Pressuretrols and Trapped pressure

Major7

Greetings:

Firstly I want to say I watched a one hour Dan Holohan video on Youtube, and am happy to be its first commenter. I was astounded by the low view count, as that video is red meat for nerds who love both technology and history.

With that said, I have a practical challenge. I recently moved into a ~2000sqft 3 floor home in Detroit built in 1930. It has single pipe steam heating. Earlier this season, it stopped working. The serviceman "fixed" the system by turning the pressuretrol up to 9PSI (cut in). My heat works, sort of, but the temperature consistency in the house isn't what it was. I've learned since then I need to turn down the pressuretrol for best efficiency, but I cannot get it down to the typical values discussed for residential steam. If I set the cut in/cut out to say 0.5/1.5PSI, the system cuts out and never turns back on because the pressure does not fall. I suppose at some point it will drift down and trip the pressuretrol on, but the pressure is falling at such a low rate, it will be 40F in here by the time the pressuretrol cutin triggers again.

So my question: Is a nearly zero pressure decrease after the boiler is shut off over hours a sign of a system problem, and if so, what are the potential root causes?

Fred

Most probably you need to take the Pressuretrol off of the pigtail (looped pipe) take the pigtail off and clean it out. That pipe will get clogged with gunk and prevent the Pressuretrol from seeing the actual pressure or, sometimes releasing the pressure trapped between it and the clog. It's a simple maintenance item. Also, keep the presseure set at .5 PSI Cut-in and the Differential at "1" PSI.

BobC

Your presssuretrol could be worn out, the spring might not be working the way it should or maybe the guy just turned the screw because he is lazy. It sounds like something is plugged up.

Do you know if the service guy cleaned out the pigtail? Did he check the base of the pressuretrol to make sure it was clear? If those steps were not taken I suggest you do them before doing anything else.

What does the pressure gauge read when the boiler is cold and what does it read when it cuts out? Be warned old pressure gauges don't always read right especially if your trying to see 1.5 psi on a 30 psi gauge. You should consider adding a 3 psi gauge and perhaps a new pressuretrol assuming everything is clear.

Running a steam pressure at high pressure does nothing but cost you a lot of money - I suggest finding a new service guy.

Bob

Major7

I set the pressuretrol to 2/3 but the boiler stayed at 3 for the whole day in sub 40F weather. I drained the boiler until the low water level tripped, and thewater temperature was tepid. Still, the pressure on the gage was north of 3PSI. I will clean the pigtail, but the pressure popped up to 4PSI after I forced the boiler on within 5 minutes by manipulting the pressuretrol. The boiler tripped on at the level indicated by the pressuretrol cutin, and that was the same value as the pressure gage. So because the pressure gage and the pressuretol "agree" and because the gage responded rapidly to an increase in boiler pressure, I'm thinking that it's not a blockage. Nonetheless, I will complete your suggestion to clean the pigtail of any potential blockages and report back.

Thanks for your help. I'm happy to be here.

Fred

That pressure of 2 PSI Cut-in and 3 PSI Cut-out is way too high. The cut in should be .5 PSI, no more than "1" PSI and the Differential should be no more than 1 PSI for a cut-out of 1.5 PSI to 2 PSI. It's hard to say that the gauge and/or the Pressuretrol are working properly since we can't say for sure that either is correct and/or working. If you could post a picture of the Pressuretrol and the gauge so we can see what they are, it would be helpful. If your Pressure gauge is a 0 - 30 PSI gauge, they typically don't even move at a couple pounds of pressure. That's why we recommend a 0 - 3 PSI gauge be added to the pigtail with the Pressuretrol so you can actually see what is going on when the boiler is running. I'm not sure what you mean when you say "you manipulated the Pressuretrol" ? Typically they Pressuretrol, for the most part, is a safety control to shut the boiler down should pressure get higher than desired. If the boiler is sized properly, the main venting is good the boiler pressure should not get high enough during a normal heating cycle to require any intervention by the Pressuretrol. The Thermostat should shut the boiler down because it is satisfied.

