boiler short cycle

benny

Installed Burnham LE this pass summer with AL 40 indirect, works well but when calling for heat H.O says boiler cycles too frequently,everything was o.k during summer just supplying DHW.( every few hours) I told H.O this was normal (8 - 10 min) now w/low mass boilers.
Sized boiler to indirect, more than enough btu for heat though, controled with priority setting.Should I have gone with a smaller boiler output? Is there a way I can reduce number of cycles during heat?

Bill Nye

Your

HO could be mistaken?? Most of the time,what people call shortcycling is really in fact the boiler cycling on highlimit. There is only a 10° differential , non adjustable, in most cases.

It is a small bolier, it heats up fast. If you have a small zone or a mild day it is going to cycle.

Give it a listen yourself, and try to explain that is the way it is supposed to be. Or, I could be wrong. But you still gotta' give it a listen, you're the pro, not the HO.

Check with Burnham tech support, maybe you can downfire it. What is your firing rate, gph?

hr

Hard to put a number

on exactly what constitudes a short cycle. I agree with Bill, check it out and time it with a light load. Further complicating the cycle issue is the number of heat sourse generatore with Fans or inducers. Much more noticeable to homeowners than the old standing pilot quietness.

Start spinning a motor and blower to 8 grand and you may hear some noise. it's that high pitch that seems to penetrate the brain

I hate to see, or hear any electro mechanical thermal generator cycling often.

Without modulation, or buffering, toadys low mass low water content boilers are more prone to this. Even cast iron boilers have shrunk in weight and water capacity and are more apt to cycling.

More like a motorcrosser than a Goldwing.

Low mass emitters worsen the issue. Manufactures tell me the components have 100,000 cycle life and don't worry about it. Seems motors, dampers, relays, and ignition systems disagree with this figure, in my experience. As does the "parts replacement market" growth.

Wish I had stock in the hot surface ignitor business.

They ought to sell HSI's in gum ball or candy machines at the parts houses! Put them outside for weekend and after house acessability!

Spreading the operating control differential helps a bit. Install an adjustable setpoint in series and use the boiler control as the high limit. Used to be that was the true job of that control

Boiler reset controls can make a great improvement. Buffer tanks help a lot.

Deciding on the fix, and available dollars is the question.

hot rod

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Mark Wolff

btu change

Check your heat loss calculations. It sounds like you can reduce nozzle size to help make a longer burn cycle. An added benefit is increased fuel efficiency to boot.