problem now when I never had an issue before with the maid-o-mist valves.

JimmyNJ

I also forgot to mention that the picture of the 0-5 gauge shows the approximate point where the boiler stops firing...looks to me about .75 PSI

KC_Jones

Pressure in the system is a function of boiler size compared to connected EDR and venting. It's not really steam pressure, but air pressure in the system pushing back against the steam production. If all you changed was the rad vents then most likely you are venting them slower now than you were before. I just checked the venting charts and with the setting you listed (3-4) you are venting at about the same rate as the smallest maid-o-mist vent (#4). So if you had bigger maid-o-mist than that before that is most likely what is going on and why you are starting to build some pressure now. Also I would suggest your mains are a bit under vented. A rule of thumb used around here is 1 Gorton #2 for every 20' of 2" main. If you had bigger maid-o-mist vents before the rads were probably contributing to the venting of the main.

Mark N

System pressure is a function of the output of the boiler, the size of the pipes, and the amount of connected load. What is the size of the boiler and what is the EDR of the radiators.

JimmyNJ

Thanks KC - I think one of the maid-o-mists I changed may have been a #5 but the rest were #4. So theoretically, if I just open up the vent-rite vents more I should get less air pressure pushing back and shutting down the boiler prematurely. I will definitely look to add more venting to the main lines (maybe add a Gordon #1 to the Gordon #2 on that longer run? not sure if I should add another Gordon #1 to the #1 already on that 11 foot section or if it would be overkill). But back to my settings on the pressuretrol - should I just leave them or should I adjust the white wheel to be closer to 2 so the boiler doesn't shut down before the thermostat is satisfied? Thanks for all your insight and taking the time to read & answer my post

JimmyNJ

Hi Mark - The total EDR of my rads is 367 and my boiler is rated at 375 sq ft.

KC_Jones

You really want the pressure as low as possible. I wouldn't touch it if it was mine.

nicholas bonham-carter

Why did you swap out the radiator vents?
Try a Gorton #2 on each main, and move the Gorton #1 to the longer main as well. As KC pointed out, your radiator vents were doing most of the system main venting. If you see more than a couple of ounces of back pressure on your gauge as steam is starting to build, then you need more main (not rad) venting.--NBC

JimmyNJ

NBC - the reason why I swapped out the vents is that I wanted a quality vent that was adjustable as I wanted the ability to slow/speed the heating on some of the rads (the kids rooms get hot today) and a smaller room with lots of windows is cold (I need to address infiltration there but for now I'm trying to get that radiator warm a bit faster/longer than the others).

Just to make sure I understand your advise - are you saying I should get another Gordon #2 for the 33 section of main + add the Gordon #1 I have on my 11 ft section (for a total of 2 Gordon #2s and 1 Gordon #1 just for the 33 ft section) and then put a Gordon #2 on the 11 ft section of main? Or just get a Gordon #2, put that where the #1 is today, and put the #1 alongside the #2 on the longer section?

For now - I suppose the course of action to take is to increase the venting capacity on the Vent-Rite's to decrease the back-pressure.

Mark N

The EDR of your rads is well matched to the boiler. You therefore should see no real pressure till the rad vents start to close. Did this happen went you were just maintaining temp or during a recovery from a set back?

JimmyNJ

I observed it happening when during recovery from a set back - but the set-back was not terrible, from 67 to 70. I have increased the venting capacity on the new vent-rite's to about 5-6 on dial so we will see what happens during the next heating cycle (when it just maintaining the set temp).

Abracadabra

I know it's a b it late now, but just FYI, you could have left the MOM vents and just replaced the orfices if you wanted to tinker a bit with venting rates.

Mark N

With a 3 degree recovery the boiler is probably running long enough for the rad vents to start to close, and when that happens the pressure will rise to the cut out setting.

Mark N

Monitor the pressure during a whole heating cycle. Observe when in the cycle it starts to rise. Also, watch a recovery from set back cycle, note when the pressure begins to rise.

JimmyNJ

Looks like the pressure starts to rise in the middle/end of the cycle. The last cycle when it was just maintaining the temp the needle on the gauge didn't move much - the highest it got was about 0.25 PSI and the boiler did not stop firing until the thermostat was satisfied. Will observe what happens tomorrow morning when it starts firing up from the night setback (2 degree difference from day setting). Thanks to everyone for all the input.

ChrisJ

Even all the way up those Vent Rites are only the speed of a Gorton #5.

If I was you, I would've started with them all wide open and then backed down the ones that heated too fast.

With the size your boiler is honestly I'd probably try Gorton 6s and Cs on most of those radiators. Many guys are against it, but personally I've had good success with venting fast, even with an undersized boiler. However, it took forever to get things to work right.

