SWEP B20

The full designation from the nameplate is enough on its own - model, plate letter, plate count, pass arrangement, material code, pressure class and the connection string, such as B20Hx40/1P-NSC-M 9.65+16+2x1"&22U.

If the plate cannot be read in full, send the cover plate dimensions, the port centres, the plate count, and the type and size of connection at each of the four ports, with photos. Add the heat pump's make, model and serial number and the refrigerant it runs. With those we can match the unit and return a quote that names the exact configuration.

It is a single-circuit unit targeting heat pumps: refrigerant on one side, water or brine on the other, in a frame only 94 mm wide. The catalogued part numbers on file are pressure class M, the category used for refrigerants such as R410A, at up to 45 bar at 135 C and fatigue tested.

It should not be used on a machine with two refrigerant circuits sharing one water stream; that needs a dual-circuit exchanger. It is not for ammonia, which attacks copper braze. And it is the wrong frame once water flow approaches 42.71 GPM, since that figure is a port ceiling and not a design flow.

The outline does most of the work, because it is unusual: 324 x 94 mm with port centres at 268.2 x 39 mm. No neighbouring model shares those numbers, so a careful measurement is close to conclusive.

Then count the plates and record the connections. The B20 part numbers on file run from 24 to 76 plates, all with the same connection pattern - 9.65 and 16 solder sizes plus two 1 in threaded/22U combo connections. If the old unit matches that pattern, only the plate count and the plate letter remain to be confirmed.

The frame takes up to 140 plates; the catalogued part numbers on file cover 24 to 76.

Each added plate brings surface and another channel, so the water-side pressure drop falls and the approach between refrigerant and water tightens. Weight rises by 0.0706 kg per plate - a 40-plate B20 is about 3.9 kg by SWEP's formula - and the unit gets deeper, which is the constraint in a tight cabinet. On the refrigerant side, more channels mean more charge and lower velocity per channel, so a much higher count than the original is not automatically an upgrade.

It stays in. Brazed units cannot be opened, so cleaning means circulating a solution through the water side with the unit isolated, then rinsing. Use a cleaner that is safe for copper, since the braze is copper.

Narrow, short channels foul faster than large ones, and the heat pump reports it before anyone looks: head pressure creeps up in heating mode, or the unit trips on low flow. Cleaning restores a scaled unit. It does not restore one that has frozen or leaked between circuits - that unit is replaced.

NSC means 316 stainless channel plates, 304 stainless cover plates and copper braze. The fluids touch the 316 channel plates and the copper braze, and that pairing handles refrigerants, heating and chilled water, and glycol or brine mixes for ground loops.

Copper is the limit. Ammonia attacks it and deionized or ultrapure water leaches it, so both need a copper-free construction. Chloride-bearing water - pool water, brackish well water, chlorinated cooling water - pits 316 and belongs on SMO 254 plates. If the source water is from a well, send an analysis with the request. Plate and Brazing Materials compares the codes.

These models are catalogued alongside the B20. Each has its own page with its dimensions, materials and part numbers.

SWEP B10T - A high plate-count small frame - 140 plates in a 289 mm envelope.

SWEP B10TS - An All-Stainless brazed plate heat exchanger - 316 plates, stainless braze, no copper.

SWEP V10T - SWEP's most compact evaporator, 289 x 119 mm, copper-brazed 316/316L, up to 141 plates.