Strange temperature question

[Jsf721]

I had a new central AC unit installed and it just got to be AC season. In NY. One degree up it is hot and one degree down it is freezing. Cannot figure this out.

3 ton unit.

 

[JakeKohl]

I've got it...your canuder valve is stuck.

 

[JakeKohl]

but, seriously...we need more info to help.


define "hot" and "freezing". Did you get a new thermostat with the unit? Have you measured the air temperature next to the thermostat and does it match what the thermostat says the temperature is?

 

[Falcon67]

It's called "hysteresis" in your thermostat. If it's too wide, you can drive the temp 2~3 degrees in either direction which is more than enough to change how the sir temp feels on your skin. If it's too narrow, then your unit will have short cycle times. So- could just be a t-stat problems.

 

[Jsf721]

Thanks guys, I will try replacing the T-Stat. If there is any info i can provide to help you better uinderstand the system, ust say so and I will get the info.

Thanks

Jeff

I've got it...your canuder valve is stuck.

but, seriously...we need more info to help.


define "hot" and "freezing". Did you get a new thermostat with the unit? Have you measured the air temperature next to the thermostat and does it match what the thermostat says the temperature is?

It's called "hysteresis" in your thermostat. If it's too wide, you can drive the temp 2~3 degrees in either direction which is more than enough to change how the sir temp feels on your skin. If it's too narrow, then your unit will have short cycle times. So- could just be a t-stat problems.

 

[Jackfre]

Before changing the stat look at its instruction sheet. This may be an adjustable setting.

 

[Jsf721]

What exactly would I be adjusting?

Before changing the stat look at its instruction sheet. This may be an adjustable setting.

 

[Eslader]

You still haven't defined "hot" and "freezing." Are we talking, 80 and 50 here, or 76 and 73?

 

[Jsf721]

When the thermo stat is set at 74 degrees, it is feeling warm and somewhat stale humid.

I move it to 73 degrees, and it is down right cold.

I ordered an IR thermo so I can get you a real true life reading. Should have Monday.

You still haven't defined "hot" and "freezing." Are we talking, 80 and 50 here, or 76 and 73?

 

[kamesama980]

this came up in a thread I was reading just 2 minutes ago: an IR thermometer reads surface temperatures, and will vary widely based on the emissivity of the surface. You want a plain jane cooking style thermometer (long stainless tube with dial on the end) in the right range (NOT 100-600f like most cooking thermometers) to read air temps.

Might also help if we knew what type of thermostat it is. I've seen old-school bimetal strip (thermomechanical) thermostats go bad from age and have either the setpoint or hysteresis be far from the mark.