Maritime Geothermal nordic dx-45, Руководство по установке

Страница: 34 / 36

Page .... 34
Maritime Geothermal Ltd. 12-Feb-00
High / Low Pressure control operation
If a high or low pressure situation occurs within the sys-
tem at any time the NCB will shut down the compressor for 5
minutes (adjustable) During the time that the pressure control
is actually "OPEN" (contacts open) the LED will flash at a
rate of once per second. When the control "CLOSES" the
LED will go out but the compressor will remain off until the
timer has expired before compressor operation resumes. The
NCB keeps track of the number of times that the system has
locked out and after 3 lock-outs (adjustable) with automatic
resets the NCB will lock the system out permanently. When a
permanent lock-out has occurred the appropriate LED indica-
tor will be ON CONTINUOUSLY. The system can be reset
from a permanent lockout by moving the SYSTEM MODE
switch to OFF and then back to HEAT or by resetting the
main breaker.
Both the OFF cycle time delay on lock-out and the num-
ber of automatic resets before permanent lockout are adjust-
able individually for the HIGH and LOW pressure controls.
EG: You could have 1 auto reset LOW pres. and 4 for
HIGH. Delays are separately adjustable.
The lock-out counter will reset itself to 0 after a prede-
termined time (set 8 hours adjustable)
so that (1) lock-out in August and (2) in September will
not cause a permanent lock-out a month later on the (1) lock-
out which occurs at that time.
The NCB will ignore a low pressure condition for a pre-
set time on initial start-up. This feature allows refrigerant to
reposition itself and begin to circulate in the system without
producing a lock-out in the unit.
On DX to air units the preset is five minutes but on DX-
to-Water units this setting is changed at the factory to 0 min-
utes delay so that the water heat exchanger would not be fro-
zen and damaged if circulation was lost during water chilling
mode.
AUX. HEAT will work normally when compressor is
locked out, if required.
If no “B” terminal
Method of Operation - Cooling Mode
Checkout
The NCB was designed to handle the unique situation of
multiple parallel groundloops which occurs in the NORDIC®
direct expansion system and as such incorporates features
which are unique to our controller board.
Move the SYSTEM selector switch to the COOL posi-
tion. The reversing valve, NORMALLY OPEN liquid line
solenoid and # 1 groundloop will activate followed by the
blower.
If the system has been in the HEAT mode there will be a
delay as the MODE switch timer keeps the compressor OFF
for 5 minutes (adjustable). The compressor will start and be-
gin to cool using only 1 of the possible loops available.
(MODE 1) The controller board keeps track of the actual run-
time hours and stores this information in non-volatile mem-
ory. Eventually the head pressure will build up in # 1 loop and
activate the loop pressure limit switch which will close and
send a signal to the NCB to switch to loop # 2. This procedure
will be repeated until all the loops have been used once. If a
further pressure signal is received then the NCB calculates the
average run time on the loops used. If the average is less than
the MODE switch time (15 minuets factory set - adjustable)
the controller board will advance to MODE 2 which will be-
gin to use 2 loops at a time.
If the advancement to MODE 2 produces a low pressure
lock-out situation the NCB will automatically shut the com-
pressor off for a predetermined period of time, back up one
MODE and try again after the timer has run out.
NOTE: The number of automatic resets & time delays
on low and high pressure in the cooling mode is adjustable,
the default is 3.
The NCB will always advance to loops which have been
unused the longest.
Similarly if MODE 2 cannot reject the heat pump's heat
to the ground without tripping the loop pres. limit switch then
the NCB will advance to MODE 3 which turns on the soaker
hose in a horizontal loop situation.
The SOAKER HOSES provide increased cooling of the
field by increasing the moisture content and thus the conduc-
tion of the loop field. Water is controlled via a 24 volt AC
solenoid valve attached to city or well water.
NOTE: Soaker hoses should be installed on all horizon-
tal groundloop fields as per the manufacturers instructions.
The soaker hose will stay on continuously for a predetermined
period of time (set 12 hours - adjustable) even if the system is
turned to HEAT and then back to COOL.
Memory Functions
1. Switching from HEAT to COOL will not affect the
MODE the heat pump was in during the cooling mode. The
unit will return to the same loops in which it was operating
before the switch occurred.
2. After a period (set at 2 weeks - adjustable) if cooling
has not been used the NCB will reset the cooling MODE to
MODE 1 automatically.
3. Retains loop settings and run time on each loop or set
of loops as per the MODE setting.
4. Stores all lock-out information and resets lock-out
counter automatically.