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E Such furnaces typically have a turn down that is 50% of the high fire input. Converting to Maxitrol’s Series 3 system can reduce the turn down to 25%, or lower, of the high fire input. By controlling the switch point of a relay connected to the gas valve and inducer we are able to create two separate modulation ranges. asily turn a 2-stage indirect fired furnace into a modulating furnace with Maxitrol’s Series 3 electronic gas modulation system. You’ll be glad you did.
TWO-STAGE MODULATING INDIRECT FURNACE M420 M520 M620 Combination Control 2-Stage (High Fire, Low Fire) EXAMPLE TYPICAL APPLICATION REQUIRING 16:1 TURNDOWN Multiple Units Large single duct system 4 duct furnaces each with a rated input of 400,000 BTUH 4 units total 1.
S e r i e s A1093 WITH EXTERNAL CURRENT LOOP CURRENT LOOP INPUT 5.0 mA = 50°F 13.0 mA = 130°F Rin = 100 ohms (nominal) Note: Connect externally powered current loop to TB1, terminals 10 and 11 as shown. No external connection is required to “LOOP” (TB1, terminal 9) or (TB1, terminal 12). Connections to TB2 are not shown. TYPICAL WIRING DIAGRAM @ 2004, Maxitrol Company, All Rights Reserved. www.maxitrol.com P.O. Box 2230 Southfield, MI 48037-2230 U.S.A. tel 248.356.1400 fax 248.356.
