Question about Honeywell Programmable Thermostat Heater

3 Answers

Honeywell ST6400C with no display

Hi, I just returned from holiday to find no display on my Honeywell ST6400C. When i went on holiday I turned the heating off but have done this before. Is this an issue with a fuse? The gas is working along with all the electrics in the house. I followed the instructions and pressed the reset button but nothing worked. Thanks

Posted by on

  • gmelville Nov 17, 2008

    Thanks for your help

  • Anonymous Jan 03, 2009

    yes we had the same problem over a holiday. The elctricity supply to the programmer was switched off. Bad idea! The solution proposed seems not appropriate. The st6400 is the programmer rather than the thermostat. The usual solution is to press the RESET button. But if this doesnt work how about replacing with the newer st9400? Circa £50-£65.. Same backplate and wiring.. (how about leaving connected to mains over holiday..?)

×

3 Answers

  • Level 1:

    An expert who has achieved level 1.

    Mayor:

    An expert whose answer got voted for 2 times.

  • Contributor
  • 1 Answer

I pressed the reset button in error and the display just would not return o no heating or hot water. Nothing tripped on the board and all wires and the unit itself showed power coming through.I got it working again by sheer determination.

What I did
I took the unit from the base plate and opened the front panel to see circuit board. It has 4 clips and it all goes back together easily.

What I did.Time taken 15 minutes.

The tiny rubber reset button was collapsed, perhaps maintaining the 'off' situation.

I moved a tiny wire from touching the side of the battery.Perhaps not important but it didnt look right.

When i remounted the unit it lit up beautifully.

So the solution lies in 1 or all of these 3.
If it happens again I will try

1. simply remove the unit from its base plate and remount to see if that is all it takes.

2. Open the front and check the reset button isnt collapsed and stuck.

3. Just move that little wire from leaning against the battery -(least sure of why this might help)

hope this might help someone else

Catherine - a determined blonde lady

Posted on Mar 04, 2011

  • Level 1:

    An expert who has achieved level 1.

    Corporal:

    An expert that has over 10 points.

    Mayor:

    An expert whose answer got voted for 2 times.

    Problem Solver:

    An expert who has answered 5 questions.

  • Contributor
  • 17 Answers

I am not familiar with this particular model but in general all digital thermostats are either powered by batteries or by the 24 volt transformer from the furnace. Usually the standard heat/cool type that you may have is powered by batteries and will show a low battery display for a few days before they go out entirely. You may have missed that warning because of your being away.
There will either be a small door on the front of the thermostat or you will need to pull the thermostat from the subbase and the batteries will be inside. Usually 2 AA size....replace with the good kind.

Good luck

Posted on Nov 14, 2008

  • Level 1:

    An expert who has achieved level 1.

  • Contributor
  • 1 Answer

Not sure that the advice above is appropriate. TheST6400 is a programmer rather than a thermostat.. we had exactly the same problem after a holiday exceeding the specified four day back up so the usual solution of pressing the RESET button didnt work. We are replacing ours with ST9400 honeywell computer that has the same backing plate and wiring. The answer seems to be, once installed do not switch off at the mains.

Posted on Jan 03, 2009

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

My st6400c Honeywell programmer blank. Mains turned of whole day. Now back on, but st6400c blank.


Have you tried pressing the 'Reset' button (with the tip of a pencil)? After doing this, you will have to re-enter the various times. It could be that your rechargeable battery is nearing the end of its useful life, by the way.
George

Feb 23, 2011 | Honeywell Programmable Thermostat Heater

1 Answer

St6400c thermostat wont run the central heating independantly


This does not sound like a thermostat problem. I would be looking for a zone valve or circulator pump problem.

Nov 05, 2009 | Honeywell Programmable Thermostat Heater

1 Answer

Honeywell ST6400C central heating programmer fault


you may vae to enter a different "Mode" to change the time....also try removing the batteries for 10 minutes and then reprogram the thermostat again

Oct 25, 2009 | Honeywell Electronic Programmable...

2 Answers

User manual for Honeywell ST6400C


Honeywell ST6400C
Times set on thermostat does not turn on or off the heating or hot water at the set times, but any time of the day

Sep 17, 2009 | Honeywell Electronic Programmable...

1 Answer

Honeywell ST6400C - hot water not working


some digital thermostats do no not work with zone valves is this a new thermostat that you had installed

May 08, 2009 | Honeywell Programmable Thermostat Heater

1 Answer

Display


hi it is most likely a faulty module
cheers grant

Sep 30, 2008 | Fisher Paykel EcoSmart GWL15

1 Answer

No hot water honeywell st6400c


HW valve was stuck in the open posiion and the micro-switch was not working so thats why boiler and pump were not starting. Bled system to below the level of the valve to be changed, and replaced valve with a drayton ( easy quick change of valve head if needed no screws )

Sep 07, 2008 | Honeywell Programmable Thermostat Heater

1 Answer

Honeywell ST6400C programmer


Hi yes sound like it not working on hot water only it would check ou the wiring on this side

Jul 25, 2008 | Honeywell Programmable Thermostat Heater

Not finding what you are looking for?
Heating & Cooling Logo

2,181 people viewed this question

Ask a Question

Usually answered in minutes!

Top Honeywell Heating & Cooling Experts

Bill Long

Level 3 Expert

587 Answers

paulcarew

Level 3 Expert

2432 Answers

Brandon Berry
Brandon Berry

Level 2 Expert

407 Answers

Are you a Honeywell Heating and Cooling Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...