Fuel Efficiency of the Re-Verber-Ray Two-Stage, High-Low (HL Series) Infra-Red Heaters.

Introduction
The Re-Verber-Ray two-stage, high-low HL Series was developed and introduced in early 1993. To objectively document the benefits of this new technology RDM Engineering, an independent research firm, was engaged in October 1993 to monitor a test and demonstration of the new product introduction

The patented design of the HL Series encompasses a (low-fire) mode for moderately cold days and a (high-fire) mode for only the coldest of Winter days when 100 percent of a typical building's designed heating capacity is actually needed. Background data incorporated in the HL Series design has showed that based on 25 year weather records, a typical industrial or commercial building in requires 100 percent of its designed heating capacity-the (high fire) mode-for only 5.6 to 9.7 percent of the time, depending on geographic location. For the remaining part of the heating season, a (low-fire) mode operating 70 percent of designed heating capacity is all that is required. Based on this and related data the HL Series was developed.

The Test Site
The test facility was carefully selected to reflect not only typical industrial building construction, but also a commitment by management and staff that consistent work patterns would be maintained during the test period. A detailed heat loss study of the test facility prior to the start of the test period documented a total building heat loss of 200,000 BTU/h.

Other parameters of the test site included the following:

Ceiling: 20 feet high with R20 insulation and steel interior sheathing and fiberglass; tar and gravel roof.
Walls: Eight inch, concrete block, non insulated.
Doors: Two three foot by eight foot exterior doors.
Windows: None.
Overhead Doors: One, ten feet by twelve feet.
Building Use: Heating and mechanical contractor used for mainly sheet metal fabrication equipment modification, repairs and some storage.

Test Procedure
Two 100,000/70,000 BTU/h Re-Verber-Ray two-stage, high-low HL Series infra-red heaters were installed along with Honeywell two-stage electronic controllers.

For this "real world" test the heaters operated on alternate days one of two ways: (1) on "auto", whereby the heaters were either "off", or allowed to switch automatically between the "low fire" mode (70,000 BTU/h) and the "high fire" mode (100,000 BTU/h) or; (2) on "high", whereby the heaters were either "off", or run only on the "high fire" mode (100,000 BTU/h)

The two alternative operating possibilities of "auto" and "high" as noted above were switched on a controlled 24 hour cycle with the level of heat output based on actual building heating demand. This methodology provided the necessary controls to objectively compare the two alternative heating methods.

The Results
The test period ran from October 15,1993 to April 15,1994. During this time, the "high" portion of the test (where the heaters ran only at 100,000 BTU/h) and the "auto" portion of the test (where the heater were allowed to switch between 70,000 BTU/h and 100,000 BTU/h based on heating demand) were each in operation for 92 days. The average temperature for the "high" portion was -2.3'C and for the "auto" portion was -1.30C.

The first of the two Re-Verber-Ray HL Series units has an average cycle time of 39.5 minutes on "high" and 69.5 minutes on "auto" demonstrating longer heater operation, on "low fire". On this first unit the overall number of "On and Off cycles" was reduced by 35 percent.

The second of the two Re-Verber-Ray HL Series units had an average cycle time of 44.0 minutes on "high" and 78.1 minutes on "auto" demonstrating again longer heater operation on "low fire". On this second unit the overall number of "On and Off cycles" was reduced by 36.5 percent.

Natural gas consumption was reduced using the "auto" operation for the two HL Series units by 12 percent during the six-month period-a saving of 23,018 cubic feet of natural gas.

Conclusions
The Re-Verber-Ray two-stage, high-low HL Series infra-red heating system has been shown to be a more efficient heating system than standard single-stage heaters.

Savings of 12 percent (minimum) in energy usage were documented with the HL Series compared with single stage heaters.

1. A reduction in "On and Off cycles" by some 35 percent resulting in improved employee comfort.
2. Improved product life due to the reduction in "On and Off cycles".
3. Overall improved operating efficiency reducing carbon dioxide and other emissions.
4. Full heat output available on demand.

RDM Engineering
Based in Guelph, Ontario Ronald D. MacDonald PhD and RDM Engineering have researched and produced a number of scientific, technical and information papers on the subject of energy efficiency, as well as tested and reported on other energy matters for a wide variety of clients. Serving as an Energy Advisor and Energy Specialist to government, major utilities and private sector clients, Mr. MacDonald and RDM Engineering remain actively involved in a broad spectrum of energy matters, including their recent testing and reporting on the  Re-Verber-Ray two-stage, high-low HL Series detailed in this Technical Report.

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