lead lag steam boilers?

gunny

Can you lead lag steam boilers? Does anyone know if there is a control that will lead/lag steam? If so how do you pipe it?

nicholas bonham-carter

lead lag steam

by lead lag, do you mean alternate firing between 2 boilers?

what result are you trying to obtain? i think you might be better off just using 1 boiler as primary, and reserving no. 2 boiler for emergency use.

there could be some use  to have 2 boilers, sized .75 X and .25 X [where X= the radiation load]. this would enable the staged firing for a steam system. stage 1 would be both boilers firing, and then cutting out the smaller boiler when a certain pressure has been developed. there may be a need for electric isolation valves to prevent back-pressuring the inactive boiler, but i think the principle deserves more investigation.

most boiler mfgs have specific instructions as to multiple boiler piping.--nbc

Jamie Hall

Nick's idea

is the way I'd go on it -- and almost did.  The split in power between the two sounds about right; basically what you're doing is hitting the installed EDR with the larger of the two, and the pickup factor with the smaller.



The biggest issue is your near boiler piping.  Most manufacturers have schemes for paralleling boilers, and there are some diagrams here and in Lost Art, as I recall.  They should be followed with fanatical precision.  Your objective is to avoid water level problems and oscillations, but there is no reason why it can't be done, if you pipe it right.  Valves should not be needed.



As to controls, each boiler has its own vapourstat.  Both can have the same differential, but the big boiler is set to cut out at a higher pressure than the littler boiler -- say 11 ounces vs. 8 ounces, just for example.  That's all there is to it.

The Steam Whisperer (Formerly Boilerpro)

Controls

Check out R&D electronics in Morton Grove, IL  847 583-9080......they may have what you're looking for or be willing to build it.  So far, I have staged two equal sized steamers off of a two stage thermostat...one in a one pipe system and another in a two pipe vapor system. Another one is just staged with different pressure settings on the boilers. 

Boilerpro