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Pressure Washer Hot Boxes

Diesel Fired Water Heaters That Turn a Cold Water Pressure Washer Hot

A hot box is a diesel fired water heater that sits between a cold water pressure washer and the gun. The machine you already own pumps cold water into the coil, the burner heats it, and hot water comes out the other side, which turns a good cold water unit into a hot water machine for grease, oil, road film and fleets without replacing the pump. The five Pressure-Pro HBS hot boxes here, joined by the two Hot Link hot water generators, cover 4, 6 and 8 GPM machines at up to 4,000 PSI, with 12 volt DC burner controls for trucks and skids or 115 volt AC controls for a shop with an outlet. All ship new from the manufacturer through High Pressure Car Washer, an authorized Pressure-Pro dealer, with free shipping to the lower 48 states, to a dock or terminal on freight machines, and liftgate service for one flat fee.

Size the hot box to the machine's flow, not its pressure: a 4 GPM machine gets the 40 series, 6 GPM the 60, 8 GPM the 80, because a burner sized for more flow than the pump delivers will overheat the water and one sized for less will not heat it enough. Then pick the control voltage by where it lives. If you are buying the machine and the heat together, a purpose built unit in hot water pressure washers is the simpler package; the guide under the products covers when a hot box is the better answer.

Hot water pressure washersGas pressure washersDiesel unitsPressure-ProAll equipment
Start here: our pick for each job
4 GPM truck unitsPressure-Pro HBS12V4012 volt controls, heats a 4 GPM machine, the mobile wash conversion.8 GPM skidsPressure-Pro HBS12V8012 volt controls for an 8 GPM skid at 4,000 PSI in a fleet yard.Shops with an outletPressure-Pro HBS115-40115 volt controls, heats a 4 GPM shop machine from a standard outlet.6 GPM machinesPressure-Pro HBS12V60The 6 GPM size for mid range commercial units on a truck.
Compare the pressure washer hot boxes buyers ask about most
ModelFlowRatingControlsBest for
Pressure-Pro HBS115-404 GPM4,000 PSI115 volt ACShops and bays, 4 GPM machines
Pressure-Pro HBS12V404 GPM4,000 PSI12 volt DCTrucks and trailers, 4 GPM machines
Pressure-Pro HBS12V606 GPM4,000 PSI12 volt DCTrucks, mid range commercial units
Pressure-Pro HBS12V808 GPM4,000 PSI12 volt DCFleet yards, 8 GPM skids
Pressure-Pro HBS115-808 GPM4,000 PSI115 volt ACShops and bays, 8 GPM machines
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How a pressure washer hot box works

The hot box is a diesel burner and a Schedule 80 heating coil in a steel cabinet. High pressure water from the machine enters the coil, a flow switch lights the burner, the water picks up heat on its way through the coil and leaves at up to 250 degrees. The machine's pump never sees hot water, which is why a cold water pump survives the conversion. The box needs diesel, a 12 volt battery or a 115 volt outlet for the burner controls, and enough flow to trip the switch.

Diesel fired hot boxes for trucks and skids

The 12 volt models run their burner controls from a truck battery, so a cold water skid or a gas unit on a trailer becomes a hot water rig with no outlet anywhere. The HBS12V40, 60 and 80 match 4, 6 and 8 GPM machines and are the mobile wash and fleet yard conversions.

115 volt hot boxes for shops and bays

The HBS115-40 and HBS115-80 take burner power from a standard outlet, the pick for a shop or wash bay that runs a cold water electric or gas unit and wants hot water without a second machine.

Hot box or hot water pressure washer

A hot box makes sense when you already own a commercial cold water machine with a pump rated for the flow, when the machine is a skid or trailer unit that would cost more to replace, or when the heat is needed only some of the time and the box can come off. If you are buying new, a purpose built hot water unit is more compact, the burner and pump are matched from the factory, and the price is close. Both classes are in hot water pressure washers.

