Hi,

I have recently had my programmer replaced to a Randal 715 with
seperate controls for CH and HW. The programmer was set for a fully
pumped system determined by the existence of a motorised valve and
only two pipes connected to the boiler. However my problem occurs
when the programmer is set to off for both HW and CH but the boiler
still fires when the room thermostat is turned up!!!!

I have checked the wiring on the programmer and no connection is made
to the 'HTG Off' as was the previous programmer (Randall 702), could
this be the problem? I can get HW seperately recently and when just
wanting CH this also works.

I have three wires going to the room thermostat but the yellow (wired
to terminal No. 3) appears not be connected to the programmer's wiring
plate.

I switch the programmer to 'gravity' based system and now the CH comes
on only with the HW and is not effected by the room thermostat when
the system is off.

Is there anything I can check to confirm what type of system I have?

and how is the room thermostat controlling the boiler directly?

Many thanks

Adam.

I have recently had my programmer replaced to a Randal 715 with
seperate controls for CH and HW.

The good news is that you appear to have a fully pumped system capable of
fully independent control. You bad news is that also appear to have selected
a complete cretin to wire up your new programmer.

Any number of wiring faults could explain the behaviour you are seeing.
Connecting one end of the thermostat to permanent live, rather than the
programmer's call for heating is one of the likely ones. Don't worry about
the lack of connection to "Htg Off". This is rarely used. The lack of
connection to one of the thermostat's terminals may be an issue, however.

Christian.

"Christian McArdle" wrote in message . net...
I have recently had my programmer replaced to a Randal 715 with
seperate controls for CH and HW.

The good news is that you appear to have a fully pumped system capable of
fully independent control. You bad news is that also appear to have selected
a complete cretin to wire up your new programmer.

Any number of wiring faults could explain the behaviour you are seeing.
Connecting one end of the thermostat to permanent live, rather than the
programmer's call for heating is one of the likely ones. Don't worry about
the lack of connection to "Htg Off". This is rarely used. The lack of
connection to one of the thermostat's terminals may be an issue, however.

Christian.

Hi Christian,

Sounds about right, I have since found out that when the room
thermostat was installed it blew the fuse for the programmer. The
original rmt was replaced and the system 'commissioned' by the
installed.

I disconnected everything and reset the programmer etc and fixed a new
rmt to the wall (a Honeywell direct replacement instead of some
generic thing). Anyway everything appears to be working ok, I have
checked the switched live to the rmt and it comes on only when the
programmer is expecting it, so all looks good, although I will be
monitoring the system for a while yet.

Adam.