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(707) 539-4533 |  Sonoma Napa and Marin Counties

Updated March 16 2022


If you’re not interested in a full ducted central air heating system, baseboard heating is a great alternative that can save you money while keeping your house nice and warm. It’s a pretty simple and straightforward system that can be installed pretty much anywhere, from an apartment to a full-sized house.


There are two types of baseboard heaters: electric baseboards, and hydronic, or hot water baseboards. Electric baseboard heaters are pretty simple. They use electricity to heat fins inside the unit, a little bit like a toaster. All you have to do is wire them into the electrical system of your home and you’re all set. However, electric baseboards tend to use a lot of juice when they’re running, making them a relatively inefficient way of heating your home. They’re best used as auxiliary heaters for specific rooms, like bedrooms.


Hot water baseboard heaters are a little more complicated. They use steam or water heated by a boiler to warm the air in the room instead of the metal fins. This makes them a lot more efficient, but they also require a little more maintenance to run. If you’re having trouble with your hot water baseboard heater, here are a few common issues that might be the source of your problems. As always, unless you’re 100% confident in your own handyman skills, we recommend bringing in professional help to fix any issues that might arise.


How Hot Water Baseboard Heaters Work

Baseboard heaters work using a scientific principle called convection. Convection has to do with the movement of molecules under different temperatures and the transfer of heat, but all you really have to remember is that it makes hot air rise up and cold air fall towards the floor. We can take advantage of this scientific principle by placing baseboard heaters low on the wall, right by the floor. That’s where the name comes from – they’re called baseboard heaters because you place them on the baseboard of your wall. They’re also typically placed by the window since windows are the biggest culprits of heat transference to the outside. As warm air reaches the cold glass of the window and cools down, it falls directly into the opening on top of the baseboard heater. Once the heater has warmed the air, it rises back out into the room. Pretty simple and easy.


Hot water baseboard heaters use hot water or steam to warm the air. Rather than making each unit heat its own water, a baseboard heating system uses a single central boiler, usually placed in the basement if you have one. The boiler heats up the water, which is then distributed to each unit through small pipes in your walls and floor. As the heat from the water transfers into the air in the room, the water cools, and so there’s a constant cycle of water flowing from the boiler to the unit and back to the boiler to be heated again.


This is an extremely effective and efficient system for heating your home. However, it does require a few different parts to all be running smoothly. If an issue develops in any of the units, the pipes, or the boiler itself, then the system can lose efficiency or even fail altogether. That’s why it’s important to keep an eye on how well the heaters are working and perform regular maintenance to keep everything working the way it should.


Airbound Heating Pipes

One of the most common problems you might run into with your baseboard heating system is air in the heating pipes that run water to and from the boiler. These pipes should usually be airtight and filled completely with water. When air does manage to enter the pipes, it can slow down or even block the whole system. When this happens, the pipes are referred to as “airbound.”


When everything is running smoothly, very little power is used to keep the pipes flowing. Generally, the system relies on recently heated water to push the older, cooler water out of the way and keep the cycle going. When air blocks the pipes, the water pump generally doesn’t have enough power to move both the water and the air bubbles. This can cause cold water to just sit in your pipes and block any movement.


The most common cause of airbound pipes is a leak somewhere along the way. The water flowing through the pipes is so hot that even the smallest hole or leak can cause small amounts to evaporate. As the water evaporates through the hole, it’s replaced with air. Even though it’s just a tiny amount of air, it can still be enough to clog the pipe and slow down the whole system.


Air can also make its way into the pipes during routine maintenance. While any good HVAC technician should be able to service your pipes without causing a leak, mistakes do happen, and only a little tiny amount of air is required to cause problems.



The easiest way to tell if your heating pipes are airbound is if some of the heating units aren’t working properly. Usually, once the water pump turns on, every unit in the house should start creating heat at the same time and at the same pace. If one room isn’t getting warm as quickly as the others, there’s a good chance that the pipes leading to that particular unit are airbound.


Air in the heating pipes can also create a bubbling or gurgling sound when the system is up and running. If you hear these sounds coming from the walls near your baseboard heaters, then it’s likely airbound pipes causing them.


