just how important is thermostat placement ?

rhodebump

We have a Weil McClain boiler (700K BTU) serving old 3 story brick building, 65'x100' (former catholic grade school)
Majority of radiators are 2 pipe system

The thermostat is on an interior wall on the ground floor but I haven't been able to find a good setting to keep everybody happy. I am considering moving the thermostat to the end of the steam line( 3rd floor, which isn't warming up). For example, the 2nd floor would be 74 degrees and the 3rd floor is 60 degrees.

While it seems obvious to some degree to move the thermostat to the 3rd floor, are there any other considerations before I run new wire?

Thanks!
Phillip

acwagner

Are the third floor radiators getting hot?

Does the temperature differential between floors happen throughout the heating season, or only during mild weather?

rhodebump

Third-floor rads are capable of getting hot, but most of the time, they seem cold to the touch..
Temperature differential has always been the case in the two years that we have started heating it. The building was empty for the previous 20 years.

Jamie Hall

You have a plain vanilla balance problem which needs fixing before you start playing with the thermostat location.

Step 1 to that is to make sure that you have adequate main venting. You may not have any at all! Follow the steam mains around in the basement and make note of their length and diameter. Somewhere near the end of each one there should be a main vent. Make note of what kind it is -- a photo is even better -- and report back what you find.

Step 2, since this is mostly 2 pipe, is going to be to check the traps on each radiator. They must be open when cool, to allow condensate and air to pass, but close when hot so steam doesn't blow by. Since your third floor radiators aren't heating, this could be tricky! But follow down the risers to those radiators and see where -- and if -- they get warm.

And while you are at it at the radiators, make sure (for the moment) that their valves are open.

If there are any one pipe radiators -- with vents on them -- check those vents for functioning.

And report back what all you find -- we can help some more.

Hap_Hazzard

If you move the thermostat to the third floor, keeping it set to 74, won't the second floor be 88?

rhodebump

I have only one main air vent, which is a Hoffman Specialty Model 75 3/4 x 1/2 in. 75 psi Steam Unit Heater Air Vent

I will take picture tonight

Jamie Hall

rhodebump said:

I have only one main air vent, which is a Hoffman Specialty Model 75 3/4 x 1/2 in. 75 psi Steam Unit Heater Air Vent

I will take picture tonight

That's what I was afraid you might say... that's an excellent vent. Nearly bulletproof and lasts forever. Unfortunately, it's almost never big enough to be a main vent nowadays (it was fine in the days of coal).

rhodebump

Here is a pic of the vent

I also made a little movie of the boiler room that shows the entire system:
https://photos.app.goo.gl/JZvjVS8Ui9NFtxMv9

I have replace countless steam traps in the system also.

rhodebump

Jamie Hall said:

rhodebump said:

I have only one main air vent, which is a Hoffman Specialty Model 75 3/4 x 1/2 in. 75 psi Steam Unit Heater Air Vent

I will take picture tonight

That's what I was afraid you might say... that's an excellent vent. Nearly bulletproof and lasts forever. Unfortunately, it's almost never big enough to be a main vent nowadays (it was fine in the days of coal).

Jamie, the pipe leading to this air vent is 1 inch. I could put a Tee on it and add a 2nd air vent. Would this help?

acwagner

Yes, but, from the general description of the building size, that's probably not enough to make an impact. You'll probably need quite a few more.

What pipe size and how long are your mains?

Jamie Hall

acwagner said:

Yes, but, from the general description of the building size, that's probably not enough to make an impact. You'll probably need quite a few more.

What pipe size and how long are your mains?

Make yourself a nice antler and put at 2 and maybe 3 or 4 Gorton #2s on it.

BobC

The vent pictured is a Hoffman 75 , but that might still be to small. A building that size must have a pretty long steam main, is there more than one steam main?

How many mains and what size and length is each main? 20 ft of main can take a Gorton #2 which has over twice the vent rate of your existing main vent

Bob

rhodebump

I was looking at the Gordon #2 air vents. However, Gordon #1 seem bigger and they are 1/3 the cost. They seem to do the same thing. Can someone explain the difference between how these are used?
With appreciation,
Phillip

delta T

Gorton #1 are smaller both physically and in terms of venting capactiy. They have a 3/4 MIP thread, and a 1/2 FIP thread inside of that. Gorton #2 have a LOT of venting capacity, though they have a 1/2 MIP thread only. The #2 has more than 3 times the venting capacity of the #1, so you are actually saving money on the bigger #2 in terms of venting capacity to price ratio.

Just yesterday I was doing some work at a post office near me on their steam boiler and changed the existing hoffman #75 they had installed, to 4 Gorton #2's. Before it took almost 20 minutes from boil to steam hitting the end of the main, now it takes about 6 minutes. Proper venting makes a HUGE difference in system operation.

Before and after pics:

acwagner

This documents has vent capacity chart at the end. It's really helpful to see the venting capacities of various vents for comparison.

https://heatinghelp.com/assets/documents/Balancing-Steam-Systems-Using-a-Vent-Capacity-Chart-1.pdf