FHP GO024 Installation And Maintenance Manual - page 7
7
GO SERIES
Each Geo-Miser model has a number of heater sizes
a v a i l a b l e . R e f e r t o F i g u r e # 9 f o r h e a t e r p a c k a g e
c o m p a t i b i l i t y w i t h s p e c i f i c G e o - M i s e r u n i t s , m o d e l
nomenclature and electrical data.
SEQUENCE OF OPERATION-SINGLE STEP UNITS
(Figure #14)
COOLING MODE:
Energizing the “O” terminal energizes the unit reversing
valve in the cooling mode. The fan motor starts when the
“G” terminal is energized. Note that the fan motor will
take 30 seconds to ramp up to operating speed and will
run at 70% of the cooling rated air flow as long as there
is no call for compressor or heater operation.
When “Y2” in the unit (“Y” or “Y1” on the thermostat) is
energized the compressor starts and the unit is now
cooling. Solenoid valves or loop pumps are brought on in
conjunction with the compressor.
When the thermostat is satisfied, the compressor shuts
down and the fan ramps down. If the “G” terminal is still
e n e r g i z e d ( f a n o p e r a t i o n i s o n “ c o n t i n u o u s ” a t t h e
thermostat) the fan will ramp down to 70% of cooling air
flow in 30 seconds. If the “G” terminal is de-energized
with “Y2” then the fan ramps down to off in 30 seconds.
HEATING MODE:
Heating operation follows the same sequence as cooling
only without the “O” terminal. During heating operation if
the thermostat calls for auxiliary heat (“W1”), the fan
ramps up to auxiliary heat air flow immediately and the
electric heaters are energized (if installed) along with the
compressor. Note that if the unit compressor locks out
f o r a n y r e a s o n a t t h i s t i m e , t h e e l e c t r i c h e a t e r s w i l l
continue to function normally.
Emergency heat (W2/EM) energizes the emergency heat
relay in the heater control box, bringing on all of the
heating elements at once. The fan immediately ramps up
to full electric heat air flow.
As in cooling, once the thermostat is satisfied, the fan will
ramp back down over a period of 30 seconds.
SEQUENCE OF OPERATION-MULTI-STEP UNITS:
(Figure #15 Wire Schematic)
COOLING MODE:
Energizing the “O” terminal energizes the unit reversing
valve in the cooling mode. The fan motor starts when the
“G” terminal is energized. Note that the fan motor will
take 30 seconds to ramp up to operating speed and will
run at 70% of the cooling rated air flow as long as there
is no call for compressor or heater operation.
When the thermostat calls for first stage cooling (Y1) the
loop pump or solenoid valve is energized and the 40%
(lead) compressor starts. The fan ramps up to first stage
cooling air flow in 30 seconds.
When the thermostat calls for second stage cooling (Y2)
the multi-step relay is energized along with the 60%
c o m p r e s s o r c o n t a c t o r . T h i s s h u t s d o w n t h e 4 0 %
compressor and starts the 60% (lag) compressor. The fan
ramps up to full cooling air flow.
At this point the time delay relay starts timing out. Once
t h e t i m e p e r i o d s e t o n t h e T D R e l a p s e s , t h e 4 0 %
compressor restarts for full 100% capacity. Depending on
the application this time delay relay can be set for 0.1 to
8 minutes. If the thermostat can be satisfied prior to the
set time delay, then the 40% compressor will not restart,
allowing the unit to satisfy the space temperature at a
much higher efficiency than if both compressors were
r u n n i n g . T h i s i s t h e s e c r e t o f m u l t i - s t e p o p e r a t i o n ,
allowing the unit to run at up to 3 stages of compressor
operation with a 2 stage thermostat.
In addition to controlling the multi-step logic, the multi-
step relay also holds the unit in full cooling until the
t h e r m o s t a t i s c o m p l e t e l y s a t i s f i e d . T h i s p r e v e n t s
compressor short-cycling and satisfies the space more
quickly.
Once the thermostat is satisfied, the compressor(s) shut
down and the fan ramps down to either fan only mode or
off over a span of 30 seconds.
Note that a fault condition initiating a lockout will de-
energize both compressors.
HEATING MODE:
The first two stages of heating (Y1 & Y2) operate in the
same manner as cooling, but with the reversing valve de-
energized. On a call for auxiliary heat (W1), the fan ramps
up to auxiliary heat air flow immediately and the electric
h e a t e r p a c k a g e i s e n e r g i z e d a l o n g w i t h t h e
compressor(s). As the thermostat is satisfied, the heaters
will shut off as soon as W1 is de-energized, but both
c o m p r e s s o r s w i l l r e m a i n o n u n t i l t h e t h e r m o s t a t i s
completely satisfied. Note that if the unit compressor(s)
lock out for any reason at this time, the electric heaters
will continue to function normally.
Once the thermostat is satisfied, the compressor(s) shut
down and the fan ramps down either fan only mode or off
over a span of 30 seconds. If emergency heat (W2/EM) is
called for, the fan will ramp up to emergency heat air flow
immediately and the heater package will energize in
emergency heat mode, all heater elements coming on.
On shut down the fan will ramp down over a period of 30
seconds.
ALTERNATE SEQUENCE OF OPERATION-
MULTI-STEP UNIT WITH 60% COMPRESSOR
AS LEAD:
(Figure #10, #16)
Multi-step units can be field converted from the factory
sequence of operation with the 40% compressor running
i n 1 s t s t a g e a n d t h e 6 0 % c o m p r e s s o r t h e n b o t h
c o m p r e s s o r s r u n n i n g i n 2 n d s t a g e t o a n a l t e r n a t e
sequence with th e 60% compressor running in 1st stage
and both in 2nd stage. This sequence would give more
capacity (but at slightly lower efficiency) in 1st stage and
a lower sensible to total ratio in 1st stage. This sequence
might make sense in areas of high humidity or where a
little extra 1st stage capacity would allow the unit to run
predominantly on 1st stage for a higher overall operating
efficiency.
To convert the unit the installer needs to switch the