No hot water but heating works....

[DavidRossitter]

Hi

Dont worry your advice re doing work is taken on board - and I am rushing nowhere - but you can only run without hot water (immersion heating aside) for so long. I just want to develop a consensus of opinion as to the best course of action so I know what kind of work I need doing if any.

I have just spoken to a local qualified person and they too suggested swapping the thermostat as a first step - ironically he said it was so easy that I could do it myself!

So I am going to watch it over the next few days and see if changing the thermostat setting gets it going or whether it is pressing the reset button. I suspect it is the first of these but want to be sure.

Thanks David

 

[DavidRossitter]

Hi

So an update on this one....

...hot water doesnt work at all now - so running on the immersion.

Looking at it further I am now coming to the conclusion that the motorised valve head is faulty. Concluded from the fact that when it was working changing the thermostat setting had no effect - the thermostat was calling for hear. And I could occasinally restart it by moving the manual lever on the valve.

Now if I move it manually right across it clicks and fires the hot water for a second and then turns off. It wont stay running.

I gather there is a switch in the valve and I wonder if this is faulty ?

Does this sound all plausible before I arrange replacement of the motor head?? Its a Honeywell 272848 by the way

Thanks David

 

[Agile]

You have not taken on board what I told you earlier!

The switch is NOT activated by moving the lever !

The switch is ONLY activated by opening the valve with the motor !

Either the motor is failed OR its not being powered.

These situations are identified by simple voltage and resistance tests.

Tony

 

[DavidRossitter]

Hey sorry - lots of posts against this and time in between.

So taking your advice I have established the following:

- moving the manual lever seems to touch a small button for a brief moment inside the valve that is triggering the hot water for a second (that is what I saw previously - but your earlier point taken)

- if i press this button down for a few seconds the boiler fires up and stays on until i release the button

- the resistance across the motor is 2.2kohm but crucially when I turn the heating control on it still reads 0V - ie no power getting to motor valve

- so I wonder if the timer control is the problem. It is a Honeywell ST6100c that shows a red light when on but I am not hearing a "click" when it is switched on. Did a reset but still the same

So is does this suggest the timer looks like it is working but the bit that sends the signal/current down to the hot water valve has packed up. It seems to be one of those controls that you replace the front plate containing all the electronics.

Does this all suggest this is the problem now ? or do i need to do more testing and checking ?

Thanks for all your patience on this

Cheers David

 

[DavidRossitter]

Also to add that I have now confirmed the thermostat as functioning by means of measuring the resistance when "on" and "off" so I believe everything has been eliminated but the timer control as per last post so this seems to be the culprit. If anyone can see a flaw in my thinking then do let me know

Thanks

 

[Agile]

Be aware that I have not seen your system and dont know how it has been wired up.

Normally the timing device will send power to the motor VIA the thermostat.

In the case of an unvented then thats usually via a thermostat AND a manually overheat stat.

You should be checking for voltage from the programmer onwards towards the motor.

Tony