How to set the heat anticipator in the mechanical thermostat for furnaces.
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- Опубликовано: 5 окт 2012
- This is a demonstration of how the heat anticipator is set to match the amperage draw of the furnace control circuit. Several different thermostat types are shown.
This video is part of the heating and cooling series of training videos made to accompany my websites: www.graycoolingman.com and www.grayfurnaceman.com to pass on what I have learned in many years of service and repair. If you have suggestions or comments they are welcome.
If you are a homeowner looking to repair your own appliance, understand that the voltages can be lethal, the fuels are highly flammable and high pressures are used. Know your limits. 
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A good tutorial, thank you. I used to do this for a living 25 years ago, and, while I knew I had to check the amp draw etc, I just couldn't remember the fine details on how to do it. You cleared all that up for me, I metered the white wire, set the stat, and all is working now as it should be. Good job.
Thanks for this, I was able to successfully replace my overly complex digital thermostat with a vintage honeywell t87 that I actually can get to do what I want.
Sometimes simple is best.
GFM
AWESOME clarity in both video and info. Thanks for the knowledge
You the man! Reading this while studying for exam and couldn’t understand how. But my brain said check with Gray and bam you hit it on the money.
Glad it helped.
GFM
Yes. Sometimes, they can be set for longer cycles because the boilers have more thermal mass (they take longer to warm up).
Hello sir,keep watching your video i really appreciate the way you explained i undertand every single word.thank you so much for your time and effort to help every body to give some ideas how to do it without hiring a profisional.im hoping if you have extra time to make a video about house hold boiler trouble shooting.again thanks a lot and may god bless you always.
I have boilers on the list. I just have not gotten to them.
GFM
I think it's worth mentioning that setting the anticipator equal to the amp draw equates to about 6 cycles per hour. In many cases with higher efficiency equipment, you want to use a multiplier greater than one to reduce the cycle rate. Honeywell used to recommend 1.4 for heat pumps, and sometimes you may want to use up to 2.0 for high efficiency equipment in a well-insulated home. So in your case 0.35x1.4=0.49 anticipator setting for less cycles. Likewise for short-cycle electric heat you should use a multiplier of 0.6 to increase cycle rate.
Good thoughts. I have meaning to go into this. The older houses needed the 6 cycles but the newer ones will work well with longer cycles.
GFM
Could I use sculpting clay to help seal a small leak at the fitting on my pilot tube instead of pipe dope? Not the pilot flame end but the other side thats cooler. I think the stubborn residue alone from the clay would pinch into the uneven gaps to seal it off. Thoughts?
Great video, very informative! I realize you work on only furnaces in your videos but I was curious if you knew if setting the anticipator for a boiler system was the same
I use the same setting for both.
GFM
Turn the thermostat temp setting as high as it will go to see if it does the same thing. If it does, the stat is ok and you may have a problem with the furnace itself.
GFM
Extremely! helpful thank you sir
Welcome
GFM
For those of us who don't have a clamp meter, could you use the multimeter leads between the red and whit wires at the thermostat?
Can I do this for hot water boilers also? Thanx
Just a note. On older natural draft furnaces where the thermostat only controlled the gas valve then setting the anticipator to the amp draw this method is acceptable. On furnace where the thermostat controls through the non-integrated or integrated control board additional information may be needed. If one checks the data label on the non-integrated boards you may see TH + 0.2 amps. This means if the amp draw on the W wire is 0.37 amps you add 0.2 to that for the correct anticipator setting. In this case that would be 0.57 amps. If you change the ignition control check the TH + rating. If it is not the same you will have to readjust the anticipator. The installation instructions will usually have the correct heat anticipator setting referenced in the instructions or on the wiring diagram. The newer Rheem/Ruud furnaces do not list an anticipator amp draw setting as they want electronic thermostats used. On high efficiency furnaces where the heat anticipator setting is not referenced multiply the W amperage by 1.8. This will usually get you very close to the setting needed when using a mechanical thermostat. When working on boilers multiplying the amperage on W by 1.8 will also work.
Gary Reecher Interesting. I will follow up on this. Thanks for info.GFM
Hi gray, like all your tech vids.
Can you clarify the correct setting of the anticipatory lever, on a white Roger's mech stat.
I have watched your vid numerous times and it's very vague ant not clear.
Now do you set the arrow end to required number
OR THE THUMB NAIL END OF THE LEVER THAT CONTACTS THE CIRCULAR WIRE.
OK THANKS FOR HELPING WITH THIS.
It is the arrow end.
GFM
I have another tip for avoiding temperature fluctuation in a home with electronic thermostats. If you have celsius/fahrenheit setting it is best to use the fahrenheit setting, because the temperature gradients are smaller.
Example 20- 21 celsius is quite a larger increase in temperature than say 69- 70 fahrenheit.
Quite true. Good idea.
