Temperature Sensor Curve ID Numbers


Need help figuring out what type sensor you need for your automation system?  This handy temperature curve chart might help.  If not, give Kele a call!


Sensor Type Temperature Sensor Description  Typical Sensor User
3 10,000Ω @ 77°F, Type III material    AET, American Automatrix, Andover, Carrier, Delta, Invensys, Teletrol, York
21 2252Ω @ 77°F, Type II material Anderson Cornelius, JCI (A319)
22 3000Ω @ 77°F, Type II material Alerton, ASI, ATS, Snyder General
24 10,000Ω @ 77°F, Type II material Alerton, Automated Logic, TAC (INET), Triangle Microsystems, Trane
27 100,000Ω @ 77°F, Type II material Siemens (Landis and Staefa)
42 20,000Ω @ 77°F, Type IV material Honeywell (XL)
63 1000Ω nickel RTD @ 70°F JCI
81 100Ω platinum RTD @ 32°F,
385 curve
Transmitter available for any user
85 1000Ω platinum RTD @ 32°F,
385 curve
JCI, Siemens, Trane (transmitter available for any user)
91 1000Ω platinum RTD @ 32°F,
375 curve
JCI, Trane (transmitter available for any user)
5 1000Ω Balco RTD @ 70°F TAC (Siebe) (transmitter available for any user)


Belimo Zip Economizer – Time Saver!

The Belimo Zip Economizer is really a cool product that captured my attention.  If you are or were in the field like I was, I’m sure you’ve struggled just as I did with the “Black Box” style of economizer modules.  They could be difficult to commission at start-up if the OSA (outside air) was not cool enough for economizing.  Also, after installation, troubleshooting the “Black Box” style module was an extremely difficult challenge at best.  There was almost no way to tell what the unit was doing or what mode it was in.  Belimo’s design team must have had input from field techs because they have designed a product that is easy to install and commission.  It is also a breeze to troubleshoot, making it easy to determine if there is a problem and what that problem is.

The “Zip” in Zip Economizer stands for zip code, as in your postal zip code.  No more fumbling with graphs and temperature curves to determine the settings or cross-referencing energy codes.  All you have to do is enter the 5-digit zip code and you are done.  Now THAT is cool!!!  This step will also set up the economizer operation for compliance with all of the following codes and standards.

  • ASHRAE 90.1 – Energy Standard for Buildings Except Low-rise Residential Buildings
  • IECC – International Energy Conservation Code
  • California Title 24 – California building energy efficiency standard
  • NECB – National Energy Code of Canada for Buildings

This cool Econ-Zip Economizer also has an LCD display that shows live status information, alarms and failures, and also operating history.  Check out these features and don’t overlook the 5-year warranty.

Belimo Zip Economizer Features

With the unit’s plug-and-play design, you only have to worry about setting up the features you want.  For example: the module, on it’s own, will work perfectly with just the Econ-Zip-10K temperature sensors installed.  However, if you want the Econ-Zip to control by calculated enthalpy, simply install the Econ-Zip-TH sensors, which measure temperature and humidity. The Econ-Zip recognizes the sensors and self-configures to control by enthalpy.  But wait!  Need a CO2 input?  The Econ-Zip-EM Energy Module provides additional I/Os to offer demand-controlled ventilation.  Any of Kele’s CO2 sensors can be used as long as there’s a 0-10 VDC output.

Belimo has included a manual mode, which can be used during commissioning or troubleshooting.  All components can be tested in the manual mode except for the thermostat.  The manual mode includes an economizer test, used to verity RTU integrated economizer operation.  The ventilation test allows adjustment to the damper minimum position for verification of ventilation rates.  The RTU test is used to test the signals from the thermostat to the RTU.  The DCV test is used for testing the CO2 input and setpoint.

In my opinion, Belimo did their homework, sharpened their pencils, listened to input from the field, and designed a really cool product that “makes it easy” to economize.  If it is as reliable as their valves and actuators, the Econ-Zip is sure to be a hit.  I can only say I wished I’d had this around during my field years.

Visit the Econ-Zip product page to learn more and to purchase. You can also check out this video.  The Econ-Zip as well as the full Belimo line of products can be found at Kele.  And don’t forget Kele’s technical support.  If you have questions on any of our products or questions on applications, please feel free to contact us.


Honeywell T775 Controller

I started at Kele about 19 years ago.  Over the years I’ve been fortunate to learn a good bit about controls from many very talented folks – mentors, fellow employees, industry experts, and customers.  It is easy to have favorites in my line of work.  Being in tech support over an extended period of time, I have a base of products that I lean on.  Usually it’s because a product is dependable, easy to use, and most importantly – it makes my customers happy.  One of those products is the Honeywell T775 series of standalone controllers.

There are many times where a full blown building automation controller is overkill and simple control devices, like thermostats, don’t give the flexibility to offer the desired level of control.  We get this call almost daily in the tech support pool.  While there are several standalone controllers out there to choose from they can be cumbersome for some “small” jobs.  Having to add on multiple modules to a basic controller adds complexity and cost.   That is where the Honeywell T775 shines.  This simple, cost effective controller can tackle many different control applications with one simple device.  Easy to use, saves time, saves money, it’s easy to see why the T775 is one of the favorites of the tech support group.

