Fluid Level Sensor
©Aqua-Hot®
250-D03 Diesel Series Service Manual
REV 220302
p. 23
Control Thermostat
Failure to disconnect all power supplies and/or allow the
unit to cool before servicing could cause serious damage or
personal injury.
Replacement Procedure
1. Ensure that the Aqua-Hot has been completely shut
down, all power sources disconnected, and the unit has
been allowed to cool completely.
2. Clamp the hoses indicated below with pinch off pliers to
prevent drainage of the heating zone loop.
3. Drain one gallon of antifreeze and water heating solution
into an external contained to be reused later.
4. Disconnect the defective ETS module’s wires.
5. Using a 14mm wrench or deep socket, unscrew the ETS
module from the Aqua-Hot’s boiler tank.
6. Wrap the threads of the replacement ETS module with 6
wraps of thread seal tape.
7. Place the replacement ETS module in its position on the
tank face, and finger tighten into place.
8. Using the 14mm wrench, tighten the module until snug.
9. Reconnect wire J4-5 and wire J4-6 to the new ETS
module.
10.
Refill the Aqua-Hot’s boiler tank with the previously
drained antifreeze and water heating solution using an
external fill pump, filling through the zone fill.
11. Once this has been completed, locate the LCD screen,
navigate to the TEST section, and run the fluid circulation
pump (and if applicable, the boost pump) for at least
twenty minutes to purge the heating loop of air.
12.
Continually fill the fluid expansion bottle as the fluid
level drops.
13. Test the Aqua-Hot for normal operation.
Hose Pinch-
Off Pliers
Clamp
Drain Valve
Zone Fill
Figure 34
Figure 35
ETS Module
