
5
I. PRODUCT DESCRIPTION
This indirect water heater (IWH) is designed to generate domestic hot water in conjunction with a hot water boiler, or other
suitable heat source, using forced boiler water circulation. This indirect water heater consists of a stainless steel tank in which a
smooth stainless steel coil is located. Boiler water is pumped through the coil and heats the water in the tank. This product is not
intended for use in pool heating applications or for heating any other fluid other than water. It is also not intended for use in grav
-
ity hot water heating systems.
This manual shows installations where a hot water boiler is used as the heat source for the IWH, however other heat sources (such
as solar collectors) may be used provided that the following conditions are met:
1) The heat source must be able to provide a continuous supply of 180F water to the coil at the flow rates shown in Table 2.1.
If lower temperatures and/or flow rates are used, the performance shown in Table 2.1 may not be achieved.
2) The thermostat provided with this IWH must be installed and wired in such a way that it will interrupt the flow of heat
source water passing through the coil when its contacts open.
Failure to control the heat source flow using this thermostat
could result in unreliable operation or personal injury or death due to scalding.
3) The fluid passing through the coil must be water or other non-toxic fluid having a toxicity rating or Class of 1 as listed in
Clinical Toxicology of Commercial Products
(latest edition).
4) The heat source must be used in accordance with its manufacturer’s instructions and those of the authority having jurisdic-
tion.
IMPORTANT NOTE
All models have a stored volume of less than 120 Gallons. When installed in accordance with these instructions, stored
potable water temperature in the tank is limited to a value of 210F or less by a temperature and pressure relief valve.
The maximum possible heat transfer rate across the coil (heat input) is less than 200,000BTU/hr with 210F potable
water provided that boiler or heat source water temperature is limited to:
MS2-030 – MS2-075: 250F
MS2-119: 220F
All models are therefore outside of the scope of both ASME Section IV, part HLW and ASME Section VIII when
installed in accordance with these instructions and with the boiler or heat source water temperature limited as shown
above.
II. SPECIFICATIONS
Notes:
Ratings based on 77F DHW temperature rise (135F outlet temp) and 180F boiler supply temperature. The ratings in Table
2.1 were obtained at the heat source (boiler) output rates and heat source flow rates shown above. Other results shall be
obtained under different conditions.
Pressure Ratings:
Maximum Allowable Tank Working Pressure - 150 psi
Design Hydrostatically Tested to 300 psi
TABLE 2.1: Mega-Stor
®
II Series AHRI Performance Ratings
Model
First Hour
Rating
Continuous
Draw Rating Standby
Loss
(°F/hr)
Minimum
Boiler
Output
(MBH)
Boiler Water Through Coil
(Gal/hr)
(Gal/hr)
Min Flow
(Gal/min)
Head Loss
(ft w.c.)
MS2-030
162
138
1.4
87
8.0
2.6
MS2-040
192
162
1.1
101
8.0
2.8
MS2-050
236
193
0.9
121
8.0
2.9
MS2-075
307
238
1.0
150
8.0
4.5
MS2-119
497
417
1.4
264
14.0
4.2
Summary of Contents for Mega-Stor II
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