heating trouble

4 Jan 2011
Reaction score
United Kingdom
Hi. so my drayton ma1 actuator broke ages ago but i didn't replace it, i just removed it and set the valve manually to CH and did without HW.

All was well until recently when the drayton rts1 thermostat wouldn't click to activate the CH(although occasionally it did when left for a while).so i decided to replace the actuator which was straight forward.

There is a lever on the side which is in the lock position and according to the instructions will release when it receives power.It is currently in the mid position.

So i tested it.with CH on the timer switched to ON the rts1 still doesn't click to activate.The actuator is still locked and in the mid position.

With the HW on the timer switched to ON the boiler kicks in,the actuator remains locked and in the mid position,so i get hot rads and water until the tank thermostat shuts the boiler down.

I'm at a loss.

Thanks in advance.
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Are you getting 230v on the grey wire when hw off or hw satisfied at the stat ?
No power on the grey then it won't move to ch only.
Unfortunately i don't have the means to test for a voltage.

To be honest i don't yet understand how it all works.

Why is it when the timer calls for HW the boiler kicks in even though the actuator remains locked but when the timer calls for CH the boiler doesn't kick in?

Could the timer be faulty?or the new actuator?or the room stat?
You'll need a multi meter to check any of these for voltage.

If you look in the sw/l terminal you'll have 3 wires, sw/l (orange) from valve, sw/l from cyl stat, sw/l to boiler.

Hw only hw/ch power comes from the cyl stat.
Ch only power comes from the valve.

When hw satisfied/off the grey becomes live from the cyl stat/programmer
then the valve moves to ch only and power then comes from the orange of valve activated by micro swtches in the valve.
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Is it possible to bypass the room stat switch so in effect it continually calls for heat as a means to test whether the room stat is at fault?
Just to make sure ....

There is a blue connected to N.
There is a red connected to L.
there is a grey connected to port 3.

Do i just move the red into port 3 in replace of the grey?
Get the blooming problem sorted instead of meddling with the wiring. One false move, you will either hurt yourself or damage the equipment that will then need a lot more than what you are trying to save at present:cool:
As you know it's not easy to understand and it's not easy to explain either.
Firstly the latch is for holding the valve at mid position for draining and re filling. So unlatch it and try again.
The motor within the head only turns about half a dozen turns and when power is removed a 'spring' returns it to the start position.
The start position is HW so without power the valve does not play an active role if just HW is the requirement as the HW port is already open.
Power goes from programmer to cylinder stat/ across stat/ then out to boiler.
Note the stat provides the power.

It's when you want CH on it's own when it is more of a problem to understand.
The valve moves over two halves.
Take the last half first assuming the valve has gone from HW to mid position.
There is a grey wire on the valve and this grey has to be 'live' for the valve to move over the last half. If it's not the valve will stay at mid position.
OK so we'll assume it's live and valve moves and during this movement it triggers a micro switch which allows power out from the valves orange wire. This orange wire then joins the wire from cyinder stat to light the boiler.
Note the valve provides the power.

Now when you select both HW and CH the valve needs to be at mid position and stay there until either HW or CH is satisfied. Obviously the grey wire must not be live.
It gets to mid position by the room stat providing power to the white wire and this power is cut off at mid point.
It is replaced with a modified holding voltage to hold the valve against the strength of the return spring.
When either HW or CH gets satisfied the valve either moves forward to CH only or drops back to HW accordingly.

Now for the grey wire.
this is made live when HW has been satisfied by diverting the power at the cylinder stat(two way switch).
Of course if HW was not selected there is no power to divert, so a wire is fitted as alternative supply from the programmers HW OFF terminal.

OK so i got one of those voltage tester screwdrivers and used this to test the live on the room stat when the timer called for CH and there was a voltage.So i knew the timer was OK.

As the actuator is brand new i assumed this to be OK also.

So i went out and got a new room stat and swapped it like for like and hey presto everything is working.

Thanks to all who contributed to this thread.[/i]

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