Here are some of the features the T775 lineup has to offer:

  • Easy to use graphical interface – it really is as easy as some smart phone applications
  • 14 different models to choose from – Boiler control, reset, temperature, and universal models
  • Optional NEMA 4X enclosures – for outdoor applications
  • Setback models with internal time clock – maximize energy savings with unoccupied control
  • Optional independent modulating output models – one controller for more than one task
  • Optional modulating high or low limit controls – protect expensive equipment
  • Reset models with simplified setup – changing control points based on environmental factors made easy

One of the most popular uses for the T775 is for controlling variable frequency drives in differential pressure applications, for both water and air. The simplicity of setup makes it ideal for these applications.

EXAMPLE: a VFD being used to control pressure in a building.

Parts List:
1) T775U Honeywell controller
1) Differential pressure transmitter (Kele DPA series, DPL series, Setra M264 series)
1) Room pressure sensor (Kele RPS, A-308-K)
1) Outdoor air pressure sensor (A-306-K)
Length of tubing (T-101, actual length determined by install)

The room pressure sensor (indoor sensor) and the outdoor air pressure sensor are piped accordingly to the high and low ports of the differential pressure transducer. The orientation of these sensors is determined by whether positive or negative building pressure is desired. If positive building pressure is required, pipe the indoor air sensor to the high port of the differential pressure transmitter and the outdoor pressure sensor to the low port. If negative building pressure is required pipe the outdoor pressure sensor to the high port of the differential pressure transmitter and the indoor pressure sensor to the low port. The differential pressure transmitter senses differential pressure and outputs an analog signal that is used as the input (process variable) to the T775 controller. The T775 modulates its output to control the speed of the fan based on the set point established in the controller setup.

T775 Controller Setup Diagrams

The ease of setup combined with the adjustability of the T775 makes this application easy.  The T775 uses an easy-to-read display and the setup is menu driven.  The graphical interface actually walks the user through the setup, which saves valuable time and money on the installation.  Pinpoint control with adjustable integral and derivative times is easy to achieve with the T775.  And that’s not just for this application, there are many others.  So the next time you have a “small” control job give Kele a call to discuss using the T775 and save yourself some time and money.

Measuring Flow in Tight Spots

Often, one of the most challenging aspects of applying a flow-sensing device is the hunt. Tracking down the elusive and mysterious twenty diameters of straight, accessible pipe that the sensor manufacturer demands can be impossible at times. Let’s face it – it isn’t often that the Architect, Engineer, General Contractor, and all the subcontractors conspire to make the automation guy’s job easier, is it?

If the length of straight pipe upstream and downstream of a flow measuring device doesn’t meet the manufacturer’s published specs, then the manufacturer’s guarantee of accuracy no longer applies. But just how bad will the results be? As long as a few common criteria are met, the answer is “not as bad as you’d expect!”

To insure the best accuracy possible, the flow profile of the fluid to be measured must be as uniform as possible across the pipe or duct, and the velocity must be high enough to ensure turbulent flow. With uniform turbulent flow, almost any placement of a differential pressure or turbine device across the pipe or duct diameter will give a good representation of the average fluid velocity. As the flow profile loses uniformity (close to an elbow or tee, for example), error is introduced since the device placement might be in a region with a higher or lower velocity than the actual average. The same effect can occur if the velocity slows enough to create laminar flow. The flow profile illustration to the right indicates these effects.

Robert Benedict’s Fundamentals of Temperature, Pressure, and Flow Measurement cites several studies in the International Journal of Heat and Fluid Flow which demonstrate that about 8 upstream diameters of straight pipe after an elbow are sufficient to produce ±1 percent variance with an orifice meter. Reduction of straight pipe to only 4 diameters yields ±2 percent variance if a constant correction factor of 0.98 is applied to the orifice discharge coefficient. In either case, the downstream straight pipe need only be two to four pipe diameters in length. If the upstream problem is more obstructive than a simple elbow (a valve, perhaps, or a bullhead tee), the lengths of straight pipe needed are closer to 16 diameters upstream for ±1 percent, and 8 diameters for ±2 percent. Table 1 is derived from Benedict’s work, and is valid for any fluid in fully developed turbulent flow. In typical HVAC applications, turbulence is pretty certain. If in doubt, check to see if the flow in question has a product of velocity (V, feet per minute) and the equivalent circular pipe or duct diameter (D, in inches) that meets the following criteria:

For Air, V x D > 650
For Water, V x D > 20
For Steam, V x D > 110

In summary, even if there isn’t enough straight pipe or duct to meet the manufacturer’s requirements, it is often possible to get a “pretty good” reading anyway, and the results will be very repeatable even if they’re off by a few percent.

Table 1: FlowChart

Table 1: Effects of Upstream Obstructions on Flow Profiles. Add the “Resulting Variance” to the manufacturer’s stated accuracy to get an idea of expected behavior of a flow transmitter when the published straight pipe (or duct) length exceeds those in the table. While we cannot guarantee these figures for every application, they are valid for most HVAC/R flow ranges, and may even be improved upon with the use of straightening vanes or honeycomb flow straighteners.