Unit installation

IM 985-1 / Page 7 of 36
Note: Be sure that one end of the hose has a swivel
tting to facilitate removal for service. Hard piping to
the unit can result in added operating noise.
4. Ifsealantcompoundisnotprovidedforexiblehose
ttings,applyTeontapetotheconnectionstohelp
prevent leaks.
5. Supply and return shutoff valves are required at each
unit. The return valve is used for balancing and
should have a “memory stop” so that it can always
be closed off, but can only be re-opened to the
properpositionfortheowrequired.
6. Do not connect a unit to the supply and return
piping until the water system has been cleaned and
ushedcompletely.Afterthisisdone,theinitial
connection should have all valves wide open in
preparationforwatersystemushing.
7. Condensate piping can be steel, copper, or PVC.
Each unit is supplied with a clear vinyl condensate
hose.
Figure 4. Typical 2-Pipe Reverse Return Conguration
Piping
1. Connect units to supply and return piping in a two-
pipereversereturnconguration(Figure4).
A reverse return system is inherently self-balancing
and requires only trim balancing where multiple
quantitiesofunitswithdifferentowandpressure
drop characteristics are connected to the same loop.
A simple way to check for proper water balance is
to take a differential temperature reading across the
water connections when in the cooling mode. To
achieveproperwaterow,thedifferentialshouldbe
10°F to 14°F (-5°C to -8°C).
A direct return system may also be acceptable, but
properwaterowbalancingismoredifcultto
achieve and maintain.
2. The piping can be steel, copper or PVC, but must
comply with local codes.
3. Supply and return run outs are typically connected
totheunitbyshortlengthsofhighpressureexible
hose which are sound attenuators for both unit
operating noise and hydraulic pumping noise.