Calibration wrench for Honeywell

acl10

Where do I get a 104994A Calibration wrench to calibrate a honeywell thermostat?

What size id s the nut so I can find a genericc wrench or does anyone know where I can find a generic wrench?

billtwocase

you can check Sids

They are probably scarce due to the fact that the mercury thermostat been out of production for a few years, too bad for that. You will never find a thin enough wrench to calibrate. I bought a few about 4 years ago. Always a handy tool. One side for T86/T87, other for T822

icesailor

Calibration?

Why do you need to calibrate it? I've never seen one that needed calibration. If it did, it was broken.

An easier way to calibrate a T87 is to move the mounting plate out of level in the direction it needs to go. But I also found that if you went by the thermometer on the thermostat, that was off, not the thermostat. By mounting the remote probe of a digital thermometer next to the thermostat, I found that the thermostat was correct. That also showed that the thermostat was mounted in a bad location and was suffering from drafts.

If none of the above fixed it, I replaced the thermostat.

acl10

Bilt can you tell me what size wrench I am looking for? What is the size of the bolt

Bilt or anyone can you tell me what size wrench I am looking for? What is the size of the bolt

Thermostat Honeywell T8090A

icesailor

T8090 Honeywell clock thermostats

A T8090 is a clock thermostat. If you try to "recalibrate it, you will probably make it inoperable. It probably has a burned out heat anticipator or an improperly set one.

The only thing I have ever seen go wrong with them is that the clock dies or the batteries go dead.

You are bound and determined to futze with it. Have at it.

I'm only posting this to save anyone else from going through the aggravation some of us have gone through.

Replace it with a Honeywell 6000 series clock thermostat. That's what i do when one of mine fail. They are not available because of the mercury bulbs and they can't be repaired.

Two out of my five T8090 thermostats have been replaced by series 6000 ones and I have another one to replace because the clock has died.

It sounds like Bill has a wrench. I lost mine from lack of use years ago. We probably have the same experience.

acl10

The instructions tell you how to calibrate it

The instructions tell you how to calibrate it. I need to know the size of the  bolt so please mesure the wrench. This is a new one that was in storage. Thank You

acl10

The instructions tell you how to calibrate it

The instructions tell you how to calibrate it. I need to know the size of the  bolt so please mesure the wrench. This is a new one that was in storage. Thank You

icesailor

Calibrations:

Not that I personally care, but I have sold and installed over 70 of those over the years. I have five in my house now but I have two that I replaced because the clocks fail.

I have NEVER had to calibrate one. And any thermostat that I have ever tried to calibrate didn't work any better after futzing around with it.

I told you, tip the backing plate so it is out of level, That's what you do when you loosen the nut. You change it from level.

You haven't even said why you think that your brand new clock thermostat needs to be calibrated. Did you set the heat anticipator properly?

Do what you want but the LAST thing that I would ever do is touch that nut. And I know what I am doing. Maybe you do too. But I wouldn't touch it until I tried everything else.

What is the control amperage?

Plumdog_2

Try Auto Parts

I got a thin open-ended wrench set for ignition points a long time ago, I believe the nut in question is 9/32 but I could be wrong. Out of the box, the Mercury Bulb stats were often 3-4 degrees off, and the thermometer in the cover was often off as well. Always let them sit awhile without handling or breathing on them, then check again. A wrong heat anticipator setting can make them flip on and off and never fully heat the zone.

icesailor

Heat Anticipators:

Especially if the control amperage is higher than the anticipator settings.

That's what an Amp Mate was made for. You connect it into the zone to see what the control ampperage is, and set the heat anticipator to that.

Zman

Ice

Ice,

If you look at his other posts, He is very concerned that different t-stats can range a degree or so.



AC10

 I would think a good electronics store would have a wrench like that. I personally don't this calibrating one t-stat precisely is very important. The bigger issue with t-stat is their location.You can easily have a 5 degree range within a room. This range will change constantly.Little changes in outdoor temp, sun angles, opening and closing of interior door ect will make this dynamic. If you are concerned with accuracy, look at t-stats with multiple remote sensors and set them up to average.Tekmar has some nice ones.



Carl