CONIFER SOLAR CONSULTING

Jon Klima, Owner
360 Trout Lane, PO Box 23, Guffey, CO 80820
Phone: 719 479-2281,  Email: jon.klima@gmail.com
In business for 37 years

 

• Article 16, Part 1 - March, 1996

 

Programmable Differential Temperature Controllers©

 

This is the third in a series of several articles that will summarize the programming capabilities of most of the differential temperature controllers used in the Colorado area. This article will cover the Independent Energy (IE) C-35, C-100, and C-120 series of controllers. The following information on the IE C-35 controllers is taken from the IE C-35 Differential Temperature Controller Applications and Installation Manual. Refer to the appropriate section of that manual for details 'of the particular C-35 model you are dealing with.

 

The IE C-35 comes in the following five models:

 

1. C-35-1S-3T, single differential output, used with pools, spas, and hot tubs (manual Section 3).

2. C-35-1SN-3T, similar to the above C-35-1~-3T except nocturnal cooling capabilities are included (manual Section 3).

3. C-35-1S-2F-3T, single differential output, second output used to supply power to a drain down valve, used with pools, spas, and hot tubs (manual Section 7).

4. C-35-1S-2S-3T, dual differential outputs, can be used with either single collector arrays and two storages or two independent collector arrays and two storages, used with pools, spas, and hot tubs (manual Section 4 for two collector arrays and Section 5 for single collector arrays).

5. C-35-1S-2S(DHW)-3T, dual differential outputs, can be used with either single collector arrays and two storages or two independent collector arrays and two storages, used with pools, spas, and hot tubs on output #1 and DHW or space heating on output #2 (manual Section 6).

 

All C-35s, except the drain down C-35-1S-2F-3T have recirculation freeze protection capability (not recommended for this part of the country).

 

Recirculation is accomplished similarly to the C-30. One method, using the collector thermistor sensor, is to wire one or more GS-1 snap switch sensors in series with the collector thermistor and move the freeze jumper down one position, i.e., one jumper contact on one freeze terminal and the other jumper contact on the collector terminal. The second method is to remove the freeze jumper and replace it with a thermistor sensor and one or more GC-1 snap switches, all wired in series. If only a thermistor is used to initiate recirculation freeze protection, the turn ON temperature is 40° F ± 2°F and turn OFF temperature is 45° F ± 2° F. When one or more GC-l snap switches are wired in series with a thermistor sensor, the turn ON temperature will be 44° F ± 4° F and turn OFF temperature will be 54° F ± 5° F. Refer to the application manual pages 8-1 and 8-2 for details of these connections.

 

When the drain down C-35-1S-2F-3T model is used, the drain down output (Output#2) turns OFF at 44° F ± 4° F and turns back ON at 65° F ± 8° F. If the J3 jumper is installed, the drain down output (Output #2) will also be de-energized at the high limit set point. (manual Section 7)

 

Output #1 ON/OFF differential temperatures on all C-35s are standard at 4/1.5° F ±1° F. These are field programmable to 8/3° F ± 1° F by cutting resistors Rl13 and R116 out of the circuit on the printed circuit board.

 

Output #2 ON/OFF differential temperatures on the C-35-1S-2S(I?HW)-3T are standard at8/3° F ± l° F. These are field programmable to 20° F ± 4° F (ON) and 5° F ±2° F (OFF) by cutting resistors R2l3 and R216 out of the circuit on the printed circuit board. Output #2 ON/OFF differential temperatures on the other dual differential C35 (C-35-1S-2S-3T) are standard at 4/1.5 ° F ± 1° F. These are field programmable to 8/3 ° F ± 1° F by cutting resistors R213 and R2l6 out of the circuit on the printed circuit board. Refer to the application manual page 9-6 for these differential temperature modification procedures.

 

The temperature adjust on all C35s, except the C35-1S-2S(DHW)-3T, ranges from 65° F ±5°F to 103° F ± 1/2° F. The second temperature adjust on the C35-lS-2S(DHW)-3T ranges from 110° F to 225° F (OUT) ± 10° F. The temperature adjust dead band is 4 ± 1° F.

 

The MODE switch should normally be set to the AUTO position for all single differential output controllers. The OUT position is a test position and will force all functions OFF except the recirculation freeze protection (if enabled). The ON position forces Output #1 ON regardless of the temperature differential, nocturnal cooling, or recirculation freeze protection thresholds.

 

For the dual differential output controllers, both MODE switches should be set to the AUTO position for automatic operation ONLY for systems having two independent collector arrays. If the collector system is a single array, one of the MODE switch positions should be AUTO while the second should be in the PRIORITY position. Which ever MODE switch is in the PRIORITY position will govern which storage is heated to its adjustment set point first.

 

As with the single differential output controllers, the OUT position on a dual differential output controller MODE switch is a test position and will force all functions associated with that switch OFF except the recirculation freeze protection (if enabled). The ON position forces the output ON regardless of the temperature differential or recirculation freeze protection thresholds.

 

One last point to make about the-C-35s involves the J1 and J2 jumpers. When the J1 jumper is installed with dual differential output controllers, the output #1 relay will be turned on from either the output #1 OR #2 circuitry. Without the J1 jumper installed, only the output #1 circuitry will turn on the output # 1 re1ay. The output #2 relay is still turned on only when the output #2 circuitry turns it on.

 

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