Question about Honeywell Programmable Thermostat Heater

1 Answer

No hot water honeywell st6400c

I have a honeywell st6400c when HW is switched on I have no HW lights work but cant hear system kicking in and boiler won't start but if I put heating on boiler kicks in and i get HW and heating? Checked wires as I had a similar problem before with a wire that came loose but no luck...any suggetions

Posted by on

1 Answer

  • Level 1:

    An expert who has achieved level 1.

  • Contributor
  • 2 Answers

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 )

Posted on Sep 17, 2008

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

Came home after a weekend away and central heating not working. Programmer not turning heating on (honeywell st6400c) but the boiler (a sentima ht 60l) looks like it has a fault. The mains light us on but...


Possible cause of lockout: boiler low water level. If you have a combination temperature/pressure gauge, it should read approximately 12 psi when the boiler is cold. When it runs, it will be approximately 22 psi. If the pressure is low feel the inlet water supply piping. Open the manual feeder valve. The cold water coming in will verify that there is no obstruction to the water flow. You may have "dirt" in the line. You may have a defective water pressure valve or check valve. Another thought. Make sure your AIR SEPARATOR is functional. Remove the cap and depress the valve. You should see water. If air comes out, continue to"bleed" the AIR SEPARATOR. You may haven't to replace the A/S.

Jan 28, 2013 | Heating & Cooling

1 Answer

Water to hot for gas boiler boiler gos off


It could be dyslexia, but I think you want to know what may be wrong with your boiler in this case!
This is a VERY old design. The diaphragm is on the water section, this operates a switch to turn ON the pump, and a further device causes the diverter valve to divert boiler water from CH duty to HW duty.
From your description it appears that the boiler is shutting down on internal boiler water temperature (too high), your 'briefly too hot' HW symptom may be caused either by the boiler side of the secondary heat exchanger being blocked/caked in sludge, OR the DHW side of it being scaled. Either way a new or replacement (descaled) secondary heat exchanger MAY inprove things. It's not easy on these old clunk-pots, and EVERY disturbed seal will subsequently leak, so get a good supply of o-rings and fibre seals before you start ("you" being the competant fitter you employ)

Dec 20, 2012 | Water Heaters

1 Answer

ST6400C programmer, heating switched off. Switch hot water on only, tank full of hot water but pump runs and radiators get hot. Wall stat is set at zero. When programmer is touched and the flap dropped to...


Have had a lot of these programmers with this fault.Integral fault with electronics.Programmer will need to be replace as unrepairable.You should be able to find a straight replacement version from your heating supplier.

May 11, 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

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

Cannot get central heating working,for honeywell ST6400 programme


with y plan 3 connections on programmer HW on HW off CH on HW on to cylinder stat then HW call to Orange on Mvalve to power boiler and pump HW off to grey wire on Mvalve to close hot water CH to room stat common then heating call to white on Mvalve

Jun 13, 2009 | Honeywell Programmable Thermostat Heater

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

Cant turn heating off


do you have a separate or built in programmer? if itis separate ISOLATE MAINS undo the screws on the bottom of programmr and checkthat ther are no loose wires ( make a note of where they go for future ref. ). If wires OK check that the valves are working switchoff HW and Heating switch one on at a time and check that each valve is opening and closing and that the boiler and pump fires up ( it could b the micro-switch in the valve is broke! )

Sep 06, 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

719 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

2097 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...