Honeywell ST9400A1002 1 Day, 2-Channel, 10 W, 24 V

Product Information

The Honeywell ST9400A is a temperature controller designed for efficient control of heating and hot water systems. Known for its reliability and durability, this controller is a trusted choice among homeowners and professionals alike.

The Honeywell ST9400A is a 2 channel programmer which is designed to control both the heating and stored hot water in a complete system, the programmes for both the heating and hot water are independent of each other to allow the system to be operated in the most energy efficient way. The ST9400A is compatible with a wide range of heating and hot water systems, making it a versatile choice for various households. Its compatibility with different system types ensures that homeowners can easily integrate it into their existing setup without any hassle. Since I got it wrong, and selected Nest Gen 3, which does not work very well, I can see your problem, but the problem only exists as I want individual room control, if I lived in a open plan house Nest would be great. Power Supply Examination: Without a detailed circuit diagram for the ST9400C, another expert suspected that the problem might lie in the power supply section of the device. The 48-volt supply, which typically involves a capacitor and diode, might be malfunctioning due to capacitor failures. Certain capacitors can lose their functionality when they remain un-polarised, leading to the deterioration of the dielectric surface. Replacing the capacitors may be a potential solution.The programmer is a 1 day programmer with two on/off switching times per day and can be used for, combi boilers, heating zones or any application where small electric loads need switching.

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. The Honeywell ST9400A Twin Channel Programmer unit is a 1 day full programmer with two on/off switching times per day (which can be increased to 3). The Honeywell ST6400A Programmer can be used for combi boilers, heating zones or any application where small electric loads need switching. Replacement: A straightforward solution proposed by several experts is simply to replace the malfunctioning programmer. Given the age of the device and the persistent issues, sometimes, it’s more efficient to replace rather than repair.The HONEYWELL ST9400A1002 1 DAY 2 CHANNEL PROGRAMMER - Now Use 4201085 is a genuine, brand new Honeywell Heating Supplies product, covered by a Honeywell Heating Supplies manufacturer's guarantee. Here's the problem: I put a nail through a pipe while refixing so loose flooring. (I know, I know). I had to shut the system off and drain it. This is probably the first time it has been off and drained since installation. With its user-friendly interface, the ST9400A allows for easy programming and customization of temperature settings. This ensures optimal comfort and energy efficiency throughout the day, while also enabling users to easily adapt the system to their specific needs. The controller offers a variety of features, including multiple on/off timings and temperature overrides, further enhancing its versatility.

It looks (and feels like) the pump is running, and from what I can tell, the motorised value is still operating. The introduction of the so called energy saving light bulb, changed what we needed to control our central heating. Tungsten bulbs give off inferred heat so one one turned the lights on the rooms felt a degree or two warmer, so a thermostat set at 18ºC was ample as in the evening the lights made it feel like 20ºC, but with no inferred with the lights, we need to lift the evening room temperature, likely the LED bulb wastes energy as now the air temperature is 20ºC so losses increase, however since electric is around 5 times cost of gas or oil, it still makes sense to fit LED bulbs.

Honeywell ST9400A 1 Day Two Channel Programmer

I opened up the programmer (see pictures) and replaced the relays and large capacitor with identical value components. Relay now does not buzz (that's good), but still getting this power cycling on/off. Obviously something is still not right. The user sought advice on potential next steps, wondering if the issue lay with the programmer or another component in the system.