Worcester Bosch Junior 28i Internal Bypass

[SplanK]

Hello,
I am about to fit some TRV valves to the remainder of my radiators bar 2 (downstairs loo and upstairs hall rad). These rads are small and I don't mind them being on at any point when another room is heated. I would however like to keep their flow rate a minimum where possible, but also aware that a auto bypass valve maybe needed if I reduce the flow too much and if the HR92's close on the other rads...

I am reading that our combi (Worcester Bosch Junior 28i) has an internal bypass valve (as detailed in the installation manual). Are these internal bypass valves suitable for the job or are they more designed for emergency use and an external one should really be fitted?

Thanks

[Richard]

Last time I spoke to Worcester about their internal bypasses and evohome (S Plan Plus) they recommended external ABV's. We sell the best ones of course - https://theevohomeshop.co.uk/16-automatic-bypass-valves

[SplanK]

Ta, thought as much. Google is full of "it will be fine", but also others suggesting that regardless of internal they would fit an external like yourself.

I have come up with a plan, just wanted to double check.

I have 5 rads with manual valves as it stands (the others are HR92's). 3x bathroom rads (master, ensuite, loo room), 1x hall way and 1x landing..

I plan to change thing by doing the following:
2x HR92's (bathroom rads - master and ensuite)
1x Normal TRV (landing rad - going to see how this goes, cant justify the cost of a HR92 for this, but still want to try and prevent overheating/waste in the landing area)
2x manual valves (hallway and downstairs loo).

Hallway is a reasonable sized rad, and the loo is a small rad. All rads are on 10mm pipework. Hallway will be fully open and loo will be partially (quarter to half open). Presently it seems as though all lock shields are fully open (inherited it this way).

I appreciate that this question is more like "how long is a piece of string", but do you think this would be sufficient until such time I can get a auto bypass fitted?

[Richard]

I would think it will be sufficient for now, however the minimum flow rate of the boilers heat exchanger always needs to be catered for irrespective of pipe size or amount of rads left open circuit.