Uneven heating gets worse when using a vaporstat to stop at lower psi

datawaym8

We have a 4 units 2 floor house.
The steam boiler is all the way at the back of the basement. It used to have a pressuretrol that short cycles around 3.5 psi after 26 mins. By that time, every units are heated up and satisfies thermostat temp around 30 min mark.

I recently replaced the pressuretrol with a vaporstat in an attempt to stop at below 3 psi. My current vaporstat setting is 14oz on main and 8oz on the diff. It stops at exactly 1 psi at around 24 min. Then every 50 seconds it would fire again. The low pressure and earlier+more short cycle seems to push more heat to the units above the boiler making them emit heat longer than before meanwhile the two units further away from the boiler already losing heat.

The 2 units directly above the boiler room is always hot and quick. Right now it's 75-78 degrees Fahrenheit. The other two units on the opposite end(maybe 60 feet) of the boiler room are 68-70 degrees Fahrenheit.

If we want to heat up the two units further away to 70, the two directly above the boiler will be hitting 75-80 degrees.
It seems like the problem with our steam system is that the two units above the boiler gets heat up too quick and was able to maintain heat for longer time than the other two units further away.

Should I set the psi to the highest possible acceptable value? What setting should I change on my Honeywell vaporstat L408J1009 to achieve that?

Steamhead

How long and what diameter are your steam mains? What vents are on the ends of the mains?

neilc

#pigtail

you didn't specifically mention,
and because it's what I do,
I'm gonna ask,

are you sure your pigtail is clear and free breathing all the way back into the boiler?

Jamie Hall

This ^^^. Odds on that it's a venting problem.

datawaym8

The main line is approximately 70 feet or 21 meters.
The pipe circumference is 19cm so I guess the diameter should be 6cm?
We have a Gorton 1 at the far end of the main pipe. Used to have 2 but tenant was complaining about radiator banging so we took one out thinking that might have caused the loud banging. Still banging but better it seems or they just being nice and not telling us.

Pigtail is clean. I just drained and cleaned last night.

EBEBRATT-Ed

@datawaym8

I think you gave the secret away.

Radiator banging.

Are the rads that are banging the ones that don't heat?

If they are or are in the same area you have water pooling in a sagged or poorly pitched pipe or radiator.

Fixing the banging will fix most of the problems and more venting

Jamie Hall

Not enough venting. On that line you should have -- in my opinion -- two Gorton #2s. @Steamhead may have a better suggestion.

As to the banging, that's not a vent problem. That's almost certainly a water hammer. Is the line insulated? Is the pitch adequate? What you've done with the smaller vent is reduce the steam velocity, so you get less banging. And slower and less heat. Fix the water problem and you can put in adequate venting.

neilc

can you post a picture of that noisy end of your main,
lengthwise, looking at the vent

datawaym8

They are well pitched if not over pitched(not sure if it's a thing). We couldn't figure out where water could be trapped. The banging is more like clanging sound. Only a few times when starting the heat and then a couple times after fire off. Loud enough to wake you up. And that only happens on the first floor unit/radiator at the far end of the main line.

We also recently started to notice the entire main pipe started making mild water hammering sound for the first 15 minutes. That sound seems to go slowly from the boiler room then to the far end. And the radiator on the first unit above the boiler room started making mild banging noise too which has not happened in the last 2 months.

It's also worth noting that pretty much all of the vents I checked has water in it and they are all brand new. Some has clear water but most have brownish sediment water. (see picture below)

The main line is not insulated and we intend to do that soon.

Picture of the main vent. Vent is on return wet line. One night I could hear water inside when it was making hissing noise.

EBEBRATT-Ed

Sounds like wet steam. How about some boiler pictures stand 8" back. Boiler and piping

datawaym8

Do you think applying water treatment would help?

Steamhead

Even from the side we can see the piping around the boiler is completely wrong. You're definitely producing wet steam. A pic from the front of the boiler would show it even better.

The I&O manual, with diagrams showing how Burnham wants the piping done, is here:

https://s3-us-west-2.amazonaws.com/catsy.782/Independence+IO+Manual.pdf

EBEBRATT-Ed

Yeah, it's piped wrong. Looks like counterflow with no drip and water treatment will not fix this

JUGHNE

There looks to be a wet copper return behind the boiler. Maybe only counter flow for the beginning of the steam main.

Usually one leaves the old pressure trol connected on existing pigtail and used as a back up for high pressure shutdown.
Vaporstat and low PSI gauge on a separate pigtail.

neilc

you could think about repiping that vent,
from the wet verticle,
a street 90, and a nipple above the main, then the tee with vent,
get the vent up higher

datawaym8

Below is a rough drawing of my steam system base on what I can see. I suspect there are two steam pipes as you can see in my previous photo. One goes directly up to the two units above the boiler and the other travel all the way to the far end of the house and up to the two units above it. We do have a drip line as seen in my drawing and some of my photos.

@Steamhead I just bought the house and the previous owner had this set up for about 10 years at least. How much work are we talking about redoing these pipes? Is there another solution to make it through the winter without redoing the pipes?
@EBEBRATT-Ed We do have wet returns on the far end of each side of the house.
@neilc Keep the current set up and make the vent go above the main line?

EBEBRATT-Ed

@datawaym8

If they lived with it for 10 years I guess you could make it through the winter, but it would be good to get a steam guy lined up there probably all busy right now.

I would check "find a contractor" on this site and post where you are located. Someone may have a recommendation

neilc

like this

datawaym8

Thanks guys. I do have a heat guy in mind. Will call him once I gather more questions.

Thanks Neilc. I will look into raising the vent.