Pressuretrol setting with over capacity boiler

Hap_Hazzard

I think it's really a "don't mess with me" sign. I didn't bother repainting mine, and the screw hasn't moved. If you want to repaint yours, a little nail polish or Testors model enamel should do the trick, but don't feel like you have to.

SteamingatMohawk

Agreed. Since the system seems to be essentially OK, I can wait for some warmer days to "experiment". The engineer in me is driving my curiosity to see if I can make it right without causing adverse consequences. For example, it would be really horrible if the screw fell out and I couldn't get to it or find it. Been there before.

dabrakeman

Apologize if I haven't seen all of your earlier threads but it seems if you are cycling on pressure at 2psi before all the radiators are full, then there is inadequate venting whether your calculation is right or not. I have an oversize boiler ratio perhaps a bit worse than yours and certainly it will cycle on pressure if it is extremely cold or recovering from a setback but only after all radiators are full or very nearly so. I would still add more main venting and if you are still cycling on pressure on normal 20F-30F degree days without the radiators full then start increasing some of your radiator vent rates as well. The vents you have back at the boiler at the end of the returns are doing you no favors vs having them at just the ends of the mains. Your mains and returns are pretty short so probably not a big difference in your case but by keeping those vents you are making the system push steam where it doesn't need to go before you start sending steam to the radiators. Best to just move them onto tees at the end of the mains.

If the 1 CPH on the thermostat could be changed to 2CPH it would help shorten your cycles but again I would make sure you are really filling your radiators before it short cycles off on pressure first. Not sure what flexibility your thermostat allows.

SteamingatMohawk

Good comments, thanks. Look back at a January 29 post, there is a sketch of the system. Before I started this journey, there were Gorton#1s on the ends of the two returns near the boiler. The two returns joined only a couple of inches after the main vents. I decided that the rear main was competing with the front main for venting, and ended up doing two things.

First, last heating season, I added a Gorton #2 where the supply portion of the main changes to the return. I tried several other combinations and none made any improvement over the #2. This is essentially what you have suggested, but was only done on the front main.

I had a false start in separating the two returns to prevent the competition. I couldn't get the piping apart in the time I had, so I had to patch the connection and wait till summer. In the summer, I took the rear return and rerouted it parallel to the front return to the bottom of the loop just before the direction change to the Hartford loop. I think that part of the system is the dry return. I also added a drain valve, because there was none. That prevents the rear main from affecting the front main. I haven't noticed any real change as a result, but a trusted plumber agreed that I should separate the two returns better. I didn't need any other supporting opinions, so I did it, besides, I wanted the drain anyhow.

The house now has 9 installed radiators compared to piping for 4 more, so the boiler has more capacity than needed. I am sure that adds to the short cycling.

I moved the ancient Honeywell round thermostat from a downstairs living room up one floor to the living room, which is the coldest room in the house (e.g., furthest from boiler, faces North, has 3 large windows, has unheated attic above and two exterior walls). I installed the Honeywell wireless thermostat, so I had flexibility in location without running wiring all over the place and added the wifi adapter to a router in the house, so I can monitor and operate the system using an app on my iPhone. It cost $300, but is worth it to me. The thermostat has a CPH setting specifically for steam and that is where it is set.

The LWCO activates every 10 minutes, which does the same thing for boiler cooldown as the Pressuretrol. I do understand the differences in the purposes of the two devices.

This escapade into the Pressuretrol is another "gotcha" existing for who knows how long. In many of the discussions on this site and other places, it is abundantly clear that higher pressure is not a benefit, plus I'm kinda annoyed the lowest setting on the Pressuretrol is 0.5 psig above the pointer on the scale. Hence the inquiries. If you look at some of my other discussions, you can see more about how I rerouted the rear return. I had to use a TurboTorch to unsweat the fittings, my MAPP gas didn't cut the mustard.

SteamingatMohawk

@dabrakeman If you go to "Steam Mains Spitting" and look at the two pictures on January 25, not the one showing the rusty pipes, you can see how I separated the returns.

dabrakeman

Just my opinion but I think the competition between the mains could have been more easily remedied by just capping those risers on the returns thus letting the returns be nothing but condensate returns and then putting your main venting only at the ends of the mains. Filling the returns with steam in order to close mains just leads to longer cycle times and more water leaving your boiler. Helped in my case.

So is the LWCO activations the reason for your short cycling or pressure or both? My understanding was you were cutting out on pressure. This before radiators are filled?

SteamingatMohawk

I don't think that the LWCO test is strictly short cycling if the boiler is running for the 10 minutes between tests, but it does cause the pressure to go down.

