HVAC and Chilled Water

No. Maximum flow on a datasheet is a ceiling set by the ports - the most the connections can pass - not a flow at which the unit performs a duty. A frame picked because its maximum flow matches the system flow will usually carry far too much pressure drop, and the figure says nothing about whether the plate count reaches the approach.

Use maximum flow only to rule frames out. The selection itself comes from the flows, the four temperatures and the pressure drop available, and it often lands in a larger frame than the flow alone suggested.

As much as the pumps can give without being upsized, and it should be stated, not left open. Pressure drop is what buys turbulence, so a generous allowance means fewer plates for the same approach and a less expensive unit. A very low allowance forces a large plate count, and at low channel velocity the pack is also more inclined to foul.

On a retrofit, the limit is whatever head the existing pump has spare at design flow - measure it instead of reading the pump nameplate.

By measurement. A frame is identified by the height and width of the plate pack and the distance between port centres, vertically and horizontally. The pack depth indicates the plate count, though not precisely enough to order from alone. Note the connection type and size on each port, and which ports are in use.

Add what the unit does: the fluids, the approximate flows and temperatures, and the equipment it serves. With those and a couple of photos we can name the frame and confirm the configuration before quoting.

It can, with conditions. Tower water is open and aerated and carries airborne dirt, scale and biological growth, and a brazed pack cannot be opened to remove any of it. A strainer matched to the frame's particle limit is the minimum; side-stream filtration and steady water treatment are what make the unit last.

Check the chemistry as well. Tower water concentrates as it evaporates, and chlorides that are harmless in the make-up water can reach a level where 316 pits - the case for SMO 254 plates. Where treatment is poor or the tower sits in a dirty location, a gasketed unit that can be opened is the better choice for free cooling.

Yes, and it is one of the more avoidable losses in HVAC. The glycol loop is protected by its antifreeze; the water on the other side of the plate is not. If cold glycol keeps circulating while the building water pump is off - a night setback, a tripped pump, a closed control valve - the standing water in the channels freezes and the plates split.

Interlock the two sides so glycol flow through the exchanger stops, or is bypassed, whenever water flow is lost, and prove water flow with a switch, not a pump run signal. The measures are set out under Freeze Protection.