Temp dif.

[Fixitvic]

First time to forum. I'm working on a tk sb 200. The unit had a code 13 alarm. Owner cleared it. I'm running it now , I have a dis. Temp of 35, a ret. Of 40 ,and coil at 38. The TDPF is -5. Should I be checking the connections to controller at this point?

[Gary]

What is a dis?... what is a ret?... what is a TDPF? Should we assume degrees fahrenheit?

[cadwaladr]

What is a dis?... what is a ret?... what is a TDPF? Should we assume degrees fahrenheit?
dis = discharge air or air of evap
ret= return airair off
tdpf=temp diff?

[Gary]

ThermoKing fault codes:

http://www.xtralease.com/specs/ThermoKingCodes.pdf

[DaButcher]

First time to forum. I'm working on a tk sb 200. The unit had a code 13 alarm. Owner cleared it. I'm running it now , I have a dis. Temp of 35, a ret. Of 40 ,and coil at 38. The TDPF is -5. Should I be checking the connections to controller at this point?

Yes, clean then lube micro connections with dielectric grease......fixes the majority of alarm 13's when sensors appear normal most of the time.

Checking of refrigeration system may be needed if the TD didn't get any better than -5

[DaButcher]

.. what is a TDPF?

Delta T may be the term your used to Gary, but in the Thermo King world known as TD or temperature differential

[Gary]

Delta T may be the term your used to Gary, but in the Thermo King world known as TD or temperature differential

This is not just the terminology I am used to. TD and dT have precise meaning accepted throughout the scientific and engineering world, as well as the refrigeration industry, all over the planet.

air in temp minus air out temp = deltaT or dT
air in temp minus saturated suction temp = TD

In this particular case the evap dT is 5, not -5.

[DaButcher]

Gary, TD in the reefer world may just be slang. TDPF is the abbreviation that is displayed on most TK displays.

Below is quoted from a Thermo King SR2 manual.


Temperature Differential – Displays the calculated difference between the control return air sensor and the control discharge air sensor.

The illustration below is the newest display TK uses, "diff"

http://i543.photobucket.com/albums/gg445/DaButcherMudMafia/reefer/diff.jpg

Below is a quote from a uPVI book, which is the controller of the SB200 mentioned from the original poster.

[TPDF] Temp Differential

Determining Temperature Differential
The temperature differential is commonly measured as the difference between discharge air temperature
and return air temperature. It can be calculated by subtracting the return air temperature from the
discharge air temperature. If the unit is in “Cool” mode, the temperature differential should be a
negative number and if it is in “Heat” mode, the number should be a positive number.
For example, if a unit is operating in “Cool” mode with a discharge air temperature of 50 F (10 C), the
Temperature Differential is found by use of the following formula.
OR
If the same unit was operating in “Heat” mode with a discharge air temperature of 40 F (5 C) and a
return air temperature of 36 F (2 C), the Temperature Differential would be determined as follows.
OR
Use of Temperature Differential
Temperature Differential is used as a measure of refrigeration performance. Box temperature will
influence the Temperature Differential, with higher values found with higher box temperatures in
“Cool” mode. Time is a factor in as much as the unit must have run in the indicated mode long enough
to stabilize the system pressures and coil temperature.
For example, in both of the cases mentioned above, the calculated Temperature Differential of –10 F
(–5 C) in “Cool” mode and 4 F (3 C) in “Heat” mode would indicate normal performance at those
trailer or box temperatures, assuming the unit has run long enough to stabilize.
However, if the unit is operating in “Cool” mode with a discharge air temperature of 48 F (9 C) and a
return air temperature of 50 F (10 C) after a substantial period of time, the –2 F (–1 C) Temperature
Differential could indicate a refrigeration capacity problem. This ability to electronically measure
refrigeration performance is used in various ways by the Thermo King microprocessor based controllers
to determine performance characteristics and generate appropriate alarm codes to indicate problems.
Discharge Air Temp – Return Air Temp = Temp Differential
40F (5C) – 50F (10C) = –10F (–5C)
Discharge Air Temp – Return Air Temp = Temp Differential
40F (5C) – 36F (2C) = 4F (3C)

Definition of Temperature Differential
For purposes of measuring refrigeration performance, many tests consider the temperature differential
across the evaporator coil. This temperature differential may be referred to as “Delta T” and is written
ΔT.

[Gary]

There is no problem with making up your own words, so long as the people you are talking to know what you mean.

Just be aware that when you say TD, others may think you are talking about something entirely different. For example, when you are selecting a coil you find they are rated by TD... and they are not talking about dT.

I'm wondering what TK calls 'air in temp minus saturation temp'? Do they reverse it to 'saturation temp minus air in temp', thus ending up with a negative number?

The transport refrigeration world can speak a different language from the rest of the refrigeration world if they want to... but why would they want to? Isn't there enough confusion in this industry?

[gravy258]

this post is getting completely off topic !

your TPDF is woefull. You want 8-9F minimum in chiller range.
Is this after you've cycled it thru a defrost?

tell us what the suction pressure is, the ETV position and ambient

Is the ball up? High speed cool, after defrost. Clean condenser coil.

code 13 usually is with another sensor code.

codes in colour as per TK:
http://www.trailerservices.com/resources/TK_Alarm_Codes.pdf

[moggy66]

Delta T may be the term your used to Gary, but in the Thermo King world known as TD or temperature differential

could i just insert the words " Carrier and" in front of the Thermoking........thank you...........:D

[DaButcher]

could i just insert the words " Carrier and" in front of the Thermoking........thank you...........:D

you could, but Carrier actually uses Delta T more than TK..........even if Carrier shows Deta T as a negative number when cooling, unlike the explanation Gary gave saying that it is incorrect to do so.

[moggy66]

excactly...in the transport refrigeration world we all know what delta t means, and like Gary says if the people you are talking too understands what you mean thats the main thing