I have seen the Pressuretrol trip at 2.0 psig while the thermostat is still calling for heat. I am sure part of this is the overcapacity of the boiler compared to the time for the radiators to heat up and release the heat to the room.

So, on one hand the answer is both, but on another hand it's the Pressuretrol. So far, I have not removed any supplies to the unused radiator locations. I have made no attempt to figure out what and how much of an effect there is by having dead ended supplies in the system.

Hap_Hazzard

They shouldn't have any effect unless they leak. If you feel any steam getting into the branch, then you've got a leak. Otherwise the air would keep the steam from entering.

SteamingatMohawk

Except for what little gets compressed at the operating pressure, which is probably negligible. Two radiators are in very small bathrooms and I took them out to provide more floor space to move around in the room. Two others are for the dining rooms, which were split across the middle to make 4 kitchens, 2 on each floor, when the house was converted from a 2 family to 4 units.
I have thought occasionally whether or not it would be worthwhile to put some of them back in. I think all four are laying around in the house somewhere between the basement and attic. Personally, other than the boiler being overcapacity, I don't have any complaints about the apartments not being warm enough in the winter.

dabrakeman

Are your radiators full when you are reaching 2psi? If they are then yes the oversized boiler can be given the bulk of the blame. If they are not then it seems there still has to be a venting issue. Perhaps you have not been able to verify not being in the apartment yourself?

SteamingatMohawk

I don't expect radiators to be 100% full of steam, because of how the steam travels through the radiators and where the vents are installed on the radiators. If you have Dan's book, look at the section in Chapter 8 where there's a sketch of how the vent works and discussion of interaction with the Pressuretrol.

Radiators don't fill completely at the outset, it takes cycle(s) of what he calls drop-away ( cut-out pressure down to cut-in pressure) for the radiator to expel the air. Plus there is discussion about having too high a pressure blowing the vent shut, preventing anything from venting.

So, since I haven't thermally surveyed my radiators since I finished "balancing" the system, I can't tell you if they are ever full. Also, I would imagine how full the radiators get depends somewhat on how often the thermostat calls for heat (e.g., warm days vs. cold days, setbacks (which I don't use)).

I realize this may be confusing to some of us, but is the best I can explain given what Dan says about how one pipe systems work.

In any event, with the Pressuretrol cut-in high and not doing something not quite common (like the above discussion about the grub screw), reducing the differential from 1.0 to maybe 0.5 might help the venting even if it does cause the boiler to cut-out more frequently and not stay off as long. Although the lower cut-out pressure of 1.5 vs. 2.0 should reduce or maybe eliminate the "blowing the vent closed" possibility, which would improve venting.

dabrakeman

I am only saying that if you are building as much as 2psi before your radiator vents actually see steam forcing them to close (and start cycling) then you likely have an overall venting issue. If you are not seeing the rise in pressure until many of your radiators have filled to the point that their vents see steam (be it 90% full or whatever) then all is fine with your oversized boiler system. IF the latter is true focus on increasing your CPH time or reducing your swing temperature time (Depending upon what type thermostat you have). Also, rather than just putting your thermostat in the coldest room maybe look for a more "dynamic" location. A location that heats up more rapidly. You may need to adjust your temperature setting up a little bit to still take care of that cold room. My condition is this latter scenario with my oversize boiler system and it doing the things I just outlined helped immensely. Now I never cycle on pressure and the boiler only trips off once on pressure just when outside temperatures are near 0F or below. This trip point I have dropped by 20 degrees by just adjusting swing temperature and relocating my thermostat.

SteamingatMohawk

Please tell me more about your system, so I have a good comparison.

Pressure buildup in my system doesn't appear to happen if the heat has been running regularly, like on a cold day. But since I don't live there, I don't get to see all the cycles. On top of that, the LWCO activating every 10 minutes tends to keep the pressure down.

My tenants are not complaining, so i think I can assume the radiators are getting heat on the first cycle (assuming the LWCO doesn't activate in the first few minutes) and ultimately heating the rooms OK.

Thanks for the info, I'll have to think about it.

dabrakeman

I can get to that but I am still a bit confused about your LWCO. Initially this post was stressing the issue that you were short cycling on pressure. I am not an expert but rather just a homeowner who has lived with an oversized boiler situation for the last 17 years. Therefore, I am not following why your LWCO would be shutting the boiler down every 10 minutes (and possibly in the "first few minutes" as you said) unless you are returning condensate too slow from a blockage of some sort in your returns or have a leak. Is there an automatic water feed on the system?

