Happy Medium for Anticipator?

John Shea

I'm running a Peerless steam boiler (1.5 million btus) on a two-pipe gravity return system.

At the begining of the heating season, the caretaker had to kick up the thermostat a degree or two when she would get complaints. She said that the boiler wasn't running long enough to get sufficient heat to the furthest radiators.

Since then, I have bumped up the thermostats anticipator from a preset of 5 to 18, which would (based on my understanding) insure that the boiler would run for at least 19 minutes. This change definitely made a difference.

However, now the owner (my mother) is now complaining about the tremendous increase in gas consumption.

Is thaere a happy medium when it comes to the anticipator?

Is it better to run the boiler frequently for shorter periods or to run it less often but for a longer cycle?

Thank you.

Firedragon_4

If you set it with a meter

you should hit it closer than anything else, like this:

http://www.mitcomfg.com/catalog/mitcofull45.htm

John Shea

Let's assume the tstat is calibrated.

Again, which do you think is more efficient and would provide better heat? Frequent shorter cycles or infrequent longer cycles?

Fred Harwood

Anticipation

Once you've set the anticipator to the current flowing in the control circuit (see below replies), you may change it further based on observation. However, in order to ensure quick response, your steam mains must vent very quickly for even heating among radiators. Tell us about your mains (diameter and length) and their vents, or post pictures. Failure to rapidly vent mains means that your burner must run long enough to get steam to the last radiator, a process that is slowed by slow venting. Once your mains vent rapidly, then the anticipation setting may approximate the run time needed to heat that last radiator, and no more than that.

Dale

Underlying problem

Usually the fewer cycles the better. This assumes and this is a big if, that the cycles are controlled by the stat. If you ask for longer cycles by increasing anticipation you may not be able to get steam out of the boiler fast enough because of a variety of problems. We know little of your system, still, 1.5meg input is alot but still could be in the 2# design area. My building is 1.2meg input 2 pipe steam at 9# because the condensate from unit heaters is lifted up into returns. We also have a big boiler feed pump. So, maybe your pressure is set too high. How does the owner know fuel use, therms by degree day is the only way to check. Also, where's the stat located? If it's in a cold area the higher antic. heat can turn the boiler off too soon. I think given the amount of fuel you use I would invest in the steam special book package at the beginning of the site. We all wish most steam problems were solvable by aticipation adjustments.

Firedragon_4

The longer the cycle the better

for the combustion process and the fuel efficiency! But, steam has pressure to deal with and it's not as flexible as water or air.