HONEYWELL ST9400C Thermostat Programmer. 7, 2-Channel, 3 on/Off per Day, 24 V, White, 1

Product Information

These work with regular and system boilers to control two separate heating circuits plus the hot water. These are only used in larger properties where the ground and first floors are separately piped to create two radiator circuits (called zones) or where there is a mix of radiators and underfloor heating. Load and weather Compensation Measures A and B are forms of advanced heating control designed to work with modern ‘modulating’ boilers, i.e. they can adjust the output of the boiler to meet a varying demand. For example they can lower the output during spring and autumn months and increase it during winter. Measure C uses AI to learn your heating patterns. Optimisation technology learns when to bring the boiler to meet your desired room temperature in the most efficient way ( for more see our Guide to Advanced Heating Controls). The Honeywell ST9400C Two Channel unit is a 7 day full programmer that gives great flexibility offering up to three on/off switchings per day, additionally each day can be programmed differently, which is ideal for when the user has different heating needs from day to day. The Honeywell ST9400C can be set to 5/2 day or 1 day programme during installation. Traditional programmable room stats turn the boiler on and off, for example if you only want your boiler to come on in the mornings and before you get home from work as well as set the room temperature. A standard central heating programmer (or programmable thermostat) will allow you to set the boiler to come on at the same times each day, for example, from 6am – 8am and 5pm until 9pm.

require time and temperature controls, i.e. a programmable room thermostat or a thermostat with separate programmer. New installations of a combi boiler: These are used with regular and system boilers where the programmer needs to control the heating and the hot water timing. (They can also be used with combi boilers where there are two separate heating circuits or a mix of radiators and underfloor heating). If you wish to control your heating and hot water from a single control you will need a programmable room thermostat with two channels: one to signal to the boiler to come on and one to control the hot water. It is common to have a two-channel programmer and separate thermostat, although we have only considered combined heating and hot water units below. We review a mix of standard and smart programmable thermostats from Honeywell, Myson, Worcester, Vaillant, Nest and Tado. For more programmable thermostats try our Guide to Wireless Programmable Thermostats. wireless thermostats for heating and hot water

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Setting times for central heating and hot water to switch on and off can help reduce your home's energy consumption. Review and compare 32 thermostatic radiator valves by style and budget: standard, premium, chrome and budget. d. Flue gas recovery unit - this sits above the boiler and recovers heat from the flue. It is reported to reduce gas consumption by upto 4%. An additional energy saving measure must also be installed for combination boilers from the following list (a-c are all advanced heating controls):

Conventional zoning is really only worth undertaking in larger properties. It involves piping two heating zones, usually ground floor and first floor. Each zone is controlled by a separate thermostat, allowing you to set different temperatures on each floor thus saving energy. For example, 21 degrees downstairs and 16 degree upstairs. Weather compensation works in the same way but uses the external temperature. This traditionally involved a temperature sensor on the outside of a property linked to the internal programmer/thermostat. The sensor is able to forewarn the boiler of a change in outside air temperature which will eventually lead to a decrease or increase of inside temperature. If you want to set different times on different days, you will need what is called a ‘seven-day’ programmable thermostat. Combi, heat only and system boilers are compatible with programmable thermostats but you will need to factor in hot water controls if you have a heat only or system boiler. A thermostat sets the desired room temperature whilst a programmer gives the user great control of the times the heating is on. A programmable room thermostat is a combined unit that does both. There are two main types of programmer: 1 day and 7 day (although some with a 5/2 day options). Most programmers will allow you set 2-6 time periods per day and also set different temperatures for each time period. If you only have a thermostat then your boiler will fire on and off all day unless 1) you turn the thermostat down when you out or 2) you switch the boiler off when you go out. Single Channel and Twin Channel ProgrammersIf you are extending your property significantly, you may wish to consider separating the ground and first floor radiators in this way. It will involve re-plumbing parts of the system and additional pipework, as well as adding zone valves to each circuit. Thermostatic Radiator Valves For both weather and load compensation controls, the boiler can respond by increasing or reducing its output slowly to meet the predicted change in temperature. This leads to less ‘cycling’ (the boiler coming on and off) and more efficient periods of operation. NB for a control of this type to work it must speak the same ‘language’ as the boiler - for more go to our Guide to Advanced Heating Controls or try our Guide to Opentherm products and compatibility. Smart controls with automation and optimisation functions Review and compare Smart Controls, including Boiler Branded smart controls, also referred to as remote heating controls, internet controls and wifi controls. Honeywell ST9400C 7 Day Programmer is a 2 channel programmer, designed for control of both heating and stored hot water in complete systems. The heating and hot water programmes are completely independent, to allow the system to be operated in the most energy efficient manner possible. Smart heating controls are all programmable thermostats that are connected to the internet and operable via a smart phone app. Most use some form of advanced heating control (i.e. weather compensation, load compensation and/or automation/optimisation features). Many are now compatible with Alexa, Apple, IFTTT and other smart home devices. This can provide additional functionality, for example you can turn your heating on and off via the voice activated smart home device or active geofencing sensors (the heating will come on as you near home via a GPS signal from your phone). NB some smart controls such as Nest and Tado come with geofencing as part of the device. For more on smart controls try our Guide to Smart Heating Controls or Guide to Home Automation Systems. 7) Zoning

