Understanding Hydronic Baseboard Heating

Understanding Hydronic Baseboard Heating, is an article that will help the average homeowner understand the basic principles behind a forced hot water, hydronic baseboard heating system.

Learning the basics is a necessity if you are going to know when to service and that the servicing of your system has been performed properly. A few simple things listed below will give you a little piece of mind.

Hot water, or hydronic heating consists of several main components. This starts with a boiler and that can be either gas fired or oil fired. Some people even have wood boilers. They all perform the same function within a hot water system. They heat the water.

After this water is heated it is simply pumped through baseboard radiation in the room we are heating. This baseboard is connected to the boiler by copper or poly lines that supply the right amount of heated water moving at the right speed for optimal heat transfer to the radiation and then to the room through the convection process.

Now all this may sound a little complicated but broken down we just pump hot water into the room and it radiates into the air from the baseboard. Thats it. There are no secret parts that only the servicemen know about. This type of system has been designed and installed in the same basic manner for many years and is still one of the best ways to heat a home today.

There are a few specifics to any Hot water system. First we may have one zone, or one thermostat. Or if you have a larger home or a newer higher end home you may have many zones and many thermostats. Each thermostat will control one room or one group of rooms and this is known as a multi zone system.

When we add zones to a hydronic system, we are simply adding one feed line from the boiler to the room we're heating through the radiation and then a return line back to the boiler. Thats a zone. Now we add a thermostat to it and a relay at the boiler to receive a call when the thermostat is turned up. Each one of our zones will have one of these setups to run the control messages to the boiler.

When there is a call from any zone, a pump in line for that zones piping will also come on and begin to circulate the heated water for that zones radiation. When the room or area gets up to the thermostat set point the equipment shuts off automatically. When the temp falls the stat comes back on and the operation repeats itself.

Some multi zone systems will have a separate circulator pump for each zone and some will have only one pump and then tee off into zone valves for each room. This is a cheaper way to install the system but can be practical when you have many zones.

Along the way we will find tees for air vents as getting the air out of a hydronic system is imperative for proper operation. Any air in the system can cause the circulator to lock and then no water gets moved causing a heat outage for that zone. Getting the air out is something that an annual service call should take care of.

Knowing you have air in a system can be ascertained by listening closely when the heat comes on. If there is air within the piping then the sound you hear will emulate a rushing stream with water flowing by slow rapids as the pump begins to move the air infested water. This air must be removed.

Sources of air in a hot water heating system are many. Number one when the system is installed the contractors don't always get all the air out initially. This leaves small micro bubbles that can eventually congeal and form larger air pockets eventually air locking a pump. This can be avoided by making sure your installer properly purges the system.

A faulty expansion tank can introduce air into a system by blowing the pre charged side into the system . To find out if this has happened tap the tank on the bottom and then on the top. The sounds emitted should be drastically different. The top of this tank is full of system water. The bottom is full of precharged air. If the sounds are the same then the tank is blown and needs replacing. The system will need to be fully purged after a new tank is installed.

One other way that air has been known to get into a hydronic system is when the pump first comes on as a zone is called. If there is a leak on the suction side of the pump, say in a circulator flange or a fitting thread. A slight amount of air can be pulled in each time it gets a call. This can eventually build up into an air lock and heat failure.

Multi zone systems will also have a Flo check valve in each feed line. This flow check valve keeps the hot water from gravity feeding up to each zone when another one is calling. If this valve fails then too much heat will go to the affected zone. Usually this valve is on the feed side just after the manifold splits into zones. If your getting too much heat to any area have these valves checked.

Automatic air eliminators are usually installed in each zone or in the main manifold of a system of this type. The include simple auto vents and high tech micro bubble resorbers that split the water and push it through fine mesh screens to break out the air and then incorporate an air vent at the top that the separated air can escape through.

Baseboard heat within the rooms should be kept clean and vacuumed out inside. The covers should be removed and all the dust removed from inside the fins. This is the area that the convecting heat transfers through. If these fins are all clogged up with dust and debris then your heat will be very inefficient and you will be wasting a lot of money. Simple vacuuming can save a lot. Keeping furniture at least a foot away from radiators also makes sure there is enough air moving around the baseboard for it to work properly.

Taking the time to read Understanding Hydronic Baseboard Heating is a start, getting to know your system will take a little time. I have included a few links below to more information if you are hungry for heating knowledge.

Automatic Vent Valve 1/8"
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400 TACO 1/8 INCH air VENT 150PSI
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(price as of Dec 6, 2013)
Amtrol 101-1 #15 Extrol Expansion Tank (2 Gallon Volume)
Amazon Price: $55.00 $30.00 Buy Now
(price as of Dec 6, 2013)