This article for troubleshooting boiler problems is not comprehensive but covers the basics. Other articles here in the boiler category of High Performance HVAC covers other problems. Other problems that can occur with boilers. Please check our other articles for boiler troubleshooting and information.
Boiler Troubleshooting Problems for Hydronic Heating Systems - Steam Boiler Problems
One of the biggest problems with steam boilers that is the cause of complaints is water hammer in the pipes. Water hammer with a steam boiler occurs when cool water meets hot steam. When water changes to steam it expands 1600 times in volume. When the cool water hits the hot steam there is an expansion. The cooler water expands as it becomes steam. The reason for the complaints is because of the loud noise it makes. When you have water hammer in a steam boiler it sounds like someone is taking a hammer and beating on the steam pipes.
Some people grow accustomed to water hammer and learn to ignore the noise the pipes make. Water hammer can occur because the boiler is oversized for the load. Or the condensation is not draining back to the Hartford loop (return) properly. The solution to fixing the problem is calling a professional. Water hammer needs the attention of a professional who specializes in steam boilers. This can be difficult in some areas as steam boilers are becoming a thing of the past. Steam boiler heating systems are not that efficient and are slowly being replaced.
Slowly the steam boiler is being replaced by hot water boilers and other sources of heating systems, Heating systems such as gas furnaces and heat pumps. If you have a problem with your steam boiler call plumbing contractors and HVAC contractors. Ask specifically for a technician who is a specialist with troubleshooting steam boiler problems.
Troubleshooting Circulator Pumps
Water circulation problems in a hot water loop can be because of the circulator pump. On older boiler systems that have circulator pumps that have couplings the most common problems is the couplings breaking. This results in a loss of the hot water circulating through the water loop. The solution is to replace the coupling with a new coupling to restore water flow to the boiler loop.
It is important to make sure that the circulator pump bearing assembling and the pump motor has the proper lubrication. Make sure it is free and moving before replacing the coupling. If the bearing assembly is seized up or difficult to turn it is likely, if you replace the broken coupling with a new coupling, the new coupling will break also. Many of these types of circulator pumps have a specific way to lubricate the bearing assembly and the pump motor.
Modern Boiler Troubleshooting
Hot Water Heating Repair - Newer boiler systems use cartridge type circulator pumps that are direct drive. Direct drive with the impeller of the circulator pump. The cartridge type circulator pumps eliminate the coupling and have less moving parts. There are fewer problems with the cartridge type circulator pumps. Cartridge type circulator pumps typically do not require any maintenance including lubrication. However, always check to make sure your particular circulator does not require periodic maintenance including lubrication.
Problems that can occur with any type of circulator pump including cartridge type or the circulator pump with bearing assemblies and couplings can be the motor run capacitor. Some run capacitors for some boiler circulator motors are proprietary and can only be purchased from the boiler circulator pump manufacturer or a manufacturer-distributor. If the circulator motor quits running or runs slower than normal then the capacitor should be checked for proper rating which is rated in microfarads. If the capacitor is replaced the microfarad rating should be the same as the one replaced with a proper functioning of the circulator motor.
Air Problems with Hot Water Boiler Loops
Hot Water Heating Repair - Another big problem that can happen with hot water boiler systems is air getting into the water loop and causing a blockage of the water circulating through the boiler water loop. This happens with poor piping designs, poor air management control component functioning, or improperly flushing the system after a repair is made. With the piping design, the risers on the piping should have a way to bleed the air from the riser with either automatic air bleeders or manual air bleeders.
Additionally, the piping design should including proper valves and boiler drains on the near boiler piping to allow for proper flushing of the boiler loop especially after a repair is made. Proper isolation valves in the near boiler piping supply and return help with flushing the loop of all the air and refilling the loop. If the boiler loop utilizes radiators or convectors then it is important that the radiators and convectors have air bleeders. Air bleeders to get rid of air in the system. Otherwise, it will slowly build up over time as the boiler uses makeup water.
There are special air management controls that can be added to the system. These controls are added where the makeup water enters the boiler loop. They eliminate excess air in the system before it gets into the main loop. It is important to make sure all the components in the hot water boiler systems, including automatic air vents, function properly. It is necessary the air is removed automatically when it develops in the hot water boiler loop system.
Please see the boiler expansion tank page for specifics about troubleshooting problems with expansion tanks.
Other Problems with Boilers and Troubleshooting:
Oil boilers can have problems with the oil burner system. Gas boilers can have a problem with the gas system. Troubleshooting these specific problems can be found on the furnaces pages. These problems are not in the scope of this article which is specific to troubleshooting boiler problems.
Boiler Troubleshooting Problems for Hydronic Heating Systems