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240 (T-H3J), 340 (T-H3S) and 540 (T-H3) models Service Manial
Ver. 1.00
CONFIDENTIAL
12-14. Adjusting manifold gas pressure
The manifold gas pressure on the water heater can be adjusted by following the procedures below.
Adjusting maximum manifold pressure
1. Ensure that water heater is not in operation.
2. Remove the screw off the manifold port of the water heater. (Fig. 1)
3. Connect a manometer to the manifold port using a tube (Fig. 2). Ensure that this connection is
secure enough to prevent gas leak.
4. Run water through the water heater to activate its operation. If presence of a gas leak is detected,
immediately shut off the water heater and inspect the tube/manifold connection; otherwise,
proceed onto the next step.
5. Press and hold down the
“MAX”
button on the computer board. While holding down the “MAX”
button, press either the
“Increase”
or
“Decrease”
button to increase or decrease the manifold gas
pressure, respectively (Fig. 3). Refer to the manometer to verify that pressure has been set to
desired value.
6. After gas pressure has been set, deactivate the water heater, remove the manometer tube, and
replace the port screw.
Adjusting minimum manifold pressure
1. Ensure that water heater is not in operation.
2. Remove the screw off the manifold port of the water heater. (Fig. 1)
3. Connect a manometer to the manifold port using a tube (Fig. 2). Ensure that this connection is
secure enough to prevent gas leak.
4. Run water through the water heater to activate its operation. If presence of a gas leak is detected,
immediately shut off the water heater and inspect the tube/manifold connection; otherwise,
proceed onto the next step.
5. Press and hold down the
“MIN”
button on the computer board. While holding down the “MIN”
button, press either the
“Increase”
or
“Decrease”
button to increase or decrease the manifold gas
pressure, respectively (Fig. 3). Refer to the manometer to verify that pressure has been set to
desired value.
6. After gas pressure has been set, deactivate the water heater, remove the manometer tube, and
replace the port screw.
WARNING
Adjusting the manifold pressure can cause unexpected combustion conditions
during operation, which can cause a health hazard, damage the water heater,
and/or shorten its lifespan. Therefore, changing the manifold pressure is not
recommended unless there are very strong reasons to do so (e.g. high elevation
installations), and with the consultation of the Technical Services Department.
