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

Product Information

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. 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. 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. Apologies, late to this party. I have the same heat mark and warm to the touch spot on my ST9400C. This is Deja Vu for me, given my other posts on a Manrose extractor fan circuit, where a resistor is used to bring down the voltage for the timer circuit, then the heat given off by the resistor eventually blows the nearby capacitors. Another bad/cheap design driving premature failure and unnecessary electronic waste. I would say if you can no longer feel heat when placing your finger on the casing heat mark, the resistor is gone and could be replaced to fix. If the resistor is still getting hot, then a nearby capacitor has popped instead. The latter was the issue with my extractor fan, replacement capacitor fixed it. 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.

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. Not what you're looking for? Try our unique Spares Finder tool or you can view all Honeywell Heating Supplies products. 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. Routine Maintenance: It’s essential to consider the health of the entire system. Even if the programmer is replaced or repaired, ensure that the boiler undergoes routine servicing as indicated in its manual. Neglecting regular maintenance can lead to a cascade of issues in the future.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. Setting times for central heating and hot water to switch on and off can help reduce your home's energy consumption.

But this shows my point, each person will have a different situation, and what suits me as some one home 24/7 with a large house, with solar panels and oil fired central heating may not suit you.

It looks (and feels like) the pump is running, and from what I can tell, the motorised value is still operating.

The old Danfoss 3060 I show was in this house, and I had to decide how much to spend and how far to go to improve my system, and you have the same problem, how far to go with the improvements? 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.

Honeywell ST9400A 1 Day Two Channel Programmer

There's a problem I'm trying to troubleshoot. I have a CH/Water system with a conventional boiler, hot water cylinder, pump, 3-way motorised valve, and a gas boiler. The boiler is an Ideal Icos HE18 (18HE?). The programmer is a Honeywell ST9400C. There's also a wireless room stat for the heating, but at the moment I'm just working on getting the HW side up and running. The user sought advice on potential next steps, wondering if the issue lay with the programmer or another component in the system. 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. 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.