Application Brochure

tekmar Control Systems Ltd., Canada
tekmar Control Systems, Inc., U.S.A.
Head Office: 5100 Silver Star Road
Vernon, B.C. Canada V1B 3K4
[phone] Fax. [phone]
Web Site: www.tekmarcontrols.com
Product design, software and literature are Copyright © 2009 by:
tekmar Control Systems Ltd. and tekmar Control Systems, Inc.
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All specifications are subject to change without notice.
Printed in Canada. A 257 - 03/09.
Specifi cations:
The following are the recommended specifications for the DHW Control 257
The control shall be able to operate a single two-stage boiler or two single-stage boilers
The control shall be able to rotate two boilers
The control shall count the number of relay running hours for each relay
The control shall display the actual temperature measured at the DHW sensor
The control shall have an adjustable DHW target temperature
The control shall operate in either P (proportional) or PID (proportional, integral, derivative) mode
The control shall have an adjustable inter stage delay in P mode
The control shall have an auto differential setting in PID mode
The control shall have a minimum on and off time for each boiler of 30 seconds
The control shall display an error message if the DHW sensor has an open or short circuit
The control shall turn off both stages if the DHW temperature rises 2°F above the target
The control shall have a field test routine which closes each relay for 10 seconds
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