Application Brochure

Table Of Contents

tekmar Control Systems Ltd. and tekmar Control Systems, Inc.

System Operation

All specifications are subject to change without notice.

6 of 8

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

tekmar Control Systems Ltd. and tekmar Control Systems, Inc.

Printed in Canada. A 256-3 05/00.

A 256-3 05/00

The Boiler Control 256 provides partial reset to three (or more) boiler 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 valves are piped into the boiler loop. The boiler pump (P1) provides circulation through these

zones when heat is required. Heat is supplied to the DHW tank through a DHW pump (P2).

DHW Operation When the DHW tank requires heat, the DHW aquastat (A1) energizes relay R2. Relay R2 provides power to the DHW

pump (P2) 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.

Boiler Demand When heat is required in the boiler zones, the zone valve end switches send a

Boiler Demand

to the 256 and turns on

the boiler pump (P1) through relay R1. 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.