Adjusting Manifold Gas Pressure - A.O. Smith T-D2-OS Service Manual

12-12. Adjusting manifold gas pressure

The manifold gas pressure on the T-D2-IN or T-D2-OS can be adjusted by following the procedures.
Adjusting the manifold pressure can cause unexpected combustion conditions during
operation, which can cause a health hazard, damage the T-D2-IN or T-D2-OS, and/or
shorten its lifespan. Therefore, changing the manifold pressure is not recommended
WARNING unless there are very strong reasons to do so (e.g. high elevation installations), and with
the consultation of the Technical Services Department.
Adjusting maximum manifold pressure
1. Ensure that T-D2-IN or T-D2-OS is not in operation.
2. Remove the screw off the manifold port of the T-D2-IN or T-D2-OS. (Figure 1)
3. Connect a manometer to the manifold port using a tube (Figure 2). Ensure that this connection is
secure enough to prevent gas leak.
4. Run water through the T-D2-IN or T-D2-OS to activate its operation. If presence of a gas leak is
detected, immediately shut off the T-D2-IN or T-D2-OS 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 (Figure 3). Refer to the manometer to verify that pressure has been set to
desired value.
6. After gas pressure has been set, deactivate the T-D2-IN or T-D2-OS, remove the manometer tube, and
replace the port screw.
Adjusting minimum manifold pressure
1. Ensure that T-D2-IN or T-D2-OS is not in operation.
2. Remove the screw off the manifold port of the T-D2-IN or T-D2-OS. (Figure 1)
3. Connect a manometer to the manifold port using a tube (Figure 2). Ensure that this connection is
secure enough to prevent gas leak.
4. Run water through the T-D2-IN or T-D2-OS to activate its operation. If presence of a gas leak is
detected, immediately shut off the T-D2-IN or T-D2-OS 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 (Figure 3). Refer to the manometer to verify that pressure has been set to
desired value.
T-D2-IN / T-D2-OS Service Manual
63
CONFIDENTIAL
Ver. 1.00