Turn the battery on. The switch on the rear of the unit must be in either the Fully Pumped or Gravity position. By pulling outward and generally downward I can clearly see the single wall box because I am dragging that towards me too. It is not separating from the main unit or the stand-off.

Should you encounter any problems, please refer to the Question and Answer section SPECIAL FEATURES For instance, I *hope* the cabling to each thermostat allows for me to install the NEST power supply (supplies?) in the hot tank cupboard (where the timer currently lives) and power each thermostat (remotely) that way. Furthermore, the H21XL thermostat has a built-in frost protection function, which prevents pipes from freezing during cold weather. This feature is particularly useful for homeowners who often leave their houses unoccupied for extended periods. The Horstmann ChannelPlus H21XL thermostat is a home heating control device that allows users to easily manage their heating system. It is designed to be intuitive and user-friendly, providing a convenient way to regulate room temperatures. Using the RESET procedure may rectify the fault. If the problem persists the programmer will need replacing.On the ChannelPlus display - Boost 1 is Hot water extension 1 or 2 hour and Boost 2 is Heating extension 1 or 2 hours ADVANCE FUNCTION I can get a screwdriver between the wall box and the stand-off but there's no way they are going to separate without my breaking one of them.

I am wondering if the stand-off comes away from the main unit. I can pull the main unit away from the stand-off enough to get a screwdriver into the gap but it's not coming away consistently - only where I exert pressure so much that the plastic deforms. The H21XL thermostat features a clear display screen that shows the current temperature and settings, making it easy for users to monitor and make adjustments. It also offers programmable scheduling options, allowing users to set different temperature levels for different times of the day, ensuring optimal heating efficiency. Your programmer will prevent you from accidentally overlapping ON and OFF times. Example: If the 2nd ON time is set at 12:00pm and then you try and set the 1st OFF at 12:30 pm the OFF setting will 'bounce' by a 10 minute period until the 2nd ON time has been adjusted. FULLY PUMPED OR GRAVITY SYSTEM If a Heating or Hot water period is not required it can be cancelled by setting the ON and OFF settings to the same time. Example ON 10:00am OFF 10:00am During power interruptions the display will be blank, after 3 days the current time of day will be lost. If the programmer is not to be used for a long period of time, the switch on the rear of the unit should be returned to the BATTERY OFF position. These are both to prolong the battery life. SERVICE AND REPAIRThe thermostat is compatible with a wide range of heating systems, including gas, electric, and oil boilers. It offers basic functionalities such as temperature control, allowing users to set their desired room temperature and adjust it as needed. Whilst the HOLIDAY FUNCTION is in operation the system will remain OFF, the display will show the number of nights remaining. The HOLIDAY setting is an instant function and cannot be set in advance. The HOLIDAY FUNCTION can be cancelled at any time by pressing any of the SELECT buttons. Normal programme functions will resume at the first ON period after the pre-set number of nights has expired. INFORMATION AND ADVICE Programming ON/OFF times The default factory settings are shown, however if you wish to change these proceed as instructed below. The programmer is fitted with a non-rechargeable, long life battery, which will maintain the programmed time settings for a minimum of ten months with the supply disconnected. A piece of plastic which may act as some sort of stand-off or interface - it's the piece that has the 2 screws in the top (not any more though). I suspect this is integral to the main unit - I only mention it because it is a separate moulding

What I really want to do is to install a NEST in place of the two thermostats, and a single timer for the water but I don't yet understand what wiring my system employs and how I might convert that for NEST. The thermostat is crafted using high-quality materials, ensuring its reliability and durability over time. It is designed to withstand everyday wear and tear, providing long-lasting performance.More manuals of Thermostats Frequently Asked Questions about Horstmann ChannelPlus H27XL Thermostat This indicates that you have reached an existing set time period, you will be unable to set a new ON/OFF time unless there is an alteration to the existing timed period