Application Brochure

Product design, software and literature are Copyright © 2000 by:
tekmar Control Systems Ltd. and tekmar Control Systems, Inc.
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. [phone] Fax. [phone]
Web Site: www.tekmarcontrols.com
Control Systems
System Operation
All specifications are subject to change without notice.
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System Operation
A 356-2 05/00
Printed in Canada. A 356-2 05/00.
The Mixing Control 356 provides full outdoor reset to three (or more) mixed zones. The output of the variable speed injection pump is
modulated to mix the water temperature to the zones, and protect the boiler from flue gas condensation. The boiler operates at the
required temperature in order to satisfy the loads. The supply of heat to an indirect Domestic Hot Water (DHW) tank is controlled through
an external relay.
Heat Source Details The heat source can be either a high mass or low mass non-condensing boiler.
Piping Details Thermostat controlled zone valves are piped into the mixed loop. The variable speed injection pump (P1) is piped in
primary / secondary in order to isolate the boiler loop flow rate from the mixed loop flow rate. Heat is supplied to the DHW tank through
a DHW pump (P4). The boiler pump (P2) provides flow through the boiler and ensures flow past the variable speed injection pump
take-off.
Domestic Hot Water (DHW) When the DHW tank requires heat, the DHW aquastat (A1) energizes relay R2. Relay R2 provides power
to the DHW pump (P4) in order to provide circulation through the DHW tank. Once energized, relay R2 also enables the boiler. The boiler
is then allowed to operate up to the operating aquastat’s setting.
Mixing Demand When heat is required in the mixed zones, the zone valve end switches provide a Mixing Demand to the 356 and turns
on the boiler pump (P2) and mixing system pump (P3) through relay R1. The variable speed injection pump (P1) is then controlled to
supply the required mixed supply water temperature. As the variable speed injection pump ramps up and requires more heat from the
boiler, the boiler is fired to a temperature that is sufficient to satisfy the requirements of the variable speed injection pump. Whenever the
boiler is fired, the 356 aims to maintain the boiler temperature above the BOIL MIN setting. While the boiler is firing, the variable speed
injection pump is also modulated to protect the boiler from excessively low water temperatures.
All control functions and specifications are listed in the Product Catalog I 000 and Data Brochure D 356.