zoned steam system

rob brown

going to call tunstall in the am. thanks for the advise boilerpro. rob

rob brown

zoned steam system

hi guys. it's my first time posting to the wall, but i've been a regular lurker and first want to thank you all for everything i've learned here. especially mr. holohan, our host. i have an interesting problem and am seeking wisdom from the wall. 2 years ago, i replaced the steam boiler in a fairly large church with a w/m lgb rated at 1,650,000 btu and 4313 feet of radiation. origanal system was set up with a nice, big dropped header, with 6-2" mains that run out to system.the problem is they were piped thru zone valves!heat works well, if you dont mind all the banging and clanging.trap matinence has been ignored for 55 yrs.(all traps are origanal warren-webster, whice i found out went ka-put in the 60's). getting ready to start replacement of all traps. including end of main traps.this is definitly going to be an expensive deal for them (54 rads and about 10 or 12 f&t traps for end of mains and change of elevation).they are complaining of high feul bills. i know the traps will make a huge difference, but it pains me to watch that boiler cycle for 2 min. on then 2 min. off. boiler is wired to be always on, always steam avail. when zone valve opens.repacking zone valves last spring, i found 3 of the 6 passing.( now i know why chapel in basement is always too hot- 3 mains run overhead-2 always hot. maint. guy was running ac last winter to compensate! yikes!) i would like to try cranking those zone valves open installing a heattimer type control. trv's could be selectively used to control overheating rooms. the only problem i see,as i'm calc. the edr, i may fall slightly short. the main part of the church is all am.st. arco c.i. convectors. total edr about 2550.basement has at least a dozen big rads, all mixed, all with homemade covers making difficult to i.d. and count sections. i think i would be in the ballpark, although i might only have 25% to 20% for pickup. i figure worst case, i could wire all zones into 2 zones so boiler see some real load. so am i crazy, or do you think any of this might work? rob

Barbarossa

I did a church/school 8 years ago that was similar to your description overheating where the pipes transited 4 classrooms were overheating they needed 2 inch fiberglass ASJ with PVC jacket to get under control. The zone valves (in horizontal runs) due to pitch considerations had to have a small bypass on the bottom to keep condensate from backing up with tees to permit blowing clean every year. That and a paragon 702 (not made anymore but still working) and 1-1/2 inch re-insulation made a big improvement in comfort and cost to operate. Best of luck to you as each job is diffrent and this is not much help.

rob brown

insulation

thanks for your input barbarossa. unfortunatly, the mains above the chapel are all covered with sheetrock( but elsewhere are accessable)and all mains are insulated. i figure i'm going to have to repair/replace the passing valves,or try the heat timer type control with all zones held open. i think the latter would save them more $$$. plus it's much less work for me, you should see where these valves are located-up against the cieling, right over the boiler. thanks again for any input rob

Boilerpro_3

Before replacing all those traps

why not look into orifice plates for the supply valves and keeping tight control on your pressure. No more trap maintenance and you can balance the heat capacity of the radiators to the current needs, which rarely match the radiation in an old church structure.

Boilerpro

rob brown

orifice plates

very interesting idea. will have to research that. i didn't know you could still buy them,or will i have to fab. myself?that would really save them a bundle. i still dont like the zoning, it's like trying to hold back the beast. like a supercharged 454 in a lawn tractor. thanks again for your input. rob

Boilerpro_3

For orifice plates head for Tunstall

They have the plates and all the data. Also, after you see what the real heat load is after calculating it for your plate sizes, you may want to put in a smaller boiler or downsize that LGB. LGB's can be step fired, so you can run on low fire (50% I believe)if necessary, but that probably isn't the most efficient. Also, to help improve heating costs, if most of the structure is unoccuppied during the week, put in a clock timer to turn on the boiler only when heat is needed for occupation and then install a freeze stat in the coldest room to cycle the boiler when the space drops below 45F. The fuel usage will plummet compared to that hot boiler thowing tons of heat up the stack sitting on standby.
A couple of electric heaters in offices will usually take care of typical usage, or better yet a small sidewinder steamer.

Boilerpro