SmartPlate Installation, Operation & Maintenance Manual
CHAPTER 8
– CORRECTIVE MAINTENANCE
OMM-0069_0H
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8.12 STRAINERS
All SmartPlate Water Heater models utilize Combination Strainers and Ball Valve on the boiler
side, and a strainer on the DHW side to prevent fouling of the heat exchanger by trapping
foreign material before it enters the unit. In addition, SmartPlate provides a Differential Pressure
Gauge on the Boiler Water Inlet to aid in determining when to blow-down the Strainer. If this
Gauge becomes inoperable, it should be replaced using the following procedure.
NOTE:
If normal maintenance does not clear the Water Heater flow path, it will be necessary to
remove and manually clean the screens in the Boiler Water and DHW piping as follows:
a. Remove Strainer end cap and remove screen.
b. Hose and wash off screen.
c. Reinstall screen and replace Strainer end cap.
DIFFERENTIAL PRESSURE GAUGE REPLACEMENT
Instructions
1. Close both Isolation Ball Valves in the Boiler Water piping (Figure 8-24).
2. Connect a hose to the Blow-Down/Drain Valve at the lower Strainer and open it to drain the
piping. It may be necessary to temporarily loosen a union on the Control Valve to allow air
into the piping.
3. Refer to Figure 8-26 and loosen the two compression fitting nuts on the Differential
Pressure Gauge tubes which are inserted into the brass Strainer body.
4. Pull and wiggle the tubes and Gauge and lift the assembly straight upward to remove it
from the Strainer.
5. Next, loosen the nuts on the Gauge body fittings and extract the tubes for use on the
replacement Differential Pressure Gauge.
NOTE:
The tube fittings are pass-thru type fittings that allow the tube to slide through the fitting
without hitting a stop. Prior to installation, make sure that the replacement Gauge has the
same type of fittings.
6. Install the tubes on the replacement Differential Pressure Gauge.
7. Insert the free ends of the tubes into the Strainer body and tighten the compression fittings.
DO NOT over-tighten the compression fittings.
8. Tighten the Control Valve union that was loosened in step 2.
9. Close the Blow-Down Drain Valve and open both Isolation Ball Valves (Figure 8-24).
10. Place the unit back in service and check for leaks. If the Strainer is clean and the flow is
within specification for the SmartPlate Water Heater model, the pointer on the Differential
Pressure Gauge should be in the Green zone on the dial.
