Three Unit Uneven Heating

steamnewb12

Hi there, I purchased an old building with a steam single pipe system in May of last year. We are in the middle of our first winter in a radiator building. I have learned so much from the discussions on this site and now have a slightly more specific question.

The building is a three unit building with very similar footprints on each floor (i.e. number of radiators, layout of unit, etc.). The thermostat-a google nest-is on the top floor in the main room. I have sensors on the other two floors to determine temp and to change as needed. At the beginning of the season the second floor was getting very warm compared to the thermostat. I set the temp for 70 during the day and 67 at night. When the third floor would hit 70ish, the second would be around 76-78. The first typically follows just behind the third. After reading about vents I gave that a shot. I changed out the two main radiators on the second floor with Gorton #4s and the two main radiators on the third floor with Gorton #6s. This worked great for about a week. All three units were hitting the same temps at about the same time. However, I'm about three weeks out from having done that change and now the second floor is the coldest and the third floor is hitting much higher temps, about 75-77 while the first and second are getting to about 70-71 at that time. I am curious if I should have used Gorton #5s instead. I didn't see much about those at the time so I went with the more common ones. I don't expect all the units to be at the same exact temps all day, but I was hoping for them to be closer so one unit isn't getting heated out and the other is just barely comfortable.

Any other thoughts or suggestions are very appreciated. Thanks!

EBEBRATT-Ed

Steam systems are a work in progress. Most were designed for coal firing when the boiler burned all day.

Converting to oil and gas with an on-off sequence did not help matters

So your 6-8 degrees out of wack. That's not horrible we see much worse here

How about a few pictures of the boiler and the piping around it. Also search the building for any main steam vents. They would typically be at the top of risers or in the basement at the far end of the steam mains.

And check the boiler when it is steaming. What pressure are you running? How stable is the water level in the gauge glass? Does it move gently or is it surging? How much does it move

We will try to help you smooth it out

No majic wand

neilc

the nest is an occupancy sensing / anticipating setback thermostat, right?
or is that option disabled?
the other sensors can override the base nest ?
who is the controlling occupant ?

steamnewb12

Thanks for the responses. It's good to hear having these differences are fairly normal. I guess my bigger question is, without having changed anything at all why would the differences go from a degree or two one week to such a wide difference the next?

The controlling unit at the moment is the first floor which is typically a degree or two cooler than the third or more depending on how the boiler is reacting. It's been a few days of the third floor not getting over heated and every level being relatively close in temp. I can change which sensor makes the boiler react though if needed.

I have attached a couple pictures of the piping. There are two main vents that appear to be Gorton #1s. They are right at the elbows that go into the back of the boiler. The gauge glass water is pretty gently moving. If anything it moves down from the middle, but nothing wild. I have an additive pressure, the diff is set to 1 and the pressure is set to just under 2psig. The pressure gauge goes up pretty high, so it doesn't seem to really change when on, it's not reacting to the small pressure I'm guessing. I know I've read the pressure should be set to about 0.5psig, however, I did try that at one point before switching out the air vents at the radiators to get more pressure up to the third floor and about two days after setting it down the boiler stopped working and said it was on, but was not sending any steam out. So I reset it and put the pressure back up assuming that was the cause.

I am concerned about wasting energy or gas when the third unit is getting to 78 but the first and second are barely hitting 70. Is there something that can be done or is it concerning that this varies so widely?