A question I have heard time and time again. “My water boiler works amazingly on the lower levels, but it is cold upstairs. Heat rises, so what could be the issue?”
There are a few variables to consider when talking about closed-loop hydronic systems. The first variable is what it takes to get hot water all the way upstairs and the components involved. The second variable is what’s fighting against us to get the hot water up to the highest farthest point.
First, let’s consider some essential components. Modern water boilers have a circulator, often referred to as a pump. This circulator moves water through your heating system. Some boilers have multiple circulators depending on the piping of the boiler system, but their jobs are the same, to circulate water through whatever heating loop it services. If this circulator does not work correctly, you may not be able to get hot water to your baseboards. Another item to consider is another component called a zone valve. Boilers with multiple zones often utilize zone valves to have different rooms with different temperatures. This zone valve opens when your thermostat tells it to open, releasing hot water to your baseboards. Once the thermostat temperature is reached, it closes. If your zone valve is faulty, it may not open, allowing hot water to travel to the upstairs. Most zone valves have an arm on them that you can use to manually open if there is a no-heat emergency.
Secondly, we need to consider what is fighting against us. We often take for granted a significant factor in improper water boiler operation; air. Air in the boiler system can cause many problems, most noticeably though is the lack of heat to the highest/farthest zone. Air in the system migrates to the highest point and frequently restricts water flow to that zone, causing low heat output or none at all. Most of the time, good maintenance and a purge of that zone will fix the issue. If the problem persists, there may be underlying issues with boiler piping, circulation, expansion, improper air elimination, or leaks causing persistent air in the piping. Don’t worry; all of these issues are relatively common, and your hydronic/boiler technician will be able to assist you with any of these concerns.
