3) Several Maxi-Therms may be used together if needed. If this must be done keep the following in mind:
•
The first hour rating of several Maxi-Therms may be added together to give a first hour rating for
the total system.
•
The boiler outputs for the individual Maxi-Therms must be totaled to provide the boiler output
required for the system.
•
The boiler water flow rate on which each individual Maxi-Therm’s First Hour Rating is based must
be developed through the coil of each tank.
•
Use Maxi-Therms of equal size (do not mix Maxi-Therms of different sizes on the same manifold).
•
See the “Piping” and “Wiring” sections of this manual for proper installation of a manifold system.
4) Before settling on the choice of Maxi-Therm made above, keep in mind the following:
•
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 Maxi-Therm 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 Maxi-Therm from Table 4 which will provide hot water at this flow rate for the
period of time required.
•
Crown does not recommend the use of a Maxi-Therm to generate 180F water for commercial
dishwashers. Use the Maxi-Therm to generate 135F water and a pre-heater to raise the water
temperature for the dishwasher to 180F.
Example 2 (Commercial):
A Maxi-Therm is to be sized for a motel with 20 rooms. Each of these rooms has the following fixtures:
(1)
Vanity
(1)
Shower
(1)
Bath
In addition, 5 rooms have an additional vanity. Also there is utility sink used by the staff for cleaning and
a laundry with two machines.
Solution:
Use Table 3 and the fixture count to complete Worksheet 2 (Fig.3) Note that the vanities are treated as
“Private Lavatory Basins” and the utility tub as a “Laundry Tub”. From discussions with the washing
machine manufacturer and the motel owner, it is found that 100 gal/hr of 135F water is used in the laundry.
This usage is recorded on the “Laundry Line” at the bottom of Worksheet 2. The demand factor of 0.25 for a
Hotel is on line 12 of Table 3. The Probable Maximum Demand is 0.25 x 1978 = 494.5 Gal./hr. To this we
add the 100 Gal/hr Demand of 594.5 Gal./hr.
Select the most cost-effective combination of equal size Maxi-Therms which will satisfy this requirement.
The total gross boiler output required is equal to the requirement for each Maxi-Therm multiplied by the
total number of Maxi-Therms installed on the zone. Total boiler water flow through the Maxi-Therm zone is
equal to the requirement for each Maxi-Therm times the total number of Maxi-Therms.
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