Materials in the cooling circuit – why copper and aluminium do not belong together

The cold plates on the hashboards of a hydro miner are made of aluminium. Heating systems are usually piped in copper. Put both into one circuit and you have built a battery.

What happens

Two different metals in the same conductive liquid form a galvanic cell. The less noble metal dissolves. Between copper and aluminium, that is always the aluminium.

There is a second effect on top: copper releases ions into the water. They deposit on the aluminium and create many small corrosion spots there. The two metals do not even have to touch for this; sharing the same water circuit is enough.

The consequence for the miner

The channels in the cold plates are narrow. Corrosion first pits the wall there, and the corrosion products clog the channels. The flow rate drops, the chips get hot, and in the end the plate leaks onto the hashboard.

What is allowed in the miner circuit

• Stainless steel: heat exchangers, fittings, pump housings
• Plastic: pipes made of PE-X or PP, with an oxygen barrier
• EPDM: hoses and seals
• Aluminium: only where the miner brings it along anyway

What stays out

• Copper: pipes and brazed heat exchangers
• Brass and gunmetal: many standard fittings, ball valves and pumps from heating installation
• Galvanised steel: glycol strips off the zinc layer

The most common mistake is a single brass part: a ball valve, an air vent, a threaded fitting. Check every component before it is installed.

Where copper can stay

In the house circuit. A stainless steel plate heat exchanger separates the two liquids completely. On one side the miner's coolant flows past aluminium, stainless steel and plastic, on the other the heating water flows through the existing copper pipes. The existing heating system does not have to be rebuilt for this.

With the heat exchanger itself, pay attention to the brazing material: many plate heat exchangers are copper-brazed. For the miner circuit you need a gasketed version or one brazed with stainless steel or nickel.

What inhibitors do

A coolant with a corrosion inhibitor lays a protective layer on the metals. In a circuit without copper, this makes the aluminium last permanently. In a mixed circuit the inhibitor only delays the damage, it does not prevent it, and it is used up faster in the process.

Checks during operation

• Look at the coolant: cloudiness, flakes or discolouration indicate corrosion.
• Measure the pH value: if it leaves the manufacturer's range, the inhibitor is used up.
• Check the filter: deposits in the filter come from the circuit, usually from the cold plates.

Sources

• AMPP: galvanic corrosion and deposition corrosion of aluminium caused by copper
• Tyforop: Tyfocor L, no galvanised components in the glycol circuit (PDF)
• Plate heat exchangers: Alfa Laval, copper-brazed, Alfa Laval AlfaNova, entirely stainless steel, Kelvion, copper, nickel or stainless steel brazing material
• Zeus Mining: aluminium water cooling plate for Antminer hydro units

As of October 2026. The manufacturer's manual states which materials your model tolerates.