Wierd one!!!!!!

[jacko57]

have a glowworm boiler,with drayton 3 port valve,recently replaced room termostat with new drayton,and this set up require three wires to the stat, plus honeywell programmer.since then when heating is on alone, stat operates perfectly,here the click at temp setting,raise the stat and boiler fires up. all summer been on hot water only all fine, but i have now noticed that when both on heating and hot water i think that the hot water is flowing round the rads,as they are red hot,even if i turn the stat down to zero Heating works fine with the stat as long as i dont put hw on,but hw alone does not get the rads hot......any ideas appreciated.

Jack'o

 

[MANDATE]

I'm not clear what your problem is! however regarding the 3 port valve when you select HW and CH the valve takes up the mid position so hot water will flow through the radiators and the cylinder until one of them is satisfied (as specified by the relevent stat). At this point the valve moves to either HW only or CH only until the relevent stat kicks in again and then its back to mid position.
If HW only is ok, that proves cylinder stat and if CH only works ok that proves room stat.
Maybe it's me but as I said I'm not clear on what's wrong. If radiators are hot with room stat at zero, then I would suspect room stat.

 

[jacko57]

Cheers for the reply....hw on only does what it says...only to cylinder
ch on only stat operates heating perfect
both on together somehow the rads are scorching hot,even with the stat turned right down i think the rads,with the ch on are being controlled by the cylinder termostat...is that possible?

 

[scatmanjohn]

If it worked ok before you changed the room stat then i would be looking at the way that you have wired the new room stat.

 

[jacko57]

yes im sure of that to..just cant get to grips with the stat..i replaced a rte1 with rts4 thought i had followed the swap over correct..trying to find wiring info

 

[MANDATE]

Stats with two wires have a 'live' going in and a 'switched live' coming out so it is easy to check if the stat is working.
If there is a third wire, it is because there is in fact a small 'load' in the stat in the form of a 'heater' and as with any 'load' it can't function without neutral wire. The neutral wire is most likely 'blue' and one of the other two will always be 'live' (with programmer on) The remaining one will be the 'switched live' ie becomes live when switched on.
O---------------neutral----------------
Z
Z
Z
O--------------switched live-------to 3 port
\
\
O-----------live------------

 

[Softus]

There's no fault. If your rads are too hot (for your skin) then turn down the boiler temperature control.