11
010.4150.0720 08.21
Fig 9
Fig 7
5. PLUMBING
5.1 GENERAL
It is not within the scope of this manual to provide specific
plumbing installation instructions as the installation should
follow the design specifications of the design engineer,
architect, or contractor. However, measures must be taken
to prevent the water from stagnating within the economizer
while the boiler(s) are in operation. Also, the water side of
the economizer must be kept free of grease and other foreign
material which can shorten the life of the economizer and
possibly interfere with the operation of controls and safety
devices. Proper feedwater treatment is a major factor in
preventing economizer failure.
Only low sulfur fuels should be used with the VHX-DR. if
fuels other than natural gas are used, there is a risk of “cold
end corrosion” when the entering water temperature falls
enough to cause condensation of the flue gases so verify the
feasibility of the application with the design engineer prior to
installation.
Generally, schedule 40 steel pipe is used in the piping
installation. In some applications other piping material may be
needed. Consider the type of liquid, operating pressures and
temperatures, and any corrosive elements in the liquid or in
the atmosphere when determining the best piping material
for your installation. The use of valves is recommended
where isolation might be required. Non-ferritic piping is
recommended if using non-deaerated water.
5.2 CONNECTING PIPING
Actual piping depends on how the heating modules are
configured. Water should flow counter flow to the exhaust.
If the heat modules are connected to a common header,
supply and return liquid pipes must be connected directly to
the common header. This is shown in Fig 7. Balancing valves
should be installed in order to ensure that the flow is equally
distributed.
If the VHX-DR is used for multiple applications, e.g. one heat
module is used for domestic water while the other is used
for boiler feed-water, each application must be connected
directly to the supply and return connections on the heat
module. See Fig 8.
Liquid connections are connected with NPT threaded fittings.
The maximum allowable connection loads given in Fig 9 are
valid for low cycle fatigue. If high cycle fatique is involved, a
special analysis should be carried out
Liquid piping should include shut-off, drain and bypass valve
piping in the event the exchanger is required to be isolated.
Drain piping should include valves of dependable
manufacture in order to further reduce the possibility of an
undetected leak.
Outlet
Headers
Flexible
Water Connection
Inlet
Fig 8
Max. Bending Torque
Torque Moment
Connections
20 Nm
70 Nm
