Why use an s plan ? get rid of the 3 port and just have a two port controlling the hot water, the op hasn't wired a hot water off so the valve will stay in ch, probably find his boiler has shut down of the overheat stat.
Thanks, I was worried about that but read that without power, the spring will trigger and return the mid position back to HW. If this is not correct, I will look for a different solution with ensures it does.Why use an s plan ? get rid of the 3 port and just have a two port controlling the hot water, the op hasn't wired a hot water off so the valve will stay in ch, probably find his boiler has shut down of the overheat stat.
Worth noting, that no extra zones have been added and the unvented cylinder was added previously, though of course should have had a 2 port, which would've made life much easier for me!They will stay at CH only if that is the last option selected, a position which has the motor powered continuously to waste electricity and shorten the life of the motor. That only lasts until HW is selected again.
Otherwise it will return to HW only.
Y plan is obsolete, and as mentioned above should be replaced with S plan where extra zones or an unvented cylinder is added.
No new system should be installed using Y plan.
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