Sizing the hot box

Match the box to the machine's GPM: a 4 GPM machine gets the 40 series, 6 GPM the 60, 8 GPM the 80. All five are rated to 4,000 PSI. A box sized above the pump's flow overheats the water; a box sized below it cannot raise the temperature enough. The machine's GPM is on its product page.

Hot boxes we recommend by job

Pressure-Pro HBS12V40 for a 4 GPM truck unit

The Pressure-Pro HBS12V40 hot box heats a 4 GPM machine on 12 volt controls, the mobile wash conversion.

Pressure-Pro HBS12V80 for 8 GPM skids

The Pressure-Pro HBS12V80 hot box heats an 8 GPM skid at 4,000 PSI on 12 volt controls for fleet yards.

Pressure-Pro HBS115-40 for a shop

The Pressure-Pro HBS115-40 hot box heats a 4 GPM shop machine from a standard outlet.

Pressure-Pro HBS12V60 for 6 GPM machines

The Pressure-Pro HBS12V60 hot box is the 6 GPM size for mid range commercial units on a truck.

Freight, delivery and returns on machines

Free freight to the lower 48. Machines ship new from the manufacturer by freight carrier at no charge to a commercial address with a loading dock or forklift, or to the carrier's nearest terminal for pickup. Orders are prepared within 0 to 1 business days and delivery takes 5 to 8 business days.

Liftgate service, $95 flat. No dock or forklift? Choose liftgate service when you add the machine to the cart. The carrier calls ahead to schedule, brings the crate to your address and lowers it to the ground with a liftgate. It lands at the curb or driveway, not inside the building. One flat fee per order, whatever the machine weighs.

On delivery. Inspect the crate before signing. Note any damage on the delivery receipt and photograph it. We file the claim with the carrier, and if a replacement is needed we ship it.

Returns. Unused machines in original packaging can be returned within 30 days of delivery. A 20 percent restocking fee applies and return freight is the buyer's responsibility, and a refused freight delivery is handled the same way, which is why we would rather confirm the model before it ships: send the job, the water and the power on site through the form on this page and we check the spec against the machine. Full terms are on the shipping policy and return policy pages.

Pressure Washer Hot Boxes questions, answered

Will a hot box work with my pressure washer?
With any commercial cold water machine whose flow matches the box: 4 GPM for the 40 series, 6 GPM for the 60, 8 GPM for the 80, up to 4,000 PSI. The machine's GPM is on its product page.
Does the hot box need power?
The 12 volt models run their burner controls from a truck or machine battery. The 115 volt models plug into a standard outlet. Both burn diesel to heat the water.
How hot does the water get?
Up to 250 degrees at the gun depending on the flow and the inlet water temperature, the same range as a purpose built hot water pressure washer.
Is a hot box cheaper than a hot water pressure washer?
When you already own a commercial cold water machine, yes, the box costs less than replacing the whole unit. Buying both new, a purpose built hot water machine is usually the better package.
Can a hot box run indoors?
The burner is diesel fired and produces exhaust, so it needs a vented space or an outdoor location, the same rule as any diesel burner.
How does shipping work on this equipment?
Shipping is free to the lower 48 states. Heavy units ship by freight carrier to a commercial address with a dock or forklift, or to the carrier's nearest terminal; smaller units ship by ground at no charge. No dock? Choose liftgate service when you add a freight unit to the cart, a flat $95 per order. Orders are prepared within 0 to 1 business days and delivery takes 5 to 8 business days.
Are these sold by an authorized dealer?
Yes. High Pressure Car Washer is an authorized dealer for BE Power Equipment, Cam Spray, Kranzle, Makinex, Pressure-Pro and Simpson, and everything ships new from the manufacturer with its factory warranty.
What if I order the wrong unit?
Returns are accepted within 30 days of delivery on unused units in original packaging. A 20 percent restocking fee applies and return freight is the buyer's responsibility. Call (219) 327-1138 before ordering and we confirm the model for the job.