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How does one heat a hot water cylinder to the recommended 60 deg (for legionella) with a sub 60 flow temp?

Immersion heater

Legionella is only a problem for infrequently used systems. If people in your house shower every day you don’t need to bother. If you’re a stickler for this sort of thing,or this is a holiday home or is otherwise unoccupied for weeks on end, then follow the official advice and “pasteurise” the tank to 60℃ once a fortnight. If your HP source isn't capable of this then you need to use an immersion.

But in the real world: don’t worry about it…

Thanks Folks.

Stinsy wrote: ↑Tue Dec 24, 2024 9:06 pm Legionella is only a problem for infrequently used systems. If people in your house shower every day you don’t need to bother. If you’re a stickler for this sort of thing,or this is a holiday home or is otherwise unoccupied for weeks on end, then follow the official advice and “pasteurise” the tank to 60℃ once a fortnight.

... and then run each shower until scalding water comes out of the shower head? I thought it was the lower-temperature water in the distribution legs (and maybe the shower heads too) which provided the home for the bugs to grow?

AE-NMidlands wrote: ↑Wed Dec 25, 2024 9:13 am

Stinsy wrote: ↑Tue Dec 24, 2024 9:06 pm Legionella is only a problem for infrequently used systems. If people in your house shower every day you don’t need to bother. If you’re a stickler for this sort of thing,or this is a holiday home or is otherwise unoccupied for weeks on end, then follow the official advice and “pasteurise” the tank to 60℃ once a fortnight.

... and then run each shower until scalding water comes out of the shower head? I thought it was the lower-temperature water in the distribution legs (and maybe the shower heads too) which provided the home for the bugs to grow?

Like I say, don’t stress it. Legionaries really isn’t a risk in domestic installations that are used. But yes if you have “dead legs” that aren’t used and you don’t run the taps getting the hot water to every outlet, then pasteurising the tank is a pointless waste of time and energy…

The reason for the question is that we have 2 showers, 2 basins and a bath that rarely get used because of the distance from the tank and the waste of 'hot' water before the rise in temperature. Most of our CH is in micro bore behind plaster board and the radiators struggle with a 60 deg flow temp. We're both 74 and no kids so we'll probably stay with oil and avoid the major disruption just to benefit our chosen charities. Currently we use a shower just inside the back door, we had 10,000 laying hens, so when we come in covered in c**p we can dump the clothes straight into the washing machine, shower and then dress in front of the Rayburn, no near neighbours I hasten to add.

Thebeeman wrote: ↑Wed Dec 25, 2024 10:54 am The reason for the question is that we have 2 showers, 2 basins and a bath that rarely get used because of the distance from the tank and the waste of 'hot' water before the rise in temperature.

I decided not to worry about this as it's still heat from the lowest-price fuel available to me and if it dissipates into the house that is less work for the CH... [Edit - and the solar thermal tubes do a lot of the work a lot of the year too, of course.] I know the "old" rules were to cut water wastage while you wait for the hot to arrive, but I just open the hot tap full bore straight away to avoid a gradual warming up from mixing en route (don't know if that is rational or not) and we are still low-volume users: every bill tells us we are using half of what an average 2-person household does. (we are similarly in our 70s still in the family house, but don't have a shower!)

Most of our CH is in micro bore behind plaster board and the radiators struggle with a 60 deg flow temp.

Do you have any zoning? I didn't bother with it on the heating side of our (gas) small-bore system (which has 28mm main flow until it reaches the airing cupboard where the cylinder/bathroom radiator feed splits off) but I did fit motorised valves for both CH and HW. CH off means that I can get the HW as hot as I want...

Sorry for the delayed reply, something got in the way.
When we had the bungalow built we had thermostatic valves on all radiators and motorised valves on CH and DHW. The DHW pipework is 22mm and CH is 22mm to 15mm dropping to 8mm behind plasterboard. As we replace radiators due to external rust or moving a wall we are installing vertical tubular of a larger output.

Thebeeman wrote: ↑Thu Dec 26, 2024 12:21 pm Sorry for the delayed reply, something got in the way.
When we had the bungalow built we had thermostatic valves on all radiators and motorised valves on CH and DHW. The DHW pipework is 22mm and CH is 22mm to 15mm dropping to 8mm behind plasterboard. As we replace radiators due to external rust or moving a wall we are installing vertical tubular of a larger output.

sounds as though it should be straightforward to turn the cylinder stat right up and tell the heating to stay off, then when the water's scalding run each tap in turn full bore - just until it's too hot to bear.