Main vents / vent balancing questions

dev_hollows

I have a 3 story building heated by Burnham SteamMax STMX299 (installed this year). Around the same time the boiler was installed, I added temp sensors to every room to get a better idea of what's going on with the balancing, and discovered 3 of the rooms on the third floor were significantly colder than the rest of the house. After replacing the Maid O Mist "D"s with Varivalves set to max, they're warmer than they were, but still consistently 6-8 degrees cooler than the rest of the house.

Rather than throttling the rest of the radiators, I'd rather get everything venting as fast as possible. Adding master vents to the tops of the risers on the 3rd floor (per The lost Art of Steam Heat Revisited, per Frank Gerety's method) makes sense — but I don't have room in several of the rooms to move the radiators over to do Gerety's exact method. Could I, instead, add master vents to the inlet side (1st segment) of each radiator on the 3rd floor? (Assuming the service valves stay open all the time, I feel like this would probably be less work and expense than re-piping everything the way Gerety does).

Alternatively, would it work to add the riser pipe volume between each radiator to that radiator's "total air" calculation, and size each radiator's vent to include its own segment of riser? Or, perhaps, add all 3 floors' worth of riser to the 3rd floor radiator calculation and add a second vent (if needed) to each 3rd floor radiator similar to the "large radiator" recommendation (with the second vent above/below the normal vent on the last segment)?

mattmia2

you have to slow the fast radiators down to some extent. the pipe itself is a factor in how fast steam can get to the far radiators, the pipe has to be heated by the steam to steam temps at the front of the progressing steam before the steam will progress further and this is a relatively fixed rate, more venting won't make this happen faster, so to balance the radiators far from the boiler with the radiators near the boiler, you have to slow the radiators near the boiler down.

patrykrebisz

slow 3rd floor might mean :

a. you need to vent the raiser (so yes, adding a coupling between valve and radiator will accomplish it)

b. your raisers are not insulated or exposed to drafts.

if you are interested, i have numerous videos on steam heat at my yt channel. this one pertains to you:

https://youtu.be/YGIG_Pg3rpA

Captain Who

Have you timed how long it takes the steam to reach the supply valve of every radiator in the house, after the burner fires up? If not, good place to start, rather than room temperature.

4GenPlumber

Figure out which 2 rads in the home heat first or which rooms are warmest. Reduce vent size. The following day, do it again. When its your home this is the most cost effective way, when you are a business owner, this is the least cost effective way.