BobC

I think your gauge and ptrol are both bad OR there is a blockage somewhere.

A steam boiler cannot have pressure when the water cools unless there is a leak feeding water into the boiler - domestic hot water coil or the valve that feeds water into the boiler is leaking. Even then the air valves open when the pipes cool and that will let air in.

Bob

Fred

I'm wondering if his gauge and Pressuretrol are both mounted on a pigtail that is clogged.

Steamhead

Fred said:

I'm wondering if his gauge and Pressuretrol are both mounted on a pigtail that is clogged.

That's how it sounds to me.

JUGHNE

Both devices seem to agree on the pressure built up by a check valve of sludge in the pigtail. Should be a different system if that is the issue and cleaned up.

Major7

Fred:

The problem with the lower pressure settings is that my boiler never gets down to those pressures. A whole day without the boiler on at it's stuck at 3PSI.

Fred

When the boiler is not running it should be at 0 PSI. Vents on the mains and on the radiators open and there is nop way for the boiler to hold pressure. If the Pressuretrol is seeing pressure, it has to be because the Pigtail is clogged. Are the Pressuretrol and the gauge on the same Pigtail? If so, take that pigtail off and clean the gunk out of it and and the opening the pigtail is mounted on and the Pressuretrol will probably work, unless it is defective and the gauge should zero out. Even if the gauge is stuck at 3 PSI, the boiler should still start if the Pressuretrol is good.

Major7

Fred, et. al. - thanks for the input. I will do two things - order a 5psi gage, and clean out the pigtail. I'll do both and report back.

Fred

Keep us posted.

Major7

I replaced the pressure gage with a low pressure gage (0-5psi) from Dwyer. Cleaned out the pigtail. The system runs from sub 1psi to about 1.3psi now. It looks like things are normal pressure-wise, but still not optimized throughout the home. There is still a 3-4F delta from coldest to warmest through the home. Goal is 2F.

I put in a Honeywell wifi thermostat, but I was disappointed that there is no programmable hysteresis setting, or even a way or the app to tell me if the system is off or on. Also, the temp sensor is off by a degree. I think I will upgrade to a Nest 2G.

Paul48

You need to verify if the overheated rooms are that way simply because they are over-radiated. This might be simply satisfying curiosity, provided you are satisfied with how the system operates. In which case, you might want to put TRV's on the radiators in the warmer rooms. Just make sure the TRV's include a vacuum breaker, or you may be back to square one.

Fred

Make sure you have enough venting on the mains. Once you are sure you have the mains vented properly, you can begin to balance the radiators with various size radiator vents or with vents like the Hoffman 1A that will allow you to adjust the venting for each radiator. That is trial and error, based on factors like radiator size, distance from the boiler, length/diameter of run-out/ riser to the boiler. This process takes a while to get all the radiators/rooms the way you want them. Changing thermostats won't balance your system. You can move a low tech thermometer from room to room to determine temp variance and adjust your radiator vents accordingly.

Dave in QCA

Fast radiator vents tend to throw a system out of balance. What vents are you using now?

Major7

I have Dole2B Vari-vents all around on the radiators. I cannot locate the main vents in the basement.

Steamhead

There may not be any main vents.

Those Dole 2B vents are vacuum vents, which date back to the Coal Era. Coal had a long firing cycle, lasting for hours, and these vents allowed the boiler to still generate steam at lower temperature as the coal pile burned down. This doesn't work well on oil or gas, since the much-shorter cycle allows vacuum to form before all the air is out. This can block steam circulation when the air expands under vacuum.

Your best bet would be to have properly-sized main vents added, and change the 2B vents to standard vents, either adjustable or not depending on where they're going. This will ensure proper steam distribution every time.

Where are you located?

Major7

Firstly I want to say thank you for all your help. I basically don't know what I'm doing, but I'm having a lot of fun so far.

