Last week I wrote about the TSI HM675 Hydronic Manometer 
. Today I will be discussing its older brother the TSI HM685 Hydronic Manometer. The HM685 manometer is an upgrade over the HM675 and has the same features but with a few upgrades. First the HM685 can calculate flow, heat flow, impeller diameter and brake power.
Finding a quality hydronic manometer can be a tough task. However, the TSI HM675 Hydronic Manometer is great choice. The HM675 can simultaneously measure and display low side, high side, and differential pressure. This unit also has a nice splash-proof case and inputs for two temperature probes. The HM675 reads pressure in H2O, ft H2O, psi, in. Hg, m H2O, kPa, mm Hg, bar and has a range of 0 to 300 psi.
