Solar Thermal Information

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CALEFFI

Differential temperature controllers

iSolar

series 257

Function

The iSolar series solar thermal controllers are multi-functional temperature differential controllers

that provide complete control of the solar thermal system for safe and long-lasting operation. The

iSolar microprocessor controller monitors and controls thermal solar energy systems by means of

a collector sensor and a storage tank sensor. The controllers also implements important system

monitoring and safety functions. The system parameters and measured values can be viewed and

altered by the large LCD display. The controller is equipped for up to four temperature sensor

inputs and one or two outputs (some models) for activating the solar circuit pump and second

output for activating a valve or second pump.

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

Technical specifications

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 triac or standard relays

Switching relay capacities: 1 (1) A 115VAC

Power supply: 115 VAC – 60 Hz

12V – 24V

Power consumption: 1W, 1.5VA

Data connection: V-Bus

Performance

ΔT adjustment range: 2–40º

ΔT

(1–20ºK)

Min. temperature differential: 2º

ΔT

(1ºK)

Hysteresis: 2º

ΔT

, ± 1º

ΔT

(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 black cable: 60 in. (1.5 m)

Length of tank sensor gray cable: 95 in. (2.5 m)

Resistance values for sensors subject to the temperature

Dimensions

Product range

Code 257210A iSolar 1 with 1 pump control relay, includes 2 temperature sensors, data connection

Code 257220A iSolar 2 with 1 pump speed control triac, includes 2 temperature sensors, data connection

Code 257230A iSolar 3 with 2 control relays for solar pump and second pump or valve, includes 2 sensors, data connection

Code 257240A iSolar 4 with 1 pump speed triac and 1 control relay for second pump or valve, includes 2 sensors, data connection

Code 257260A iSolar Plus with 2 pump speed triacs, for second pump or valve, includes 4 sensors, data connection

Code 257260A PV1 iSolar Plus 12V with 2 pump control relay, for second pump or valve, includes 4 sensors, data connection

Code 257260A PV2 iSolar Plus 24V with 2 pump control relay, for second pump or valve, includes 4 sensors, data connection

°F 14 23 32 41 50 59 68 77 86

Ω

961 980 1000 1019 1039 1058 1078 1097 1117

°F 95 104 113 122131140149158167

Ω

1136 1155 1175 1194 1213 123212521271 1290

°F 176 185 194 203 212 221 230 239 248

Ω

1309 1328 1347 1366 1385 14041423 1442 1461

3/8"

6 3/4"

Code

257series

Weight (lb)

0.9