Install Instructions

ManualsBrandsTekmar ManualsHeating SuppliestekmarNet 4 Thermostat - Two Stage Heat, Two Stage Cool, Two Fan

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A Watts Water Technologies Company

Heating Operation

Section A

Sequence of Operation

Set Heat Temperature

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The 557 can operate radiant floor heating, heat pump stage 1 and stage 2, and a backup

heat source to provide heating in different combinations depending on the outdoor air

temperature. The illustration below shows when each of the available heating units are

available. The “Heat On” symbol is shown on the display when the thermostat is heating. If not

operating a heat pump, the first and second stage of heat (W1 and W2) are allowed to turn

on below the Warm Weather Shut Down to maintain the Set Heat Room temperature.

No heating Air heating only All allowedNo backup heat

Colder

Outdoor

Temperature

Set Heat

Room

Warmer

Room

Colder

Warm Weather

Shut Down

Default = 70°F

Radiant Floor

Warm Weather

Shut Down

Default = 60°F

Balance

Point

Default = Off

Lockout

Default = 60°F

Heat Pump - Heating Mode

No heat pump

Y2 off

Y1 off

Y2 on

Y1 on

W2 off

Y2 off

Y1 off

W1 off

W2 on

Y2 on

Y1 on

W1 on

Y2 off

Y1 off

W1 off

Y2 on

Y1 on

W1 on

W2 off

W1 off

W2 on

W1 on

Air Temperature Heating

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When using only a room temperature sensor, the thermostat operates the heating

system to maintain the Set Heat Room temperature.

Floor Heating

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When using both a room and a floor temperature sensor, the thermostat always maintains

the Floor Minimum temperature, even when the air temperature is satisfied. When the

air temperature is below the Set Heat Room temperature, the thermostat operates the

heating system to maintain the Set Heat Room temperature. The floor is never heated

above the Floor Maximum setting in order to protect the floor covering. Suggested

Floor Maximum settings are 90°F (32°C) for tile, stone, or concrete floors and 85°F

(29°C) for wood floors.

Radiant Floor Baseload

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When the terminal unit is selected to be a Hydronic Radiant Floor (HRF1 or HRF2)

and no floor temperature sensor is installed, the thermostat has option to provide

baseload heating. This allows the radiant floor to be heated even though the room air

temperature is satisfied. This is useful in areas where a radiant floor heating zone is

overlapped by an air heating system. The radiant floor heating is overwhelmed by the

quick heat up rate of the air heating system, resulting in a radiant floor heating zone

that rarely turns on. The radiant baseload option allows the radiant floor to counteract

the air heating system by heating the floor at a reduced output even when the room air

temperature is satisfied. This is also useful in areas that experience large solar gains

through windows. The radiant baseload is automatically shut off in the summer by the

warm weather shut down feature.