Both issues would be aided by allowing your system to cycle more often than 1 CPH. Does your thermostat allow adjustment of swing temperature or just CPH. If just CPH try 2 CPH and just see how it goes for a while.

ethicalpaul

His LWCO is shutting down his boiler every 10 minutes possibly because he has a Cycleguard LWCO (lovingly referred to as "Psychoguard" around here) and that's what it does.

It does that so that the foaming from the boiling water doesn't trick the LWCO into thinking there's more water than there is.

dabrakeman

@Ethicalpaul. Thank you. Not sure I would want that.
https://hydrolevel.com/cyclegard-cg400-series-steam/

ethicalpaul

A lot of people would agree with you but I think it might be fine. And in the case of an oversized boiler, it might be beneficial.

SteamingatMohawk

Mine is the CG400-1090 which cycles every 10 minutes for 90 seconds. By doing that the system pressure falls until the LWCO resets after 90 seconds allowing the boiler to go back to work. I apologize to those who I confused. The interesting thing is the LWCO acts independently of the rest of the operation of the boiler, which means depending on when the boiler starts relative to the LWCO automatic cycle, the LWCO could be anywhere from 10 minutes to the next test to immediately for the next test.

I also should have differently stated, " On top of that, the LWCO activating every 10 minutes tends to keep the pressure down." The key word in that sentence is "tends". As ethicalpaul stated above, the main purpose of the LWCO test is not pressure control.

By the way, when I tried the link it didn't work. I got something completely unrelated. Just copy from hydrolevel.... then paste it on a new tab and go to the specs.

Personally, with my situation of the oversized boiler, I think it helps prevent higher pressure and may help with venting by keeping the pressure lower. Also, I don't think the 90 second duration will allow the steam to condense enough to draw a vacuum in the system, but I wouldn't bet on it.

By the way, regarding my Pressuretrol cut-in dilemma of the actual being 1.0 vs the setting on the scale of 0.5, I tweaked it and messed things up. Like an idiot, I didn't count the adjustment turns I made to change the setting so I could go back to where I was before I started. I had to do some guesswork and maybe I have it back close enough.

Can anyone explain what I would see as the Pressuretrol goes through the cut-out to cut-in position? It looks like the differential mechanism is fixed in place and the "U" shaped metal touching the little protrusion (like a button to move something inside the differential mechanism) is what rotates to go between cut-out and cut-in. . I don't have a drawing or photo to show those details. That being said, I could be totally out to lunch on how the mechanism actually operates

SteamingatMohawk

Something just occurred to me. This heating season, I see the level in the gaugeglass go pretty high. I hadn't thought much about why, but foaming has been mentioned in the discussion and I wonder if that could be what is happening. Over the summer (it's in my other discussions), I separated how my two returns connect back to the boiler. They had been meeting near the ceiling in the basement with the main vents only inches apart. I split them up and ran two lines to the bottom of the wet return ( I think that's what it is called). After I soldered the joints, I didn't do any flushing, etc.

What say you?

Hap_Hazzard

SteamingatMohawk said:

Mine is the CG400-1090 which cycles every 10 minutes for 90 seconds. By doing that the system pressure falls until the LWCO resets after 90 seconds allowing the boiler to go back to work. I apologize to those who I confused. The interesting thing is the LWCO acts independently of the rest of the operation of the boiler, which means depending on when the boiler starts relative to the LWCO automatic cycle, the LWCO could be anywhere from 10 minutes to the next test to immediately for the next test.

There's a setting you can set (with a jumper) so the CycleGard cycle starts when the system starts up, i.e. when the thermostat calls for heat. Do you still have your installation manual?

SteamingatMohawk

Yes, and I think I have it downloaded too. I'll take a look at it. Today my dilemma is with the Pressuretrol, no matter what I do short of taking the thing apart and/or messing around with the tiny little screw, I get more than 1 psig for the cut-in. There must be something binding up the diaphragm or whatever it is that converts the pressure to mechanical motion. It's probably a good idea to check the pigtail while I am at it.

By the way, I don't have a problem with the LWCO Intermittent Level Trip, since it does tend to lessen the highest pressure, at least until I get the problem sorted out.

Does anyone have a simple way to exercise the Pressuretrol on the bench? I think the secret is the low pressure source needed. I saw a couple of videos, but don't know where to get the squeeze bulb with a pressure release. Maybe a blood pressure cuff...

SteamingatMohawk

One thing I was thinking is to file down the bottom of the slot where the indicator fits to see how much lower it can go without affecting the actual mechanism. If you try to lower the indicator past the end of the slot, the head of the screw just rises, because there is no place for the indicator to go...until the screw is disconnected and comes loose...which isn't a good idea if the system is energized.

