Replacement Locomotive Boilers

The Mackwell Boiler Technology was developed as a direct result of our founder’s experience maintaining, firing and driving historic steam locomotives. As a result, we are dedicated to supporting the operation of steam locomotives around the world.

The preservation movement faces many challenges; spark, smoke and carbon emissions, high maintenance and expensive inspections are some of the most significant. In many locations, volunteer shortages are just as challenging.

With the boiler accounting for the lion’s share of maintenance (91% of cost) for steam locomotives, Mackwell Replacement Boilers improve viability of heritage lines. Inspections reduce to a fraction of the cost, and may not be required at all. Fuel costs reduce by 70% and overall running costs by 60%. These savings have the potential to preserve heritage steam railways whose survival is threatened by lack of volunteers and funds.

We offer new locomotive boilers embodying our technology, custom designed and built to suit the specification and appearance of any heritage steam locomotive boiler. 


Identical appearance

Ensuring that external authenticity is retained.

Zero spark emissions

Eliminating the risk of line-side fires.

Zero smoke, soot and char emissions

Removing unpleasant maintenance and avoiding public objection.

Zero carbon

Achieved through the use of low grade biomass fuels e.g. hog fuel and wood chip, or high grade biomass fuels e.g. biocoal, pellets or briquettes.

Zero explosion risk

Reducing or eliminating inspection requirements.

Zero priming

Delivering high purity steam, reducing engine wear and preventing damage.

Low maintenance

No stays to break or crownsheets to collapse. Our heat exchanger design eliminates washouts and cleaning in combination with Porta treatment. Fewer volunteer hours are required to operate locomotives fitted with our technology.

30 minute lightup

Allowing crews to arrive hours later or trains to depart earlier.

High efficiency

Reducing fuel consumption, particularly important when using solid biofuel.

Easy steaming

Ensures full steam pressure even with less experienced firemen.