My combi boiler is connected to an FCU that joins the ring main. All
well and good and proper. Now I have a HC60 relay unit that needs
connecting to the boiler. It is the receiver for the CM67 RF
programmable thermostat.

My question is, can I take a connection from the FCU to the HC60, so
that both the boiler and the relay work from the same FCU. It means
that if the switch is off, neither the boiler nor the relay/thermostat
will operate but that's OK because we wont need one without the other
will we.

Schematically this will look like...

Mains-----------[FCU]--------------Boiler
                  |
                  |----------------HC60 Relay/CM67 Thermostat

Otherwise I'll have to break into the ring and add in an extra FCU
for the relay, which seems to be a bit over the top to me.

In an earlier contribution to this discussion,
dean@bluerose.freeserve.co.uk   wrote:


> My combi boiler is connected to an FCU that joins the ring main. All
> well and good and proper. Now I have a HC60 relay unit that needs
> connecting to the boiler. It is the receiver for the CM67 RF
> programmable thermostat.
>
> My question is, can I take a connection from the FCU to the HC60, so
> that both the boiler and the relay work from the same FCU. It means
> that if the switch is off, neither the boiler nor the relay/thermostat
> will operate but that's OK because we wont need one without the other
> will we.
>
> Schematically this will look like...
>
> Mains-----------[FCU]--------------Boiler
>                   |
>                   |----------------HC60 Relay/CM67 Thermostat
>
> Otherwise I'll have to break into the ring and add in an extra FCU
> for the relay, which seems to be a bit over the top to me.


What you're proposing is fine - except that your diagram makes it look as if
you plan to connect to the supply side of the FCU, whereas you must, of
course, connect to the outlet side. That way, the whole heating system can
be isolated by turning off a single switch - which is the way to do it.
-- 
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

In article ,  
wrote:

> My question is, can I take a connection from the FCU to the HC60, so
> that both the boiler and the relay work from the same FCU. It means
> that if the switch is off, neither the boiler nor the relay/thermostat
> will operate but that's OK because we wont need one without the other
> will we.
> 
> Schematically this will look like...
> 
> Mains-----------[FCU]--------------Boiler
>                   |
>                   |----------------HC60 Relay/CM67 Thermostat
> 
> Otherwise I'll have to break into the ring and add in an extra FCU
> for the relay, which seems to be a bit over the top to me.


No, you definitely want everything related to the CH to go through one 
switch and fuse or one day someone will have a nasty accident.

-- 
Tony Bryer SDA UK  'Software to build on'  http://www.sda.co.uk
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