Hap_Hazzard

SteamingatMohawk said:

One thing I was thinking is to file down the bottom of the slot where the indicator fits to see how much lower it can go without affecting the actual mechanism.

Don't do that. The indicator will probably fall off the end of the screw. Just adjust the rocker grub screw. It's easy.

SteamingatMohawk said:

Does anyone have a simple way to exercise the Pressuretrol on the bench? I think the secret is the low pressure source needed. I saw a couple of videos, but don't know where to get the squeeze bulb with a pressure release. Maybe a blood pressure cuff...

If you can make a ¼" NPT to Schrader valve adapter you could pump it up with a bicycle pump. Just be careful not to blow out the diaphragm.

Precaud

SteamingatMohawk said:

Does anyone have a simple way to exercise the Pressuretrol on the bench? I think the secret is the low pressure source needed. I saw a couple of videos, but don't know where to get the squeeze bulb with a pressure release. Maybe a blood pressure cuff...

This pressure bulb with release valve works fine for me, it will set you back all of 5 bucks:
https://www.ebay.com/itm/BLOOD-PRESSURE-BULB-with-Valve-NEW-latex-Bulb-4-59-New-York-Seller/233194352121

I had the tubing and adapters laying around, and got the cross and other piping from Supplyhouse.com

SteamingatMohawk

I already unscrewed the screw, but was too embarrassed to admit it. You seem to have some knowledge, which direction do I turn the screw to lower the cut-in setpoint? Looking at the mechanism lever arms doesn't give me a good clue as to which way to go. Like in The Hunt for Red October, it's a 50-50 guess.

neilc

"loosening" the adjuster screw turns the setting lower, psi and scalewise,
so that's counterclockwise as you look down at the head of the screw,
you could always tighten up 3 or 4 full turns to make sure you're attached, the scale should rise,
then loosen it back down the same count of 3 or 4 turns, or till you feel slight resistance,
don't force past resistance or you could detach at the lever,
post a picture of the Ptrol

Chris_L

You should be able find all the information you need (and more) in this thread: https://forum.heatinghelp.com/discussion/comment/1442631#Comment_1442631

Note that only a very slight adjustment of the screw is needed, probably not more than half a turn from where it was before you started.

Hap_Hazzard

neilc said:

"loosening" the adjuster screw turns the setting lower, psi and scalewise,
so that's counterclockwise as you look down at the head of the screw,

I think you've got it backwards. Turning the screw clockwise raises the rocker, decreasing the distance the diaphragm needs to push it in order to trip the switch, which reduces the amount of pressure required.

SteamingatMohawk

@Hap_Hazzard Look at the movement of the indicator. Turning the right hand threaded screw (no shenagins with left handed threads) clockwise raises the top of the spring, pulling (not pushing) more on the rocker. As the screw is turned the indicator tab moves up to a higher setting.

This is exactly why it's not so easy for me to figure this thing out.

The switch in mine is a microswitch which doesn't need much movement. I made a sketch to try to figure it out, but haven't gotten it settled enough in my mind to attach it with the explanation on how this works.

I appreciate the reference and noted the cautions by the professionals about monkeying around with the internals and legal liability for any problems. My steam system is in a converted 2 family, so I have to be extremely careful.

If these devices have been around for so long, it bothers me that the apparently most commonly desired cut-in of 0.5 is in the "flaky" range of the device.

In all likelihood I am going to replace mine with a new one, but am also considering a vaporstat.

The curiosity factor is I really want to see what it takes to get the installed one working like it should. It's been in place for almost 20 years and when I do remove it I will check the pigtail and inspect for corrosion or any other problem that causes the higher setpoint.

More to follow.

Hap_Hazzard

Oh, you're talking about the other screw. I was talking about the grub screw. I never messed with the adjusting screw, other than adjusting the cut-out point, as intended.

Precaud

The flaky cut-in point is largely a function of the diaphragm, which is basically a circular bellows. The center of the bellows deflects as pressure behind it changes. At some point Honeywell changed to a smaller diaphragm on their Ptrols, so that the bellows moves less for a given pressure change. That's what makes it flakey sensing very low pressures.

The solution is to get an older one with the larger diaphragm. They also happen to have the mercury switches, which will not fail in your lifetime. There are lots of the old ones brand new on eBay for cheap. Examine the pics to see which is being offered. I posted a pic above that shows the difference, it's pretty obvious.

Mine is from the mid-1970's and still works fine... it adjusted for 1.5psi cutout and 0.5psi cutin easily.

neilc

ok,
wait a minute,
which screw are we talking about?
I was referencing the main setting screw that's thru the cover, and sets the scale, and pressure setting.
and I think you're after the calibration screw, deep inside, which would be opposite direction, as you've noted.

