Steam boiler controls

Vernon P. James_2

I have an account with big masonry and brick building, two pipe steam, 4 zones, with relatively new twin weil Mclain 6 section boilers Beckett lo-hi-lo burners. Each zone thermostat opens supply valve on header.Old system was one boiler turned on with call from thermostat. When system replaced by low bidder a few years ago twin willies with emcs system by Heat timer. System now keeps constant 1-5 lbs steam pressure and controls boilers with lead/lag and auto rotate. System now soaks up 2x fuel keeping constant head of steam. The big demand is only first thing in am. Once the building is warm each zone only needs a few short cycles thru day to maintain temp.
I would like to return the boilers to cold start off stats but keep lead/ lag and auto rotate for boilers. All controls I find from heat timer and others all run by constant pressure or temperature from the building. My 4 zones are all very separated so the constant temp by sensor seems out to me. Any body know of any simple boiler controls for lead/lag and auto rotate that would do what I want?

Al Letellier_9

steam controls

I would ask some questions before considering changing controls. Maybe you have, but share the answers if you did.
Why is it using 2x the fuel? The boilers are only the "pots" we make the steam in.....are they properly sized? What controls the system? Has a trap survey been done? Where is all the steam going, how does it get there, and how does the condensate get back? How did the system work before the new boilers where changed? All this and more should be taken into consideration. HeatTimer makes excellent controls and we'd had good luck with them. Did the boiler installer get caught thinking you can stage fire smaller boilers like you would on a hydronic system? Doesn't work well with steam, generally !! As Dan says in his books, get out of the boiler room and look around....understand the whole system and evaluate the operation of the system before changing what may be a very good control system.

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Steamhead (in transit)

Stage-firing steamers

can work if done right. Check out the literature for modular boiler systems such as Slant/Fin's Caravan. As with anything else, it needs the right controls and piping.

I think part of your problem is the system is maintaining pressure all the time. This results in much greater standby losses. The boilers should only fire on a call for heat. With zone valves this is typically done with an end switch, but you may have to handle it a bit differently when using reset.

If you get stuck, talk to Noel Murdough at Slant/Fin and tell him I sent you. Even though you have Weil-McLains, Slant/Fin might be able to supply a better control system.

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zeb_3

what zone valve

what do you have for zone valves? I have worked on a few
jobs where we had honeywell zone valves and added an
optional end switch to each. t-stat opens valve, cam on
zone valve closes end switch then starts burner.

Unknown

tekmar

Tekmar have controls designed for steam boiler(s)