Honeywell programmer goes on and off

Aleksandra Miniewicz · Feb 22, 2020

Hi gents

You helped me massively before so I thought I'll give it another go as is Saturday evening and I'm totally stuffed with my Honeywell programmer. The problem is it doesn't stay in just click on and off. Lights off and back on when I try to set it to water heating or central heating....

programmer keeps turning on and off with a "click" each time it turns off. It started doing it every 10 seconds or so and now is doing it every 2-3 seconds. No chance to beat the water. I have joule water think. How to turn emergency eater heat at least on this till I can find someone to fix it in a week days?

I've attached picks of the system and YouTube video how the Honeywell behaves. My does very simmilar thing :

View: https://youtu.be/gF7VfyUnjH0

Please let me know if you have any ideas what I can try....

P.s there is a switch that has white cable going to water tank but it didn't kick in emergency water heat as water is cold. I just changed fees in this plug ( the right one on the photo attached) and am writing for miracle....

Looking forward to hearing from you.
Aleksandra

OffshoreGas · Feb 22, 2020

Either a faulty programmer or a wiring fault, the latter being more likely IMHO.

it’s hard to say without being hands on.

Have you changed anything?

Brambles · Feb 23, 2020

Check that the programmer is properly mounted into its back plate and that the securing screw ( in the middle under the programmer) is in place and tightened up.

If it is not properly mounted you can get intermittent connection across the pins.

If it is properly mounted, I would just change out the programmer - they are around £40 on ebay - it would cost you that to get someone out to look at it - who will then probably propose changing out the programmer!

r w Honeywell ST9400c · Sep 26, 2022

Have just spent £100 on a new programmer, I have dismantled the old one. There is a Lithium battery cell inside and I did notice that the time and date was all over the place before removal. The programmer was about 17 years old. My theory is that without a stable date and time the internal software can't reliably operate and goes in a loop and resetting with all the clicks etc.