Bryant 50YEW Design Manual page 65

From Radiant Heat
Transformer (Secondary Side)
To Radiant Heat
Controls (R)
24VAC to backup boiler
24VAC to emergency
DHW contactor coil
Common for
relay coils
F C EH
W
Legend :
F Radiant Floor 24VAC interrupt
C Common
EH Electric Heat (DHW)**
W2 2nd Stage Heat***
RT 24VAC to cooling thermostat****
RU 24VAC from water-to-air unit****
DH DHW Tank Thermistor
BT Buffer Tank Thermistor
OA Outdoor Air Temperature
BT/OA Gnd connection for Thermistors
WWSD Warm Weather Shut-Down
Factory Wiring
Field Wiring
14Sep07
Bryant Geothermal Heat Pump Systems
Drawing 4-4: 50YEW Unit - Internal Pumps* /
Water-to-Air Unit for Cooling / Indirect
Drawing 4-4: THW Unit / Internal
DHW Tank
Pumps* / Water-to-Air Unit for Cooling /
Indirect DHW Tank
R Y1 G O
R Y G O
RT RU DH DH
W2 F
WWSD
O Y2 C GND SW
G
MPC
*THW unit pumps are controlled by unit controls. External pump(s)
for water-to-air unit controlled by its unit controls.
**Optional backup electric elements in DHW tank. Connect this
24VAC output to a contactor to allow the elements to operate.
Note that this signal is only energized during a heat pump lock-out.
***Optional 2nd stage heating, provided by a backup boiler or
electric elements in a buffer tank. Connect 24VAC output to a
contactor (elements) or relay (boiler) to control the 2nd stage device.
****These connections (RT/RU) allow the 50PSW unit to manage
seasonal change-over by enabling or disabling the cooling t-stat.
If a water-to-air heat pump is used for cooling, this unit can also
provide forced air heating during mild conditions to avoid keeping
a warm slab when cooling may be needed during the day and heating
at night. The WWSD (Warm Weather Shut Down) feature provides
this function. NOTE: If the water-to-air unit also provides forced
air heating to zones where there is no radiant floor heating, this
feature should not be used (N.O. contacts of the relay). However,
the N.C. contacts should still be used to disable the radiant floor
system during warm weather conditions.
Water-to-Water System Design Guide
Part IV: Controls / Wiring Diagrams
W L C
Cooling Thermostat
W AL1 C A
Water-to-Air Unit*
Buffer tank thermistor
OAT thermistor
50YEW Unit terminal strip
BT BT/OA OA
LAT/
LWT/ GND Y1
LWTL
LWTS
DHW thermistor
63