ReplyA heating system is going to transfer the same number of BTU/h regardless of the heat loss it is working against. The limitations of heat transferred includes the capacity of the heat source, the circuit surface area, thermal conductivity of all heating system components and and insulative properties of the flooring.Originally Posted by nevea2be
Adding an additional length of tubing in any or all circuits increases the radiant surface area of a circuit, giving the liquid more surface area and more time to transfer heat, regardless of the length of other circuits in that zone or the heat loss in that zone.
There is certainly a point of diminishing returns, for example, at some point a lengthened circuit will return the liquid at room temperature, and all extensions of length beyond that do not add any BTU/h to the room. When that point is reached is driven by the heat loss.
Electrical resistance is additive in series and reduces the amount of radiated heat by reducing the current, and therefore the wattage. Less watts, less heat.
Increasing a single circuit from the manifold gives the opportunity for more heat transfer up to the point where the liquid comes back at room temperature.
Each circuit from a given manifold is operating in parallel to the next. Increasing the length of every circuit increases the efficiency of heat transfer up to the ability of the heat source to keep up. Once the circuits are all lengthened to the point that all liquid is returning at room temperature, a larger heat source is required to increase the number of BTU's transferred per hour.
-HF
