Thanks for the reply. The bypass has a gate valve on it.
Re stat: I am happy enough to instal this myself but just wandered if there was any reason not to have one.
1. When we discussed the initial installation, they pondered how to do it and suggested programmable stats for up/downstairs. I was happy with this. Final instal had new 3 channel programmer and no upstairs stat.
2. Yes, 15mm pipe to cylinder. Eixisting 28mm gravity cirulating pipes retained...
We have recently had our heating system upgraded (new radiators and conversion from gravity hot water to fully pumped system). In doing this we took the opportunity to have the heating zoned for upstairs/downstairs.
Everything works well but I would welcome thoughts on the following:
1. No...