Where are the AC Thermocouples?

[dasams]

We have a new 2018 FC 27 with two A/C's. Very happy with it

Can anyone tell me where the thermocouples are located? I assume near the A/C units but not sure. The reason I ask is that we haven't dialed in the set points and it would be helpful to know where they are. Thanks, Dave

[Bgibbs]

Don't know where yours are, but in our 26u, the one for the main a/c is in the controller on the wall and the other one is mounted under the rear overhead storage in the bedroom.

[carl2591]

ODD are they use to measure air temp or something like that. usually you think of thermocouple in gas furnace type appliance. or the gas oven..

Originally Posted by Bgibbs

Don't know where yours are, but in our 26u, the one for the main a/c is in the controller on the wall and the other one is mounted under the rear overhead storage in the bedroom.

[uncle_bob]

Originally Posted by carl2591

ODD are they use to measure air temp or something like that. usually you think of thermocouple in gas furnace type appliance. or the gas oven..

Hi

I think in this case "thermocouple" is being used as a term for "generic temperature sensor".

Bob

[jayseejay]

Originally Posted by dasams

We have a new 2018 FC 27 with two A/C's. Very happy with it



Can anyone tell me where the thermocouples are located? I assume near the A/C units but not sure. The reason I ask is that we haven't dialed in the set points and it would be helpful to know where they are. Thanks, Dave

Hi Dave. If by thermocouple you mean the temperature sensor for each zone, in the 27 FC, one is located in the thermostat controller itself (generally this is Zone 1) and another is located behind the TV, protected by a small white plastic cage (generally this is Zone 2). Note that many of us with 27 footers have a problem with the Zone 2 sensor reading 8+ degrees higher than ambient because it is mounted on the wall that encloses the refrigerator and hold the TV - both of which elevate the temperature in that area.
Joe

[carl2591]

right,,, not using my right side brain. I usually called them "temp sensors" when used for air temp measurements and thermocouple when used in gas appliances.

One thing you could do would be install two strips of wood behind the t'stat to elevate it and with a space allow air flow helping the sensors detect accurate air temp not the temp of the warm wood cause by the refrigerator running.

I had the same issue with a 12" clock with Humidity and temp sensor reading like 80 degrees when i know It was not that warm.. I cut some opening in the base top and bottom, which was plastic and "sealed" quite well to the painted wall, to allow air flow thru the back which helped with accuracy of the devices.

I have seen issues in home with the AC over cooling the interior due someone putting a light on table under the tstat causing it to think the interior was higher that it was and running a lot more.

Sometime thing are not well thought out especially in TTs so you have to figure out the issues sometime.. fun fun fun.

Originally Posted by uncle_bob

Hi

I think in this case "thermocouple" is being used as a term for "generic temperature sensor".

Bob

[dasams]

Originally Posted by jayseejay

Hi Dave. If by thermocouple you mean the temperature sensor for each zone, in the 27 FC, one is located in the thermostat controller itself (generally this is Zone 1) and another is located behind the TV, protected by a small white plastic cage (generally this is Zone 2).

OP here and I'm a chemical engineer. Most temp sensors in the lab or in the field are thermocouples so yes that is what I was referring to.

Joe - Good info as I see the white cage behind the TV. Thanks, Dave

[uncle_bob]

Hi

Ummm ..... errrrr ....

A thermocouple is a very specific type of sensor. It is made up of a junction between two metals. They generally have a very low output voltage (which varies over temperature), but also a low output impedance . Wiring them up properly involves keeping the types of metals in the wiring matched up. Short runs or extreme temperatures are good for thermocouples.

A thermistor is a different type of sensor. It varies resistance over temperature. They generally are easier / cheaper to hook up for things like room temperature sensing. Of all the common sensor types, they are the most sensitive from a signal to noise perspective.

Bimetal springs are yet another approach to temperature sensing. Here a contact is opened or closed by the differential expansion properties of the spring. If you look in most older homes, that's what is in the thermostat. They are very reliable and dirt cheap to produce.

We live in a world of silicon this and that. Temperature sensors are no exception. There are an enormous number of them on the market. Most modern microprocessor based thermostats are based on silicon (chip / IC) sensors.

If you are going to get fussy about temperature, you likely use a platinum RTD (resistive temperature device). For a few thousand dollars you can get a pretty good one. They are pretty rare in things like wall thermostats. They (and precision thermistors) are pretty common in precision lab temperature controllers. Both have limited temperature ranges, outside those ranges, thermocouples do show up.

Somehow I suspect that's more than you ever wanted to know

Bob

[carl2591]

yeah bob,
I am with you.. the term thermocouple threw me no if you would have used thermistor that is a different animal and more in line with a AC unit type application ..

more than likely most temp sensors, especially on RV's would be more of the thermistor type than a thermocouple type.. just saying..

gotta love the chem engineers all-ways thinking out side the box or in this case AC case..



OK this horse is officially DEAD.. moving on..

Originally Posted by uncle_bob

Hi

Ummm ..... errrrr ....

A thermocouple is a very specific type of sensor. It is made up of a junction between two metals. They generally have a very low output voltage (which varies over temperature), but also a low output impedance . Wiring them up properly involves keeping the types of metals in the wiring matched up. Short runs or extreme temperatures are good for thermocouples.

A thermistor is a different type of sensor. It varies resistance over temperature. They generally are easier / cheaper to hook up for things like room temperature sensing. Of all the common sensor types, they are the most sensitive from a signal to noise perspective.

Bimetal springs are yet another approach to temperature sensing. Here a contact is opened or closed by the differential expansion properties of the spring. If you look in most older homes, that's what is in the thermostat. They are very reliable and dirt cheap to produce.

We live in a world of silicon this and that. Temperature sensors are no exception. There are an enormous number of them on the market. Most modern microprocessor based thermostats are based on silicon (chip / IC) sensors.

If you are going to get fussy about temperature, you likely use a platinum RTD (resistive temperature device). For a few thousand dollars you can get a pretty good one. They are pretty rare in things like wall thermostats. They (and precision thermistors) are pretty common in precision lab temperature controllers. Both have limited temperature ranges, outside those ranges, thermocouples do show up.

Somehow I suspect that's more than you ever wanted to know

Bob