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.