17
LP- 446 REV. 9.3.14
the system, you must install an additional tee for a suitable potable hot water expansion tank. Connect the Storage tank return line to
the return connection located on the Mod Con VWH (shown in Piping Diagrams). Then connect your hot water outlet located on the
storage tank to your hot water plumbing lines.
Never use dielectric unions or galvanized steel fittings when connecting to a stainless steel storage tank or boiler.
When raising tank temperature, you increase the risk of scalding. Use a water tempering or mixing valve and extreme caution. Consult
codes for conformance.
E. SCALDING
When raising tank temperature, you increase the risk of
scalding. Please use a water tempering or mixing valve and
extreme caution when raising tank temperature to lessen
the chance of scalds. Consult codes for conformance.
This water boiler can deliver scalding water at any faucet in
the system. Be careful whenever using hot water to avoid
scalding injury. Certain appliances such as dishwashers and
automatic clothes washers may require increased water
temperature. By setting the thermostat on this water boiler to
obtain the increased water temperature required by these appliances, you may create the potential for scald injury.
To protect against injury, the installer should install a mixing valve in the water system. This valve will reduce point of discharge
temperature by mixing cold and hot water in branch supply lines. Such valves are available from your local plumbing supplier.
Table 5 details the relationship of water temperature and time with regard to scald injury and may be used as a guide in determining the
safest water temperature for your applications.
The table below represents the combined flow rates and pipe sizes when using multiple boilers to design the manifold system for the
primary circuit. To size, simply add up the number of boilers and the required flow rates for the system design temperature. Example:
(5) Mod Con 500 boilers with a design of 30
o
F temperature rise, with each boiler having an individual flow rate of 33 gpm. To correctly
size the manifold feeding these (5) Mod Con 500 boilers, you would need a pipe size of 4
”.
F. HIGH VELOCITY CIRCULATOR PUMP
Every VWH system requires special attention to pump size in order to overcome the pressure drop through the boiler and its related
piping. All circulators installed on the VWH system must be designed for a potable water system.
Water temperature above 140
o
F requires the circulator pump to run continuously and water hardness between 5 and 7 grains.
Hardness above 7 grains will damage the heat exchanger and shorten the service life of the boiler.
In addition, the heat exchanger has a minimum total water volume that must be taken into account when sizing the circulator. Minimum
flow rates are listed in the table below.
MINIMUM HEATER FLOW RATES
MODEL
MINIMUM FLOW (GPM)
MODCON500VWH
33
MODCON850VWH
54
Table 6
– Minimum Flow Rates
APPROXIMATE TIME /
TEMPERATURE RELATIONSHIPS IN SCALDS
120
o
F
More than 5 minutes
125
o
F
1 ½ to 2 minutes
130
o
F
About 30 seconds
135
o
F
About 10 seconds
140
o
F
Less than 5 seconds
145
o
F
Less than 3 seconds
150
o
F
About 1 ½ seconds
155
o
F
About 1 second
Table 5
Содержание 500 HL
Страница 12: ...12 LP 446 REV 9 3 14 Figure 2 Dimensions and Specifications ...
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Страница 52: ...52 LP 446 REV 9 3 14 Figure 33 Mod Con Internal Connection Diagram LP 428 K ...
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