• Hydronic Manometers

Hydronic Manometers

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Hydronic Manometer Model HM675 is used to balance hydronic heating and cooling systems, check pump performance and set balancing valves. It can measure and display differential, high side, and low side pressures simultaneously, without the need to change hose connections or instrument valve settings.

Features and Benefits

  • Provides for inputs for two temperature probes
  • Measure and display high side, low side, and differential pressure simultaneously from 0 to 300 psi
    (0 to 2068 kPa)
  • Reads in. H2O, ft. H2O, psi, in. Hg, mm H2O, kPa, mm Hg, or bar
  • Large backlit display for use in low light areas
  • Operates on four alkaline or NiMH rechargeable batteries
  • Robust, splash-proof case
  • Meter weight with batteries is 2.65 lbs (1.20 kg)

Kit Includes:

  • Instrument
  • Hard carrying case
  • (2) 6.7 ft x ¼-in. (2 m x 6 mm) hoses with shut-off valves
  • (2) B&G readout probes
  • (2) P/T gauge adapter probes
  • Power cord



  • Test and balance heating and cooling systems
  • Check pump performance
  • Set balancing valves

HM675 kit includes hard carrying case, (2) 6.7 ft x ¼-in. (2 m x 6 mm) hoses with shut-off valves, (2) B&G readout probes, (2) P/T gauge adapter probes, and power cord.
HM685 kit includes all items in HM675 kit, plus a temperature probe, CompuDat USB downloading software, and USB interface cable.


Differential Range0 to 300 psi (0 to 2,068 kPa)
Gauge Range0 to 300 psi (0 to 2,068 kPa)
Resolution (best)0.001 psi (0.01 kPa)
Accuracy1±1% of reading or .072 psi (0.5 kPa),whichever is greater
Unitspsi, in. H2O, ft H2O, kPa, mm Hg, in. Hg, m H2O, bar
PressureConnection ¼” 37• flare fitting, Male
Operating (electronics)40 to 113°F (5 to 45°C)
Storage-4 to 140°F (-20 to 60°C)
Liquid Media32 to 180°F (0 to 82°C)
Probe-40 to 250°F (-40 to 121 °C)
Resolution0.1°F (0.1°C)
Accuracy±0.5°F (0.3°C) from 32 to 160°F
(0 to 71°C); max ± 2.0°F (1.2°C) from
-40 to 32°F (-40 to 0°C) and from
160 to 250°F (71 to 121°C)
Units°F, °C
Flow (HM685)
Range20 to 2,271 m3/h, 0 to 9,999 USGPM (0 to 6,31 l/s)
Resolution (best) Accuracy0.0001 USGPM (0.00001 l/s) per pressure accuracy + valve deviation
Units TimeUSGPM, UKGPM, m3/h, l/s, l/m Constant
Statisticsmin, max, average, sum up to 4,000 readings (HM685 only)
Data Storage4,000 combined readings, 100 Test IDs (HM685 only)
Logging Interval (HM685 only)User selectable (1, 5, 10, 20, and 30 seconds)
External Meter Dimensions11.1 in. × 4.7 in. × 3.5 in. (28.2 cm × 11.9 cm × 8.8 cm)
Meter Weight with Batteries2.65 lbs (1.20 kg)
Power RequirementsFour AA-size cells, or AC adapter
1. Accuracy statement applies from 0 to 250 psi (0 to 1724 kPa)
2. The flow reading is a calculated value determined from the measured Differential pressure, user entered valve flow coefficient (Kv or Cv),and fluid specific gravity

Specifications subject to change without notice.


Product feature comparisonHM675
Differential, high side, and low side pressures displayed simultaneously+
Range 0 to 300 psi (0 to 2,068 kPa)+
Reads in in. H2O, ft H2O, psi, in. Hg, mH2O, kPa, mm Hg, bar+
Performs flow calculations 
Downloading software and USB cable 
Temperature probeoptional
Hard carrying case+
Certificate of Calibration+