Section 3: Installation
The following are general recommendations for installing a Johnston Packaged Boiler. Project plans and state and local code requirements must also be followed. These legal requirements take precedence over information found in this manual.
B. Installation Recommendations
The boiler should be set on a raised concrete pad. The boiler should be level and its base frame should be grouted to the raised concrete pad. A 36” aisle space at the sides and to the rear of the boiler is recommended. Adequate space for boiler tube removal and replacement should be provided to the front of the boiler. Refer to the specified boiler size requirements, in this regard.
The flue gas outlet connection on a Johnston Boiler is only intended to support a limited boiler stack, or breeching. The minimum stack diameter for a given size boiler should be adhered to.
Where a breeching is used, a round breeching is preferred. If a rectangular breeching is used, stiffeners should be provided in large flat areas of the breeching, not only for strength, but to minimize the possible vibration and noise that may be experienced from using a rectangular breeching.
If two or more boilers are installed in a common breeching, the breeching size should get progressively larger from the boiler farthest from the stack to the boiler nearest the stack. This is done to accommodate the additional volume of flue gas from one boiler to the next.
A rain cap is recommended on a stack connected directly to the boiler. The rain cap should be mounted no less than the diameter of the stack, and above the end of the stack.
Boiler feed, steam or water, fuel piping and electrical supply lines should be properly installed to the boiler. It is recommended that feedwater and fuel supply lines be properly valved, so the supply lines to the boiler can be shut off when it is not in use or when preventive maintenance or repairs to the boiler are being made. A “dirt trap” should be installed in the gas supply line, just prior to entering the main gas train of the boiler. A means to disconnect and lockout the power supply to the boiler control panel should also be provided. Installation of boiler feedwater, fuel and electrical power supply piping and lines should be checked, so as not to interfere with operation of any component part of the boiler, or interfere with the ability to perform preventive maintenance or make repair. Special attention should be given to making sure that no piping or lines interfere with the boiler fluebox doors.
Very often boiler safety relief valves are removed from the boiler, following factory testing of the boiler, just prior to shipment. These safety relief valves must be properly reinstalled on the boiler, using only a safety valve wrench. Using a conventional wrench often damages safety relief valves. This type of damage is not covered under the boiler warranty. All safety relief valves should be piped to a safe point of discharge. Safety relief valve discharge piping should have an internal area equal to or greater than the internal area of the valve outlet. The discharge piping should be arranged and installed so that no strain is imposed on the safety relief valve.
All blowoff and blowdown valves, including any Johnston supplied piping, whether water column, surface/continuous or bottom, should be piped, or further piped, properly and to a safe point of discharge. If they are piped into a blowdown separator, the blowdown line should be properly valved, so the boiler is capable of being completely drained.