Say Steam experts, anybody tried this...Boilerpro

Boilerpro

I have a pretty big, old church with one pipe steam with condensate pump....single stat. Sancuary, classrooms, offices and big below grade meeting room. Problems are typical, meeting room too cold in spring and fall, whole building is heated when only needing one space, and no easy way to seperate steam supplies for zone valves. Was thinking of replacing the standard vents with Paul vents on the rads, tying each group of radiators for a zone on a single air line and then using a tight closing zone valve to control the venting of each zone. The zone valve would be controlled by a thermostat in that zone. I have looked at the electrically controlled radiator air vents by Danfoss, but they are very pricy. Probably could spend some extra running air lines instead of wires and end up with only one motorized valve per sone instead of one for every rad. The only down sides I can see so far, is if there are any in leaks at the rads, they will still heat when another zone is calling for heat and the higher velocity in the rad supply risers (condensate and steam flow in the same direction), which is typical of any zoned steam system with one big boiler supplying the system. Any thoughts would be appreciated.

Boilerpro

Dale

How about a hot water loop?

If the main stat isn't calling the low limit ( which you would need to add ) would keep the boiler at 180 degrees or so and pump into a hydro air zone or some added baseboard. If the main stat calls a relay would lock out the pump relay.

Dennis - Reliable Services

Sounds like

rocket science, a cool idea, but think the dead men would have done this if it could have worked.
I think that when those rads go offline the air vents on those other rads are going to look like Old Faithfull.
If you are a member of this church you could experiment and see what happens, they will forgive you.

Steamhead

Good idea

the only thing I can think of that would be a problem, is that when the rads are heated and the zone is shut down- as at the end of a service or meeting- they would continue to draw steam unless there was a way to shut the steam off too. A vacuum breaker might help here.

I'd use a regular thermostatic steam trap as a main-line vent on such a system, connected to the air lines, unless you want to keep the mains charged with steam when the boiler is running and just regulate the rads.

If you can get hold of a small air pump, you could put one on each zone and have it start up when the zone calls. I'd use another thermostatic trap before the pump to keep steam from reaching it if the Paul vents fail.

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Boilerpro

Had that thought too this afternoon

Need a vacumn breaker so when the valve shuts it won't pull in steam on the next boiler cycle. Was figuring on using the end switches on the zone valves to fire the boiler. Also was thinking, though, that in order to break the vacumn the system pressure must drop to zero...so this idea only can work as a "sub zone"....something else needs to control the boiler... maybe an outdoor control? Maybe this could work, just like the danfoss units only several rads at a time. I was thinking air pump too, however, I was wondering what kind of steam velocity we might get in the radiator risers when only one small part of the system calls for heat and the boiler is producing enough steam for the whole system. Could cause the spouting air vents mentioned above! A modulating gas valve sure would be nice based on pressure!


Boielrpro

Steamhead

Either a modulator (hey Noel!)

or a high-low fire, or several small boilers on a staging controller like they use on the Caravan. I can see all three scenarios working if they're configured right.

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Unknown

Honeywell

has modulating gas valves and a pressuretrol that can run them. You wouldn't have an approved burner if you modified it so.

However, I know of a Power Flame gas J-burner set up this way and it modulates from barely a pilot at setpoint, through full fire at 1 PSI below that. It is on a multi-million BTUH boiler running a Hobart dishwasher. The boiler couldn't keep up with solenoid steam valves opening and closing without hitting high limit, and going right into a 90 second pre-purge. That 90 seconds killed the steam.

Remember that one, Steamhead?

Noel

Boilerpro

Was thinking along those lines too...

pretty sure installing all that equipment won't happen, but I would like to continue pursuing this as a "what if" scenario and there was the money to back it up. I am also thinking that maybe we could keep the zones large enough that the steam velocity in the risers would stay low enough that we wouldn't need to go to a modulating burner on the existing boiler...maybe just an outdoor control to cycle the boiler. We also have the other complictating factor that the system goes stone cold when the building is in setback (50 to 55F) so on startup we have lots of condenstate trying to get back down those radiator risers in addition to alot more steam going up, since the full boiler capacity is getting thrown at only a part of the system. Slower venting should help allow those rads to warm up slowly, cutting down on the volumn of condensate going down the risers on warmup. Some additional info..I have already removed and shut off several rads in the system to get it balanced and prevent overheating when coming out of setback (building heat load has been substancially reduced with insulation and closing up of windows)... so we already have extra steam capacity. However, with less load on the mains we can run lower pressures.. this may help keep rate at which steam enters the rads lower. I plan on meeting with the building committee of this congregation in the next few weeks and will take a closer look at the existing equipment....been a few years since I've seen it. Big 1,000,000 firetube boiler with multiple atmospheric burners like on newer residential boilers, if I remember right. Supposedly installed in the 1970s.

Steamhead

Sure do

that's one thing that prompted the "Hey Noel"!

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