Weil-McLain GOLD CGS 550-110-260/02002 - Manual (Page 22)

Part number 550-110-260/0200
22
GOLD CGs Gas-Fired Water Boiler
Water piping — low temp systems
3f
1. Start with valve 7a fully closed and 7b fully open.
2. Gradually open valve 7a while closing valve 7b until the temperature at gauge 8 reads 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
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 12 is an alternative piping method that provides return water temperature control for
boilers installed on converted gravity systems (large water content or steam systems).
Do not apply the piping of Figure 12 on radiant heating systems . It provides no method
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 12 can be used with either zone valve or circulator
zoning. When used with circulator zoning however, the boiler circulator (item 3 ), 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.
System-bypass
piping method
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 temperature at 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.