How warm does a coat keep you without gloves and a hat? Accessories are sometimes necessities.
Find out here what accessories you need to best serve your needs. Boiler accessories can make your system a lot more efficient and effective.
Knowing which accessories are right for your boiler and your home will ensure a more efficient system, and a more comfortable home.
Like air, water will want to expand when it is heated. In a closed system, this will cause system pressure to increase rapidly, unless the water is given a volume to expand into. If left uncontrolled, this increase in pressure can lead to property damage, injury, or even death. An expansion tank is the most common way to control and prevent this pressure rise during normal operating conditions.
The most common expansion tank design consists of a closed tank with a diaphragm or bladder splitting the tank into two sections. One side of the tank is filled with air and pressurized to match desired system conditions. The tanks come pre-charged from the factory, but often include a valve allowing the pressure to be adjusted for different applications. The other side of the tank is where water from the system will enter as it expands. The diaphragm acts as a barrier to keep the air and water from mixing. As the water increases in volume it displaces and compresses the air within the tank. Because air is much more easily compressed than water, this allows the system pressure to increase in a controlled, predictable, and safe fashion.
Expansion tanks are sized based on the amount of water contained within the system, the change in temperature of the water, and the maximum acceptable pressure within the system. The appropriate expansion tank can also be estimated based on the type of heat emitters used and the output of the heat source. For radiant systems, required expansion tank volume can be estimated from the diameter and total length of tubing installed. If your system has a larger water volume than is typical due to a storage tank, buffer tank, or exceptionally long piping runs, the sizes in the chart below may not be large enough to adequately protect your system.
|Type of Heat Emitter|
|Boiler output in BTU/hr.||Finned Baseboard or Panel Radiators||Hydronic Fan Coils |
or Unit Heaters
|Cast Iron |
|Cast Iron |
|Based on Average Water Volume, 12 PSI Fill Pressure, 30 PSI Relief Pressure, and 200° F Max Temperature|
|Nominal PEX Tubing Size|
|Based on water-filled system with 12 PSI Fill Pressure, 30 PSI Relief Pressure, and 120° F Max Temperature|