Dunkirk ARTESIAN 220 Installation And Operating Instructions Manual page 14

b) If the water heater is to be installed with an existing boiler, go to table 1 and select a
water heater which has a 140°F first hour rating greater than or equal to the adjusted
probable maximum demand calculated in1g. Note the boiler's gross output required to
achieve the selected water heater's first hour ratings. If it is more than the gross output
of the existing boiler, the existing boiler is too small to provide the proper input to the
water heater.
3) Several water heaters may be used together to provide a greater first hour rating than the
largest available single Artesian, if needed. If this is done, keep the following in mind:
* The first hour ratings of several Artesians may be added together to give a first hour
rating for the total system.
* The gross boiler output required for each individual water heater must be totaled to
provide the gross boiler output required for the system.
* Use water heaters of equal size. Do not mix tanks of different sizes on the same
manifold.
* See the "Piping" and "Wiring" sections of this manual for proper installation of a
manifold system.
4) Note: Use of a storage tank can increase the system's performance by providing a buffer for
periods of high demand.
5) Keep in mind the following before settling on the choice made above:
Many building's peak demands result from the constant use of one type of fixture or
machine for a relatively short period of time (showers in a gymnasium, for example).
The procedure outlined above may not provide adequate hot water in these cases. The
best way to size water heaters for this type of application, is to determine the total flow
rate of all fixtures. Which are, or could be, in use at once and select a water heater from
Table 1, which will provide hot water at this flow rate for the period of time required.
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