National Oilheat Research Alliance 15 to as a “branch header system”. When there are multiple zones, each loop is piped parallel to each other, but the loop itself is series piped. Advantages • Requires less pipe and fittings than other systems • Relative lower cost to install • No special valves or fittings required Disadvantages • Temperature at the first heat emitter is significantly higher than what is supplied to the last heat emitter. Rooms at the beginning of the loop may over-heat while rooms at the end may under-heat. Care should be taken when sizing and selecting the heat emitters due to the temperature drop of the fluid and the heat output of the emitter with reduced temperatures. A split series loop (Figure 2) system overcomes some of the disadvantages of a standard series loop by dividing the radiation into separate zones. These systems have either a common supply or a common return and literally “split” the radiation into separate zones. These two “loops” can be on the same zone or split into separate zones, each with its own balancing valve, thermostat and/or zone valve/circulator. Advantages • Better control of temperature and thus more comfortable than a standard series loop. • Smaller diameter pipe can be used due to shorter runs. Disadvantages • Requires additional pipe, fittings and components. • Slightly more expensive to install Figure 2
NORA Advanced Hydronics
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