LAARS Heating Systems
Page 20
SECTION 4B.
Water Connections —
Mighty Therm2 Water Heater
4B.1 Water System Piping —
Water Heater
Hot water piping should be supported by suitable
hangers or floor stands. Do not support piping with
this appliance. Due to expansion and contraction of
copper pipe, consideration should be given to the type
of hangers used. Rigid hangers may transmit noise
through the system resulting from the piping sliding in
the hangers. It is recommended that padding be used
when rigid hangers are installed.
The Mighty Therm2 can be used with several
different types of readily available storage tanks. A
pump draws water from the storage tank and pumps
the water through the heater and back into the tank.
Pump-mounted units have a circulating pump built
into the water heater. The pumps used are sized for
the head loss through the heater, plus 30 feet (9.1 m)
of full-sized piping (same size as boiler outlet) and
a normal number of fittings. Pumps used on pump-
mounted unit are sized for soft/normal or hard water,
so make sure a pump-mounted unit matches the water
quality of the installation.
Pipe the outlet from the heater’s relief valve
such that any discharge from the relief valve will be
conducted to a suitable place for disposal when relief
occurs. Do not reduce line size or install any valves in
this line. The line must be installed to allow complete
drainage of both the valve and the line.
Suggested piping diagrams are shown in
Figures
9, 10, 11 and 12.
These diagrams are meant only as a
guide. Components required by local codes must be
properly installed.
Note the recommended location of the
temperature sensor on the diagrams. The Mighty
Therm2 is shipped with an additional sensor that can
be used for more full-featured domestic water heating
control. To get these features, you must provide a
location for the additional sensor. It can be strapped to
a pipe from 1" to 4" diameter, or inserted into a tank
immersion well.
The minimum inlet water temperature for the
Mighty Therm2 is 120°F (49°C) to avoid condensing
on the copper coils.
4B.2 Hot Water Supply Piping —
Water Heater
Follow the tank manufacturer’s guidelines for
completion of the hot water system connections.
NOTE: A listed temperature and pressure relief
valve listed as complying with the Standard
for Relief Valves and Automatic Gas Shutoff
Devices for Hot Water Supply Systems (ANSI
Z21.22/CSA 4.4), of suitable discharge capacity
must be installed in the separate storage tank
system.
If the Mighty Therm2 water heater is installed
in a closed water supply system, such as one having a
backflow preventer in the cold water supply line, the
relief valve may discharge periodically, due to thermal
expansion. Means (such as a properly-sized expansion
tank) shall be provided to control thermal expansion.
Contact the water supplier or local plumbing inspector
on how to control this situation.
4B.3 Water Flow Requirements —
Water Heater
In a water heating application (an open system),
new water is constantly being introduced. With the
new water comes a fresh supply of minerals that can
be deposited on the unit’s heat exchanger. This is
commonly known as scaling. The amount of minerals
will depend upon the hardness of the water. Water can
also be aggressive, and can erode metals, including
copper, if the water is moved too quickly. The water
flow requirements for the Mighty Therm2 water heater
are based upon the hardness of the water. The water
flow is kept high enough to prevent scaling, but low
enough to prevent tube erosion. For extremely soft or
hard water, cupro-nickel tubes are available. Contact a
Laars representative if you have questions or concerns
about water quality.
Pump-mounted water heaters can be ordered with
standard pumps for soft or normal water. The pumps
used are sized for the head loss through the heater, plus
30 feet (9.1m) of full-sized piping (same size as heater
outlet) and a normal number of fittings. For hard water
conditions (more than 17 grains per gallon), use a
non-pump-mounted heater with a properly-sized field-
installed pump.
Table 9
specifies water flow rates for water
heaters, which will enable the user to size a pump. The
head loss shown is for the heater only, and the user
will need to add the head loss of the piping system to
properly size the pump.
4B.4 Combined Water Heating (potable)
and Space Heating — Water Heater
NOTE:
These systems are not allowed in the
Commonwealth of Massachusetts.
Piping and components connected to this water
heater for the space heating application shall be
suitable for use with potable water.
Toxic chemicals, such as used for boiler
treatment, shall not be introduced into the potable
water used for space heating.
This water heater when used to supply potable
water shall not be connected to any heating system
or component(s) previously used with a non-potable
water heating appliance.
