AERCO ECS Retrofit - Manual (Page 39)

39
4.2.4 NPT Plugs
Each Retrofit Kit contains four NPT Plugs in the following sizes:
• 1/4 inch
• 1/2 inch
• 3/4 inch
• 1 inch
These plugs are installed in the remaining tapped holes in the Top Head where components used with
the previous Control System were installed. The location and size of the required Plugs may vary
depending on the specific AERCO Heater Model being retrofitted. Refer to Figure 2-1 for reference.
Ensure that all tapped holes in the Top Head have been plugged before proceeding with the
installation.
4.3 Flow Meter Installation
As part of the Electronic Control System (ECS) Retrofit, a new Flow Meter must be added to the
Packaged Heater. The purpose of this meter is to provide a feed-forward signal to the Temperature
Controller contained in the ECS Control Box. The installation location will vary depending on whether
the AERCO Water Heater Model being retrofitted is a Helitherm Heat Exchanger (A-Plus, B-Plus, B-
Plus II and E-Plus), or a Double-Wall Heat Exchanger (DW-24, DW-45, DW-68). For Helitherm Model
Heaters, the Flow Meter is installed between the Cold Water Inlet and the Drain Outlet on the Bottom
Head of the Heater (Figures 4-5 and 4-6). However, for Double Wall Heater Models, the Flow Meter is
installed between the Cold Water Inlet and Drain Outlet on the Heater Shell. See Figure 4-7. All
required installation components are included in the Retrofit Kit. Proceed to paragraph 4.3.1
(Helitherm) or 4.3.2 (Double-Wall), as applicable.
IMPORTANT
Prior to installing the inlet or outlet tubes to the Flow Meter (step 2 of
paragraphs 4.3.1 and 4.3.2), it will be necessary to first temporarily remove
the strain relief assembly shown in Figure 4-8. After removal, perform the
following steps:
1. First, hand-tighten the inlet and outlet tube compression fittings to the Flow
Meter. Position the “flats” on the fitting to avoid interfering with
reinstallation of the strain relief in the next step.
2. Next, attach the strain relief to the Flow Meter cable (Figure 4-8).
3. After the strain relief is installed, fully tighten the inlet and outlet tube
compression fittings to the Flowmeter.