I should have asked before! I just bought a bunch of new 2B's off eBay. Nice and shiny, but apparently not the right ones for the job. So the difference is that the regular style pulls air back into the system as the steam condenses?

I live in Detroit proper in a historical district. It's a three floor home + a basement, which means four total floors with registers. The top floor is just one large room.

I did manage to get the three floors very close in temperature, but I had to vent down the main floor registers near the stat, which resulted in quite a bit of hammering on turn-on throughout the whole house. I suppose this results in too much entrapped air. This also caused some noise on the second floor registers as well.

Could you please recommend a nice quiet adjustable valve (I tried a Hoffman Hoffman Steam Air Vent 401422 1A. Nice enough and easy to adjust, but I pulled it out of the system when the rest of the 2B's arrived.

And as long as I'm pestering you with questions, is there a general rule or guide about how to get the right venting over the whole house and adjust registers to get the temp distribution you want?

Steamhead

Post the 2B vents on the Buy, Sell, Barter page of this site. One of the people who is experimenting with vacuum techniques may want them.

The Hoffman 1A is a very serviceable vent. For bedrooms and other areas that you may want to keep cooler but turn up occasionally, I like the Vent-Rite #1 since it is very easy to adjust without using tools.

But the main vents are the most important thing. How long is each steam main, and what pipe diameter?

Jamie Hall

I would avoid the Nest for steam... much money, not so much results. Most of the Honeywells have an indicator to show that they are calling for heat, which might be what you want.

As to evenness all around the house... difficult, though it can be done. As has been said, main vents. If you have very tall risers, you may even want riser vents. Then fiddle with the radiator vents until you get what you want -- keeping in mind that changing one somewhere will affect everything else, although if your main venting is really good it's usually not all that much.

Also -- keep in mind that what gives you near perfect balance on any given day may not be so good if the wind is different, or the sun is different...

Major7

I did skip the Nest... For an Ecobee3 ;-) Multiple sensors allow me to regulate the top floors at night when people are sleeping, then averaging the main floor and top floor during the day. It's not a real fix, but it is pretty cool. Also, I've found that the more often systems cycle (within reason), the less temp delta between the main and top floors. The stat generally sits on the main floor over the furnace/boiler due I suppose to ease of routing the thermostat wires, but it's one of the warmest places in the home (at least the ones I've lived in) because of radiant heat through the floor.

I will keep working on the balancing. First step I was advised was taking out the vacuum valves. That will take some time. Also, I've only located on basement vent, and I don't know how to check if it's OK or not.

vaporvac

Do you mean valves or vents? any chance we could see some pics of a typical radiator before you go through that trouble?

Major7

vents. my bad. I will take a few pics of the system beforehand. Earlier in this thread I was advised to can the vacuum values for regular type, as those were optimized for coal heat and I'm on gas right now.

Major7

Here's a basic rundown.

https://drive.google.com/file/d/0B5i7F2vCipjdc3lVb1BmN2pJQ00/view?usp=sharing

Fred

How long are the mains? One or two Mains? If two, give us the length and diameter of each. Based on your pictures, I would say you probably need more main venting. That one vent most likely isn't enough. Until you get the mains adequately vented, you won't be able to balance the radiators, especially when it's not really cold outside and the boiler runs a relatively shout cycle.

Major7

There are two mains that encircle the house. They T out right at the boiler, and meet at the opposite side of the house. Both have their own main vents and feed into the same return. I have no way to tell if the main vents are still working. I do know that some of the main floor radiators hiss for an awful long time (10-15min). I will cut away some plaster/drywall from the second main vent to gain access in case I want to replace it.

I will measure the pipe diameter and length, map it out, and report back.

Several radiators have been decommissioned. I want to decommission one more, and recommission one of those that that been decommissioned because inexplicably the prior owner decided to convert to baseboard heating. Yuck! That experiment was ugly, and it leaked onto my hardwood floors and stained them.

Again, thank you. This is becoming a labor of love for me. I hope I can learn a little about this craft with your help.

