Weil-McLain Gold CGa 3d

GOLD CGa Gas-Fired Water Boiler

20 Part Number 550-110-593/1099

Water piping — low temp systems

Failure to prevent low return water temperature to the boiler could cause corrosion of the

boiler sections or burners, resulting in severe personal injury, death or substantial 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 of this manual if the system is equipped with an outdoor reset

control. Instead, provide controls and piping which can regulate the boiler return water

temperatureat no less than 130 °F regardless of system supply temperature. Contact your

Weil-McLain 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.

Primary/secondarybypass piping is preferred because the flow rate and temperature drop in

the heating circuit(s) is determined only by the heating circuit circulator(s). So adjustment of

the bypass valves in the boiler circuit will not cause a change in the heating circuit rate and

temperature distribution.

Figures 13 and14 show suggested bypass arr angements using primary/secondary bypass

piping (preferred) for low temperature systems such as radiant heating systems or converted

gravity systems. For alternatives, see pages 22 through 25.

The bypass valves (items 7a and 7b) provide mixing of hot boiler outlet water with cooler

system return water — set to assure a minimum return water temperature (at least 130 °F) to

the boiler. Set the valves as explained below.

Temperature gauges Gauge 4a is suggested, but optional on any system.

Gauge 4b is optional on converted gravity systems, but required on radiant heating systems —

to display the water temperature being supplied to the radiant tubing.

Gauge 8 is required on all systems to assure the return water temperature is accurately set for

a minimum of 130 °F. If this gauge is not available however, adjust the valves such that the

boiler-mounted temperature/pressure gauge reads at least 150 °F when the system return water

is cold (approximately 60 °F water temperature).

1. Set the valves while the system is cool, setting for the coldest expected water temperature

(usually 60 °F since the system will often drop to room temperature between cycles).

2. Start with valve 7a fully closed and 7b fully open.

3. Gradually open valve 7a while closing valve 7b until the temperature at gauge 8 reads

130°F when gauge 4a reads 60 °F.

4. Note that valve 7a regulates the amount of hot water from the boiler supply which mixes

with return water. Valve 7b regulates the amount of system water flowing through the

boiler secondary loop.

Valve adjustment

(Figure 13 and 14 only)