I also would advise caution if changing the vents on your mains. I have an 11' main and a 29' main and it's very difficult to keep them matched. I even had a slow Hoffman 4A on my short main for a while. A Gorton #2 is way too much for such a short pipe in my opinion.

I currently have a single Gorton #1 on my 11' and five Gorton #1's on the 29' main because #2's don't fit vertically.

nicholas bonham-carter

What you are trying to do with the venting of the mains is to balance the resistance of the escaping air from each, no matter what it's length, so that one main is not filled before the other.
Getting this backpressure of venting to the lowest pressure possible (2ounces) achieves this, without a lengthy period of experimentation.--NBC

ChrisJ

I run around 0.50 -1.00" w.c. during main venting and if I vent the short main even close to the other's speed it throws everything out of balance.

Mark N

The Ventrite's are very high quality adjustable vents. The adjustments according to Gerry Gill's tests are quite proportional. Take the time to tweak their setting and you should arrive at excellent balance. Lets us know how things go today with you setback recovery. Very cold and windy today here in NJ.

Mark N

My system has 2 main of exactly the same length. That makes it very easy to balance them. They're each vented with 3 Gorton #1's, steam arrives at the end of each concurrently. Also, both mains have nearly the same amount of EDR attached to them. If I was to reattach the small rad that was in the cabinet under the kitchen sink they would be probably equal.

JimmyNJ

Hello all - Thanks for providing your collective wisdom, lots of good thoughts! As Mark noted, freezing cold here in NJ today with a howling wind. This morning I set the thermostat at 70 (from 67) and the boiler fired continually until the thermostat was satisfied and I didn't notice the PSI gauge moving much more than it did yesterday while maintaining temperature. So it looks like just opening up the vent-rite valves a bit more solved my short-cycling problem (when starting from set-back).

When I was down in the basement a while ago (must have been a few minutes after the thermostat shut down the boiler) I noticed a hissing noise and it was coming from my Gordon #1 on that short 11 ft main section. Any idea why it would be making a hissing noise after the heating cycle? Is it "air' being sucked back into the mains? I went over to my Gordon #2 on the long section of main and did not hear that noise.

I think though after hearing everyone's thoughts, that I will order myself another Gordon #1 to add to the #2 on that 33 section of Main. Chris, I'm glad to hear that you think a Gordon #1 on my 11 foot section is sufficient as I was debating getting 1-2 more for that part and adding another Gordon #2 for the long main -- but I think if I just get another #1 for the long section that I should have sufficient venting for both sections of mains.

Mark N

With current venting does the steam arrive at the end of the mains at the same time? A few minutes after the boiler shut down the main vents are most likely still closed. I would take the #1 out and rinse it out, might be some crud in the valve seat.

JimmyNJ

Mark - I hate to say this, but I actually haven't checked to see if steam arrives at the end of the mains at approximately the same time.....The rads at the end of the long main do appear to start getting warm at the same time as the rads on the shorter main. Is there a more scientific why I should be using to make sure that the main venting is balanced?

ChrisJ

The hissing noise you heard was likely a vacuum pulling air into the vent.

Mine does this if it runs long enough.

As long as all of your rooms heat properly, that is what is important. Not even the radiators getting warm at the same time, but all rooms staying where you want them.

I have two rooms that cheat and heat before others because they are always chilly. I need to insulate them badly but for now I get steam to them a little sooner than others.

Mark N

A Gorton #2 has 3 times the venting rate of a #1, Your long main is 3 times longer than your short main so one would think it would be close. Check it out next time the boiler runs.

Mark N

Jimmy have you ever visited the Heating Museum on Heating Help? As Dan says it pays to wander off the wall. There are 3 articles in the Old Steam section you should read. It's All in the Venting, The Big Fault in One-Pipe Heating, and Controlled Air Venting of One-Pipe Systems. Check them out.

JimmyNJ

Thanks for the tip Mark. Will check those out.

JimmyNJ

Mark N said:

A Gorton #2 has 3 times the venting rate of a #1, Your long main is 3 times longer than your short main so one would think it would be close. Check it out next time the boiler runs.

Mark - excellent observation! It didn't even cross my mind that my longer section of main is 3X the length of the short one. So the current set-up of having a Gordon #2 on the long (3x the venting capacity of a #1) with the #1 on the short end should in theory be pretty balanced and in practice the rads do appear to start getting warm at the same time.

So keeping that in mind (and Chris's comment about being careful with messing around with the main vents as it may throw whatever balance I have off) -- does anyone have any reason why I should not get another Gordon #2 for the long run and another Gordon #1 for the short one? It would keep the current venting proportions the same (long run is 3X longer than short and would have 3X venting rate of the short one). Appreciate any feedback as I'm contemplating pulling the trigger on an order.

