Installation manual

Webasto Product N.A., Inc. 16 www.techwebasto.com
Connection to the Vehicle Cooling System Thermo 90 S / Thermo 90 ST
Figure 12: System configured in series with rear heat exchanger in a “dual” circuit heating system.
Figure 13: System configured in the rear heat exchanger circuit using an optional 4-way back-check valve.
Figure 14: System configured with a bypass circuit within the rear heat exchanger circuit where an automated flow
control valve is installed. Bypass is required in the event the valve is closed during heater operation.
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1. Coolant supply connection
2. Vehicle heat exchangers
3. Coolant pump
4. Thermo 90 S / ST heater
5. Coolant return connection
6. Engine coolant pump
7. Thermostat
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22
3
4
5
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7
1. Coolant supply connection
2. Vehicle heat exchangers
3. Coolant pump
4. Thermo 90 S / ST heater
5. Coolant return connection
6. Engine coolant pump
7. Thermostat
4-way back-check valve
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22
3
4
5
6
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1. Coolant supply connection
2. Vehicle heat exchangers
3. Coolant pump
4. Thermo 90 S / ST heater
5. Coolant return connection
6. Engine coolant pump
7. Thermostat
8. Automated control valve
9. Wye connectors
10. Bypass hose 13-16mm I.D.
(1/2”- 5/8” I.D.)