Weil-McLain Gold CGa 3f

GOLD CGa Gas-Fired Water Boiler

24 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.

This piping method is called a system-bypass because part of the circulator flow bypasses the

system (through valve 7a). This bypassed hot water from the boiler outlet mixes with cooler

system return water temperature in order to provide minimum 130 °F return water to the

boiler. Valve 7b will most often be full open, but may need to be slightly closed on some low

pressure drop systems in order to cause enough flow through valve 7a.

Figure 17 is an alternative piping method that provides return water temperature control for

boilers installed on converted gravity sy stems (large water content or steam systems).

Do not apply the piping of Figure 17 on radiant heating systems. It provides no method of

regulating the water temperature provided to the system and could result in excessive water

temperature in the radiant tubing.

System-bypass piping as shown in Figure 17 can be used with either zone valve or circulator

zoning. When used with circulator zoning however, the boiler circulator (item3), must be

piped as shown. It cannot be used as one of the zoning circulators.

Do not apply system-bypass piping if the reduced flow in the system could cause poor heat

distribution. That is, system-bypass piping reduces the flow in the system and increases the

water temperature supplied to the system. This can cause increased heat from radiators at the

beginning of the system and reduced heat from radiators near the end of the system.

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

2. Gradually open valve 7a while closing valve 7b until the temperature at gauge8reads at

least 130 °F at all times.

3. Valve 7a regulates the amount of boiler supply water mixed with return water. Valve 7b

causes a pressure drop in the system needed to balance flow through valve 7a and the

system.

4. The valve adjustment should be done with the system at the coldest expected temperature

(60°F for converted gravity systems or high mass radiant systems).

Valve adjustment