Pipe runs are simplified compared to the previous option, with only two pairs of pipes running in the riser. A more efficient utilization of the solar panels is also possible, often reducing the overall cost of the solar installation.
However, there are disadvantages to this type of solar heating system in some situations.
The need for a plant room means giving up valuable habitable space, the centralised hot water needs to be distributed to the dwellings - either free of charge (with a risk of over-use) or requiring metering. Heat losses from the hot water circulation can be high.
This type of system is generally most suitable for buildings where a centralised heating system is acceptable such as Extracare, hotels and healthcare buildings. (See Case Study 003 here)