Application Brochure
Product design, software and literature are Copyright © 2000 by:
tekmar Control Systems Ltd. and tekmar Control Systems, Inc.
System Operation
All specifications are subject to change without notice.
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tekmar Control Systems Ltd., Canada
tekmar Control Systems, Inc., U.S.A.
Head Office: 5100 Silver Star Road
Vernon, B.C. Canada V1B 3K4
Tel. (250) 545-7749 Fax. (250) 545-0650
Web Site: www.tekmarcontrols.com
Control Systems
A 256-4 05/00
Printed in Canada. A 256-4 05/00.
The Boiler Control 256 provides partial reset to three (or more) zones. The supply of heat to an indirect Domestic Hot Water (DHW) tank
is controlled through an external relay. The boiler operates at the required temperature in order to satisfy the loads.
Heat Source Details The heat source can be either a high mass or low mass non-condensing boiler.
Piping Details Thermostat controlled zone pumps are piped into the boiler loop. Heat is supplied to the DHW tank through a DHW
pump (P1).
DHW Operation When the DHW tank requires heat, the DHW aquastat (A1) energizes relay R4. Relay R4 provides power to the DHW
pump (P1) in order to provide circulation through the DHW tank. Once energized, relay R4 also enables the boiler. The boiler is then
allowed to operate up to the operating aquastat’s setting.
Boiler Demand When heat is required in the boiler zones, the zone pump relays send a
Boiler Demand
to the 256. The boiler supply
water temperature is based on the
Characterized Heating Curve
settings. The boiler is fired to satisfy the required boiler supply water
temperature. Whenever the boiler is fired, the 256 aims to increase the boiler supply water temperature to at least the BOIL MIN setting.
All control functions and specifications are listed in the Product Catalog I 000 and Data Brochure D 256.