Q&A on How & Why to Adjust the Thermostat Heat Anticipator

Q&A ion Heat Anticipator Setting Numbers

Starting Heat Anticipator Setting FAQs

Where to set the heat anticipator on a White Rodgers Thermostat

Where should I set the heat anticipater on a white rodger thermostat? On 2017-07-08 by Jorge Acosta

Reply by (mod) - match the primary control amps rating or use Honeywell's table of settings

Jorge,

Adjust anticipator to match current rating of primary control. Rating is usually stamped on the control name- plate.

If you can't find that data, use the table below, recommended by Honeywell,

Or you can consult the complete and detailed heat anticipator setting tables given in our article

HEAT ANTICIPATOR ADJUSTMENT - Daniel

Here's an alternative to using a mini-Ammeter to check a thermostat heat anticipator circuit setting

An alternative to using a Mini-Ammeter is using a loop of wire with 10 wraps of wire; such as 10 wraps of 16 or 18 gauge wire around 4 fingers. Hook this up in series with the thermostat just as you would the mini-ammeter.

Put the jaw clamps of any journeyman's type ammeter through the loop and divide the reading by 10 for the systems' current draw. This way you won't need an extra, sensitive low reading ammeter. You can also use any number of wraps for sensitivity or ease of division.

Most good DMM's also now have a current scale for measurements up to 10 amps. The point is, as you make it, is to MATCH the thermostat to the system. Then, any fine tweaking is easier from there. Thanks for a great article. Greg- On 2016-12-15 by greg riutzel

Heat anticipator adjustment to match the gas valve amps rating?

Thank you for incorporating my comments.

The thermostat heat anticipator needs to be adjusted at installation to match the furnace gas valve. Doing that will make the thermostat behave the same way for any furnace.

For example, my furnace gas valve is rated at 0.6 amperes. So the anticipator should be set at 0.6.

Another furnace gas valve might be rated at 1.0. So the anticipator should be set at 1.0.

The 0.6 setting for my gas valve will give the same thermostat behavior as the 1.0 setting for the other furnace. - On 2015-04-13 by Qprew7U

Reply by (mod) -

Thanks QP

What I mean is that as shipped from the factory the typical wall thermostat - among those that had a heat anticipator adjustment such as the famous Honeywell T87, will work well with most heating systems.

Unless the installer reads the data tag giving different heat anticipator adjustment recommendations (we show this tag in the article) and matches it to the heater then she or he should leave it alone.

Your point about matching the gas valve is helpful and certainly applies to gas fired heating equipment.

Keep in mind that this thermostat is very widely used on furnaces, but also on hot water and steam heating systems and with both oil and gas fired equipment. So there is not a single "right" number

Recommends not using the heat anticipator for steam heat systems

Good article - but in steam systems, you should tell people to cut out the anticipator entirely.

Because the steam systems take so many minutes between the time the thermostat detects a need for heat and the time the boiler boils water, delivers it to the radiators, then heat up and finally warm the room, the anticipator function isn't really needed.

I didn't see any instructions for how to cut it out entirely, using the other lug or a drop of solder on the coil. - Bob On 2017-03-11 by bob

by (mod) -

Bob

Thanks for the interesting and important comment about heat anticipators on thermostats controlling steam heating systems.

The total amount of anticipation time effected by those thermostats that include a heat anticipator is not that great that in my opinion there is any need to try to remove the feature.

One could simply set it to the recommended generic setting for the type of heat in use. For steam heat for a typical Honeywell setting that's at 1.2A.

Remember that the anticipator is functioning by basically turning the call for heat off slightly early - that's all.

The heat anticipator in a room thermostat has little to do with when the heat turns ON, only when it turns OFF.

Heat Anticipator vs Thermostat Sensitivity to Room Temperature FAQs

How can I make my room thermostat more temperature sensitive

Our furnace comes on at a 4 degrees difference I want 2 what can I do to change it - On 2019-03-22 by Anonymous

Moderator reply: How to improve the temperature sensitivity of your room thermostat

Most room thermostats do not themselves have a temperature sensitivity adjustment. And if you made the thermostat too sensitive to room temperature, it might try to switch your boiler or furnace on and off too frequently, leading to oscillating and heating equipment damage.

I infer that you feel that rooms are too chilly - getting too cold before your heat cycles back on.

If I'm right, you can take these additional steps to improve your room comfort and the performance of your heating thermostat:

• Choose a good thermostat mounting location:
  
  not in a draft, not in direct sunlight, not on an abnormally warm wall such as the wall behind which your boiler or furnace is located
• Set the appropriate thermostat turning OFF point
  
  for your thermostat with its heat anticipator (if your thermostat has one) - that will keep the thermostsat from turning your heat off too early before the thermostat is satisfied.

  For adjusting the point at which your thermostat turns OFF, take a look at your thermostat and see if it includes an adjustable heat anticipator such as we discuss
  
  at HEAT ANTICIPATOR ADJUSTMENT

  OR post photos of the thermostat front cover and interior and we can comment further.

• Review our Building Heating Cost Energy Saving Steps and Priorities
  
  Found at ENERGY SAVINGS PRIORITIES
• Check your home for excessive heat loss points & drafts
  
  as we explain at INSULATION INSPECTION & IMPROVEMENT - home
  
  and at ENERGY SAVINGS in BUILDINGS - home

Line Voltage Thermostats vs Dayton Low Voltage Thermostat temperature swing

Thank you for sharing your expertise regarding thermostat setup. I live in a 1970's ranch house equipped with electric baseboard throughout.

Line voltage thermostats in the bedrooms provide consistent temperature but a large part of the house is controlled by an old Dayton low voltage thermostat that would allow a 5-6 degree temperature swing.

