Installation / Operation Instruction Manual

Pre-installation continued-

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.