Boiler Repair: 3 Tips On How To Troubleshoot The Expansion Tank

Most boilers can last for around 15 years. After that, more and more problems will begin to arise, and you'll eventually have to replace the boiler, as repairing it will no longer be a feasible nor practical option. As your boiler ages, most of the problems that arise with its functionality will stem from either the expansion tank or the circulator. The expansion tank is filled with not only water but also air to prevent the water from boiling. It is an essential part used to regulate the temperature of the water. If the temperature of the water is off, one of the first things you'll want to do is troubleshoot the expansion tank. Here are 3 tips on how you can accomplish just that.

Inspect the Pressure-Relief Valve

First and foremost, you should always inspect the pressure-relief valve of the expansion tank before you attempt anything else. The pressure-relief valve will basically tell you whether there is an appropriate amount of air and water within the expansion tank. If there is water coming out from the pressure-relief valve, this is an indication that there is too much water within the expansion tank itself. Without enough air in the expansion tank, your boiler will not produce sufficient heat.

The solution to this problem is as simple as it gets. Just drain some of the water from the expansion tank. Before you drain the expansion tank, make sure you allow it time to cool down. Even though the water should be cooled, be careful when draining the tank. Remove water little by little from the purge valve using a hose until water no longer leaks out from the pressure-relief valve. You should be able to see a significant difference in the temperature of the water produced by the boiler almost immediately.

Feel the Temperature of the Outside of the Tank  

Just because the pressure-relief valve may not be squirting out water, it does not necessarily mean that there is nothing wrong with the expansion tank. The proportion of water and air inside the tank may still not be ideal. The next step you should take is to feel the temperature of the outside of the tank. Be careful not to burn yourself when doing so. The bottom half of the tank should be significantly hotter than the top half of the tank. If the bottom half is just as hot or almost as hot as the top half, then there's a good chance that there's too much water inside. Once again, you'll have to drain some water from the tank via the purge valve using a hose.

Reset the Valves

Even if the expansion tank was seemingly perfect, the last thing you want to do when troubleshooting the tank is to reset all of the valves back to their normal setting before you start the boiler again. This will help reset the system, so to speak. If some of the valves were not set properly, it may have affected temperature control of the water. When resetting the valves, you should also take a quick peek at the combination gauge to make sure that the pressure of the system is still within an appropriate range. If it isn't, you should contact a boiler repairman immediately.


Troubleshooting the expansion tank of the boiler is quite easy an easy task. You should definitely try to do it yourself, as you will not need any special equipment or tools to do so. If the temperature of the water is still too hot or too cold after you have troubleshooted the expansion tank or if the expansion tank seems to be operating properly, call a boiler repairman from a company like Robinson Heating & Cooling Inc.