x-plan and ABV

[lloyd]

I've always wondered if a system that is x-plan needs an automatic bypass? As there is always a path through the pipework, even if all TRVs have closed, what benefit does a ABV give?

[Richard]

X Plan doesn't require an ABV, but that is assuming you do have an open radiator (normally we don't control the towel rads when fitted). If you do have TRV's on all rads, and they are all closed, if the central heating water cannot flow around the system, what stops the boiler overheating? You will find most boiler manufacturers require a minimum flow rate through the boiler heat exchanger, and this is what the ABV is for.

[lloyd]

Surely the water still flows if all radiators are shutdown, it just flows around the pipes. Or are you saying the flow rate is too low.

[Richard]

Surely the water still flows if all radiators are shutdown, it just flows around the pipes. Or are you saying the flow rate is too low.

Heating systems don't work like this. They are piped in parallel so no flow through TRV's = no flow at all.