Differential temperature controllers
iSolar
257 series
Function
A multi-functional temperature differential controller with add-on system functions, the iSolar series
can be used for a wide variety of applications and has inputs for four PT1000 sensors. Preset factory
defaults are defined for control of a standard solar water heating system with a second relay (some
models) to divert any surplus heat. The auxiliary relay can be used to maintain the tank temperature,
protect the system from overheating, or use another source to heat the storage tank.
This controller features a large Liquid Crystal Display (LCD) user interface with three function keys.
The easy-to-use icons assist to operate and customize a solar heating system.
Product range
Code 257210A iSolar1 controller with 1 standard output relay for pump control, includes 3 temperature sensors
Code 257220A iSolar2 controller with 1 electronic output relay for pump speed control, includes 3 temperature sensors
Technical specifications
Dimensions
CALEFFI
Housing plastic: PC-ABS
Protection type: Indoor only
Mounting: wall or in 255 series pump station
Display: LCD with symbols and text
Interface: three soft push buttons
Inputs: 4 temperature sensors
Outputs: 1 or 2 electronic or standard relays
Switching relay capacities: 2 (1) A 115V
Power supply: 115 V - 60 Hz
Bus interface: V-Bus
Performance
Δ
T adjustment range: 2···40º Ra (1···20ºK)
Min. temperature differential 2º Ra (1ºK)
Hysteresis: 2º Ra, ± 1º Ra (1ºK, ± .5ºK)
Max. tank temperature range: 35···205°F (2···95ºC)
Max. collector temperature range: 210···375°F (100···190ºC)
Emergency shut down of the collector: 230···395°F (110···200ºC)
Min. collector temperature range: 50···195ºF (10···90°C)
Antifreeze temperature option: 15···50°F (-10···10ºC)
kWh (BTU) flow input: 0···5 gpm (0···20 lpm)
Agency approvals cTÜVus
Temperature sensors
Platinum RTD type: 1,000 ohm
Collector sensor working range: -58···355ºF (-50···180°C)
Tank sensor working range: 15···175ºF (-10···80°C)
Length of collector cable: 60 in. (1.5 m)
Length of tank sensor cable: 95 in. (2.5 m)
°F
14
23
32
41
50
59
68
77
86
Ω
961
980
1000
1019
1039
1058
1078
1097
1117
°F
95
104
113
122
131
140
149
158
167
Ω
1136
1155
1175
1194
1213
1232
1252
1271
1290
°F
176
185
194
203
212
221
230
239 248
Ω
1309
1328
1347
1366
1385
1404
1423
1442 1461
Resistance values
for sensors subject to the temperature
Code 257230A iSolar3 controller with 2 standard output relays for pump control, plus valve or second pump control, includes 3 temp. sensors
Code 257260A iSolarPlus controller with 2 electronic output relays for pump speed control, plus valve or second pump control, includes 3 sensors
US
US
C
C
Tested and Approved by TÜV Rheinland as an approved U.S. Nationally Recognized
Testing Laboratory (NRTL) Exceeds or is equivalent to:
UL 60730-1A
CAN/CSA E60730-1
A
4
3/8
”
B
6
3/4
”
C
6”
D
2”
A
B
D
Code
250
041A
Weight (lb)
0.9
C
