Ranco digital thermostat is a MUST for folks hooking up to an
inside boiler in their home. Since indoor boilers normally run
at 180° F, there is very little room for play. If the water
temperature exceeds 180° F, your Pex pipe can be damaged. The
water temperature coming into the indoor boiler has to be as hot
as the indoor boiler normally is (to trick the boiler into not
coming on). The mechanical thermostat that comes with the stove
can vary by 10 to 20°. This may raise the water temperature to
way over 200 degrees. It is $125 installed (but not wired up)
and comes with a dry well, for the probe, also installed.
mechanical thermostat is very good thermostat because it is
pretty much impervious to power surges but a better one is
needed in these applications. However the digital thermostat is
better because it can be adjusted to as tight as 3° F, though
there is very little chance of overheating the Pex pipe.
activated damper needs to be included as well (if not
installed), to stop the air from bleeding into the firebox when
the fan turns off. It is $125 installed and comes with a fan
that is 50% bigger; 75 CFM vs 50 CFM. Air from bleeding into the
a fire to smolder, raising the temperature of the water even
when the fan is supposed to be off.
Note the markings, in black, below the terminals (partly covered
You'll need a short jumper wire to go from the "120" terminal,
to the "C" on the bottom three terminals (2 to 2A)
the top 3 terminals, you'll connect black from power to "120"
and white to "COM". (2A and 3)
You can see the location of the white jumper wire (from
terminals 'C' to '120') more clearly in this photo.
Then you'll come off the "NO" terminal, with a black wire and
connect it to your blower (and solenoid if equipped) along with
a white wire either from "COM" (or from a junction box you
installed in your furnace.)
All ground (bare copper) wires go to a secure, fully seated
screw, as shown above.
The dry well needs to be screwed into the fitting that is
at the top (center) on the back of the furnace, behind the door -
above the pumps. (Shaver Furnace)
You will see what looks like a bolt head (but is actually a
plug). You will need to unscrew that and screw the dry well in
its place, using Teflon tape.