Help with adulterated vapor system

dborden

Hello, I'm not a heating professional but I've been tasked by my New York City co-op to try and understand (and fix!) our poorly functioning steam heating system (uneven heating, water hammer). I’ve read Dan’s “The Lost Art of Steam Heating” and many of the articles on this site, and I’ve conferred with some heating professionals here in NYC. I'm writing here to ask for this community's help and feedback on my understanding of our system and my proposed changes. Thank you all in advance.

We're a small building (5 floors plus a basement) built in 1862; the steam heating system was likely installed around the turn of the century (1900). It is clear from the piping that the original heating system was designed to heat only the upper 4 floors; the ground floor piping is clearly of more recent vintage. Diagram 1 shows my understanding of our current system, along with notes showing what I think is wrong; basically, I think it is likely that our steam traps are shot, our boiler is oversized, we're running at too high pressure, we're producing wet steam, and later ground floor alterations resulted in improperly piped radiators.

Diagram 2 shows how I think the original system was configured (probably a simple wet-return vapor system).

Diagram 3 shows my proposed changes.

Have I missed anything? Are my proposed changes sound? Any feedback you can provide will be greatly appreciated! Best, Doug

KC_Jones

One thing I notice, your new proposed boiler is still oversized. You calculated 1800 and you need to compare that directly to the boiler rating, the 19HE-5 @1835 is the boiler you would want.

Also in your diagram the venting you call out near or on the radiators is confusing. Could you post a picture of a typical radiator with this venting? Something isn't clicking in my head with that description and pictures can always clarify things.

dborden

Absolutely. Here is one picture. Each of the radiators on the upper floors has a 1/2" pipe going straight up from the return (the return runs under the radiator from left to right) just before the radiator return joins the building return; that pipe has an air vent on it.

Jamie Hall

Probably was vapour, once upon a time. Why not bring it back to that? I'd not bother with the F&Ts at the bottoms of the two risers which you show without condensate drips. Is there any way they can be run to have condensate drips instead? Also, you don't really need vents on each of the radiator returns. That's overkill. So long as there is one good sized vent -- a single BigMouth will do -- on each dry return somewhere before it becomes wet, you'll be fine (you show such vents on the dry returns for the three risers on the right).

Since you have low headroom in the boiler room, you can do yourself wonders by piping the boiler with a drop header. Bring the riser or risers right up near the ceiling, then over, then drop into the header.

dborden

Thanks Jamie. The two risers that don't have drips (that currently have 24" condensate loops) are on the other side of a 24" thick concrete support wall in the basement. While I cannot imagine that cutting 2" diameter holes through that wall will bring the building down, convincing the other tenants of that may be impossible. I'm trying to only re-pipe in open space.

And I thoroughly agree that we should replace all of these little return vents with one big one. Convincing the other tenants of that may produce a lot of anxiety.

dborden

KC, don't I need to add ~33% to account for the main, run-outs, and risers when sizing my boiler?

KC_Jones

That's already accounted for by the manufacturer. So for a 19HE-5 here are the numbers.

587000 gross output
587000/1.33=441400 Net output (33% pickup factor)
441400/240=1835 sq ft

If you went with the -6 it looks like this
762000 gross output
762000/1.33=572932
572932/240=2387 (they say 2382 most likely rounding)

If you went that route you would actually have roughly a 76% pickup factor.

Steamhead

What KC said about sizing the boiler.

I think this system started life as a two-pipe-air-vent system. This explains all those air vents. This type of system did exist in the mid 19th century, therefore it could be original to the building. See page 125 of "The Lost Art of Steam Heating" for one example of this system.

If you want to make this run as a true Vapor system and get rid of all the radiator vents, you'd have to vent every return riser at the basement-ceiling level. This would let the air escape from a point well above the boiler's water level.

And there are plenty of great Steam Men in NYC!

dborden

Thank you all! This is great feedback. @Steamhead, if you could recommend some Steam Men to me I'd very much appreciate it. Best, Doug

Steamhead

Take your pick:

https://heatinghelp.com/find-a-contractor/state/NY