ChrisJ

JimmyNJ said:

Mark N said:

A Gorton #2 has 3 times the venting rate of a #1, Your long main is 3 times longer than your short main so one would think it would be close. Check it out next time the boiler runs.

Mark - excellent observation! It didn't even cross my mind that my longer section of main is 3X the length of the short one. So the current set-up of having a Gordon #2 on the long (3x the venting capacity of a #1) with the #1 on the short end should in theory be pretty balanced and in practice the rads do appear to start getting warm at the same time.

So keeping that in mind (and Chris's comment about being careful with messing around with the main vents as it may throw whatever balance I have off) -- does anyone have any reason why I should not get another Gordon #2 for the long run and another Gordon #1 for the short one? It would keep the current venting proportions the same (long run is 3X longer than short and would have 3X venting rate of the short one). Appreciate any feedback as I'm contemplating pulling the trigger on an order.

What kind of pressure are you seeing while the mains are venting?

On mine I typically see anywhere from 0.50" w.c. to 1.00" w.c. depending. 1.00" is 1/2 an ounce if I'm remembering correctly.

If your pressure is really low, then I would save the money. If you're seeing a 1/4 pound or more, then by all means add venting.

Fred

If your long main is 33' long, adding another Gorton 2 to that and an additional Gorton 1 to your short Main should keep things balanced. I would definitely pull the trigger. It may not significantly reduce your operating pressure but it will fill the mains and get steam on its way to the radiators faster, which is where you want it.

JimmyNJ

It gets up to around 1/4 PSI's (attached pic shows the highest I've seen the needle go after I opened up the Vent-Rite's more). I couldn't readily find a 0-3 PSI gauge when I was looking which is why I got the 0-5 - now I wish I had more granular readings, but maybe I'll wish for a 0-3 PSI gauge for my birthday this summer (My wife thinks I'm nuts obsessing about our steam heating system!!).

ChrisJ

JimmyNJ said:

It gets up to around 1/4 PSI's (attached pic shows the highest I've seen the needle go after I opened up the Vent-Rite's more). I couldn't readily find a 0-3 PSI gauge when I was looking which is why I got the 0-5 - now I wish I had more granular readings, but maybe I'll wish for a 0-3 PSI gauge for my birthday this summer (My wife thinks I'm nuts obsessing about our steam heating system!!).

If that's about as high as it ever gets now I'd go for a 10 or 16 ounce gauge. I'm running a -8" to +16" w.c. gauge as well as a 0 to 2" w.c. gauge on mine.

My wife knows I'm nuts.

JimmyNJ

Fred said:

If your long main is 33' long, adding another Gorton 2 to that and an additional Gorton 1 to your short Main should keep things balanced. I would definitely pull the trigger. It may not significantly reduce your operating pressure but it will fill the mains and get steam on its way to the radiators faster, which is where you want it.

Thanks Fred - I am going to order the vents. As commented I may not see any significant operating cost savings, but the steam will get to the rads quicker and I should be able to adjust the Vent-Rite's to vent slower on some of the rads if I wish hopefully without running into the short cycling issue again.

Mark N

Have you ever timed how long it takes to get steam from the header to the end of the mains?

JimmyNJ

Mark N said:

Have you ever timed how long it takes to get steam from the header to the end of the mains?

No I've never timed it. Is there a rule of thumb to follow there?

JimmyNJ

ChrisJ said:

JimmyNJ said:

It gets up to around 1/4 PSI's (attached pic shows the highest I've seen the needle go after I opened up the Vent-Rite's more). I couldn't readily find a 0-3 PSI gauge when I was looking which is why I got the 0-5 - now I wish I had more granular readings, but maybe I'll wish for a 0-3 PSI gauge for my birthday this summer (My wife thinks I'm nuts obsessing about our steam heating system!!).

If that's about as high as it ever gets now I'd go for a 10 or 16 ounce gauge. I'm running a -8" to +16" w.c. gauge as well as a 0 to 2" w.c. gauge on mine.

My wife knows I'm nuts.

I am unfamiliar with ounce gauges - to really show my ignorance I thought those were used on vaporstat systems (not pressuretrols) but again, that just shows I know nothing about vaporstats either! And quite frankly, not a lot about pressuretrol's other than that having a cut in at 0.5 PSI and cut-out at 1 on the white dial is a "good thing"

Mark N

Depending on the length of the mains you're looking for 2 to 3 minutes.

JimmyNJ

Did end up installing additional main venting. Pressure gauge doesn't even seem to move now!

Steamhead

Is it still balanced, i.e. does the steam get to the ends of both mains at about the same time?