GFM
Hi there! What is the typical amp draw for radiant in floor heating in a condo pls? The building's about 25 yrs old. Need to set/adjust 2 thermostats anticipator settings but not sure to what number. Cheers!
There are 2 ways you can go here. If you have a clamp ammeter, you can check the amp draw of the control circuit and set the anticipator accordingly. You can also adjust the anticipator to about 3, and if the unit cycles too often, set it higher and vice versa. Hope this helps.
GFM
Thank you GFM! I'll have to try the latter. Sorry if this is a dumb question but would you clarify please. By higher do you mean 1 - 2, or 4-5??
Can you please, simply tell me the proper anticipator settings for my Honeywell Class 2 LR95329? The furnace is constantly clicking/cycling, but the house stays fairly warm.
The anticipator setting is determined by checking the amperage draw of the furnace. The thermostat anticipator must be adjusted to match the amp draw. If you do not have or do not know how to use a meter, you can set by trial and error. Adjust the anticipator by moving the lever about 1/4" toward "longer cycles" on the anticipator. If that does not help enough, set it farther. You can also check my video "Adjusting the anticipator without a meter"
GFM
He did.
My thermostat is internal. Inside the combination gas valve. The copper wire jogs 45º to the left rounding a peg as it turns 45º to the right. From here it begins coiling about 2 1/2 times toward its center connected to an aluminum disc with ripple rings shaping it out to the edge. It is about the size of nickel. Below that sets another round disc part with ripples( not like an accordion but allows for movement up and down triggered by a magnet or something or space of the gap from the temp of the thermostats copper wire. Anyway above the first disc it is connected to the control knob for heat. Does that knob also serve as my anticipator or is my set up void of one entirely? -Propane
You have a hydraulic valve. There is no effective anticipator. As the disc warms, the cap tube transfers the pressure to the opening mechanism of the gas valve. Hope this helps.
GFM
Thank you sir, it does help because it's not transferring the pressure to the opening mechanism when it's supposed to. That must be why even though my pilot flame is working and the pilot knob set in the "ON" position, my burners still won't fire up.
Thanks for the education, I've watched many of your videos and appreciate you sharing the wisdom you have with everyone.
Welcome and hold onto your wallet when replacing the valve.
GFM
I loosened the two screws of the aluminum cover for the thermostat/control knob and I heard it disengage . A faint "thump". The knob wasn't backing out far enough to allow this. We had heat all day for the first time in 4 years. :)
Hope it keeps working.
GFM
and when my furnace turns on it last for 1 min turns off then it turn on for 7 mins why das it turn on and off for that 1 min thk
What is the normal operation? Is it Burner/Flame come, then the blower turn on the same time or
the Burner/Flame come on for 30 second then flame turned off, then the blower turn on next?
I have problem that the Blower turn on too late and it is blowing kind of "warm" air and not hot air.
(flame come out then after 1-2 minute the blower turn on).
What is the average number (ie 0.34) for an old 1995 Carrier Furnace. Thanks.
Burner should come on, 30 seconds later, the fan should come on. If the flame goes off soon after the fan comes on, the thermostat anticipator may be set for too short of cycles.
GFM
@@grayfurnaceman Thanks for the information. Appreciated all your inputs. I think I need a new digital thermostat. The old analog mercury thermostat may not working after 25 years. I just wonder why the blower did not turn on right after the flame shut down or blowing when there are still flame. Don't know why the blower delays for 1-2 minutes when the flame turn off and because of that, the air is not that warm. Thanks again.
Notes: New air filter, new OEM flame sensor and new OEM igniter.
So,,, the amperage variates on all the air handlers ?
Ernesto B It varies with the ductwork application.
GFM
grayfurnaceman thanks
grayfurnaceman one more question ,
On heating mode my blower turns on first then the heater ,anything that I can do in order for the heater to star few seconds before the blower ?
Thanks in advance
what whould happen if u put the heat anticipator up all the way
it would shut the furnace off early
Sometimes the control will say the correct amp draw.
If you set it to the highest number (1.2 usually) the furnace will cycle longer and the temperature in the structure will vary widely if the actual circuit amp draw is lower than the 1.2. If you set it at the lowest setting (.1) it will cycle about every 2 minutes. Hope this helps.
GFM
I just checked the amp draw on the white wire on the furnace and got a clamped reading of .099 while running with fan running as well. Does this mean I should move the anticipator all the way to .1 to get 6 cycles per hour? It is summer so we are typically using the air conditioning. It's a regular gas furnace and a normal central air unit. Could a different setting be desirable in the summer with ac?
why can't you use a analog gauge ?
They are not sensitive enough. You can use one if you wrap the wire that is sensed around the jaw of the meter 10 times.
GFM
Same for AC, but yellow wire ?
The A/C has an anticipator, but it is energized when the A/C is off, and thereby it is non adjustable.
GFM
10 wire wrap lol