Johnson Control Pressuretrol Setting - one pipe system

Meredith

We bought a historic home outside Detroit with a one pipe steam system and I’m slowly learning all I can. It’s got a Weil McLain boiler which has been well maintained and I had it inspected in the fall. 

We’ve been having uneven, balancing issues with the heat all season. Some radiators weren’t heating up, others were blasting heat. Nothing was comfortable. I replaced most the air vents on rads following the schematic on Gordon air vents website. Heat kicked in and everything started heating full blast - all new vents and old were hissing steam and spitting. We lowered the thermostat to 60 to find a manageable temp. All was fine for a few weeks. Fast forward another week or so and heat wasn’t coming on for a few days no matter what setting on old Honeywell T87f thermostat. Called who was supposed to be another “steam expert” in the area who replaced the thermostat and confirmed it was calling for heat. Boiler kicks on, rads start warming up and he leaves. 20 min later all the vents are hissing and spitting again and heat is blasting. It’s way too hot and thermostat is set at 63.  Upstairs rooms were registering over 78. 

After all this I find this forum and all of Dan Holohan’s books and check out the setting on our pressuretrol - which is Johnson Control P47 and the cut in is set at 3 and cut out at 3.5. From what I read this seems way too high for a 2700 sq ft single family home, correct? For reference this is the pressuretrol we have: https://cgproducts.johnsoncontrols.com/MET_PDF/125450.PDF

Earlier today I crank down the setting to 0.5psi for Cut In, and it automatically moves Cut Out to just under 1. So far, the heat feels even, no spitting, no hissing from vents. 

If you’re still with me - thank you! Did I just fix my issues with that setting change? I’ve literally had 4 different techs out here to help me understand and look at why it wasn’t even etc and not one mentioned the pressuretrol setting. 

1. Is there anything I should look out for by lowering that pressuretrol setting? Do you think sufficient for our home? 

2. Does anyone have referrals for someone who actually understands steam in the Detroit area? I’ve used your find a pro but the nearest is in Ohio. 

Thanks so much,
Meredith 

EBEBRATT-Ed

Sounds like you have fixed the pressure control issue.

Most recommend removing it once a year and cleaning out the "pigtail" the pipe that connects it to the boiler. They tend to plug up along with the other fitting connecting it to the boiler. This can wait until summer

The thermostat is only going to control (turn the boiler on-off) at the temperature it is set for and in the room, it is located in.

The next step is to adjust, replace steam vents as needed to try and balance the heat distribution in each room.

Lets say your venting capacity needs to be adjusted. Smaller/slower vents in the overheated rooms. larger/faster vents in cold rooms.

The room the thermostat is in should not be the largest vent (you may be cold in the other rooms)

The room the thermostat is in should not be the smallest vent you would overheat the other rooms.

It will take some time and patience to balance. Make small changes at a time.


Put a vent in the thermostat room that allows all the rads to heat. Then try faster vents on cooler rooms and slower vent in hot rooms

mattmia2

Hutzel here in an arbor at one time knew steam, not sure if they do now, you'd have to ask some questions.

bburd

I wonder if your thermostat is being affected by a draft coming through the hole in the wall behind it, or something like that. It should be on an inside wall, and the hole for the wire needs to be sealed.

TonKa

Upping the pressure only hides certain problems and creates others. If the Empire State Building can get by with less than 2 psi of steam, I think you're fine.

Mad Dog_2

I done good.. just make sure yiu have good main vents. Gortons or Hoffmann ONLY. MAD 🐕 DOG

Meredith

Thank you all for you advice! It seems the heat is much more even now that the pressure it lowered. 

However I am getting more water hammer noises (bangs, pings) from under the floors (guessing mains?), gurgling noises at the rads, and several of the air vents (even the new ones) are emitting a high pitched whistle as they warm up. Eventually it stops but I think you’re right about the “pros” upping pressure to hide other issues.

From what I read, it sounds like I may have water in the radiators with those issues? I went around with a level and not one of them is properly pitched and they’ve all been lacquered down as the floor was refinished. Is lifting them to properly pitch something I can do on my own? 