Fred

Hopefully you realize that with each radiator you take out of service, you increase how much the boiler becomes over-sized and will short cycle. What size is the boiler? (there should be a plate on it that says the Sq. Ft. od steam it produces). Also measure the total EDR of all the radiators in use today and the EDR of the Raditaors after you remove those that you want to decommission. Removing radiators is never a great idea, until a new boiler is installed. At that time, the new boiler can be properly sized to the reduced radiator EDR. For now, let's get the main venting up to par.

Major7

don't know enough yet to calc edr, but i did map the mains and took down boiler info.

https://drive.google.com/open?id=0B5i7F2vCipjdWDdFVkVuZ3ZEZEE

Major7

Here's the EDR:

Basement: 20
Floor 1: 145
Floor 2: 145
Floor 3: 71
Total EDR: 381

Fred

Can't see the info on your google page. Requires a log-in

Major7

https://drive.google.com/file/d/0B5i7F2vCipjdWDdFVkVuZ3ZEZEE/view?usp=sharing

Steamhead

Not only is that boiler oversized, but it's not piped properly. Here is an example of a similar (though smaller) boiler with proper piping:

http://forum.heatinghelp.com/discussion/151513/lets-start-the-new-wall-off-properly

Major7

Thanks. Can you give me some hints about what is wrong with the piping? I believe the original pipes were optimized for steam, but the boiler is relatively new.

Also, is there anything that can be done about an oversized boiler? It seems to run in 30 o 45 minute on times every two hours or so with 32F outside temperature.

It does look like neither mains vents are working, and they are both vacuum valves like the ones through most of the rest of the house.

Abracadabra

It doesn't appear to me that the near boiler piping is incorrect, unless we are talking about the sizes of the risers and the header. I believe what everyone is seeing is a optical illusion. Zoom in and you'll see the risers feeding the header on the left side, main takeoff and then the equalizer. I can't tell if they could have done 2 main takeoffs off the header. Need a wider angle.

Major7

Abr.. You are right. The pipe on the right does a funny out-and back, and the pipe lengths are identical. Good catch.

So, my original goal was temperature stabilization from room to room. I've achieved that with an Ecobee and some tweaking of my Dole 2Bs. But now I've learned I need to set better goals.

New goals...

1. Imperceptible system noise - No banging, and no hissing audible from more than 3' away from radiators. I can hear one hiss like an alley cat from the next room.
2. Green - run boiler for as little time as possible to lower heating bills. My goal would be to get half way between a period and a modern home, on a cost per square foot and degree day basis.

To reach those goals, I discovered with thanks to the contributors in this forum that I need to start with the main vents. I have old Dole vacuum main vents. They do not work. Two mains and zero working main vents.

I will swap out the vents, but I'm worried about taking them out. It's a tight space, and they are at the elbow. I understand that's a no-no, so I'm thinking about a bigger re-do. I'd really like to make the main vent at the elbow work, but the knucklehead ran into a joist and it's a pretty short stub.

I love steam heat. No drafts. No filters to replace. No ducts to clean. Heat is delivered well after the fire is out. Cool retro look. Remarkable temperature stability. It might just become a temporary hobby to get my final goals done!

Steamhead

That piping does look incorrect. We can't see the funny out-and-back from here, but it looks like it's all 2-inch pipe. That size boiler requires a 2-1/2" header at minimum. If we were piping one we would probably use 3-inch for the header since at least around here it doesn't cost that much more.

Major7

Yes, that's right. The Weil McLain manual that came with the boiler said 2-3", so I suppose the installer took some license. I do agree that the relative cost for the larger pipe is a nominal one.

The brochure is here:

http://www.weil-mclain.com/en/assets/pdf/EG-Brochure-Series-5_new.pdf

Anyway, I think I have bigger fish to fry at the moment. I do appreciate all your input and help.

Steamhead

Weil-McLain?

The boiler in the pics is a Utica...............

JUGHNE

OP must have been given the wrong book. Says Utica on front panel, OP labeled picture with both names.