Hope someone can help! Fitting Hive thermostats to a large home which has a fully pumped system with dual zone central heating and hot water cylinder running off a Potterton gas boiler.
Confused by the three 2-port valves which are on the flow side of the system immediately after the pump. Please see picture. I can understand the two horizontal valves as being for upstairs and downstairs zones but can’t figure out the need for the vertical valve which feeds into the two horizontal valves. There is also a fourth 2-port valve (not shown on pic) on the feed into the hot water tank coil as expected, making a total of four 2-port valves! Any help / advice appreciated and apologies for the poor quality picture.