Hiscox’s Hotchkiss boiler cleaner circulates surface water through an external settling globe. A temperature difference between the rising and returning water drives circulation, and suspended material settles in the globe. The separate calculator below compares two scale thicknesses; it does not predict the cleaner’s performance or boiler heat loss.
Hotchkiss Boiler Cleaner Interactive Calculator
Compare an entered scale thickness with a reference thickness. The ratio does not determine heat loss, remaining heat transfer or improvement after cleaning. Both sliders change the length comparison; they do not set a thermal loss.
Equation Used
The dimensionless index compares two lengths. Heat transfer also depends on deposit conductivity, tube geometry and the other thermal resistances; thickness alone does not establish a percentage loss.
- The thickness index is the entered thickness divided by the positive reference thickness.
- No clean-tube heat-transfer baseline is calculated.
- The thickness illustration is separate from the historical cleaner.
- Thermal performance and cleaning gain are not calculated.
The animation follows the cleaner’s rising and returning pipes and the settling space in its external globe. The separate bars compare scale thicknesses on one length scale.
Circulation through a settling globe
Hiscox describes the Hotchkiss cleaner as a way to take surface scum from a boiler through an external globe. Water circulates through rising and returning pipes because of their temperature difference.
Inside the larger globe, suspended material settles and can leave through a separate discharge connection. This is the historical arrangement described in the source, rather than a chemical metering pot.
Historical boiler-water cleaning
The appliance belongs to the history of separating suspended material from boiler water. Its description does not establish the pressure rating, condition or suitability of any surviving installation.
Settling suspended material and treating dissolved water constituents are different tasks. The page does not prescribe boiler-water chemistry, maintenance intervals or operating settings.
Thickness ratio
The calculator’s one numerical comparison is s/sref, with both thicknesses in millimetres. A ratio of 1 means equal thickness, 2 means twice the reference thickness, and 0 means zero entered thickness.
This ratio is not a heat-transfer model. Deposit conductivity, tube dimensions, fluid conditions and the rest of the thermal path are required before a thermal effect can be calculated.
Worked length comparison
For an entered thickness of 1.5 mm and a reference thickness of 1.5 mm, the index is 1.5/1.5 = 1.00. If the entered thickness becomes 3.0 mm with the same reference, the index is 2.00.
The calculation does not assign a heat-loss percentage to either thickness. The ratio compares lengths only; neither thickness sets a thermal-loss percentage.
What the comparison can tell you
The index compares two dimensions. It cannot identify a deposit, measure its conductivity, determine how much material the historical cleaner removes, or estimate fuel savings.
Any assessment of boiler water or an existing pressure appliance requires its actual condition, manufacturer information and applicable engineering requirements.
Frequently asked questions
Was the Hotchkiss cleaner a chemical dosing pot?
Hiscox’s description is a circulating settling globe for surface scum. It describes a different arrangement from a chemical dosing pot.
Does thicker scale always imply a fixed percentage heat loss?
No. A thickness ratio alone does not determine thermal resistance or overall heat transfer.
Why does the calculator not give a heat-loss percentage?
The inputs do not include the conductivity, geometry and thermal conditions needed to calculate it.
What do the two thickness bars show?
Their lengths represent the entered and reference thicknesses on the same millimetre scale. They are separate from the historical cleaner’s circulation and settling animation.
Historical source
Gardner D. Hiscox, Mechanical Movements, Powers, Devices and Appliances, page 111, describes the Hotchkiss cleaner’s circulating pipes, settling globe and discharge. The text explains circulation through a temperature difference.
The thickness ratio on this page is a separate dimensional comparison. The source does not provide the thermal or performance data needed to turn that ratio into boiler heat loss or cleaning gain.
Building or designing a mechanism like this?
Explore the precision-engineered motion control hardware used by mechanical engineers, makers, and product designers.
