Multiple Unit Piping And Flushing - ClimateMaster Trilogy Q-Mode (QE) Series Manual

Trilogy Q-Mode
®
R e v i s e d : D e c e m b e r 2 2 , 2 0 2 1

Multiple Unit Piping and Flushing

Often projects require more than one heat pump. Where
possible, it makes sense for multiple units to share a common
ground loop. Common ground loops for multiple units bring
new challenges including the need to avoid backward flow
through inactive units, increased pumping requirements,
and more complex flushing needs. Below are guidelines for
multiple unit piping and flushing on a common loop.
Units equipped with an internal flow controller (vFlow
include an internal variable speed circulator controlled by
the EXM microprocessor, internal 3-way flushing valves and
an internal bladder type expansion tank. The internal pump
includes an internal check valve. The pump curves for the
internal circulator are shown in Figures 13a and 13b. The
internal expansion tank will operate as a pressure battery
for the geothermal system. It will absorb fluid from the loop
when loop pressure rises and inject fluid into the loop when
loop pressure falls. In this way the expansion tank will help to
maintain a more constant loop pressure and avoid flat loops
due to seasonal pressure changes in the loop.
When using the internal variable speed pump as the loop
pump in multiple unit installations it is important to ensure
that the variable speed pump can provide adequate flow
through the heat pump against the loop head when all units
are operating.
It may be possible to flush a multiple unit system through
the unit's flushing valves. Flushing pressure drop of the
valve may be calculated to determine if it is acceptable.
Engineering data for the 3-way flushing valves can be found
in Table 2.
Table 2: Internal 3-Way Flushing Valve Data
Inlet Flushing
Model
Valve
QE*0930 3/4" FPT
QE*1860 3/4" FPT
Straight Flow
Valve Size
(Normal Operation) Cv
¾"
1"
⚠
CAUTION! Never exceed a pressure of 100 psig or a flow
rate of 30 gpm in a Trilogy unit. Pressure greater than 100
psig or flow rates greater than 30 gpm will damage the unit
sensors causing the unit to miscommunicate certain data
points and may cause the unit to nuisance fault.
18
(QE) Series IOM - 60Hz HFC-410A
®
Outlet Flushing
Valve
3/4" MPT
1" MPT
90° Flow
(Flushing) Cv
25 10.3
58 14.5
⚠
CAUTION!
G e o t h e r m a l H e a t i n g a n d C o o l i n g
For example, if a system includes two QE0930 units and four
¾ loop circuits we can calculate the flushing pressure drop as
follows. From Table 1 we know that it will take 4 gpm to flush
each ¾" circuit. If there is no provision to isolate the circuits
for flushing, we will have to flush with a minimum of 4 circuits
x 4 gpm/circuit = 16 gpm total. A check of other piping sizes
used must be done to ensure that 16 gpm total flow will flush
all piping.
)
™
Pressure drop through the flushing valve can be calculated
using the following formula.
ΔP = (GPM/Cv)
ΔP = pressure drop in psi through the valve while flushing
GPM = flushing flow in gallons per minute
Cv = valve Cv in flushing mode
We know from Table 2 that the Cv for the flushing valve in a
QE0930 is 10.3 in the flushing mode (90° flow). Therefore,
ΔP = (GPM/Cv)
two flushing valves). So long as the flushing pump is able to
provide 16 gpm at the flushing pressure drop of the loop plus
the 2.4 x 2 valves = 4.8 psi (11 ft of hd) of the flushing valves,
the internal flushing valves may be used. If the flushing pump is
not able to overcome the pressure drop of the internal flushing
valves, then larger external flushing valves must be used.
Unit Configuration
Multiple vFlow
™
controller and check valve, piped in parallel sharing a
common loop MUST be properly configured. The unit
configuration settings can be configured either through the
myUplink Pro app or Service Tool. In the Loop Configuration
menu ensure the unit is set for "Parallel". This will configure
the unit to utilize special control logic for parallel units on a
common ground loop.
where,
2
= (16/10.3) = 2.4 psi per valve (there are
2 2
units with internal variable-speed flow