Want a megaflow - can my old oil heater be a primary heat source?

[Madrab]

A 3 port, mid-position valve cannot be used as it won't necessarily close the hot water side of the circuit.

It can, it just means you also have to put a 2 port on the cylinder feed close to the cylinder that's controlled through the HL/cylinder stat.

Just for clarity - The G3 or UVHW cert, it is a stand alone qualification that is certified by specific bodies - BPEC/Logic/etc - as long as the installer holds that qualification they can install and notify that installation. If they don't belong to a competent members scheme they cannot self certify but can still notify directly through the LABC with it's associated costs and rules

If a qualified installer is registered with a competent members scheme - GasSafe/NAPPIT/others the installers can notify (self certify) UV installs at a nominal cost, that is then subsequently lodged with the specific LA and BC.

 

[MeldrewsMate]

Thanks @oldbuffer

@MeldrewsMate...The arrary I am installing is a 6KW PV with a 5KVA invertor. (Overspecced the arrary to improve winter capture)....

I most definitely approve of those extra panels, but beware of going too large in case the open circuit voltage (Voc) adds up to more than the inverter can handle.