SWEP DS500

Treat 83 m3/h (about 365 GPM) as the limit of the ports, not as a target. It is the flow at which port velocity reaches the published ceiling, whatever the plate count, and a unit designed near it leaves the pump fighting a high pressure drop.

Adding plates does not raise the ceiling; it only lowers the pressure drop through the channels. If the chilled-water flow is near the limit, the answer is a frame with larger ports from the over-400 GPM band, such as the DP700, or two units in parallel.

From the DS400 it differs in plate length and flow ceiling. Both are True Dual evaporators 304 mm wide, but the DS400 is 694 mm tall with a published maximum of about 335 GPM, against 980 mm and 365 GPM for the DS500.

From the DB500 it differs in duty. The two share the 980 x 304 mm outline, the 316/316L plates and the copper braze, but the DB500 is published as a condenser and the DS500 as an evaporator. Neither difference can be worked around on site. The pipework will not reach a shorter unit, and a condenser model installed as an evaporator is a different selection that has to be rated first.

Yes, and it is easy to overlook because the short designation - DS500x90, say - leaves it out. On the nameplate it follows the slash after the plate count, with /1P meaning single-pass.

Keep whatever the original has. A different pass arrangement moves connections between the front and rear cover plates and changes both pressure drop and thermal performance, so the unit would no longer be a drop-in replacement.

Begin with the outline: 980 x 304 mm (38.58 x 11.97 in). Then check the port centres, 866 x 191 mm (34.09 x 7.52 in), measured between connection center lines. A unit with the right outline and the wrong port centres does not connect.

Depth is the variable. It follows plate count, so it only matches if the plate count matches. Finally, go round every connection - the water pair and both refrigerant circuits - and note type and size. On a unit this tall, also check the height available for lifting it into the frame.

The model is built with up to 298 plates, and the part numbers on file run from 50 to 220. More plates mean more heat transfer surface and more parallel channels, which lowers pressure drop and tightens the approach between leaving water and evaporating temperature.

The costs are depth and weight, and on an evaporator there is a limit in the other direction as well. Spread the same refrigerant flow over too many channels and the velocity in each falls, which hurts oil return and makes superheat harder to hold. Adding plates to an existing duty is a re-rating, not a free upgrade. Plate Count and Capacity explains the trade.

SWEP publishes threaded, Victaulic, solder, flange and weld connections for the model. Which of those a particular unit carries is set port by port, and the nameplate's connection string records them in port order.

Match the existing pipework rather than adapting to it. A solder connection designated with a U accepts both imperial and metric tube, which removes one common mismatch. On a True Dual unit, write down both refrigerant circuits separately - they are usually the same, but assuming so is how a wrong connection gets ordered.

Keep water moving through it whenever a compressor runs, and keep the evaporating temperature where the water cannot freeze. Water that freezes in the channels can split a brazed unit, and the damage cannot be repaired.

On a dual-circuit evaporator the usual exposure is at start-up and at part load, when flow is low or one circuit is pulled down hard. A flow switch, a low-pressure cutout and a pump that starts before the compressor are the standard defenses. Where the leaving temperature has to go near or below freezing, use glycol and rate the unit for it - glycol is more viscous than water and raises pressure drop. See Freeze Protection.

These models are catalogued alongside the DS500. Each has its own page with its dimensions, materials and part numbers.

SWEP B400T - Asymmetric pass arrangement - two passes one side, one the other.

SWEP DB400 - True Dual brazed plate condenser for flexible chillers and climate control, 694 x 304 mm.

SWEP DP400 - True Dual brazed plate evaporator for flexible chillers and climate control, 694 x 304 mm.

SWEP DS400 - True Dual brazed plate evaporator with two refrigerant circuits, 694 x 304 mm, up to 282 plates.

SWEP DV400 - True Dual brazed plate evaporator, 694 x 304 mm, up to 282 plates, Victaulic and solder connections.

SWEP P400T - Copper-brazed 316/316L evaporator on the B400T frame, up to 280 plates, 365.44 GPM max flow.

SWEP S400T - High-capacity chiller evaporator on the B400T frame, 316/316L plates, copper brazed.

SWEP V400T - Copper-brazed 316/316L plate heat exchanger on the B400T frame for high-capacity chiller duty.

SWEP DB500 - True Dual brazed plate condenser with two refrigerant circuits, 980 x 304 mm, up to 298 plates.