IBC IWT 119, Installation And Operating Manual, Page: 18 / 40

2.2 System zone control
Caution
To avoid water damage from leaks, install a drain pan under the water heater unless it is
located where leaks will not cause property damage. See Figure 8 .
If unable to direct discharge from a T&P relief valve into a drain or into an area where water
damage will not occur, install a drain pan capable of draining away the full, continuous
discharge flow of the relief valve.
You must install the water heater as a separate zone from the space heating system. The water heating
zone’s piping and circulator must be sized for the minimum flow rate with all the zones in use and a
maximum flow with only the water heater in use. The best method for zone control is the use of circulators.
The three most common systems are:
1. Zone Circulators . Space heating zones use a circulator for each zone, and the water heater is
controlled with an additional circulator.
2. Hybrid System . Space heating zones use zone valves for each zone, and the water heater is
controlled with an additional circulator. See Figure 4 .
3. Zone Valves . Space heating zones use zone valves for each zone, and the water heater is
controlled with an additional zone valve. Select a valve with a low pressure drop and adequate
pipe size to ensure maximum flow.
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Section: Pre-installation overview