SWEP E5AS

It is the pressure class, and every E5AS configuration on file is class S. S is the category covering 31 bar at 155 C, the class used across a wide variety of applications, tap water heating among them.

A class is a category, not the stamped rating of the unit in your hand. The figure that governs is the one on the nameplate, read together with its design temperature. When matching a replacement, quote the class letter exactly as written rather than treating another letter as an upgrade - a different class is a different build.

Start with what is left of the text. The letters AS matter most, because the E5T has the same 192 x 73 mm face and cannot be separated from an E5AS by size.

Then measure. Port centres should be 154 x 40 mm. Count the plate edges along the side of the pack - catalogued E5AS builds run from 18 to 36 plates - and note whether the four connections are threaded or solder; every build on file is 3/4 in.

A photo of the label remnant, a photo of the connections and those measurements are normally enough for us to name the unit.

Too few plates and the tap water leaves cooler than the setpoint at full draw, while both circuits see a higher pressure drop than the pumps and mains pressure were chosen for. In a boiler that shows up as lukewarm water at high flow and a primary circuit that cannot shed its heat.

Too many plates is less obvious. Channel velocity falls, and in hard water a slow channel scales faster, so the unit that looked generous on day one loses performance sooner. The pack is also deeper and may not fit the bracket. On a replacement, keep the original plate count unless the duty has changed; the E5AS tops out at 40 plates.

Field by field: E5AS is the model, the AsyMatrix tap water unit on the B5T frame. H is the plate type, the obtuse chevron with high heat transfer and high pressure drop. x18 is the plate count. /1P is a single-pass arrangement.

SC is the material code - 316/316L stainless plates with copper braze. S is the pressure class. 4x3/4" is the connection callout: four 3/4 in connections, listed in port order.

Some E5AS builds on file carry a suffix in the connection field, such as 4x3/4"(20). Copy that field exactly; it distinguishes one connection from another of the same nominal size. The Model Number Guide covers each field.

Every E5AS configuration on file is /1P, single-pass, with both fluids crossing the plate once in counter-current.

A multi-pass arrangement puts groups of channels in series. That lengthens the thermal path and raises pressure drop, and it changes where the connections sit, so it is never a drop-in substitute for a single-pass unit. If a tap water duty cannot be met inside the 40-plate limit of the E5AS, a longer plate is usually the cleaner answer than more passes. On a replacement, simply carry the /1P field across unchanged.

It can usually be recovered. A brazed unit cannot be opened, so cleaning means circulating a descaling solution through the tap water side, against the normal flow direction, then flushing thoroughly. The cleaner has to be safe for both stainless steel and the copper braze.

Cleaning will not fix a unit that is leaking between circuits, and a pack blocked solid may not pass enough solution to clean at all - those are replacements. If scale returns quickly, look at water hardness and whether the unit is oversized and running slow channels. See Cleaning in Place.

These models are catalogued alongside the E5AS. Each has its own page with its dimensions, materials and part numbers.

SWEP B5T - Compact 316 stainless frame for low-flow heating and cooling loops.

SWEP B5 - Very compact brazed plate heat exchanger for small flows, used as a small oil or water cooler.

SWEP B5AS - Very compact AsyMatrix brazed plate heat exchanger for low flows - small oil and water coolers.

SWEP E5T - A very compact copper-brazed plate heat exchanger for wall-hung, non-condensing boilers.