Extend the Life of Your Heat Exchanger With a Few Basic Checks

Refrigeration systems constantly need to move heat between two fluids, which is exactly what a plate-and-frame heat exchanger does. With its high surface area, it packs more heat transfer into a smaller footprint than older shell-and-tube equipment, and because it holds far less refrigerant, the whole plant is safer to run and cheaper to maintain.

Depending on where it sits in the system, it can fill several roles:

It also comes in two broad types. The gasketed version has bolted sides that can be opened and serviced, while the all-welded version cannot be opened.

Josh Bell, VP of Western Canada, Ontario at CIMCO, explains that a plate-and-frame heat exchanger behaves differently from most others in the plant. On a compressor or pump, you can lubricate parts and replace wear items to maintain efficiency. A plate exchanger offers none of that.

Let scale or debris build up, and the exchanger simply cannot move heat the way it was designed to.

The failure modes are where the stakes turn serious. On a gasketed unit, you can have a gasket or a plate failure. On an all-welded unit, a weld leak or a plate failure.

During normal operation, the heat exchanger is the least of an operator's worries. That is the trap, because when problems do appear, they escalate fast. A daily inspection is the cheapest way to catch a problem early.

When walking into any room with heat exchangers, look out for a refrigerant leak. Ammonia is easy to smell. Otherwise, watch for the secondary signs: glycol, oil, or brine leaking from the plates, and on an evaporator, fluid pooling in the drain pan. Pink liquid in the pan points to a glycol leak, and any fluid other than water invites corrosion or mold.

The visible signs are only half the picture. The other half is what David Fauser, Director of Sales at CIMCO, calls the silent killer of performance: pressure. The most useful reading is the fluid pressure drop across the exchanger, measured on the inlet and outlet gauge valves during daily rounds. A change there is an early sign of fouling or lost flow.

On an evaporator, sufficient fouling eventually reduces suction pressure. On a condenser, fouling raises head pressure, and a high-side pressure rise in cooler weather is a telltale sign that the exchanger is scaling up. Left alone, this ends in a system that no longer has the capacity to run.

One reading on its own means little, though.

A drop in suction pressure can also come from low refrigerant or a temperature setting, not just fouling. History is what turns a reading into a diagnosis.

Taking over an unfamiliar plant calls for a different first step. Bell's advice is to bring in a contractor experienced with heat exchangers or ice rinks to do a once-over, set a clean baseline, and act on any cleaning recommendations right away. From there, you settle into a rhythm.

The daily walk-by is backed by a monthly visual inspection and, once a year, a leak-detection check when nothing is visibly wrong. Larger units also warrant an annual deep look under the shroud covering the plates, best folded into shutdown, startup, or seasonal maintenance. The value of that outside visit is a set of eyes not distracted by the rest of the building, which is exactly what a plant's own maintenance staff are always juggling.

Maintenance here is mostly about keeping fluids and surfaces clean rather than replacing components. In the early years, it is simple: general cleaning of dust and debris, and keeping the drain pans clear under evaporative units so they drain properly rather than dripping onto the floor and growing mold.

From there, Bell recommends the following scheduled tasks:

That last task is important for safety because the bolts sit in a constantly wet, freezing environment, which causes them to rust, and when service day comes, they sometimes have to be cut off under extreme tension. Keeping the bolts and their bearing points lubricated is a favor to whoever eventually has to open the machine.

The deeper maintenance is about the fluids. On the evaporator or chiller side, test your secondary fluid every year by sending a sample to a lab, so brine can be kept from turning too acidic and debris can be tracked.

On the condenser side, if you run a tower with recirculated water, chemical treatment becomes the priority. It is best handled by a reputable chemical treatment contractor who keeps records and sends regular reports. Keep the cooling tower itself clean, too, because debris coming off it can clog the plates. The inlet strainers, especially on the condenser side, should be cleaned seasonally, roughly in spring and fall.

Once debris has built up inside, cleaning it out is a bigger job and varies by unit type. On an all-welded unit, a chemical treatment company can try to wash it clean, though a badly fouled unit may eventually have to be removed or replaced. On a gasketed unit, the thorough clean means a full dismantle, pulling the plates and cleaning them externally. That is exactly the job people fail to schedule for.

And a neglected exchanger tends to reach its breaking point at the worst time, when the weather is hottest and the system is already running flat out. As capacity slips, it starts shutting down on high pressure, or the compressors back off, and temperatures climb just when the facility can least afford it. Bell's rule for avoiding that is simple:

Both Fauser and Bell struggled to recall ever replacing a plate-and-frame heat exchanger on its own. It is usually swapped out only as part of a full system overhaul.

The heat exchanger is built to be rebuilt, not discarded. The focus is the plates and gaskets, not the unit itself. The OEM-recommended gasket change-out is around eight years, so budgeting should start at the six- or seven-year mark. When you regasket a condenser, Bell recommends carrying a contingency budget for cleaning too. And if the off-season allows, ship the plates back to the OEM. Their factory cleaning returns them to near-new condition, something you cannot match on-site with pressure washers, which risk damaging the plates.

None of this is a do-it-yourself job.

It demands large wrenches, hydraulic rams to press the pack, and specialized tools. Reassembly follows a precise sequence so the gaskets seat properly in the channels. Get it wrong and the unit leaks on the pressure test, forcing another teardown, and the gaskets that did not seat are now damaged and must be reordered.

For a branded unit, Bell's advice is to use a company certified by that manufacturer, because they know the small things the untrained will miss. It is also worth confirming that the gaskets are OEM, since aftermarket materials that are not compatible with your refrigerant or secondary fluid can fail and leak.

The unit itself lasts as long as you maintain it. Bell found that OEM guidance generally points to a 25-year lifespan, but because this is a steel-and-bolt component with no moving parts, how long it actually lasts depends entirely on upkeep. Once it passes the 24-year point, by which time the gaskets have been changed a third time, the plates may be distorting from being taken apart and reassembled so often. For many operators, that still means changing the unit only near the end of a career. To Bell, that is the highest compliment you can pay a machine.

If you need more capacity, you can often add plates rather than replace the exchanger, because the rail usually has room. There are limits, since a fresh set of gaskets expands the pack considerably. So, Bell advises having your contractor confirm the maximum dimensions with the OEM and check that the pump can still perform. Done properly, you can add around 10% more plates, a rare bit of built-in headroom.

For a piece of equipment that asks so little, the plate-and-frame heat exchanger punishes neglect harder than most. It runs quietly for years, gives no daily trouble, and then, if the fluids go unmanaged and the plates go unwatched, fails, flooding a secondary loop and taking a system down when you can least afford it.

The good news is how little it takes to prevent that. The attention it needs is simple, cheap, and mostly routine, and it is nothing next to the cost of an emergency. Give it that, and one of the few components you can genuinely keep for a whole career will keep its side of the bargain.