"Needed to replace my 25yr old ST7100. Changed back-plate followed wiring instructions, switched back on - worked. Screwfix not cheapest but available locally. Can't tell about reliability but would like to think this controller will also last 25yrs :)"
"I reqired a controller for our local church which was versatile, easy to use and install. It replaced two timers controlling two zones and needed to be easily operated. A seven day programme was a must since Sunday is the main day. Fitting was straight forward and the large display is excellent. The override feature is very handy."
"a quality Replacement for my old, and faulty, timer/pgrammer.
clearly well buit, with sturdy casing and a good display window for easy reading in a poorly lit (under shelf) location. A well written installation note ensured no problems with replacing an older Honeywell model.
but, as always, ensure the backplate is cleaned of debris My only problem was in the poor connectivity with the contact pins as previous debris prevented a flush fit - presenting as poor power connection and a therefore a 'dead' display.
Once the backplate was cleaned, and the new unit re-presented, this problem was never seen again"
"Purchased this programmer to replace existing older version. Easy to install. You simply take off the front of the old one and place the new one on the back plate left on wall. An improvement on the old including a better, lit display. I would recommend this product."
"Only used this Programmer now for approx. one month but very pleased with it to-date. Still to use holiday programme. Great that it just fitted into existing backplate from previous Honeywell Programmer."
"I needed to replace a faulty type 721 programmer and this unit was a straight replacement.Just removed the old unit and plugged in this one no messing, even the date and time were correct, brilliant."
"I used this to replace an existing one that had only lasted a couple of years. After fitting (which was very easy due to the universal backplate) i spoke to a neighbour who told me about half the estate had had these programmers replaced. Maybe in hindsight i wouldn't have fitted it, however i can't fault it while it does work. Very good, easy to understand but fully featured. Excellent price as well."
"Good Programmer but not having an industry standard backplate means i needed to get an electrician in to install it, this addedd to the cost. The backplate is the same but with an aditional piece to prevent you using other manufacturers in the event of failure, If i had known this i would have opted for a Drayton , Siemens, Horstmann or any other as they all use the same backplate and interchangable with no wiring changes and no need to call out an electrician....."
"Good features, easy to fit. However, reliability and quality control are not up to Honeywell standards. The first controller was defective out of the box: the display wouldn't light up. Screwfix replaced it under warranty. The second unit lasted only three years before it failed: wouldn't send power to the motorised valves. I wonder how long the third unit will last??"
"I have three of these controllers installed to control different parts of the house. One failed after 1 year. The controller would turn itself off and then on again every few minutes. The second failed after 2 years, the relay only turns the heating on every now and again at the designated start up times. The product is easy to set up and contains some useful features but falls down on the most important quality you need from a controller, reliability."
"Had this piece of rubbish installed 14 months ago. Nothing but trouble. Would only let me have either hot water or heating but not both at the same time. Was told by the fitter who came and fitted a danfoss to replace it that I was lucky to have got 14months out of it. Will not be buying any of Honeywells products in future"
"Had one of these fitted as part of a boiler replacement. Gave trouble from day one with intermittent hot water and no heating at all. Spent weeks (and money) chasing other faults around system with re-visits from Installer and Baxi (The boiler manufacturer).
Eventually decided controller was faulty, quick google of "Honeywell ST9400C Problems" revealed other people with the same issue.
Replaced with a Siemens controller from this website (for half the price!) and Heat and Hot Water were restored!"