Fixing the Problem

Luckily, this is one of the issues that can actually be fixed by any homeowner. Every hot water baseboard heating system should come installed with air bleeder valves. They’re usually higher up in your house since air rises above the water. To bleed the air from the pipes, you should first turn the boiler off using the service switch. Use your hand to make sure none of the units are receiving any heat. If you leave the boiler on while bleeding the air, you can end up with boiling hot water spraying from the valves, so be careful and make sure the water in the pipes is cold before you start.


Next, attach a hose to the boiler drain so the air can escape. If your system has a water feeder bypass, you should open that as well. Water coming in from the city pipes will create more pressure in the system, forcing the air out faster. At this point, all you have to do is open the bleeder valves and wait until all the air is gone. If you feel comfortable handling this maintenance by yourself, it’s relatively simple. However, if you’re unsure, a trained technician can easily handle the problem for you.


Leaks in the Baseboard Heater

Another common issue with baseboard heaters is a leak somewhere in the system. This happens much more often with older systems that haven’t been well maintained or have just aged so much that corrosion is setting in. Leaks are most commonly found in the piping system rather than the actual unit itself, but very old baseboard heaters can also spring leaks inside the unit. A leak in the boiler can also be a problem, but we’ll discuss that later on in the post.


Wherever the leak happens to be, it can wreak havoc on the function of the hot water baseboard heating system. If water is escaping through a leak, it can reduce the efficiency of the system as well as lowering the pressure in the pipes. Air can also enter the pipes through the leak, causing them to become airbound. You know how to fix airbound pipes now, of course, but that still leaves the leak itself. Finding and repairing a leaky pipe can be difficult, so we tend to recommend bringing in outside help for this one.


One of the most common causes of a leak in the heating pipes is a failure to winterize the piping system. During the winter, a sudden drop in temperature can sometimes cause the water in the heating pipes to freeze. As you might remember from science class in school, when water turns into ice, it expands. This increases the pressure inside the pipes, and can sometimes cause them to burst or spring a leak.



Like many problems with a hot water baseboard heater, one of the first signs of a leak is a lack of heat coming from one or more units. If you notice that some rooms aren’t as warm as they should be, even though the system is on, you know there’s something wrong with the heating system. That can often mean a leaky pipe.


You can also recognize a leaky pipe if you hear dripping sounds coming from inside the walls or the floor. By the time you hear dripping, however, the problem has become fairly serious and you should get it fixed pretty much immediately.


To find the leak, you’ll just have to check along the pipes. It’s kind of a painstaking process, but it’s important to identify exactly where the leak is. Keep an eye out for any small pools of water or other signs of moisture underneath the pipes. That’s a telltale sign of a leak.


Fixing the Problem

First things first, the best way to fix a leaky pipe is by preventative maintenance, making sure the pipe never bursts at all. The best way to do this is to have your pipes winterized every year. This process involves draining the water from the pipes and flushing them with antifreeze to make sure ice can’t form inside.


Once you’ve identified the location of the leak, we recommend hiring a technician to fix the problem for you. If you own a blowtorch and feel confident in your plumbing skills you can try to fix it yourself, but that can be both difficult and a little unsafe. For the vast majority of homeowners, a leaky pipe is a problem that requires professional help to fix.


Leaky or Corroded Boiler

Most hot water boilers are made of metal. This is a good thing for the efficiency of your system since metal is an excellent surface for the transfer of heat, but it can cause problems if that metal starts to rust or corrode. It’s a good idea to keep your boiler clean and free of any rust or corrosion since allowing it to build up will cause more damage to the metal. Generally, surface-level rust can be easily cleaned, but serious rust can force you to scrap the whole tank and replace it with a new one.


When cleaning rust away from the boiler, you should keep an eye out for any leaks. Some leaks will have water gathered or pooled around the hole, making them easier to spot. However, since the water inside the boiler is so hot, it will sometimes evaporate as soon as it touches the outside surface of the tank. In this case, there will be no water around the leak, making it harder to spot. You can identify these leaks by looking for a build-up of corrosion. Additionally, when water evaporates, it leaves behind any minerals or sediments that were suspended in it. You can sometimes identify leaks by looking for green or white mineral salts left behind when the leaked water evaporated.


Exfoliated rust, or thick rust that flakes off the metal, is a very bad sign. By the time this occurs, it may be too late to repair the boiler. That’s why it’s important to catch corrosion early, either by checking the boiler yourself or having it serviced once a year or so along with the rest of your heating system.


