High Limit/Low Limit recycling

Martin Romero

Ron Jr.,

Thanks for the reply. The hot water boiler is the 0090 Raypak Copper Fin. The aquastat is a honeywell and it has "l6008G 1009" on the top.

I don't believe it's the thermostats that are causing the cycling, because the ciruclator often is not running during these cycles.


Thanks,

Martin

Martin Romero

High Limit/Low Limit

Heating Helpers,

Allow me to report something I've noticed on numerous occasion.

I hear clicks from my boiler room indicating that the burner is coming on and shutting off. I observe this on/off cycling and notice the following: the temperature guage on the hot water boiler reaches the high limit setting (170 degrees) at which time the burner turns off. The temperature continues to climb (to over 200 degrees) then eventually drops to about 10 degrees below the high limit setting. The burner then kicks on again. All of this is happening in about 1 - 2 minute cycles.

During this cycling, the circulator is not running and the thermostats are at their lowest setting.

I can eliminate the cycling by turning up one of the thermostats.

I wonder if the short cycling is due to a malfunction. Any help will be welcomed.


Thanks,

Martin

P.S. Plumbing for Solar System is about 90% done. I'll give updates and photos soon.

Steamhead (in transit)

Sounds to me

like you have a control problem. Either a relay contact is stuck, or the boiler is wired to maintain temperature all the time.

If the boiler does not have a tankless coil in it, maintaining temps this high is very wasteful.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Martin Romero

High Limit/Low Limit recycling

Steamhead,

If the boiler is wired to maintain heat all the time, does this mean that there is a low limit switch somewhere that is not tied to the thermostats? It sounds to me like such is the case, since the circulator is not coming on during those cycles.

I don't know how to check for a stuck relay. Any suggestions?


Thanks,

Mart

Unknown

If the boiler

is cycling every 1 to 2 minutes , then something must be making it cycle - either a heat or hot water demand . Does the boiler produce hot water also ? What type of aquastat is it ? And what brand boiler ?

Chris Jorgensen

High/Low cycling

It sounds like a Triple Aquastat with the LOW & DIFF settings in conflict with the HIGH Limit. The LOW has to be set to a lower number than the HIGH. The book has a little drawing that isn't exactly user friendly. In words: you add 10 to the DIFF setting and subtract from HIGH-then set the LOW at a smaller number.

http://customer.honeywell.com/techlit/pdf/PackedLit/95-6571.pdf

Martin Romero

High/Low cycling

Chris,

I'll have a look at this. Thanks for taking the time to help.


Peace,

Martin

Unknown

I'm not familiar

with that aquastat or the boiler . But I forgot to ask - how many times will the boiler cycle for every minute or 2 ?

I see that type of heat overide alot . An upswing of 20 to 30 degrees after the boiler shuts off with no call for heat or hot water is fairly common .

What you're saying is the boiler temp will go from 200 to 160 , then 200 , cycling like that every minute or 2 ?

Martin Romero

high limit/low limit cycling

Ron jr.

I re-read this thread tonight, and I realized I had missed your question. You're right; about every couple of minutes, the burner will cycle. The temp increases to 200 degrees or so, then back down to just below the high limit where it kicks in again.

My guess is that the thermostats are not calling for heat during some of this cycling, because the circulator is off.


Thanks,

Martin