Cylinder thermostat & C-PLAN question

[jameshunt]

Is a C PLAN allowed to be installed now under the Building Regs? As I believe the hot water AND htg need to be FULLY PUMPED.

Also, my main post- i believe the cylinder thermostat is not working - and not making the circuit - i have tested the terminals voltga eusing a multimeter safely, and there is power to the C terminal (when the programmer is on for HW) but nothing to the 1 terminal (which means the thermostat must be stuck) ... but reading the honeywell website fault finding guide, there is notes saying to remove terminals 1 and 2 when testing to prevent backread signals - what exactly does this mean? Have i do remove the 2 termianl when testing the 1 terminal?? Just want to clarify this really and be 100% sure the thermostat has failed before replacing and going off to the diy store.

Thanks in advance.

 

[doitall]

1-C should be close circuit when calling, you pull the wires out so you don't get a false reading.

For a C plan which as you say is not allowed on new installs.

The grey in the MV is permanent live from the programmer.

C in the cyl stat goes to the brown.

White is the room stat on and pump.

Orange is the boiler.

T1 in the cyl stat is the call from the programmer.

 

[jameshunt]

Thanks for your help. I understand the wires and how they shouls read (now)! .. but when you say pull the wires out for testing (obviously with the power off and 3 amp fuse removed) - but do you mean take a reading of the wires with the wire ends loose and removed from the wiring centre terminals ? or do you mean remove the other wires in the same terminal blocks that i am testing? thanks for helping.

 

[doitall]

Obviously you make it safe

You are testing the cylinder stat not the wires.

With the wires removed from the stat C-1 should be closed circuit when calling, if it aint it's busted.

If it is then the problem is elsewhere, most likely the Mv.

 

[jameshunt]

OK so i leave the wire in the stat from the programmer (hw on terminal) and remove the other 1 (the C terminal in my case).. and c and 1 should be live (240V betwene them, otherwise the stat is not making) - i have never known to test this way before - always tested the wiring centre terminal boxes.

 

[doitall]

No take both wires out and do a continuity test.

 

[jameshunt]

ok good idea - will try this; all fault finding guides mention testing via the wiring centre terminals though - and i was curious about what to remove exactly to prevent the chance of backread signlas from other controls, etc.

i will try your way now tho... thanks for your advice.