System Zone Control

Answer:

New Rating

=297 gal/hr x (180,000 BTU/h)/(220,000 BTU/h)

=297 gal/hr x 0.818 = 243 gal/hr

NOTICE

Increasing the boiler DOE heating capacity above the values listed in Table 3 will not increase the rating of the water heater.

Ratings are based on 200°F boiler water. If 180°F boiler water is supplied, First Hour and Continuous Draw ratings will be reduced by approximately 27%.

2.Circulator Sizing – Refer to Table 4 for the corresponding pressure drop through the coil for the given model. Calculate the pressure drop of all straight pipe and fittings on the supply and return of the water heater at the selected flow rate. Add the piping/fitting pressure drop to the pressure drop through the water heater coil.

Select a circulator that will provide an appropriate flow rate at the combined pressure drop.

The Single-wall Indirect water heater must be installed as a zone separate from the space heating system. The domestic hot water zone’s piping and circulator must be sized for a minimum flow rate with all zones in use and a maximum flow rate with only the water