H37XL Series 2 Channel Plus offers three independently timed channels, hot water plus two heating zones. Easy to read back-lit LCD display, seven day programming with different settings for each day of the week. Up to three on/off periods per channel in each 24 hour operation. 30 day holiday programme. 1 or 2 hour boost and advance on each channel. Clock (12 or 24 hour) changes for winter/summer time automatically. Uses 9 pin wall fixing plate. Mains powered with lithium battery back up.