Winter / Summer Optional Kit

5
Answer:
New Rating
= 4.2 gal/min x (175,000 BTU/h)/(220,000 BTU/h)
= 4.2 gal/min x 0.795 = 3.3 gal/min
2. Circulator Sizing – Refer to the water heater’s installation manual 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.
SYSTEM ZONE CONTROL
The indirect-fired 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 heater in use. For this reason, the preferred method of zone control is
with circulators.
1. Circulators – With space heating zones using circulators, the indirect-fired heater should be added as an
additional zone with a circulator.
2. Zone Valves – Select a valve with a low-pressure drop to assure adequate flow through the water heater.
3. Hybrid – The space heating zone can be zoned using zone valves and the indirect-fired heater zoned with a
circulator.
DOMESTIC HOT WATER PRIORITY
Two options are available, Priority and Non-Priority.
1. Priority – Demand for space heating is interrupted or postponed until the domestic hot water demand is
satisfied. This option provides maximum delivery of domestic hot water. Priority is recommended when:
a) Boiler net output is 100,000 Btu per hour or less, or
b) When boiler output required to satisfy domestic hot water demand is at least 50% of the boiler output
required to satisfy space heating demand, or
c) When an interruption in space heating can be tolerated during a long domestic hot water draw.
2. Non-Priority – Boiler output is divided between space heating and domestic hot water heating. Delivery
of domestic hot water can be reduced during simultaneous space and domestic hot water heating
operations, depending on such factors as boiler output, boiler over-sizing, number of space heating zones
calling for heat, and the ratio of domestic hot water load to space heating load.
PIPING CONNECTIONS
The heat exchanger interior has been designed for non-potable water, such as in a hydronic heating system. If
replacing an existing water heating appliance, be sure to turn off electrical power and / or gas supply to the
existing appliance.
The return and supply system connections should now be identified on the side of the water heater. The use of
shut off valves and unions are recommended for future service convenience. A suitable expansion tank must be
installed in the heating circuit. Consult local codes for proper use, sizing and installation of an expansion tank.
DO NOT operate this water heater in a closed system without provisions for controlling thermal
expansion.
NOTICE
Increasing the boiler heating capacity above the values listed in Table 1 will not increase the rating of
the water heater.
CAUTION
Maximum boiler water supply temperature to the indirect heat exchanger must not exceed 250°F
(121°C).