17
c l i m a t e m a s t e r. c o m
Tranquility
®
30 Digital (TE) Series IOM - 60Hz HFC-410A
R e v. : 2 9 M a y, 2 0 1 5 J
Multiple Unit Piping and Flushing
Figure 16a: Multiple Units with Internal Flow Controllers
Multiple Units with Internal Flow Controllers
The simplest multiple unit system is one with two (or more) units utilizing internal Flow Controllers with no external pumps
or
fl
ushing valves. In this case the units are piped in parallel and use the internal
fl
ushing valves to
fl
ush the system. The
variable speed pump includes an internal check valve to prevent back (short circuiting)
fl
ow through the units.
In this case,
fl
ush the loop through the internal
fl
ushing valves in the unit farthest from the loop
fi
rst. Once the loop is
fl
ushed,
then change the internal
fl
ushing valves to
fl
ush the heat pump. Next, move the
fl
ushing cart to the next closest unit to the
loop.
Again,
fl
ush the loop through the internal
fl
ushing valves. This is important as there may be air/debris in the lines from this unit
to the common piping. Once
fl
ushing begins the air will be move into the loop and will need to be
fl
ushed out. After the loop
is
fl
ushed through the second unit, change the
fl
ushing valves to
fl
ush the second unit. This process should be repeated for
additional units working from the farthest from the loop to the closest to the loop.
This type of application can generally be employed for systems to 12 tons depending on loop design. However, it is important
perform appropriate calculations to con
fi
rm that the variable speed pump can provide adequate
fl
ow through all heat pumps
against the loop head when all units are operating.
Multiple Units with Internal Flow Controllers and External Flushing Valves
When the number of units or
fl
ushing requirements reaches a point where it is no longer feasible to
fl
ush through the internal
valves (generally systems of more than 12 tons depending on loop design), external
fl
ushing valves should be installed. In this
case, three-way
fl
ushing valves should be used or additional isolation valves must be installed to be able to isolate the loop
during
fl
ushing.
First,
fl
ush the ground loop. The installer should close the indoor loop shut-off valve (or the internal
fl
ushing valves in all units)
and open the ground loop shut-off valve to prevent
fl
ow through the indoor loop while
fl
ushing the ground loop.
Once the ground loop is
fl
ushed, close the ground loop shut-off valve and open the indoor loop valve(s) to
fl
ush the units and
indoor piping. Remember that there is an internal check valve in the variable speed pump and that backward
fl
ow the unit is
not possible.
Water Out
Water In
Heat Pump
B
Water Out
Water In
Heat Pump
A
To Ground
Loop
Size for Heat Pump
‘A’ Flow
Size for Heat Pump
‘B’ Flow
Size for ‘A’ + ‘B’ Flow
