Horizontal 3” Boiler Instructions v1.2
Copyright - Chiltern Model Steam Engines
Page 6.
This system is designed for use with butane or a butane/propane mix. There are a variety of mixes
ranging from 90/10 to 60/40 with one of the most common being 70/30 (70% butane and 30%
propane).
The burner is best lit whilst inside the boiler enclosure (under the boiler cylinder) using a long nozzle
oven/hub piezoelectric lighter or taper. The burner can be lit outside the boiler enclosure but be
aware the flame can initially spread out beyond the burner and the burner will become hot very
quickly.
To light the burner, hold the lighter/taper over the top of the ceramic element of the burner and
slowly open the gas control regulator. The gas should ignite almost immediately and the burner
should be audible.
If not already in place push the burner into the boiler enclosure, keep it central in the enclosure and
for the first couple of minutes keep the burner on low. This is important, as until it warms up, the
flame will be a little unstable and turning it up too much could cause it to go out. Also, with a
completely full canister/tank, liquid gas could be drawn off instead of vaporized gas, which can also
extinguish the flame.
After a couple of minutes, the gas control regulator can be opened slowly to speed up steam raising.
Conversely when the boiler is up to pressure reduce the gas flow.
Safety Pressure Valve
The boiler is fitted with a safety valve to prevent the steam pressure rising above the maximum
allowable working pressure.
It must not be adapted to increase this value.
The safety valve will start to release/blow off as the pre-set pressure is reached. It is factory set to
start venting steam pressure around 20 psi.
During operation, check that the safety valve is releasing and not allowing the pressure to continue
to rise. Do this by opening the outlet valve.
If the safety valve does not appear to be working properly it can be removed as mentioned above.
The valve consists of a piston/spring which needs to move freely. Clean and lubricate as needed or
replace.
If the safety valve becomes defective in any way do not use the boiler and repair or replace the
valve.
Pressure Gauge (optional extra)
The pressure gauge and its siphon pipe are easily damaged and can if needed be removed. The cone
fitting does not require sealing but be careful not to overtighten when replacing. If required, the
siphon pipe can be bent to a more convenient position but this must be done with care.
Steam Connection to Engine
The boiler should be securely connected to the steam engine by a pipe specifically designed to
withstand the operating temperature and pressure of the boiler - preferably a copper pipe with
silver soldered connections - these are available ready made from Chiltern Model Steam.