OP ?

Hap_Hazzard said:

neilc said:

"loosening" the adjuster screw turns the setting lower, psi and scalewise,
so that's counterclockwise as you look down at the head of the screw,

I think you've got it backwards. Turning the screw clockwise raises the rocker, decreasing the distance the diaphragm needs to push it in order to trip the switch, which reduces the amount of pressure required.

dabrakeman

A few years ago I played with that screw when I was cutting out at 3.5psi (on recoveries) while I had cut-in set at 0.5psi and differential at 1. Fred had instructed me to minutely turn that screw clockwise and evaluate. I got it after a few tries to about a 2.5psi cut-out. Then I got cocky and gave it a little bigger turn and after verifying that the boiler came on went to bed. I woke up in a cold house. It had come on for the first cycle when I turned the powerswitch back on the night before but obviously would not allow the boiler to fire subsequently since it must have pushed the cut-in too low. I eventually got it functional again and to this day have lived with a 2.0-2.5psi cutout. Haven't worried about it too much because I no longer do setback of more than a degree unless away on vacation. Otherwise only is a factor on extreme cold days. However, now with all this talk going on you have me thinking I can still improve it a bit more with a little more effort. Damn you...

neilc

dabrakeman said:

Damn you...

I hope you're not skyballing a 0 - 30 gage,
and have a low range gage you're working with

dabrakeman

Yep. 0-5psi gauge, pigtail clean.

SteamingatMohawk

Well, after a slight diversion to watch my 8 year old granddaughter who had the flu B last week, I am back into this exercise in frustration. Today, I removed the Ptrol and inspected and cleaned the slight coating in the pigtail. It didn't seem like there was enough water in it, so afterward, I flushed it to make sure it was clean and left whatever wanted to stay in the pigtail. I found no problems with the Ptrol, but did not disassemble anything inside or outside (diaphragm side). There was nothing in the diaphragm end. It has been consistentlly cutting out at 3+psi and back in around 2.3ish.

After getting frustrated with trying to identify and locate a vaporstat, including talking to two guys from Honeywell, who didn't know anything, I gave up and went to my local supplier and got a new PA404A additive Ptrol.

I made sure the cut in was 0.5 and the diff was set at 1. Guess what! On two cycles it cut out at 2.7 and 2.8 and cut back in at 0.7 and 0.6. So, while I did get the cut in where it belongs, the diff is double what the dial is set at.

With all this mystery, I decided to swap out my gauges to make sure there was no issue with the 0-5 psig one and installed my 0-30psig and ran a cycle again. With the greatly compressed scale, all I can conclude is that the results are essentially the same.

I swapped the gauges back, set up my wifi camera (that can also see the gauge glass) and came home.

I still have the vaporstat in the back of my mind, but since I spent some $$ on the Ptrol, I'm going to see how things go for a while.

Is it time to declare victory (at least partial) and move on?

SteamingatMohawk

I want to pursue a solution to this problem with Honeywell.

Does anyone know how to make contact with a Honeywell Technical Support person for Pressuretrols? I have struck out so far.

dopey27177

Spent a lot of time reading this post.

1. Big problem, LWCF cycles boiler every 10 minutes. Some localities require manual reset on LWCF for multiple dwellings. since you converted to a 4 family unit you may be in that category where a manual reset LWCF is needed.
2. Fooling around with pressure controls can get you into trouble.
3. As far as a boiler being over sized all steam boilers have about 30% additional sizing to account for the piping pick up factor.
4. If you are really over sized cut back on your fuel supply to the burner.
5. Is your steam piping insulated, lack of insulation caused excessive condensate to form in the steam piping and that condensate may not return to the boiler fast enough.
6. Is the wet return piping, hartford loop and piping into the boiler clear of scale,mud or other crap that can impede the flow of water back into the boiler.

Here is a suggestion, replace Ptrol with a Vaporstat. Set vapor stat at .5 cut in and 1 psi cut out.
the steam pressure in the piping system needs to be cut back some to allow air to enter the system. Air entering the system will break any amount of vacuum that forms as the steam shrinks and becomes condensate.

If there is a small amount of vacuum in the system it can prevent the condensate fro returning to the boiler fast enough to sstop the short cycling caused by the LWCF's operation.

See Attachment

This Vaporstat is available at Sid Harvey. They also have a technical department that may be able to help you.

Sid Harvey been in business at least 75 years,if they don't know it nobody does.


Jake

SteamingatMohawk

@dopey27177 See my separate message to you.

For the other contributors, I agree with his comments.

retiredguy

Why not replace that pressure control with a honeywell L408J-
-1009 and not try to invent a new wheel