Weil-McLain CGA25SPDN 3d Piping - low temperature systems continued, SYSTEM-bypasspiping method

GOLD CGa Gas-Fired Water Boiler — Boiler Manual

3d Piping — low temperature systems (continued)

SYSTEM-bypass piping method

This piping method (&IGURE , page 25) is called a SYS TEMBYPASS because part of the circulator flow bypasses the system (through valve A). This bypassed hot water from the boiler outlet mixes with cooler system return water temperature in order to provide minimum 130°F RETURN WATERTTO THEHBOILERL6ALVELB 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 A.

&IGURE  is an alternative piping method that provides return water temperature control for boilers installed on CONVERTEDEGRAVITY SYSTEMS (large water content or steam systems).

$/ ./4 apply the piping of &IGURE  on RADIANTI HEATINGTSYSTEMS. It provides no method of regulat- ing the water temperature provided to the system and could result in excessive water temperature in the radi- ant tubing.

System-bypass piping as shown in &IGURE  can be used with either zone valve or circulator zoning. When used with circulator zoning however, the boiler circulator (item ), must be piped as shown. It cannot be used as one of the zoning circulators.

$/ ./4 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.

Valve adjustment

1. Start with valve A fully closed and B fully open.

 'RADUALLYUOPEN VALVELA while closing valve B until the temperature at gauge  reads at least 130°F at all times.

 6ALVELA regulates the amount of boiler supply water MIXEDXWITH RETURN WATER 6ALVELB causes a pressure drop in the system needed to balance flow through valve A 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).

Failure to PREVENT LOWWRETURN WATERTTEMPERATURE 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 THEHBOILER RETURN WATERTTEMPERATURE and the SYSTEM SUPPLYYTEMPERATURE (such as provided by an INJEC

TION PUMPING CONTROL).

"OILER RETURN WATERTTEMPERATUREAWILL BE ADEQUATELY CONTROLLEDEUSINGITHEGMETHODSESHOWNE in this manual provided the SYSTEM SUPPLYYTEMPERATURE is RELATIVELYYCONSTANT

DO NOT apply the methods of this manual if the system is equipped with an OUTDOORD

RESETSCONTROL Instead, PROVIDE CONTROLSLAND PIPING which can REGULATE THE BOILERTRE

TURN WATERTTEMPERATURE at NO LESS THAN —& regardless of system supply temperature.

#ONTACTTYOUR 7EIL-C,AIN REPRESENTATIVECFORASUGGESTEDEPIPING ANDDCONTROLNMETHODS

Failure to PREVENT COLD RETURN WATERTTEMPERATURE to the boiler could cause corrosion damage to the sections or burners, resulting in possible severe personal injury, death or substantial property damage.

24 Part Number 550-101-009/0107