SWEP B28

Every B28 build on file carries four 1 1/4" threaded connections, and the datasheet lists threaded only - there is no solder, flange or Victaulic execution to fall back on.

The catch is the suffix. The catalogued strings end in (27), (D24.70) or (D33), and those are three separate connection executions. Two units both described as "inch and a quarter" can differ there, so copy the whole string off the nameplate, bracket included.

It can usually be recovered. A brazed pack cannot be opened, so the method is chemical: isolate the unit, connect a small pump and tank to valved tees at the ports, and circulate the cleaning solution through the fouled side against the normal flow direction untill the return runs clear, then flush thoroughly.

Two cautions. The solution has to suit the copper braze as well as the 316/316L plates, and cleaning dissolves scale - it does not reverse corrosion or a channel packed with debris larger than the 1 mm limit. Fit the cleaning tees at installation; adding them to a unit that is already blocked is the expensive way. See Cleaning in Place.

Too few plates shows up immediately: the leaving temperture falls short at full load and the pressure drop is higher than the pump was selected for. Pushing more water through does not fix it. The 16.9 m3/h (74.41 GPM) figure is a port ceiling, and a short plate pack runs out of pump head well before the ports do.

Too many plates is quieter. Channel velocity drops, solids settle instead of being swept through, and the control valve hunts at part load because a small movement swings the outlet temperature. The catalogued B28 builds run from 36 to 136 plates, so there is room to land the selection properly rather than rounding up "to be safe".

If any part of the loop can drop below freezing with the pump stopped, yes. Water trapped in a brazed channel has nowhere to expand, and it splits the plates. The failure usually appears later as cross-leakage between circuits, long after the cold night that caused it.

Glycol is not free. It is more viscous and carries less heat than water, so the same B28 gives a higher pressure drop and less capacity on glycol than its water rating suggests. State the glycol type and concentration when the unit is selected, and expect the plate count to move. Our Freeze Protection page covers the flow-proving and low-temperature cutouts that back the glycol up.

Not as a like-for-like swap. The /1P builds, which is what every catalogued B28 string on file shows, send each fluid down the plate once. A two-pass build turns the fluid around inside the pack so it travels the plate length twice, which gives a longer thermal length and a larger temperature change per unit, paid for in pressure drop.

Fit a two-pass pack where a single-pass came out and the pipework will not line up and the flow will fall.

These models are catalogued alongside the B28. Each has its own page with its dimensions, materials and part numbers.

SWEP SXB28 - Sealix-protected copper-brazed plate heat exchanger for district heating, radiator and tap water duty.