Some leaks can occur inside the boiler itself. These will be extremely difficult to diagnose and find by yourself, but any reasonably skilled technician will be able to find and fix those leaks before they become a problem.


Finally, many leaks can be found in the valves and pipe fittings attached to the boiler. These are always the weakest points of any pipe-based system, so they’re the first place you should look when you’re checking for leaks.



If your heating system isn’t working properly and you haven’t been able to identify any other issues, you should check the boiler for leaks and rust. While you’re looking for leaks, make sure you don’t touch the actual surface of the boiler. Touching any spots of corrosion, especially bad ones, can cause the leak to widen and sometimes spray hot water out in your direction. We recommend turning the boiler off and being very careful when cleaning it.


Fixing the Problem

Small spots of corrosion can be cleaned by hand, but any large leaks should be handled by a professional. As always, the best way to avoid this problem is through responsible preventative maintenance. Get your boiler looked over every time you have a technician come to check the rest of the system and make sure any leaks are fixed early before they become too large.


Regular Maintenance

The best way to avoid any of these problems is through taking care of your heating system and maintaining it regularly. It’s a lot like owning a car. Sure, you could hold off and only take it to the mechanic when you notice a problem, but that’s going to be a lot more expensive in the long run than regular tune-ups. Plus, there’s always the risk that the problem will turn out to be un-fixable, and you’re stuck having to buy a new car. For that reason, we highly recommend getting your heating system checked out by a professional about once a year or so. The same goes for any HVAC system, ducted or otherwise.


There are also plenty of things you can do by yourself to keep things running smoothly. One of the simplest is just keeping all the heating units clean and free of dust and debris. You’d be surprised how quickly dust can accumulate on a heater, and it can easily end up partially blocking the air vents on the unit, preventing hot air from flowing into the room. If you have small children, you should also check the units regularly to make sure there’s nothing stuck in there. A buildup of dust or other debris will also cause an unpleasant burning smell when the unit is turned on, and nobody wants that in their bedroom or anywhere else in the house.


When spring rolls around and the weather starts getting warmer, you’ll eventually hit a point when you won’t need to keep the heaters on anymore. Once that happens, you should perform a little maintenance before leaving the system off for the summer. Give it a thorough cleaning and vacuuming before you leave it, making sure there’s no dust or debris anywhere on the unit. We also recommend buying a heater cover for every unit in your house. This will just make things a little easier when the time comes to turn them back on in the fall.


Bleeding air from the heating pipes is also an important part of maintaining your hot water baseboard heating system. If you feel comfortable doing that, you should expect to do it a few times a year to make sure there’s no air at all in the pipes. If you don’t think you can do it by yourself, it should cost under $100 to have a professional do it for you. Either way, leaving the air in your pipes for too long can create problems for the whole system, so it’s better to handle it as soon as you notice anything wrong.


Finally, if you plan on leaving your home for any significant period of time during the winter, we recommend draining the heating pipes before you go. Leaving water sitting in your pipes over the winter can cause it to freeze, causing leaks and burst pipes in the system and creating a big problem for you to fix as soon as you get home.


As a general rule, if something seems wrong with your heating system and you can’t figure out what it is, it’s safer to call a professional instead of just leaving it. Even if you end up having to spend a little money to fix a minor problem, you’ll still be better off than you would be if you left it to get worse and worse. Regular preventative maintenance is the key to keeping any system running, whether it’s a hot water baseboard heater or a standard ducted central air system.


Need Help? Call a Professional Today

If you’re in Sonoma, Napa, or Marin Counties and you need help with your hot water baseboard heating system, you can call Valley Comfort Heating and Air for help. Our technicians have all the experience and knowledge you need to take care of any problem, big or small. We can also help you install a new system, or give you more information if you’re on the fence. We have experience handling every kind of HVAC system, both residential and commercial, from the biggest central air split-system air conditioners to the smallest electric heaters.


You can get in touch with us through our website or give us a call at (707) 539-4533. Our offices are open Monday through Friday from 7:30 am to 5:00 pm, and we’re always happy to help in any way we can. Your perfect heating and cooling solution could be just a phone call away, so feel free to give us a call any time.