-
54
-
'15 • HM-T-246
(3)-1 Defrost control
In order to recover from dropping the heating capacity for producing hot water due to the frost on the air heat exchanger of
heat pump water heater, defrost operation is done periodically.
By cutting jumper wire (J15), it can switch from normal defrost control to defrost priority control*1
*1. If there is any frosting problem on the air heat exchanger in case of the operation in heavy-snow area and like that, please
cut (open) J15.
In case of defrost priority control (J15 is open), defrost operation can start earlier to prevent from growing frost on the air
heat exchanger, but heating capacity may decrease.
(1) Starting condition
①
Starting condition A
If all of following conditions are established
(a) 8 minutes has elapsed after compressor started operation.
(b) 8 minutes has elapsed after outdoor fan started operation.
(c) The cumulative operation hour after starting operation is 60 minutes or more.
Or the cumulative operation hour after the end of previous defrost operation is 60 minute or more.
(d) E ither one of temperature sensors on the inlet of heat exchanger (Tho-R1, -R2) detects lower temperature than the
defrost start temperature, which is decided by the outdoor air temperature, for 30 seconds continuously. (Fig 1-1)
(e) Or the suction pressure saturated temp calculated from the low pressure detected by LP sensor is lower than the de-
frost start temperature, which is decided by the outdoor air temperature, for 180 seconds continuously. (Fig 1-2)
②
Starting condition B
If all of following conditions are established
(a) to (c) Same as the Starting condition A
(d) The ending condition of previous defrost operation is forced to end by the forcible end time of defrost operation.
Fig 1-1 Defrost starting condition by temperature sensor Tho-R1 or -R2
Defrost priority control
(Cold region setting)
(J15: Opened)
℃)
℃)Outdoor air temperature (
Defrost
starting
zone
Normal defrost operation
(Factory default)
(J15: Shorted)
−2
−4
−15
−23
−31
−35
−46
−40 −25 −15 −9 6
Heat exchanger temperature (
Fig 1-2 Defrost start condition by suction pressure saturated temperature
Defrost
start
zone
Defrost priority control
(Cold region setting)
(J15 Opened)
Normal defrost control
(Factory default)
(J15 Shorted)
℃)Outdoor air temperature (
℃)
pressure saturated temperature (
−40 −25 −15 −9 6
−6
−8
−19
−27
−35
−39
−54
(3) Control of refrigerant piping system
www.ampair.co.uk | sales@ampair.co.uk
To Next Page
Loading...
Need help?
General
