honeywell 4073a valve staying hot

[cricketruss]

Hi, I have recently updated my central heating controller to a st6400c.I do not have a room thermostat.The controller works fine,central heating,hot water and /or both when asked for.The problem is when the central heating has been on the 4073a motor casing remains very hot even when the water in the pipes has cooled.If I turn the power to the system off and back on the casing cools and everything goes back to normal.This only happens after the heating has been activated.Could anyone please explain what is wrong.Many thanks.

 

[Chr!s]

Hi, I have recently updated my central heating controller to a st6400c.I do not have a room thermostat.The controller works fine,central heating,hot water and /or both when asked for.The problem is when the central heating has been on the 4073a motor casing remains very hot even when the water in the pipes has cooled.If I turn the power to the system off and back on the casing cools and everything goes back to normal.This only happens after the heating has been activated.Could anyone please explain what is wrong.Many thanks.

You have probably wired it up incorrectly, sound like the motor is continuously being energized.

 

[no one likes us]

As long as it all works correctly then you are prob ok.The 3 port valve will allways stay in last position req.So if on hot water it will be in closed position,on both c/h and h/w in mid position and more likley this time of year c/h only even after clock and stat turned off it would stay in fully open position.Only if power is totally isolated by mains then it will return back to h/w position.

Hope this helps,Graeme

 

[topquark]

Could be a number of things (most likely as Chr!s has said above as it resets itself when power is removed and reapplied), best advice would be to get someone in to check it for you.