1. Liquid Level
Control
Control
Valves
Pressure
Control
Temperature
Control
Glycol
Pump

2. Temperature Controllers

3. Indirect Thermostat T12 Negative feedback for linear output
5 to 30 psi air or
gas supply pressure
Stainless steel housing
Bi-metal sensing element
for accurate control
Single adjustment over
Wide temperature range:
T to 400oF
HT to 700oF
Output pressure proportionate
to temperature at any setting
T12

4. ? Direct or Indirect ? Direct Mode Indirect Mode
Rising Temperature Rising Temperature
Rising Output Falling Output
Direct
Indirect

5. Indirect Thermostat
Indirect

6. Thermostat with Separable Socket
Maximum Working Pressure
Without Separable Socket psi
With Separable Socket psi
With Special Separable Socket psi

7. Direct Acting Thermostat
Supply Output
T 12DA
Direct

8. T 12DA Thermostat Reversed for Indirect Throttle Mode Supply Output

9. High Temperature Thermostat
Supply
Output
HT 12
Indirect

10. Direct Snap Thermostat
Output
Supply
Direct

11. Indirect Snap Thermostat
T 12DAS
Output
Supply
Indirect

12. Indirect Throttle Thermostat
Output
Supply
Indirect

13. Direct Throttle Thermostat
Output
Supply
T 12TDA
Direct

14. Direct Semi-Throttle Thermostat
T 12DAT
Output
Supply
Direct

15. Indirect High Temperature Shut-Down
T 12M
Output
Supply
Indirect

16. Direct Low Temperature Shut-Down
T 12DAM
Output
Supply
Direct

17. High Temperature Pilot Guard
Supply
HT 12PG
Output
Direct

18. Typical Installation High temperature shutdown thermostat
Burner control
thermostat
Burner
valve
Main burner
Safety
shutdown
valve
Pilot
Pilot Guard
thermostat
Instrument Gas

19. Typical Burner Control Installation
Low liquid
shutdown pilot
High temperature
shutdown thermostat
Burner control
thermostat
Main burner
Pilot
Instrument Gas
Pilot Guard
thermostat
Safety
shutdown
valve
Burner
valve

20. Trouble Shooting SYMPTOM CAUSE Bent sensing element
Erratic temperature changes
Continuous venting
Bent sensing element
(element should be centered
in base and should “ring”)
Incomplete immersion of probe
Dirty pilot plug seat
Hole in diaphragm
Weak pilot plug spring
Faulty ‘O’ ring

21. Trouble Shooting To check small seat: increase temperature setting
several degrees and see if venting stops.
To check large seat: decrease temperature setting
Replace pilot plug and seats if unable to stop venting
by cleaning seats.