Hot pressure washers have a boiler/coil that heats cold water fed from the pressure pump. Typically, the machines PCB or other control systems will look for water pressure, the flow of water, spark, fuel level, and temperature setting. Once these are in place the fuel solenoid will energise and open allowing fuel to the burner head. The fast-flowing air from the blower motor and the fuel-injected will then allow for a constant flame.

The boiler coil is normally made from mild steel and can come in varying in lengths, from 15- 45 m long. The steel is normally 3/8 in bore. Either due to wear, frost or just unlucky you may find the boiler full of water. This would really mean you need to replace the coil.

When buying a pressure washer boiler coil please check all dimensions and thread sizes to ensure you get the correct one.

Removing a coil

IPC/ Edge machines have an O ring and a white backing ring. (Don’t lose these!)
Nilfisk Neptune 5 and MH5 plus allows for a service crane to be used in order to lift it out
Karcher, Kew, Kranzle, DTE, Dirt Driver, MAC, and many more simply needs a strong person to lift them out. Keep an eye on the orientation that the coil came out.

Once the coil has been removed, make sure the boiler jacket and fan is clean. If funds are good to replace the fuel jet and electrodes. This combination of cleaning and re renewing parts will allow the boiler to have the best start when firing up for the first time.