Water Piping — Multiple Zones; Zoning With Circulators; Converted Gravity (Or Steam) Systems - Williamson-Thermoflo GWA 3 Series Manual

4 Water piping — multiple zones
Piping multiple zones
Follow instructions on pages 11 and 12 to install near-boiler
or single-zone piping. (Also refer to Piping for radiant heating
systems or converted gravity systems, below, if applicable.)
See Figure 10 or Figure 11, page 14, to complete installation.
Zoning with circulators (Figure 10)
(return temp over 130°F)
1. Size each circulator to individual circuit requirements.
2. Do not install circulator on boiler (except for primary/
secondary piping).
3. Install isolation (balancing) valves to adjust flow to distrib-
ute heat to all zones.
4. Install and wire a separate relay for each zone circulator.
Zoning with zone valves (Figure 11)
(return temp over 130°F)
1. Install isolation (balancing) valves to adjust flow to distrib-
ute heat to all zones.
2. Provide a separate 24-volt transformer to power the zone
valves. Size the transformer to handle the total rated load
of all connected zone valves.
DO NOT connect directly from 3-wire zone
valves to the T-T terminals on the boiler
When using 3-wire zone valves, install an isola-
tion relay. Connect the zone valve end switch
wires to the isolation relay coil. Connect the
isolation relay contact across the boiler T-T
terminals. Failure to comply can result in dam-
age to boiler components or cause unreliable
operation, resulting in severe property damage.
Radiant heating system piping should include a means of regulating the boiler return water
temperature and the system supply temperature (such as provided by an injection pumping
control). Boiler return water temperature will be adequately controlled using the methods
shown in this manual provided the system supply temperature is relatively constant.
DO NOT apply the methods in this manual if the system is equipped with an outdoor reset
control. Instead, provide controls and piping which can regulate the boiler return water tem-
perature at no less than 130°F regardless of system supply temperature. Contact your William-
son-Thermoflo representative for suggested piping and control methods. Failure to prevent
cold return water temperature to the boiler could cause corrosion damage to the sections or
burners, resulting in possible severe personal injury, death or substantial property damage.
Part Number 550-142-320/0720
GWA Series 3 Gas-Fired Water Boilers – Boiler Manual
Piping for radiant heating systems
or converted gravity systems

Converted gravity (or steam) systems

Whenever possible, use the primary/secondary piping
shown in Figures 12 or 13 on page 16. This piping design
allows changing boiler flow rate without affecting primary
circuit flow rate.
If Figures 12 or 13 cannot be used, use the boiler-bypass
piping shown in Figure 14 or Figure 15 on page 18. You can
also use the piping shown in Figure 8 on page 12 (system-
bypass), if the reduced flow rate in the heating system will
not cause heat distribution problems.
Radiant heating systems
Preferably, use primary/secondary piping, as shown in
Figures 12 or 13 on page 16. Alternatively, use the method
of either Figure 14 or Figure 15 on page 18. Do not use the
piping of Figure 8 (system-bypass), because this method
does not control radiant system supply temperature.
If radiant system tubing has no oxygen barrier, a heat ex-
changer must be used.
.
Failure to prevent low return water tempera-
ture to the boiler could cause corrosion of the
boiler sections or burners, resulting in severe
personal injury, death or substantial property
damage.
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