TonyL

Further to my post, anyone seeking to use a six port valve to switch a heat pump between differnent destinations also needs to consider the pressure in the pipework as the valve effectively creates two seperate systems (with some common pipework that includes the heat pump). Normally a single expansion vessel would be used to accomodate the expansion and contraction of the circuit operating through the heat pump. While there is a single circuit, a single expansion vessel (if appropriately sized) will be fine, but using a six port valve would seem to need at least one appropriately-sized expansion vessel per seperate system. The Johnson Controls valve lacks a seal at the OFF position that can be used for isolation, and this provides a degree of protection against over-pressure. In theory, this would allow any overpressure at the heat pump to be disippated to a expansion vessel in either of the two systems, but this only works when the valve is used to isolate the heat pump from both systems. For safety, I am inclined to add a third expansion vessel on the common piping to the heat pump.

I arrived here looking for information on the same application that OP was interest in. I came across a new Johnson Controls six-port valve that would appear suitable. I know the OP will have solved their problem by now, but wanted to leave some details here in case others found it useful. The valves are VG1611BL (3/4") and VG1611AF (1/2"), and the actuator is VA9905-KGA-1. www.hvac-sanitary.co.uk have them in stock, and the price for the 3/4" valve and actuator is about £450 (inc VAT). This valve is somewhat novel in that it rotates 270 degrees to switch between the sources/destinations. Johnson Control have a video on YouTube that explains how this allows them to get more flow through the valve than competitor products. Not cheap, but a good solution if you need to switch both the flow and return lines of your heat pump between two destinations.