Skip Ribbon Commands
Skip to main content
Item 1 Of 4
High and Low limit Aquastat Controller


High and Low limit Aquastat Controller

  • Product Info
  • Literature


High limit, low limit and/or circulator controllers used to regulate boiler water temperature in gas- or oil-fired hydronic heating systems.


  • An immersion type liquid-filled sensing element actuates two snap switches.
  • One switch operates as a high limit control.
  • The other switch operates as a low limit and/or circulator control, depending on the model.
  • Controller may be mounted in any positioning and needs no leveling.
  • Separate, easy-to-read, calibrated dial and setpoint adjustments for each switch.
  • Differential adjustment on low limit or circulator switch on select models.
  • All adjustments accessible inside front cover.
  • Push-in terminals for quick connecting.
  • Single sensing element for easy installation.
  • Two SPST snap switches act independently at respective temperature settings..

Product Specifications

Hazmat Information
UN 1294, TOLUENE, 3, II
High and Low limit
Dimensions (in.)
3 7/8 in. high x 4 1/8 in. wide x 2 3/4 in. deep.
Dimensions (mm)
98 mm high x 105 mm wide x 70 mm deep.
Temperature Range (F)
Maximum--150 F at switches; 265 F at sensing element
Temperature Range (C)
Maximum--66 C at switches; 129 C at sensing element
Electrical Ratings
0.25 A @ 0.25 to 12 Vdc; At Full Load-- 8A @ 120 Vac: 5.1A @ 240 Vac; At Locked Rotor-- 48A @ 120 Vac: 30.6A @ 240 Vac
Approvals, Underwriters Laboratories Inc.
UL Listed: File No. MP466, Vol. 12, Sec. 4, Guide No. MBPR2
Approvals, Canadian Standards Association
Certified: File No. LR95329-1
Operating Humidity Range (% RH)
0 to 95% RH, non-condensing
Operating Temperature Range (F)
High Limit-- 130 F to 240 F; Low Limit-- 110 F to 220 F
Operating Temperature Range (C)
High Limit-- 54 C to 116 C; Low Limit-- 43 C to 104 C
Differential Temperature (F)
High limit : 10 F fixed; low limit: 10-25 F adj.
Switching Action
SPST: High & Low Limit
Well Spud Size (in.)
3/4 in. - 14 NPT
Well Spud Size (mm)
19 mm - 14 NPT
Insulation Depth (in.)
1 1/2 in.
Insulation Depth (mm)
38 mm
Electrical Ratings, Ignition
Transformer Load: 360 VA