only getting small voltage

[chelsea]

problem with heating controls,its a conventional with 2 2port valves and the problem is no heating or hot water

basically getting 240v up to programmer but after that only getting 50volts to pump and 2 port valves and boiler is only getting 120v

can someone please share their knowledge on this one??

 

[aggis]

Check that the switched lives from clock are 240v 1st & not low voltage, should be 240v [look at wiring diagragm, prob on back of clock]
Try bridging the live on clock to heating or dhw connection on wallplate , make sure stats are calling. This should put 240v thro' to valve, will make switch to give 240v to boiler. If so change clock/prog.
If valve moving over but no power to boiler, check grey & the orange wires, both should be 240v to Earth ,if not change valve
The reason I say check both is permanent live should be grey, but some people use the orange, which is wrong but it can work ok.

 

[ringer]

Had something similar on mine though was only CH not working, HW was fine - problem was CH zone valve motor burnt out. Because the motor was open circuit it screwed up the expected voltages in the rest of the system (see note at end of this post). The pump will not come on (at least, not on my system) until the zone valve has operated and the contact made to complete the circuit via the microswitch within the zone valve . My circuit for CH (using Honeywell V4043 zone valves and separate room stat) is:

240v->programmer (CH on) -> room stat -> zone valve motor(zone valve then moves and operates microswitch to connect rest of circuit) ->(simultaneously) pump on + boiler call for heat terminal

Diagnosis:
First do as Aggis suggested to bypass the programmer
Assuming problem still exists, remove the bypass on the programmer
turn heating (or hot water) off at the programmer
take off the cover of the zone valve.
check the manual lever on the side of the valve - you should fell resistance to operate it
put the manual lever back to its original position (i.e. not hooked open)
Turn heating (or HW) on at programmer and stat
Does the motor turn when CH is on (or HW, depending on which valve you are looking at)
It will only turn by a small amount. The manual lever should then be floppy.
If it doesn't turn the motor is probably burnt out.

To check if motor burnt out:
Turn programmer off
Disconnect both blue wires to the motor (trace the cables back to the terminal block - one may be a different colour).
Turn the programmer on and ensure stat is on high
Now measure voltage from each terminal where the (now disconnected) motor was connected.
One of those should be 240V. If so, this indicates problem with motor.
Now turn off programmer.
Measure the resistance from one blue wire on the (disconnected) motor to the other blue (or whatever colour) wire. Reading should be somewhere in the order of 2kohms. If it reads open circuit (infinite resistance) then the motor is burnt out. Get a new one for £10 from Toolstation.

I have no idea of your level of knowledge, and appreciate your fault is slightly different to mine, but the above is how I went about diagnosing/fixing my faulty system.

Note:
Getting voltages of between approx half and quarter of expected value usually indicates a disconnected neutral. Because the motor was short circuit, there was no connection (albeit normally via a load in the motor) to neutral.

 

[chelsea]

Thanks fellas going to have a look at it today

wish me luck