Materials and durability

Technical info

Here are the figures behind the claim. Not marketing, but measured material properties for the tin bronze we cast, and what they mean for your engine.

Material data

Marine tin bronze, HX series

Material Solid marine tin bronze, cast in Denmark

Corrosion rate 0.015-0.020 mm per year under extreme conditions

Theoretical lifespan Several hundred years with the applied wall thickness

Surface Self-healing, stable oxide film (patina) upon contact with water

Pavement Natural anti-fouling. Resists algae, salt crystals and biofilm

Thermal Unaffected by a hot engine compartment and constant temperature fluctuations

Mechanical Unaffected by constant engine vibration. No fatigue

Suitable for Volvo Penta D1-13, D1-20 and D1-30 (HX-13 / HX-20 / HX-30)

Mounting Plug and play. Same dimensions as the original, no modifications needed.

Warranty 2-year manufacturer's warranty against rust-through, plus 2-year right of complaint

The data applies to the heat exchanger housing. The copper bar, end covers, thermostat, high-temperature sensor, drain cock, and 3/8" blanking plug are to be reused from your current exchanger.

The machined bearing the copper rod slides out of.

About oxide jacking

The reason why the copper insert can still be removed.

Corrosion of aluminum leads to the formation of aluminum oxide, which occupies more volume than the base metal. This generates a powerful expansion pressure in the component seat, resulting in deformation or a completely seized tube bundle, making the planned disassembly during service impossible. Often, the extraction process causes irreparable damage to the expensive copper rod.

Since bronze does not develop voluminous corrosion, the geometric dimensions remain intact. The tube bundle can therefore be easily pulled out during service.

In shortWhen aluminium corrodes, the material expands and locks the tube bundle in place, which often makes it impossible to remove for service without damage. Since bronze does not form this space-consuming corrosion, the internal dimensions of the housing remain the same. The tube bundle can therefore be pulled out without difficulty during every inspection.

Are you missing a number that we haven't written down?

Ask directly. You are speaking with the person who cast and measured the part.

See the currency exchange booths About the product Chat with us

What is included in the box?

Two lists. Read them before you order.

The house is supplied as a complete assembly kit. However, six parts must be reused from your existing exchanger, and that is the most important sentence on the entire page.

Included with the house

In the box, ready for installation

Support bolts M6x100 mm
The threaded rods that the housing is slid onto.
Collar nuts M6
Nuts with integrated flange to distribute pressure.
Manifold gasket
The flat gasket between the housing and the motor.
Exhaust gasket
The seal on the exhaust side.
Complete O-ring set
4 to the copper rod, 2 to the thermostat, 1 to the drain valve.
Silicone grease
Apply to the rubber rings so they slide into place without breaking.

The number of bolts and nuts depends on the size: 7 for HX-13, 9 for HX-20, 10 for HX-30.

Reused from your current

NOT included

Copper rod (tube bundle)
The bundle of thin copper tubes that keeps seawater and coolant separate.
End caps
The lids on the ends of the house.
Thermostat
The valve that opens when the engine gets hot.
High-temperature sensor
The sensor that triggers the alarm if the engine gets too hot.
Drain tap
Located at the bottom of the housing and used to drain the coolant. The O-ring for it is included, but the tap itself must be reused.
3/8" plug
Closes the port that is not used on your motor. Must be moved over from your current exchanger.

The parts are independent of the housing material, so yours will fit directly into the bronze housing.

The Ultimate Comparison: D1 Heat Exchanger Options

Property / Criterion	Schott Tech(Cast tin bronze)	Volvo Penta Genuine(Aluminum)	"The isolation method"(Plastic bushings/washers)
Technical principle	Permanent elimination of galvanic voltage by using noble red metals.	Factory default setup with unfavorable material composition.	Symptom management, which attempts to interrupt electrical contact with plastic.
Internal voltage difference (relative to copper insert)	Reduced to < 0.05 V. The system is in natural balance and does not corrode.	Critical 0.55 V. The housing acts as a sacrificial anode for the copper.	Remains at a critical 0.55 V. The battery is still there - just "wrapped up".
Corrosion risk in saltwater environments	None. Tin bronze is by far the most resistant metal to salt water.	Extremely high. Especially in the flange at the exhaust bend.	Unchanged high. The saltwater inside quickly forms an electrical bridge around the plastic.
Mechanical strength	Indestructible. Robust metal-to-metal construction that withstands vibrations.	Medium. The aluminum becomes weak and porous in the material once corrosion sets in.	Vulnerable. Plastic bushings and washers decay, deform over time, and lose tension.
Risk of acute leakage / engine failure	None. The original O-rings and flanges are working exactly as they should.	High. Risk of freshwater leaking into the exhaust due to corrosion holes.	High. When the plastic yields under engine heat, microscopic leaks occur.
Assembly & Maintenance	Simple "drop-in". Mounted exactly like the original part without any extra loose parts.	Simple. But must be inspected and disassembled annually to check for corrosion.	Complex. Requires surgical precision. If one plastic washer is overtightened, the system fails.
Economy & Life Expectancy	Boat lifespan (Permanent). One-time investment that increases the boat's value.	Expensive over time. Typically needs to be replaced again after 10–12 years for over 15,000+ DKK.	Temporary. Requires ongoing inspection and frequent replacement of the plastic parts.