21/01/2025
Production will be limited in 2025, so order early if you want a heater for your dredge this season. There will be no last minute builds for anyone! Plan ahead.
Over the last 10 years, DWX has designed and built a variety of heat exchangers that are being used by hundreds of commercial & recreational gold miners around the world. With 1000’s of hours of operation in a variety of gold mining environments, DWX heaters have proven to be extremely reliable and efficient. A DWX heat exchanger on your dredge, will not only give you maximum hot water, but also years of trouble free operation. DWX heat exchangers are the benchmark in dredge heater design and are much more reliable and efficient than cheap DIY copies or coiled tubing heaters built by other manufacturers.
DWX heat exchangers are built exclusively for use on gold dredges! They are not intended to be used on an engine that isn’t directly driving a water pump. For safety and liability reasons, I don't sell heaters for use on air compressors for surface supplied diving. Dredge water heaters bolt directly to the exhaust port of the dredge engine and convert otherwise wasted exhaust heat into hot water for the diver operating the dredge nozzle. A dredge engine directly drives a high flow/pressure water pump that feeds water to the heater. So, when operated properly there’s a steady flow of high pressure water to the heater whenever the dredge engine is running. If for some reason the water flow to a dredge heater stops (clogged strainer screen, kinked hot water hose, water pump losing prime etc.) and the engine continues running, the water inside the heater can become superheated.
DWX heat exchangers have several design features that are intended to reduce the chance of water becoming superheated. Every DWX heater is equipped with a shell mounted thermal relief valve that opens and diverts hot water out of the shell if the water temperature inside the heater reaches 145°F. They also have ¾” I.D. clear water feed hose from the pump to an oversize strainer (with 50 mesh screen and 1” ports) that connects directly to the shell of the heater. This ensures maximum water flow and pressure to the heater. High pressure water is less likely to get stopped by a kinked hose or debris in the strainer/water line. The clear water feed hose shows water flow and turbidity and the clear strainer cup shows when the strainer screen needs to be cleaned. Both of these give visual indicators of water flow through the system. The oversize strainer with a 50 mesh screen used by DWX is far less likely to clog with small debris (stopping water flow to the heater) than the smaller strainers with 150-200 mesh screens used by another manufacturer and almost all DIY builders. Using this type of cheap, undersized strainer not only reduces water flow and pressure to the heater, but the extremely fine (150-200) mesh of the screen quickly plugs up with debris and creates the exact problem the strainer is there to prevent; water flow stoppage.
DWX heat exchangers are much more efficient at converting hot engine exhaust into hot water, and produce an average of 60% more hot water (on the same engine) as coiled tubing, used by other manufacturers. DWX uses tube and shell heat exchangers, made entirely of 316L stainless steel. All fittings and hardware (except the strainer) are stainless as well. The shell of the DWX 2.5 heat exchanger houses 22 internal 1/4" ID sealed stainless tubes through which the engine exhaust passes. Cold water from the pump first passes through a 50 mesh strainer then enters the shell of the heat exchanger through the 1" lower side port. Water circulates inside the shell and around the sealed exhaust tubes, heating the water. Hot water flows out of the top 1" port and the temperature is regulated by either opening or closing the 1/2" stainless valve; adjusting the flow. Each DWX heat exchanger is equipped with a thermal relief valve that will open and divert hot water out of the shell if the water inside reaches 145°F (standard max temperature of the average residential hot water heater). The shell of the heat exchanger holds 22oz of water which, coupled with the temperature relief valve, reduces the chance of superheated water. Hot exhaust leaves the engine through a robust TIG welded stainless manifold and is diffused through the 22 internal stainless exhaust tubes. Exhaust flows vertically thru the heat exchanger, exiting cold at the top. The heat exchanger is stabilized and vibration isolated with a heavy-duty stainless clamp and support bar bolted to the engine block.
DWX uses only the highest quality parts that have proven over the years to be reliable. Due to their superior design and build quality, DWX heaters don’t suffer from common problems like stress cracking, water leaks, poor thermal efficiency, low water flow/pressure and inconsistent water temperature that plague poorly built and DIY dredge heaters. The fabricated exhaust manifold and reinforced TIG welds on a DWX heater resist cracking and the heavy-duty support arm & wide band exhaust clamp dampen engine vibration that would otherwise lead to internal/external stress cracking. Also, every DWX heater is pressure tested to +100 psi to confirm that all internal/external welds and connections are leak free. This far exceeds the 30-40 psi working pressure of the average dredge pump. With 40 years of welding and metal fabrication experience, my customers appreciate the exceptional build quality of DWX heat exchangers.
As a general rule, larger dredge engines (GX270-GX390) burn more fuel and produce more exhaust heat than smaller dredge engines (GX120-GX200), so a heater on a larger engine will produce more hot water than the same heater on a smaller engine. More exhaust heat = More hot water! However, this does NOT mean that a GX390 (which has twice the CC’s of a GX200) will produce twice the exhaust heat as a GX200. Remember, only half the thermal energy produced by the engine exits through the exhaust. The other half is absorbed by the engine block and is radiated away by the cooling fins and flywheel fan. Heavier engine blocks absorb more heat and larger cooling fins/fans dissipate more heat. Although a GX390 burns twice the fuel as a GX200 (.92 gph vs .45 gph) it also weighs twice as much (70lbs vs 35lbs) and has larger cooling fins and a larger flywheel fan. Similarly, a GX270 burns 40% more fuel than a GX200 (.63 gph vs .45gph) but weighs 60% more (55lbs vs 35lbs) and also has larger cooling fins and a larger flywheel fan.
A DWX 2.5 heater on a GX200 - GX390 dredge engine/pump (under load at 3200 rpm) can increase water temperature +80°F @ ½ gallon per minute flow rate.
A DWX 3.0 HP heater on a GX270 dredge engine/pump (under load at 3200 rpm) can increase water temperature +100°F @ ½ gallon per minute flow rate and +120°F on a GX390.
The DWX 3.0 HP heater was designed, built and tested for use on GX270 & GX390 dredge engines for extremely low water temperature (
