|It is possible to treat a radiant loop the same as any other hydronic
system by circulating the hot water as the thermostat calls for heat, but it is not recommended.
Constant circulation through the loops will keep the floor an even temperature and prevent
cold spots from forming when there is no call for heat. It also helps keep air out of the
system as well as reducing the risk of freeze up in applications where a domestic hot water
is used as the heat source and anti-freeze cannot be used.
Sophisticated control units on the market sense indoor and outdoor temperatures and adjust
the temperature of the water in the loops to keep the floor warm enough for comfort with
minimal cool down. This type of control will also adjust the boiler temperature accordingly
for fuel conservation. Another function is injection or mixing hot water into the return
water to prevent shocking the boiler with a surge of cold liquid.
Non-Electronic controls use a thermostat for the primary heat call that actuates a zone
valve and/or circulator to feed hot boiler water to a mechanical control that uses a sensing
bulb with a capillary tube to meter the hot water into the distribution manifold.
Many brands of manifolds are available that can be customized to any application. If individual
valves for each loop are not built into the manifold, ball valves should be added so that
each loop can be flow adjusted to balance the system.
Custom distribution manifolds can be made to order that include the circulator, automatic
zone valves, a control panel with indoor and outdoor sensors, supply and return water sensors,
and individual adjusting valves, nicely packaged on a frame for ease of installation. These
appear expensive at first glance, but if one adds up all the components and the time it
takes to construct it from scratch, the price is understandable.