Re: oil fired furnace X-10 off/on swich control

[Lewis Gardner <lgardner@xxxxxxxxxxxxxxxxxxxxxxxxxx>]

BruceR wrote:
>  Lewis Gardner wrote:
>
>>BruceR wrote:
>>
>>>Place one of these in series with the existing switch.
>>
>>Parallel would work better...
>
>
> Yes, parallel would work - but no better and, for safety reasons I think
> I'd stick with series which would require both switches to be on to
> operate.

Modern codes require a complete power disconnect to be within easy reach
of all HVAC equipment. For service work the tech should shut off this
switch. The low voltage switch the OP asked about is the equivalent of
the thermostat wiring. NO tech would ever simply turn off the thermostat
before servicing a unit.

If the switches are in series both have to close to operate the furnace.
Not ideal since it would require the X-10 bit to stay closed to get
heat. This is a bad idea since a X-10 glitch could leave you without
heat in the middle of the winter.

In general I wire automated controls in parallel with thermostats so
they provide supplemental control.

Each to his own but I strongly feel that paralleling the switches is
MUCH better and would pose no safety issue. If you want the advantages
of both methods simply add another another switch in series with the
paralleled switches or replace the switch with a center off DPDT switch
that would provide X-10 OFF ON positions.

                  /
power -------o  o  o--------- furnace
                 |/    |
              o  o  o  |
              |        |
              |   /    |
               --o  o--
                 X-10

The top switch is a center off DPDT with the center terminals connected.
The lower switch is a low voltage X-10 module. In the left ON position
the low voltage X-10 switch has control. The center OFF position and
right ON position work like current switch.