Short Cycling

ChasMan

I have this exact same issue. I also have another short cycle issue. Often the heat will be satiated by the hot water in the boiler. After the temp drops and the burner comes on the zone valve shuts off and then the boiler shuts off after only running for 10 seconds...

I have been looking for a good control guy to help me but so ar no luck.

Flatswalker

Short Cycling

I have a Honeywell L8151 Triple Aquastat Relay with a fixed 10 degree setback ( not adjustable) on the high side,one and one half year old boiler,40 gallon Super Store, Beckett Burner, .85 nozzle, 2 zone hydronic system, one circulator, downstairs zone rarely comes on. When the thermostat calls for heat, circulator turns on, as soon as 10 degree drop is sensed by aquastat, boiler fires and quickly shuts down as soon as high side limit is reached. As cooler water enters boiler, temperature drops fairly rapidly causing burner to fire again. Besides new Beckett Heat Manager, or new Honeywell aquastat with adjustable
high side, what are my options so that I may extract more heat out of the system and stop the short cycling. I was told that adjusting the flow back to the boiler may help.
Any input would be welcomed. Sorry about being so " long winded. "

Ron Schroeder

There are several possabilities.

Most outdoor reset controls like Tekmar have adjustable differential and would save more fuel than the heatmanager.

Depending on your boiler and your heat loss, you may be able to go down a nozzle size or two and re-adjust your burner.

If you have an extra tapping on the boiler, you may be able to install an additional thermal well and put in a L4006 single aquastat with an adjustable differential. Wire the new aquastat in series between the B1 terminal of the triple aquastat and the burner. Turn up the triple aquastat high limit to about 190 or 200 degrees and set the new aquastat for what you used to have the triple aquastat set for. Then set the new aquastat differential for at least 20 degrees and you will double your run time.

Or just get the new L7124U aquastat to replace your present aquastat.

Ron