I don’t even know where the mains are to check if they’re vented. I’m assuming they’re under the floors or should I have access to them from the basement? Our pipes were wrapped in asbestos which they just encapsulated instead of removing. Would that be an impediment in case there are no main vents? Is that possible? 

Also most recent service call (no heat in Michigan winter) they replaced our old Honeywell T87F 2873 with a baseline digital thermostat. I’ve since purchased a few old Honeywell T87F 2873 on eBay to have as backup. Should I replace the digital and put back the mercury T87F? If so, what setting on anticipator? 

I can take some pictures if helpful but lowering the pressure definitely revealed that wasn’t the only issue. But we are getting closer. I really appreciate all of your help. I’ve gone down this rabbit hole and balancing this system is literally all I think about. 

Jamie Hall

The mains should all be visible -- or at least parts of them -- in the basement. The encapsulation will make checking their pitch harder, but not impossible.

I'd replace the baseline digital with one of you mercury T87's. Lots less hassle. Start off with the anticipator on 1.2, but you can fiddle with it until you like the results. Make sure it is level.

Meredith

Looks like there are no air vents on our mains. I've attached pictures of our set up.

Also looks like there is not enough water in the sightglass. It's all rusty brown and a lot of oil floating on top. I did remove about 2 qts of water when the service tech was here and they told me to do that weekly, but then I read in Dan Holohan's "We've Got Steam!" that we have a probe low water cut off and we shouldn't need to do and just have the probe cleaned annually. I doubt that happened in our inspection in the fall.

Would we call a plumber to come in and add air vents to the mains? Would they also be able to skim the boiler and make sure the low water cutoff/probe is working? Or do I try another HVAC team? Could they do this now in the winter or should I add to my list of summer jobs?

Thanks so much - I greatly appreciate the advice!

mattmia2

If you have oil on the surface of the water then your boiler needs to be skimmed. If there isn't a skim port in it then it needs to be added. When the boiler is skimmed it is heated to near steaming and water is drawn off the top of the boiler slowly through the skim port so the oils on the surface of the water float out. It can't be done with drains at the bottom.

Oil on the surface of the water will cause surging, the steam will erupt violently from the surface of the water which will throw liquid water up in to the mains and cause the water line to bounce in the sight glass.

Meredith

@mattmia2 That sounds exactly like what's happening! Is that also contributing to the loud water hammer throughout the system?

Would you suggest getting someone to do this immediately or do I have to wait until warmer weather?

mattmia2

It isn't an emergency but that elbow and valve under the pressuretrol looks like a skim port so it wouldn't be difficult to do and it would probably help with efficiency.

Meredith

@mattmia2 Thanks! I'll reread the books and look through here on how to skim it. Was there any concern with the waterfeeder light not being on? I can't remember if the green light stayed on always or only when feeding water into boiler. I'm concerned bc when I push the manual feed button - nothing happens.

If I skim the boiler, do I use this manual feed button to refill with water, or would it automatically sense and fill? Sorry for basic questions.

mattmia2

fire the boiler just until it begins to steam then turn it off

Open the valve on the skim port all the way(There may be a cap you have to take off) and you would open the bypass valve on the water feeder just slightly so a trickle of water runs out of the skim port. put a bucket under it or otherwise let it run to a drain and do that for a couple hours. you use the manual feed valve to bring a small stream of water in to the boiler. first you will have to use the manual feed valve to get it to the level of the skim port.

Close the manual valve and the skim port and drain the boiler down to the water line mark with one of the drains on the boiler.

Fire the boiler until it steams to drive the air out of the fresh water you added.

You may need to skim again in a couple weeks depending on how much oil is in there and how much of it got thrown in to the rest of the system.

mattmia2

As for the lights on the lwco, you would have to look at the manual for that model. Note that it needs 24vac from the boiler's transformer to work so if the boiler is off, it will be off too. Depending on how it is wired it may also be off when the thermostat isn't calling for heat.

mattmia2

It looks like whoever installed it piped it properly so you might want to find out who that was.