Y plan system locking on.

[Agile]

This is an unusual fault and its for a friend which makes it more important that I get it fixed soon but I dont have much time to spend and she talks a lot which means that it takes longer to get it done. I have only had a quick look and not fully checked the wiring but it seems to be correct.

Its a basic "Y" plan with programmer downstairs, motor valve and receiver for wireless stat in bathroom, Worcester Ri boiler on landing and cylinder in loft. Motor valve is quite new and seems to work correctly and switches are operated and click in the right positions as expected.

She is adament this is a recent fault and nothing has been touched. I have seen the fault occur that the boiler stays on when the timeclock is off for CH and HW.

Disconnecting the orange from the motor valve for a second removes the demand ! It seems that the call for heat is somehow causing something to "lock on" but once this is removed everything goes off as it should be.

If what she says is correct then something has changed/failed.

Tony

 

[wetshoes]

Have you checked if the microswitch in the 3 port valve is sticking in the on position ?

 

[gas4you]

Do we presume this only sticks on after a demand for ch has ended?

If you replace the orange wire immediately after this 'second' of disconnection, does the demand manifest itself again, or remain off?

 

[seco services]

what voltage are you getting on the orange when heating/hw are off ?

 

[Agile]

Both microswitches "click" reliably in the positions that would be expected.

If the timeclock is off and the boiler has stayed on then disconnecting the orange for a second then reverts to system to the normal off senario.

I would remind you that there is a Drayton wireless stat connected to the system.

Tony

 

[MANDATE]

I understand there is a resistor that links the 'grey' to the 'orange'.
If this has failed, the 'orange' could be receiving 240v power to light boiler direct from the 'grey', whereas I believe it is normally about 100v.

 

[gas4you]

Both microswitches "click" reliably in the positions that would be expected.Tony

Surely there is only 1 microswitch in the valve head, for activating the ch.

HW is activated from the cylinder stat, or are we talking a traditional diverter valve here?

 

[glasgowgas]

Both microswitches "click" reliably in the positions that would be expected.

Competent htg engineers and registered gas installers never assume that a "click" means anything, without actually checking voltages at all terminals

do you own a multimeter?

do you feel competent working with live electricity?

it can be a pain in the ass can`t it Tony

 

[BingoBongo]

wouldnt this be better posted in the cc as we dont want members of the public thinking we cant solve problems

 

[MANDATE]

Surely there is only 1 microswitch in the valve head, for activating the ch.

Depends what is meant by 'activating', both switches play an active role.
Sw 1 is fed from 'white' and 'grey' Valve can't get to CH position without a live 'grey' (that is from mid position).
Sw 2 (which is also fed from the 'white') when triggered after Sw 1 diverts power from internal pcb out through 'orange'.
With both HW and CH off, the 'grey' is left 'live'. This I believe is both holding the valve at CH and supplying the orange output.
I can't think of any other explanation

 

[petit_pablo]

Cylinder stat back feeding into valve, have had before. Frost stat installed in loft?

 

[ajrtd]

It would help if the OP told us the make of valve.

 

[namsag]

Cant be the real Agile as the real Agile fixes everthing first visit

 

[buck51]

You may be "AGILE", but you aint versatile enough to listen and work at the same time!!!
Tell her to shut the fu@k up !!!

 

[RichardBothwell]

Hope this finds you well Telly Tony & you had a good Christmas & wee holiday.

Here's a good wee link for faults on 'Y' plans.

http://octaveblue.co.uk/c_heating/index.htm