LAARS Mighty Therm VW (Sizes 2000-5000) - Installation, Operation and Maintenance Instructions - Manual (Page 10)

LAARS Heating Systems
Page 10
Cold
Water
180 °
Water
To Bldg.
Conventional
Tank
To Drain
140 °
Water
To Bldg.
To
Drain
Pump
180 ° Water
Return
From Bldg.
140 ° Water
Return
From Bldg.
B
D
E
K
C
H
C
H
J
I
recommended pipe size, a
larger pump may be
required. Consult the
factory if in doubt.
6. Install a pipe in the tank
drain fitting that goes to a
floor sink, and install a
drain valve. If a floor sink
is not available, install a
hose bib.
7. Hot water tanks in an
existing installation are
likely to have a deposit of
silt on the bottom.
Therefore, it is important
to extend the pump suction
pipe in the tank to a
position near the top. Pipe
the return from the heater
to the bottom of the tank.
Note: Incorrect installation
can cause rapid failure of water
tanks due to electrolysis. Tanks
must be installed with dialectric
connections to electrically
isolate the tank from stray
current. Note that use of brass or
bronze connectors does not
replace the need for dialectric
connections.
2.10 Water Pressure
It is very important that at
least 30 psi water pressure in the
system is maintained. If the
pressure drops below this level,
damage to the heater through
lack of circulation can occur. If,
for any reason, the water supply
is turned off temporarily, to
service a piece of equipment for
instance, the manual gas valve
on the heater should be closed
until the water pressure has been
restored and the lines bled of
accumulated air. If the heater
fails to fire when it is turned
back on, it could be airlocked.
To eliminate the airlock, open
the pressure relief valve and
allow the air to escape. When
full circulation is restored, any
residual air in the lines will be
released through the faucets.
Figure 9. Supply-Flo Two Temperature Hot Water Supply System with
Vertical Tank.
Figure 10. Safety-Flo Two Temperature Hot Water Supply System with
Horizontal Tank.
Cold
Water
180 °
Water
To Bldg.
Conventional
Tank
To
Drain
24" Min.
To Drain
Pump
H
140 °
Water
To Bldg.
140 ° Water
Return
From Bldg.
180 ° Water
Return
From Bldg.
H
C
C
B
D
I
K
K
E
J
2.11Piping of Heater to System
Legend
B – Check valve in Hot Water Supply
To Tempering Valve
C – Check valve in Return Line from Building Loop
D – Tempering Valve
E – Venturi (Suction) Tee H - Throttling Valves in Building Loop Returns
I – Circulating Pump for 180° Building Loop
J – Circulating Pump for 140° Building Loop
K – Service Valves to isolate Heater and Pump
for service