Heat Anticipator Setting

Scott Kuchta

I have a Honeywell Round thermostat similar to the T87F, it just doesn't have the fan settings at the top. This controls my oil-fired, one-pipe steam system.
My question is how to set the Heat Anticipator correctly. I went to the Honeywell website and got the directions, which include the use of an ammeter if the setting is not stamped on the control nameplate. What is the control nameplate and where do I find it and this rating, if present? Or is there some other advice on getting this set right? What is the skinny on this thing and why is it important to get it right?
Thanks.

Fred Harwood

Anticipation

It's important to set anticipation for your building and heating system so that you have even heat with little or no overshoot and wasted energy. The best method is with an amperage meter. Just connect it appropriately, read the amperage, and set the anticipator slider to that number. Often, that number approximates 0.2 amps, about the middle of the anticipator movement. Once set, you then observe how many cycles per hour your equipment runs, and if you have overheating rooms. Try for three or four cycles per hour, and increase anticipation if necessary to stop overheating. (Move the slider up to the right, lower number, a bit at a time.) Then tell us how it went.

Dale

Much asked question

I'll differ a bit from the other post so you may want a 3rd opinion. I think you have a t87f and the lack of switches makes me guess you have a heating only subbase. Honeywell thinks of the stat and sub base as separate parts. If you have an amp meter you can turn the stat down, hold the meter on the 2 left hand screws (2 of the 3) and read amps for a few minutes. Or you can loosen the 3 screws, remove the stat part and see the 2 wires on the left of the subbase and amp accross them. Set the anticipator slider to what you read. If you look at the slider numbers real close you will see "longer" on the right with an arrow pointing left. On the right is .1 amps on the far left 1.2 amps. The more amps the less resistance, the less resistance the more heat,the longer the cycle since the more heat is generated to trick the bimetal into opening sooner. For steam I usually set them to 1 or 1.2 so I can get as close to 1 cycle per hour as possible. This assumes the stat is in or near a room with a working radiator. If in a cold room the stat heat can shut it down too soon.

Kyle Kubs - Benchmark Home Inspections

Reason

Scott, you've got two sound answers. I'm just going to stretch it a little more to make it easily understandable. The reason for the heat anticipator is that without it, if you set your t stat to 70, the boiler runs until it reaches 70 in the room. Problem is after the stat tells the boiler to shut off there is still a bit of latent heat that is still on its way up and you would wind up with the room being more like 74-75 and then droping to 68 before it turns on again. What the anticipator does is gives you an adjustable preset on when to shut off the boiler before the room reaches 70 (thats the anticipating part) so that when that latent heat that was still in the boiler and pipes finishes coming up you just arrived at 70. - Kindof like shuting off your car and throwing it into neutral a half block before your house, letting it coast and stopping right in your parking spot. (your boiler doesn't have brakes...- if it does, let me know, I want to see it...) If you don't have an ampmeter to check it, .2 is a good place to start and you can just monitor the stat for a while (actual temp. versus the temp. you set it for) and move the slider one way or another until you get reasonable close.