In an earlier contribution to this discussion,
Christian McArdle wrote:

Whether or nor you need a by-pass depends on a number of factors.
Does your boiler have a pump over-run stat, and is the pump
connected to it? Do you have an S-Plan (2 x 2-port zone valves)
system or a Y-Plan (3-port mid-position valve) system?

Very unlikely, as it is a combi boiler...

Christian.

Fair point - I had overlooked the "combi" reference. It is likely,
therefore, with no zone valves and one permanently-on rad, that a by-pass
*isn't* required.

I was more concerned (in the part of my post which you didn't quote) with
the fact that a TRV had been removed, but that there was no mention of a
room stat.
--
Cheers,
Set Square
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