Preparing for a Thermal Fluid Heater
Proper planning helps avoid problems when installing a new thermal fluid heater.
Failure to adequately plan for the arrival of a new heater can cause major frustrations and unnecessary costs. Here are some common issues related to scheduling and preparation for installation of a new heater.
Problems often occur because of poor communications among the various parties involved in acquiring and installing the heater. Consulting engineers may design the new heating system and provide the heater manufacturer with heater design criteria and delivery schedule. Plant personnel at the facility where the heater is to be installed may need to plan for unloading the heater upon arrival and to arrange for installation. Installation may require the services of several outside contractors as well as plant workers.
Obviously, with this many parties involved, it is easy for important details to be overlooked before the heater is even put into operation. All involved parties need to share information that may affect scheduling and preparation.
Scheduling is usually where problems begin. A number of unavoidable issues can result in either early or late delivery of the heater. So, if a crane crew has been scheduled for a specific unloading time, this can result in extra expense and inconvenience. Moreover, delivery delays may postpone operation of the heating system. So, the plans need to allow for such possibilities.
Another issue that frequently occurs has to do with local regulations and codes pertaining to electrical power, fuel and venting. The heater manufacturer does not normally have this information. It needs to be obtained locally.
Another common issue is incomplete readiness when heater service technicians arrive to start up or commission the heater after it is installed. Complete startup service requires actually running the heater and tuning its burner. Thus, the heater itself is not the only thing that needs to be ready. The entire system that is heated needs to be ready. Therefore, if the heater heats thermal fluid, it needs to be connected to the system it heats, and the entire system should be filled with thermal fluid. If the heater heats other types of material, it too must be ready to test.
Sometimes, even the seemingly obvious things get overlooked. For example, the pressure of the fuel supply needs to comply with the heater piping and instrumentation diagrams (P&ID). The same applies for the heater electrical power requirements.
When the heater manufacturer schedules a service technician for startup, they should attempt to confirm that the installation is actually complete and ready for startup. However, despite assurances that everything is ready, technicians frequently arrive to find it is not ready. He may either have to stand by idly for a day or more until he can complete the task or return another day. In any case, the owner incurs extra costs and delays for the service.
Some useful tips are presented here for installation of your heater. The information included is based on the most common concerns but please note that it does not cover all aspects and details of installation.
It is important to be sure that you comply with all local and national codes and standards that apply to installation of heaters. The heater manufacturer is not in a position to advise you on local codes and standards. Instead, heater providers recommend that you contact local agencies or inspectors if you have questions. If you engage a local contractor to install your heater, make sure they are prepared to deal with local codes and standards. Regulations pertaining to electrical safety, venting of gas trains and fluid discharge from relief valves are areas of special concern.
Follow all the instructions provided by the manufacturer when installing the heater, including:
- Piping and instrumentation diagrams.
- General arrangement drawings.
- Electrical drawings.
- Foundation specifications.
Set the heater on a concrete slab, foundation or supporting structure to provide a stable base for the heater. When installing a vertical heater, make sure that its supporting structure is level. Otherwise you will need to shim its base to make the heater perfectly level. Use anchor bolts to secure the heater base to the supporting structure. Make sure you comply with local regulations for foundation design, especially in areas prone to windstorms and earthquakes.
Install the heater in a location where there is at least 3’ of space around the heater for easy access to all sides of the heater. Leave enough space in front of electrical enclosures or panels to allow the doors to open fully. Consider the need for space to remove the helical coil if that ever becomes necessary. Do not place anything in that space that would be unduly difficult to clear.
Make sure that the exhaust stack is well supported. Some stacks are designed to be mounted on the heater without extra support while some require additional support. When additional supports are used, they should allow for expansion and contraction.
Install provisions to ensure an adequate supply of air for combustion, ventilation and dilution of flue gases. Such provisions for gas-fired heaters should be in accordance with NFPA 54, National Fuel Gas Code, paragraph 5.3. Such provisions for oil-fired heaters should be in accordance with NFPA 31, Standard for the Installation of Oil-Burning Equipment, Chapters 5 and 6. Please note that heaters installed outside the United States should meet applicable codes for the location.
Make sure that the fuel supply for the heater conforms to requirements for pressure, flow and pipe size as shown on the furnished P&IDs. Otherwise, please contact the manufacturer’s engineering department for advice before you connect the fuel supply to the heater.
When a gas-fired heater is installed in a hazardous location or inside a building, install venting provisions for all gas pressure regulators and relief valves. Such provisions should be in accordance with NFPA 54, National Fuel Gas Code, paragraph 2.7. Again, heaters installed outside the United States should meet applicable codes for the location.
Make sure that there is a suitable relief valve in the thermal fluid piping. Some heaters are furnished with relief valves installed. If not, install one or more as needed in the piping near the outlet of the coil and upstream of shutoff valves. Install vent piping for the thermal fluid relief valves. The piping can empty into a container at a safe, remote location. Insulation or shields should be installed as needed to prevent personnel from getting burned by contact with hot surfaces. Likewise, padding should be installed on hard surfaces of obstructions that are at heights or locations that are apt to cause head injuries.
When installing the thermal fluid piping system and making connections to the heater, use welded connections as much as is possible. Welded connections are less prone to leakage than threaded pipe and flanged connections. Follow applicable welding codes and procedures.
Install suitable expansion loops in thermal fluid piping to minimize stress on piping and pumps caused by expansion and contraction due to variations in temperature. In addition, valves that can be used to isolate pumps and tanks in the thermal fluid piping system should also be installed. Also, 0.5” bleeder lines should be installed at all high points in the thermal fluid system to facilitate expelling trapped air and other gases such as water vapor. Make sure they are turned in a safe direction and do not accumulate water. Install 0.5” drain lines at all low points in the thermal fluid system to facilitate expelling trapped water. It also is important to leak test all fuel and media piping before filling systems.
All electrical installation should comply with NFPA 70, NEC (National Electric Code). Use only qualified electricians to install electrical service to the heater. All electrical wiring and components should be specified by a qualified engineer or electrician. Ampere loading information is shown on electrical drawings furnished with the heater. And, again, heaters installed outside the United States should meet applicable codes for the location.
Make sure all controls on the control panel of the heater are in the off position before connecting and energizing the electrical service. Run electrical power wiring to the control panel on the heater and connect the wires to its main disconnect breaker. Many heaters are normally intended for connection to a power source of 460 V, three-phase, 60 Hz. Voltage variations should be no lower than 440 V or higher than 480 V. Heaters often are available for other power sources when specified at time of order. Verify that your power source matches the power requirements specified on the electrical drawings.
Before operating your heater for the first time, make sure the driveshaft of each hot-oil pump is properly aligned with its motor driveshaft. Do this after the heater is installed in a fixed location and not subject to additional handling. Alignment instructions are contained in applicable documents published by the pump manufacturer. Many heater manufacturers include a copy of these documents with each new heater.
Check alignment again immediately after initial operation of the heater before the system has cooled down. Thereafter, follow maintenance instructions covered in the documents. Misalignment can damage the pump and motor. Repairing damaged pumps and motors can incur significant costs for which the owner is fully responsible. Setting alignment is an exacting task and should be done only by a qualified technician.