System Zoning Questions

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Can I control different areas of the house?

Yes indeed. Your radiant heating system can be designed with separate “automatic zones” of control which can also have “sub-zone” controls for individual rooms and circuits within a zone. Each zone in a house will have a manifold location which serves as the junction point for individual tubing circuits. Each tubing circuit will have a balance valve installed at the manifold which allows the sub-zone balancing. These additional controls exist to provide you lasting comfort even if your heating needs change for particular areas.


What is "zoning" and how many of these can I have?

Zoning refers to separating the system into different areas of thermostatic control. A separate thermostat works in conjunction with a zone valve which open and closes upon heating demand to allow the flow of water through the heating circuit. Zoning is usually recommended for every 2-4 rooms or every 700-1000 square feet of living space in new construction. Through zoning the system can be custom tailored to meet the customers heating needs and increase efficiency at the same time.

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How much tubing can go in one zone? Do all the loops need to be the same length?

The length of tubing within a zone is generally determined by the size and pattern of the tubing used. Considering overall system design, the goal is to keep the flow rate through the individual tubing circuits as close as possible. For areas requiring different lengths of tubing, different nominal sizes are available to keep the flow rate consistent. Standard system design incorporates a 1-2 gallon per minute flow through each tubing circuit. This is in accordance with maintaining an ideal design length set for each size of tubing. For instance, we do not design 3/8" copper circuits to be over 150’ in length, 1/2" circuits over 200’, and 3/4" circuits over 300’ in length. If a tubing circuit of the same size and length has more bends resulting in more resistance, then sizes are affected as well. Copper radiant panel design really lends itself well towards this accomplishment. Since joints can be welded inside the slab, main supply lines and circuit connection points can be placed at any place the design suggests. Plastic and rubber piping systems do not allow joints in the slab and proceed to manifold locations regardless of length. Plastic and rubber systems can also be designed for similar flow standards if ample supply and return manifold locations exist; however, many systems are designed concentrating on the manifold systems to balance flow rather than the design. The largest problem with the tubing design is excessive circuit length. If circuits are too long, the warm water at the supply entrance is too cold by the time it reaches the end of the loop for affective heat transfer. This can lead to spotty heating which is unacceptable for exposed floors. Some plastic and rubber installers design circuit lengths up to 500 feet or more with 1/2" tubing. The long and short of it is, for most residential purposes, an unlimited amount of tubing can go in a zone, as long as it designed properly for the flow rate. Many residences are controlled by just one thermostat and work fine.

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Do I need a thermostat in every room?

No. A system can be designed as such but we do not recommend it. When you start over controlling a house with thermostats in every room, you complicate the system and increase your service and maintenance costs. More thermostats and more zone valves equal more moving parts, more electronics, and more potential for problems. A normal residential boiler system does not require a storage buffer tank for radiant panel water and distribution but rather has just a boiler. Unless additional system equipment is installed, a single room zone operation can lead to system problems like the boiler over firing, short cycling, and inefficiency. We do recommend taking advantage of the zoning ability of a radiant panel system. Usually we recommend having a thermostat for every 700-1000 square feet of living space. This equates to every 2-4 rooms. Realize each thermostat which controls a zone and manifold has balancing valves for each circuit within the zone. This means every room can be regulated manually without having a thermostatic control. Some homes have only one zone of control for the whole house. Proper system design that takes into effect heat loss, infiltration, circuit length and flow rate, will allow a central thermostat to control the space without the inside temperature of the home varying more than a degree or two from room to room. Some system installers rely on individual thermostat control to compensate for the lack of system design for keeping the areas evenly heated. Of course each system design requirements are different so reviewing your plans is essential to the decision making. Some situations may actually lend preference to individual room control such as multi-tenant housing.

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How would you normally zone a house?

The system zoning really depends on the particular house, floor finishes, and owner requirements. As a minimum, we suggest controlling the bedroom areas separate from the living areas of the house. Further zoning recommendations may increase as the size of the house increases. Also certain floor finishes, such as exposed tiles and carpet with padding, have different insulating properties and might affect zoning areas. If certain areas of the home receive more sunlight than others, we would suggest additional control as well. On an average we normally add a zone for every 700-1000 square feet of living space or every 2-4 rooms.

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ANDERSON RADIANT HEATING
520 East McGlincy Lane, Suite 16
Campbell, CA  95008
Phone: (408) 378-3868
Fax: (408) 559-0818

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