Jon Klima, Owner
360 Trout Lane, PO Box 23, Guffey, CO 80820
Phone: 719 479-2281,  Email:
In business for 40 years



Conifer Solar Consulting supports the solar industry by designing and repairing active solar heating system controls and providing controls-associated consulting. Brands of controllers that I repair include Heliotrope, Independent Energy, Novan, Honeywell, Solar Controls Corp., Rho Sigma, Taco, Solaron, Johnson-Penn, Apollo (NDI), Webb, SDI, Dynatech, Richdel, Dencor, Western Solar Products, and upon occasion, other brands. Brands I don't repair are Robertshaw, HI Square/Hawthorne, Dan-Mar, and those controllers that use thermocouples for the temperature sensors. Typical turn around time is two days.


Several years ago I acquired the controller inventory from a Denver solar service company and a Denver metro area community college that had shut down its solar technology program.  I've gone through these controllers and have repaired and checked them out and they are now ready to sell. They include:



DTT-400, 1 available, Delta Ts = 9/3 F

DTT-403, 3 available, Delta Ts = 15/1.5 F


The above controllers are priced at $32.50 each.


Heliotrope models

DTT-600, 1 available, Delta Ts = 9/3 F

DTT-690, 5 available, Delta Ts = 9/3 F (2 w/o cover)

DTT-692, 2 available, Delta Ts = 15/5 F

DTT-5080 (drain down), 2 available, Delta T ON is adjustable, DeltaT OFF = 1.5 F

are $35 each.


A note about using 10 K ohm sensors with the above Heliotrope controllers - these controller were designed to work with 3 K ohm sensors. To make the turn ON and turn OFF functions work, the controller is looking for a temperature difference between the collector and storage sensors. To make the high limit function work, the controller is looking for a specific temperature. If you are using the controller for only the turn ON and turn OFF functions, you can use 10 K ohm or 3 K ohm sensors, but don't mix them, i.e., use either one or the other value for both sensors. If you are using the high limit function, use the 3 K ohm sensor. This can easily be changed though to work with a 10 K ohm sensor by changing out one resistor on the PC board. Do not attempt to use 10 K ohm sensors with the controllers that have a digital readout as part of the controller. If you try this you will get temperature readouts that are about 45 - 60 F low. For a description as to how a controller works you can download this 80 KB PDF file by clicking here

Independent Energy - GoldLine:

C-35 HV-10 relay modules, $7.50, 2 available

C-35 HV-30 relay modules, $10, 3 available

ABC-14F/14F cable - joins non-series A SP or CM controlers to DM or DLX monitors.  4 ea. available, 10' length cables @ $7.50 ea., and 1 available, 50' length cable @ $12.50.

Webb Systemizer III (Continental Solar), $129, display box only, 6 available

NDI/Apollo 44 model A, $20, 1 available

SDI SEC III DHW $50, 1 available

Solar Controls Corp. 80-171RA $20, 1 available

Solar Age Partner/HI Square 4020 $20, 2 available

Cyclops SW-210 controller with ST-310 control tester $25, 1 available


Sensors -

FS-5 snap switch (used, 1 available) @ $7.50 ea. This sensor is closed with lowering tempeatures until 42 ºF when the sensor opens and then re-closes at 52 ºF.

New (Old stock) Heliotrope FS-5 snap switch (11 available) @ $15 ea.

New (Old stock) Heliotrope SAS-3 3 K ohm sensors (5 available) at $16 ea.

Prices shown do not include postage.  Colorado sales will be charged the appropriate sales tax.


Yes, I accept credit card payments through PayPal, checks, and money orders.  You do not need to have a PayPal account to go the credit card route. To place an order, send me an email stating what you are interested in along with your zip code.  I'll check the postage to your zip code and send you a return email with the total cost.



















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This page was last changed on 7-20 -2019