HTP Mod Con 300 HL, Installation & Maintenance Manual

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3. Install purge and balance valve or shut off valve and drain on system return to purge air out of each
zone.
4. Install a back flow preventer on the cold feed make-up water line.
5. Install a pressure reducing valve on the cold feed make-up water line (15 PSI nominal on the system
return). Check temperature and pressure gauge when operating. It should read a minimum pressure of 12
PSI.
6. Install a circulator as shown in piping details (this section). Make sure the circulator is properly sized for
the system and friction loss.
7. Install an expansion tank on the system supply. Consult the tank manufacturer’s instructions for
specific information relating to expansion tank installation. Size the expansion tank for the required
system volume and capacity.
8. Install an air elimination device on the system supply.
9. Install a drain valve at the lowest point of the system.
NOTE: The boiler cannot be drained completely
of water without purging the unit with an air pressure of 15 PSI.
10. The relief valve is installed at the factory. A pipe discharge line should be installed to discharge 6”
above the drain in the event of pressure relief. The pipe size must be the same size as the relief valve
outlet.
NEVER BLOCK THE OUTLET OF THE SAFETY RELIEF VALVE.
H. CIRCULATOR SIZING
The boiler heat exchanger does have a pressure drop which must be considered in system design. Refer
to the graph in Figure 11 for pressure drop through the boiler heat exchanger.
Figure 11 – Heat Exchanger Pressure Drop Chart