Petersen MFG Waterer Fenwal Thermostat 100-1130
Petersen MFG Waterer Fenwal Thermostat 100-1130 is backordered and will ship as soon as it is back in stock.
Delivery and Shipping
Delivery and Shipping
All products will ship according to shipping option selected at checkout. Standard USPS and UPS average shipping times are 2-7 and freight up to 2 weeks. Allow extra time during peak season and the holidays. For more information see our Shipping Policy.
Description
Description
This thermostat replaces the Franklin FRU, and it needs a brass nut
The Petersen 100-1130 is a direct replacement for the Franklin FRU thermostat, part 41604, on the older Franklin waterers that used one. It is also a more economical replacement for the Ritchie Fenwal thermostat. All three are Fenwal thermostats and the thread is the same. The brass nut is not included, so add the Petersen 100-1131 Fenwal thermostat nut to your order. That is the nut made for this thermostat.
This Petersen replacement thermostat regulates the temperature of the heater in your waterer. It comes factory preset at 40 degrees. Set higher, it will keep the whole bowl ice free, though it will use more electricity than the factory setting.
There is no knob on this thermostat. The setting is changed with a flat head screwdriver in the slot on the face, which is the main difference between this one and a thermostat with a dial you can turn by hand. The same is true of the Ritchie Fenwal.
Adjusting a Fenwal thermostat
These steps come from Ritchie’s own manual for the Fenwal thermostat, and they apply to both the Petersen and the Ritchie Fenwal. The adjustable range is 0 degrees F, which is minus 18 C, up to 100 degrees F, which is 38 C.
- Fill the trough to the proper water level.
- Check the water temperature with a thermometer.
- The next morning, check the water temperature again.
- If the water is warmer than you want, turn the thermostat down. If ice is forming on the surface, turn it up.
Make only slight adjustments at any one time. A 1/16 turn changes the water temperature about 7 degrees F, which is 4 C. Around 44 degrees F, or 7 C, in the trough is the most economical setting to run.
Counterclockwise raises the setting. Turning toward H makes it warmer, turning toward C makes it cooler.
Turn counterclockwise, toward H, to raise the setting. Turn clockwise, toward C, to lower it.
Replacing a Franklin FRU, two ways
If your older Franklin waterer has an FRU thermostat, you have two choices.
- This Petersen thermostat. It threads in the same, so it is a straight swap. Order the brass nut with it.
- The Franklin Maverick thermostat with bracket, part 41606. This is a conversion kit, and the instructions and a video are on that page. It only fits the older style Franklin waterers that came with an FRU thermostat.



