Installation / Operation Instruction Manual

Pre-installation continued-

IMPORTANT DECISIONS REQUIRED BEFORE INSTALLATION

SIZING

1. Boiler DOE Heating Capacity – The indirect-fired water

heater will provide the rated performance only if used in

conjunction with a heat source with a DOE heating capacity

(Heat Output) at least as much as the minimum noted in

Table 3. If the heat source has less capacity, the output of the

tank will be reduced. To determine the approximate reduction

in output from the tank use the following formula:

New Rating = (maximum continuous draw rating) x

Actual Output of Heat Source

Minimum Output of Heat Source

For example, what would the continuous draw rating be if a 50-

gallon indirect-fired water heater were installed with a heat

source having a DOE heating capacity of 85,000 BTU/h?

Answer:

New Rating

= 229 gal/hr x (85,000 BTU/h)/(145,000 BTU/h)

= 229 gal/hr x 0.586 = 134 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.

2. Circulator Sizing – Refer to Table 5 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.