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TSI HM675 and HM685

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The TSI HM675 and HM685 manometers are used to balance hydronic heating and cooling systems, check pump performance and to set balancing valves. Both models can calclulate flow using valve manufacturers Cv (Kv) factors (up to 100 Cv (Kv) can be entered). They can also measure and display differential, high side and low side pressure simultaneously, without having to change hose connections or instrument valve settings. 

Each model features a backlit display and operates on four alkaline or NiMH rechargeable batteries. They have a robust, splash-proof case ideal for transporting to and from site. 

Product Features

  • 2 model types
  • Calibration options
  • Document downloads
  • Instrument video

Instrument product options

1. Select a model (2 available)

Continue to select accessories

2. Select accessories

3. Select a calibration



  • Measure and display high side, low side and differential pressure simultaneously from 0 to 2,068 kPa (300 psi)
  • Robust, splash-proof case
  • Inputs for two temperature probes
  • Calculates flow using valve manufacturers Cv (Kv) factors (up to 100 Cv (Kv) can be entered)
  • Stores up to 4000 data points to memory for later recall/download to a PC using CompuDat USB Software and USB interface cable
  • Intuitive menu structure for easy navigation and instrument set up


For full technical details, please see the data sheet.

Pressure (HM675 and HM685)

Differential range      0 to 2,068 kPa

Gauge range      0 to 2,068 kPa

Resolution (best)      0.01 kPa

Accuracy      ±1% of reading or 0.5 kPa, whichever is greater

Units      psi, in. H2O, ft H2O, kPa, mm Hg, in. Hg, m H2O, bar

Hose pressure connections      1/4" x 37° flare male fitting

Temperature (HM675 and HM685)

Operating (electronics)      5 to 45 °C

Liquid media      0 to 82 °C

Immersion probe      -40 to 121 °C

Accuracy      ± 0.5 % of reading + 0.7 °C

Units      °F, °C

Flow (HM685)

Range      0 to 2,271 m3/h / 0 to 6,31 l/s

Resolution (best)      0.00001 l/s

Units      USGPM, UKGPM, m3/h, l/s, l/m



TSI HM675 and HM685 hydronic manometer BSRIA data sheet

  • Technical Document
  • PDF file
  • 2 MB

TSI HM675 user manual

  • Technical Document
  • PDF file
  • 3 MB

TSI HM685 user manual

  • Technical Document
  • PDF file
  • 10 MB

Demonstration videos

TSI hydronic manometers – Set up 1 - Zeroing sensors and purging air
TSI hydronic manometers – Product overview
TSI hydronic manometers – Set up 2 - Taking measurements
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