Harman P38+ thermostat

[Harman Lover 007]

I have a friend with a Harman P38+ looking to install a thermostat. Looks like wireless is too pricey for him so what can you guys give for a recommendation? The P38 is a manual stove. Thanks.

 

[silverfox103]

I have an older P38, a have a Robert Shaw thermostat. It's just a mechanical thermostat. Another forum member used that and it worked, so I ordered one. I think it came from Calif. After I got I realized that HD & Lowes have them that are the same and a lot cheaper. I think they cost about $12. It is a basic mechanical thermostat. It is rectangle shape and has a sliding lever on the top. Try those, I think they will work.

Tom C.

 

[Harman Lover 007]

I have an older P38, a have a Robert Shaw thermostat. It's just a mechanical thermostat. Another forum member used that and it worked, so I ordered one. I think it came from Calif. After I got I realized that HD & Lowes have them that are the same and a lot cheaper. I think they cost about $12. It is a basic mechanical thermostat. It is rectangle shape and has a sliding lever on the top. Try those, I think they will work.

Tom C.

Thanks Tom, I think he wants to go programmable if possible so he can control the stove during the day on low burn and then have it ramp up before he gets home from work.

 

[DAKSY]

Harman Tech Bulletin from 2007

Adding a programmable set back thermostat for all Harman Pellet Stoves
Thermostat must be:


1) Millivolt compatible
2) Gold Contacts
3) Low Voltage
4) Low current
Recommended Honeywell Thermostats.
RTH230B
RTH6300B
These thermostats are available at hardware stores and home improvement retailers.
Note:


If there is a jumper between Rh and Rc it must be removed from the thermostat’s terminal block. Use
minimum 2- conductor 24 gauge twisted pair wire to connect the thermostat.
Connect the thermostat in series with the room sensing probe using the Rh and W terminals on the
thermostat. (See Fig. 1) The set back thermostat

must
be used in conjunction with the room sensing probe
(except the P38).
Thermostat Settings:
Occupied Mode:
In occupied mode program the thermostat to its maximum temperature setting. (i.e. 82 Deg. F) The stove’s
room sensing probe will control the room temperature. Set the stove’s temperature dial to the desired room
temperature. (i.e. 72 Deg. F)
Unoccupied mode:
In unoccupied mode program the thermostat to the desired set back temperature. (i.e. 60 Deg. F) When the
thermostat opens (is satisfied) the stove will go into a 4-blink status. If the stove is an auto ignite stove and
the auto-manual switch is in auto mode the stove will shut down. When the thermostat closes (calls for heat)
the 4-blink status will automatically reset and the stove will ignite.
If the stove is a manual ignite stove or an auto ignite stove with the auto-manual switch in manual mode, the
stove will go into a 4-blink status when the thermostat opens (is satisfied) and the stove will go to a
minimum burn and stay there until the thermostat closes (calls for heat). When the thermostat closes (calls
for heat) the 4-blink status will reset automatically.
Note:


A 4-Blink status is described in the owner’s manual. The status light on the stove will blink 4 times,
pause, and blink 4 times continually. This error code is the board recognizing that the room sensing probe is
not connected or has failed. Breaking one leg of the room sensing probe wiring with the thermostat, as we
are doing here, causes the 4-blink status. This error automatically resets when the board recognizes the room
sensing probe has been reconnected.

I tried to get the wiring diagram to copy, but no luck... I'll work on it...

 

[saladdin]

I have a Cab50 and just bought the RTH230B at amazon for 25. Not installed yet. Still debating whether I need it.

 

[silverfox103]

If your friend has an older P38, you cannot use programmable thermostats. You have to use mechanical ones. That's why I used a mechanical thermostat.

Tom C.

 

[Harman Lover 007]

If your friend has an older P38, you cannot use programmable thermostats. You have to use mechanical ones. That's why I used a mechanical thermostat.

Tom C.

I think its a P38 plus maybe 5-7 years old......

 

[silverfox103]

Not sure where the dividing line is, but if you can't get a programmable thermostat to work, you know why. I think mine might be 10 to 12 years old.

Tom C.

 

[Harman Lover 007]

Not sure where the dividing line is, but if you can't get a programmable thermostat to work, you know why. I think mine might be 10 to 12 years old.

Tom C.

His purchase date is 11/01/04 s/n 5615. Manual says P38+