Baldseagull
Well-known member
I'm, not following your Q - 'They' ?
Ref 50 deg cylinder - yes you can do that but under approx 55 degC is a good temp for legionella/bacteria growth, so we keep above to kill it off. Some boilers and heat pumps have a weekly anti legionella program built in to do this.
The other side to this with heat only/system (single temp) boilers is that rads in your house are currently designed for 70deg flow temp. A room with heat loss of say 1kw should have a rad with output of 1kw+; Once you start dropping the flow temp, that rad doesn't give out 1kw; at 50deg flow temp it's more like 500w and a probability your room will be cold in winter.
By they, I mean other condensing boilers than Combi condensing boilers.
The rads on the system are no different to the rads on a combi boiler system are they?
If the only issue is legionella or other bacteria, I think I will risk it with a copper tank and pipework, plus I have solar which hits the immersion set to 70 when it can, but it makes sense why it isn't recommended for non combi boilers, from a safety point of view, rather than the efficiency can't be improved.