Radiant Heat Manifolds
Brass or Stainless Steel Radiant Heat Manifolds are an essential component of any radiant heating system.
Each radiant heat manifold package (set) has (1) supply manifold, (1) return manifold, all factory pre-assembled, pressure tested and includes other vital system components such as manual balancing valves and flow indicators for every circuit, automatic air vent on each manifold, drain valves, shut-off ball valves, temperature gauges and mounting brackets.
Radiant heating manifolds are suitable for a wide range of installations, such as for concrete slabs, staple-up systems, in-floor heating systems, baseboard radiators and more.
Manifold's outlets are at 2" OC (On Center). Maximum flow per branch is 1.4 GPM (Gallons Per Minute)
1/2" PEX compression adapters are included with every radiant heat manifold set by default. To replace with 3/8" or 5/8" PEX adapters - include a message at the checkout page.
Manifold on the picture is an SSM103 radiant heat manifold set.
To select a proper size radiant heat manifold, match the number of PEX tubing circuits (loops) in the system with the branch size of the manifold. General recommended installation practices for radiant heating applications are:
200-250ft for 3/8" PEX tubing per circuit.
300-350ft for 1/2" PEX tubing per circuit.
400-500ft for 5/8" PEX tubing per circuit.
For Snowmelt applications:
250ft for 5/8" PEX tubing per circuit.
300ft for 3/4" PEX tubing per circuit.
For instance, a 900 sq ft area, with 1/2" PEX tubing installed at 9" OC (On Center) spacing, will require approximately 1200ft of 1/2" tubing. Divide this number by recommended length per circuit: 1200 / 300 = 4. If number has a decimal, round it up to the nearest value. Number 4 indicates that the radiant heat system requires a 4-branch radiant heat manifold set. Dividing the total length of tubing by number of branches and you will have an average tubing run per circuit: 1200 / 4 = 300ft.
Proper installation of a radiant heat manifold will guarantee the best system performance. Radiant manifold with balancing valves is the return manifold and it should be the one on top. Supply manifold is the one with flow indicators (flow meters) and it should be the one on the bottom.
One of the advantages of the mounting system is that it offsets the radiant heat manifolds from the wall and allows for more convenient access, maintenance and easier PEX Tubing installation. Flow indicators also serve the purpose of secondary valves and can be adjusted to increase or decrease the water flow. By default, shut-off ball valves are 180 degrees (straight). 90 degree valves (angle) can be purchased to upgrade the manifold.
Manual balancing valves on the return radiant heat manifold allow to adjust the water flow through a selected branch from 0% to 100%. Since radiant manifolds often service several zones (i.e. rooms), and it is nearly impossible to have all circuits to be the same length, flow through the manifold's branches should be adjusted, so that each circuit gets the proper amount of hot water.
In order to automatically control the hot water flow for each branch, radiant heat manifold actuators (automatic balancing valves) have to be installed. If the manifold serves a single zone (i.e. one large room, a warehouse or a garage), actuators are not required and a single zone valve can be used instead.
Note that this radiant heat PEX manifold type can be installed upside down, where PEX tubing outlets are pointing upwards, which is convenient when manifold is located in the basement and is heating the floor above. However, air vents would need to be kept closed and a separate air elimination device would have to be installed.
Q: Why is the return manifold shown on top and the supply on the bottom?
A: If PEX tubing is installed on the same level or below the level of the manifold station, the air will always try to escape to the highest point in the system, which is the return manifold. If the manifold system is in the basement, the supply manifold should be the top one.
How to shop for a Radiant Heat Manifold.