I posted back in January looking for (and getting, thanks) advice about upgrading a very basic CH installation in a new home in Ireland.
I'm now in the process of doing the upgrade and I'd appreciate some more advice about whether I need a differential bypass valve. The system is currently the very basic installation described at the start of the "Valves" section in the FAQ. The boiler (an external WarmFlow boiler) does not require pump over-run. The system is currently controlled by a mechanical timer. There is a ball-valve to shut off the CH zone when no heating is required and a gate valve to shut off the HW cylinder.
My plan (as per the advice received here), is to install a 2-channel
7-day timeswitch, 2 motorized valves, cylinder stat and room stat, with S-plan type wiring. At the same time, I will install TRVs on all the radiators, except for the two radiators in the hall and landing (which I'm treating as one room) where the room stat will be.My question is, given that there is no need for a pump overrun, will the two rads without TRVs be sufficient as a bypass, or do I need an additional bypass valve in the circuit before the motorized valves?
Cheers, Jonathan