New minimum efficiency standards were introduced in April 2018 aimed at reducing the amount of fuel we use to heat our homes. It is now mandatory for every new boiler installation to be fitted with a programmable room thermostat and, for combi boilers, an additional energy saving measure: A room thermostat controls the heating in your home. If the room's temperature drops below your chosen temperature, the thermostat will switch on. Once the room has reached the chosen temperature, the thermostat will turn the heating off, preventing overheating and reducing energy consumption. This can help reduce your home's energy consumption. A programmable room stat will have commonly have one (single) or two (twin) channels, although some have three. The first channel will control the boiler. The second channel will control the hot water. Every boiler installation must have an ErP efficiency of at least 92% (see our Guide to Boiler Efficiencies).Review and compare smart radiator valves, including compatible smart heating controls. 6) Jargon Buster Thermostats and Programmers For all new a boiler installations a thermostat must be accompanied by a separate time control or programmer (or use combined a model see below). For existing installations it is still permissible to use a standalone thermostat. The table below shows standalone wireless thermostatic controls, but they will also be available in wired models. wireless thermostats with programmers (non smart control) Some weather compensation systems use data from the local weather station to inform your heating system of a change in temperature. This is less accurate but makes for a more straightforward installation with fewer parts to go wrong. The common aim of all advanced controls is to ensure the boiler is on for the shortest possible time to meet the room temperature. Standard controls tend to overshoot the room temperature by 1 or 2 degrees which is very inefficient. Advanced controls reduce the heat output of the boiler as it approaches the desired temperature to prevent overshooting. The net result is a reduction is gas use and lower fuel bills. Read our guide on wireless heating controls , both standard and smart controls, and the boiler plus scheme.

Smart radiator valves will also individually control heat radiator, the difference is that the temperature can be controlled by a central programmable room stat. Smart valves can be grouped together to operate as a single circuit or controlled individually. They are a very easy fit to most radiators. For smaller properties, the work and cost involved in re-piping the system to create two zones is rarely worth it. There are more cost effective, and less disruptive, ways of achieving variations in temperature. require the same time and temperature control but with an additional ‘advanced’ energy saving feature, i.e weather compensation, load compensation or smart controls that combine automation and optimisation features. (Or a flue gas recovery unit) New installations of a combi boiler: A ‘channel’, like a radio channel, is the means by which the thermostat communicates with the systems it controls.The conventional way is to fit Thermostat Radiator Valves (TRVs). This will allow you to control the temperature of each radiator, e.g. turning off radiators in little used rooms and turning them down in the bedrooms. This is a manual exercise but once done rarely needs changing. TRVs can be fitted to most radiators by a plumber. For a comprehensive review of 32 TRVs regard our Guide to Thermostatic Radiator Valves. Smart Radiator Valves All new boilers must be fitted with time and temperature controls e.g. a programmable room thermostat, if not already present These are used with combi boilers, as it is not necessary to control the hot water separately (this is done by the boiler). Advanced controls are also programmable room stats but have the addition of operating the boiler more efficiently during its periods of operation. Programmable thermostats for combi boilers All Honeywell ST9400 models incorporate the Line of Text (LoT™) display that gives clear plain English instructions whenever any button or slider is used. This means that installers, customers and users can operate all of the controls reliably, without needing to find an instruction manual.