Ive managed to adjust that down to 1.5-2 degrees.

Much better! On 2019-02-24 by Tom from Bethlehem Pa

Reply by (mod) -

Tom

Nice going, and thanks for the feedback. It would be helpful to know the brand and model of the thermostats involved.

by Tom from Bethlehem Pa

The thermostat in question is a Dayton 2E156.

I did not find any direct info online about this model. Perhaps as old as the house, mid 70's.

I had touched it up with a bit of deoxit this fall. Ill be interested to see how sungle digit outside temps change the indoor temp swing but right now its less than 2 degrees. Ill post a couple and let you decide whats helpful.

Thanks again for the wisdom!

by - (mod) - Dayton Room Thermostat Information & sources

Thanks for those excellent photos. More about Dayton thermostats is

at THERMOSTAT WIRING DAYTON where you can download the IO manual for your Dayton thermostat as a free PDF.

Heat Anticipator Settings for Hydronic Boilers

What's the right heat anticipator setting for a hot water boiler?

What do you set the heat anticipater on a low pressure boiler? I think the brand is a Hydro On 2019-01-31 by Larry

by (mod) - at or above 0.6A

Larry

please check out the three approaches to deciding on the thermostat heat anticipator settings given in the article HEAT ANTICIPATOR ADJUSTMENT - T8

One of those three is a useful

Table of General Heat Anticipator Settings

Here's a drawing giving similar guidance

That you could follow if you have no other information.

So start by setting your T87 thermostat heat anticipator somewhere between 0.6A and 1.25A.

Heat Anticipator Setting vs Room Temperature Overshoot FAQ

How to Fix a Honeywell T822D Thermostat Temperature Overshoot Problem

Our house thermostat is a Honeywell T822D, and we recently added a Beckett Genysys 7505 as primary.

The product has draw of .1amp, the lowest setting on thermostat is .18, which I now use as setting, yet there is overshoot, which has been the case even before new primary. Any suggestions. On 2018-12-07 by Pat A

Reply by (mod) -

If you changed your thermostat to the T87 shown here, that scale goes as low as 0.1 A. But Honeywell warns not to set the anticipator beow 0.3A.

I would expect the overshoot problem to be most serious if you have large cast iron hot water heating radiators.

Is that the case? If so you might consider some thermostatically operated radiator valves as a better solution.

by Pat A

Not really. A few, but the boiler is a WM SGO3, with heating capacity of 354 SF of steam, and radiation sf is 218.

Reply by (mod) -

I'm talking a bit beyond my expertise here so you should consider this an opinion only.

Considering that we're discussing steam heating and not hot water heating if there is an overshoot problem I would have dress that by installing the proper steam vents on the radiators.

I might need an adjustable vent.

That's because it may be but events are taking so long to vent air but the whole heating cycle is being extended. I also would look carefully at the thermostat location.

See STEAM VENTS 

or better, to make each radiator into a controlled heating zone

see AUTOMATIC RADIATOR VALVES - Automatic or Thermostatically Controlled Radiator Valves

- Daniel Friedman

My service tech said set the heat anticipator to 0.2Amps - room temperature overshoots

I am reading your section on " How & why to adjust the heat anticipator on a room thermostat" and my oil burner service man installed a new control on my baseboard oil/hot water burner lately.

It has a L7224/L7248 Electronic Aquastat next to it. When I take the cover off ther is a piece of cardboard that tells you to set the Thermostat anticipator to 0.1 amps.

The oil burner serviceman had it set to 0.2 amps and the burner seemed to be overshooting the thermostat reading.

I just turned it down to 0.1 amps. I question your article that says you should never turn down below 0.3 amps.

Can you help me there? I have copper tubing/finned baseboard heat in a small apartment so NO mass (cast iron radiators).

Your article also says the recommended setting to be 0.8? Can you help me out with these contradictions? Thank you, Thomas Spero On 2018-04-09 by Thomas Spero

Reply by (mod) -

Thomas,

Thank you for posting your question and opinion.

My 0.3A quote is excerpted from Honeywell's "general" guidance for the heat anticipator setting.

But I agree that it makes perfect sense to follow the instructions on the specific heating equipment you've installed.

Another approach that's beyond the scope of most service techs is to actually *measure* the current draw on the heating thermostat control circuit. That requires using a special low-range ammeter or a digital VOM/DMM with a suitable range sensitivity. Most techs wing-it.

The apparent contradictions in heat anticipator setting advice aren't as ugly as they may seem.

In the article above on this page you'll find a summary table titled

Table of Heat Anticipator Setting Recommendations for the Honeywell CT87A,B,J Round® Thermostat

there you'll see a range of recommended heat anticipator settings that depend on the type of heat being controlled. Those numbers range from 0.3A (electric heat) to 1.2A (steam heat). And yeah, you'll see Honeywell's recommendation for forced hot water heat as 0.8A at the heat anticipator.

Keep in mind that Honeywell recommended these settings as a general number - the company (and I) can not possibly know the specific performance or behaviour of every installed heating system and I think Honeywell's engineers would agree that further adjustment could be needed.

Certainly you can try lower settings down to 0.1 if your particular heating system is continuing to overheat or over-shoot.

Compare the actual room temperature - measured independently but AT THE THERMOSTAT with the thermostat's set-temperature.

For example if the thermostat set temp is 68F and you see that after your boiler turns OFF your heat continues to rise to say 70F or more, then you might try setting the heat anticipator to a lower number.

Finally, don't forget to look for other reasons for heat overshoot, such as a zone valve that's not closing or a check valve at the boiler that's stuck open when it should be closing.