How to correct minor problems with your hot water baseboard heating system including cleaning and silencing noises.
Fin tube radiators, often called Slant Fin after the major manufacturer, is a type of hydronic heating system that pumps hot water from a boiler through a copper pipe covered with aluminum fins.
These baseboard radiators work by convection; cool air enters the bottom, gets heated by the copper tubing and aluminum fins and then exits out the top as warm air. Obstructions that block or restrict airflow through the unit reduces its heating capacity. Loose or poorly installed carpet is a common culprit. Sometimes the damper at the top of the baseboard has been accidentally closed.
Typical Baseboard Radiator
However, on older units it is often the accumulation of dirt and debris on the heating element that reduces heating output.
Cleaning and Adjusting Dampers
Loose carpeting and closed damper are easily fixed. Remember to keep large furniture at least 6 inches away from the front of the baseboard heat to allow the warm air to circulate in the room. Also keep in mind that the baseboard heating units are often installed on all exterior walls of a room, but there may be bare piping behind some of the covers. If a certain length of heating element, the portion with the aluminum fins, has enough heating capacity to heat the room, then the remaining baseboard is installed without fin tubes. If the entire run was installed with fin tube radiators, the room would become overheated.
Carpet tack strips cannot be installed under the baseboard radiators and the carpeting is cut so that it extends to the wall. Over time the carpeting curls up and can block the flow of air through the heating element. If the carpeting is too short, you may have to secure it with a small piece of trim or install a few 3-inch drywall screws and leave them stick out far enough to hold the carpeting down.
Inspect the entire run of baseboard heat and make sure the dampers are horizontal or angled up. The greater the angle, the faster the warm air will rise to heat the room. It is best to maintain a horizontal position and lower the dampers to reduce the heat flow and raise them when more heating is needed in a room.
To clean the fins you will need to take off the metal cover in front of the heating element. Remove the metal end caps off the housing, open the metal damper, and pop the front panel off its brackets. Older units may have a hinged end cap cover where the front piece can be lifted out of the way without removing the end cap. Remove any debris by hand and use a brush attachment to gently vacuum the element's fins. After cleaning, use needle-nosed pliers to gently straighten any that are crooked or touching adjacent fins. Reinstall the front cover and end caps if removed.
Banging or clicking in the piping when your baseboard heat comes on this could be caused by a few problems that could be related to the installation or the operation of the system.
To determine if this is air trapped in the heating system or if the baseboard heat was improperly installed. The first reason you could have noisy baseboard heat is because there is air in the heating system. When there is air in the heating system the water in the baseboard will produce a gurgling or boiling sound.
If the boiler and piping is not completely filled with water the system will not function properly. To see how much water you have in your boiler you will need to look at the pressure gauge. Depending on what type of boiler you have will determine what the actual boiler pressure should be but most residential forced hot water boiler systems run at between 12 – 28 PSI. If you find that you do not have any boiler pressure at all then you will need to add some water to the boiler using the fill valve that is located on the boiler. If you have never used an automatic fill valve on a boiler then you will want to be careful not to overfill the boiler. This is one of the main reasons you will have a noisy forced hot water heating system.
You may also have a leaking air bleed valve or pump packing which are causing a loss of water. See my article on Heating System Maintenance: https://knoji.com/heating-system-maintenance/
If your boiler has been off for several months and you are hearing a rolling noise inside of your hot water loop when you turn your heat on then you could have some air in your pipes. When air is trapped inside of the heat loops there is space for the hot water coming from the boiler to roll or twist the water around inside of the heat loops and the baseboard heating elements creating a noise. This rolling noise can be fixed by bleeding the air from the heating zone.
Another installation issue is how the fin tube heating elements are resting on the internal metal bracket, but not the expansion clip. As the baseboard heating elements heat up and expand the fins on the heating element will rub against the mounting bracket and cause a clicking noise.
While this is commonly found in new construction where the expansion clips have been removed during installation, they may have come off in older baseboard heating elements. You can buy new plastic or Teflon expansion clips, or install a piece of foam insulation between the pipe and the metal support.
Another area that can cause noise during heating is where the pipe comes through the floor. If the pipe is off to one side it can rub against the subfloor and create a squeaking noise. You can carefully enlarge the hole with a small saw or cut a piece of PVC pipe in half and slip it in between the pipe and the floor. Foam pipe insulation may work for a while, but it will eventually wear down and the noise will come back.
Misaligned Floor Penetration
Water hammer is caused when valves close suddenly and cause a shock wave to travel through the pipe until it reaches a 90-degree fitting when it hits some support or framing member. Typically control valves on hydronic heating systems open and close gradually to prevent this, so if you are experiencing water hammer, you will need to check the operation of your zone control valve and possibly replace it. See my article covering this topic here: https://knoji.com/troubleshooting-boiler-and-hydronic-control-problems/
The heat loop is the run of pipe that connects from the boiler to the baseboard heat and then loops back to the boiler again. When cold water is laying inside of the heat loop and then the boiler forces hot water into the loop that’s when the “water hammer” can happen. Most forced baseboard heat elements like Slant Fin will have plastic clips on the bottom of the element to help prevent the baseboard from banging so loud if water hammer was to happen.
Always inspect your hot water boiler prior to the heating season so that you have ample time to perform any repairs. Hire a qualified HVAC technician who is experienced with hot water baseboard heating systems to make any necessary repairs that you are not familiar with.