Servel Acd 36-00

*Continued down to 45°F as the thermostat started cycling.

*Continued down to 45°F as the thermostat started cycling.

The most significant problem after installation was that the chiller would not fire up when the ambient temperature was over 90°F (32°C). The electronic spark igniter was failing. A serviceman came down to look at the problem, but was puzzled. He did give us a lot of good advice, and left us a service manual. We substituted two new igniter modules, but continued to have the same problem. Lighting the gas with a match (which we were advised not to do) proved that all other parts of the system worked.

Why was the igniter failing? The igniter was powered from the 24 VAC control transformer. On a hunch, we disconnected the control transformer from the system power, and powered it separately from a portable generator, and voila—everything worked. Why? Putting an oscilloscope on the circuit, the only change we observed was the modified sine wave from the inverter, versus a relatively smooth sine wave from the generator.

I called Fenwal, the manufacturer of the igniter module, and discussed it with their engineering department. They agreed that the waveform was the culprit. They suggested putting in their 12 VDC igniter, which is widely used in motorhomes and similar installations. This looked like an attractive solution.

Next, I called Trace, ready to bawl them out for saying I could probably get by with the modified sine wave inverter. They suggested that I put a small power conditioner ahead of the control transformer. So we tested a Sola 60 W Power Conditioner^, which worked

The Servel ACD 36-00 makes the summer heat bearable.

The Servel ACD 36-00 makes the summer heat bearable.

like a charm. We installed it, at much less cost than changing the inverter from modified sine wave to sine wave, and even lower cost than putting in a DC igniter. Problem solved.

Off-Grid Air Conditioning

The solar/propane air conditioner works just as we dreamed it would. Careful calculations in sizing the system paid off. Now we can laugh at those who said it wasn't practical, and the contractors and companies who were reluctant to get involved because they had never worked on this kind of installation.

The gas input for this system is 75,000 BTU/h. Though the propane usage should be measurable, the total number of refills per season has not increased and the owner does not yet have a figure. Since the electrical system does not have to drive a compressor, the only electrical loads are a condenser fan motor and a circulating pump motor.

We were disappointed with some members of the industry, who could not deliver on a timely basis. We were pleased with the people at Robur Corporation and at Edwards Engineering, where we got encouragement and advice. Though we had planned to have it working in the springtime with the long hot days of summer ahead of us, we were pleased to have the system functional for the last hot days of summer before the coolness of fall set in.

We feel like pioneers, since we haven't encountered another system like it. While there have been other installations using this cooling equipment, as far as I know, this is the only one in the U.S. that is totally off-grid using solar energy.


Ed Sheldon, 2946 Cottle Ave., San Jose, CA 95125 408-264-3066 • Fax: 408-448-2799 • [email protected]

Bill and Carol Hoover, Lawrence Livermore National Laboratory, L-794, Livermore, CA 94550-7808 925-422-9787 • Fax: 925-422-8681 • [email protected] and [email protected]

Robur Corporation, 2300 Lynch Rd., Evansville, IN 47711 • 888-424-1800 or 812-424-1800 Fax: 812-424-8909 • [email protected] • Air Cooled Absorption Water Chiller model ACD 36-00

Edwards Engineering Corp., 101 Alexander Ave., Pompton Plains, NJ 07444 • 800-526-5201 or 973-835-2800 • Fax: 973-835-2805 [email protected] Valance cooling coils

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