Knowledge base
In short
Where a cooling circuit stands outdoors in cold weather, water alone can freeze and damage the equipment, so glycol is added to protect it. A plate heat exchanger keeps the glycol circuit apart from the clean water circuit, but glycol changes how the unit performs and how the circuit must be looked after.
Wherever a cooling circuit runs outdoors, the winter is a risk. Water that freezes expands, and it can split pipes, coils and the plates of a heat exchanger. The usual answer is to add glycol to the liquid, and a plate heat exchanger is often the point where the glycol circuit meets the clean water circuit of the plant. This guide explains in plain words why glycol is used, what changes when it is, and how to look after such a circuit.
Why Glycol Is Used
Glycol mixed with water lowers the temperature at which the liquid freezes, so the circuit survives a cold night even when the plant is stopped. It is the standard protection for radiators, dry coolers and outdoor pipework, and it is the reason a glycol circuit can stand outside all year without being drained.
The price of that protection is that the liquid is no longer plain water. Glycol is thicker, carries less heat for the same flow and needs its own care, and these differences reach every part of the circuit, including the heat exchanger.
Why A Plate Heat Exchanger Sits At The Boundary
It is rarely sensible to fill a whole plant with glycol. The outdoor part of the circuit needs the protection, but the engine, the process or the building system on the other side is usually better served by clean water, which cools more effectively and costs less to maintain. A plate heat exchanger lets the two liquids exchange heat without ever meeting, so each circuit holds the liquid that suits it.
The same arrangement means that a fault outside, such as a damaged pipe or a leak in a dry cooler, stays outside. The protected side of the plant is not exposed to the glycol or to the weather.
What Changes When The Liquid Is Glycol
Because glycol moves heat less readily than water and flows less easily, the exchanger for a glycol circuit is not simply the water exchanger with a different label. The plates, the number of them and the pump on the glycol side are all chosen with the actual mixture in mind, and a unit selected for water will usually fall short when glycol is used instead.
The strength of the mixture matters too. A stronger mixture protects against harder weather but costs more performance, so the mixture is chosen for the real climate of the site rather than for the worst case imaginable. This is exactly the kind of decision where the engineering team needs the site data.
Looking After A Glycol Circuit
Glycol carries protective additives that wear out over time. A circuit that is never tested can slowly turn acidic and attack the plates and gaskets from the inside, which is a common hidden cause of leaks. The mixture is therefore checked from time to time, topped up with the right product and replaced when it has aged.
Gaskets and materials also have to suit the glycol in use, and different glycol products should not be mixed casually. TECS Engineering designs and delivers plate heat exchanger solutions for engine, power plant and industrial cooling circuits; send the circuit details and the site climate, and the engineering team will answer.
In Short
- Glycol protects outdoor circuits from freezing damage
- A plate heat exchanger keeps glycol and clean water circuits apart
- Glycol carries less heat than water, so the exchanger is chosen for it
- The mixture is chosen for the real climate of the site
- Glycol must be tested and renewed, or it can attack the unit
- Gaskets and materials must suit the glycol product in use
What To Send With An Enquiry
- The liquids on both sides and the glycol product, if known
- Where the glycol circuit stands and the lowest winter conditions on site
- The heat to be moved and the temperatures wanted
- Whether the exchanger stays in service all year or is drained in winter
- The existing circuit, pump and dry cooler or radiator, if any
- Any maintenance or testing routine already in place
Questions We Are Often Asked
Why is glycol added to a cooling circuit?
It lowers the freezing point of the liquid, so a circuit that stands outdoors is protected when the weather turns cold, even if the plant is stopped.
Why not use glycol in the whole plant?
Glycol cools less effectively than water and needs more care, so it is normally kept to the outdoor circuit and separated from the clean water side by a plate heat exchanger.
Can a water heat exchanger be used with glycol?
Not safely without checking. Glycol changes the performance, so the unit has to be selected for the actual mixture.
Does glycol damage a plate heat exchanger?
Good glycol does not, but an old mixture that has lost its protection can turn acidic and attack the plates and gaskets. Testing and renewing it prevents this.
How strong should the glycol mixture be?
It depends on the coldest conditions at the site and on how much performance can be given up, so it is agreed with the engineering team from the site data.
Contact Us
Send us the heat duty, the fluid temperatures and flow rates, the ambient conditions and the installation limits. We answer with a design proposal - or write to us on WhatsApp.
