Question about Boiler water heating temperature

FreeBear

Scot_39 said: Checking Scot gov website there were seemingly 44 recorded cases last year in a population of over 5 million - which was up on Covid and precovid levels - but no breakdown of likely domestic vs industrial sources. 

https://publichealthscotland.scot/news/2023/august/slight-increase-in-legionnaires-disease-incidence-in-scotland-in-2022/

Some takeaway points from that report -

• Legionnaires' disease cases were observed to peak in Q3 (July to September) of each year from 2017 to 2022. This was driven largely by travel-associated cases, highlighting the peak travel season over summer months. This trend was also observed during quarter three of 2020 and 2021, during which time COVID-19 travel restrictions were reduced.
• Travel-associated Legionnaires' disease accounted for most cases (59.4%) during the period 2017 to 2022, consistent with previous years. During 2020 and 2021, the proportion of travel-associated cases was less than community-acquired cases, reflecting reduced travel due to lockdown restrictions.
• Between 2017 to 2022, there were nine deaths in Legionnaires' disease cases equating to an average case fatality rate (CFR) of 5% and a range of 0% to 15% in this period. In Europe, CFR for Legionnaires' disease cases was reported to be 9% in 2021.

The risk of contracting legionella domestically is so small, one has to question the levels of hysteria associated with it. Plenty of other interesting ways of dying that no one seems to concern themselves about. Then there are the mundane preventable deaths that hardly ever get a mention - e.g. Deaths from road accidents which seem to kill a disproportionate number of younger people.

daveyjp

My combi hot water is set to a temperature where I can wash hands with no discomfort.  Having it hotter than that to then need cold water makes no sense,  This is mid 40s degrees C.

Scot_39

Yes one suplier site I found suggested 46C min iirc.

But that wouldn't necessarily get a low risk lra assessment report - for the OP as a landlord.

As hse specifies 50C - at outlet - for instance in its low risk scenarios section for landlords.

My HW from tank was running at 58C last night by time kitchen sink basin filled - running it over a kitchen meat thermometer - far too hot for prolonged skin contact.


Most of the cold though at start of basin fill was from pipe run from tank to tap - in litres in many even smallish houses depending on relative locations.

But then arguably that x litees hot remaining in pipe run wasted heat in summer - combined with tank heat losses - why other forms of water heater in use these days. 

And why modern plumbing regs iirc insists on thermostatic mixer taps or valves etc. Quick google of few sites suggest those limitting flow to c48C in general 44C in care  - despite iirc an often higher 55C at outlet hse limit.  48 44 Maybe not uk numbers.

Scot_39

FreeBear said:

Scot_39 said: Checking Scot gov website there were seemingly 44 recorded cases last year in a population of over 5 million - which was up on Covid and precovid levels - but no breakdown of likely domestic vs industrial sources. 

https://publichealthscotland.scot/news/2023/august/slight-increase-in-legionnaires-disease-incidence-in-scotland-in-2022/

Some takeaway points from that report -

• Legionnaires' disease cases were observed to peak in Q3 (July to September) of each year from 2017 to 2022. This was driven largely by travel-associated cases, highlighting the peak travel season over summer months. This trend was also observed during quarter three of 2020 and 2021, during which time COVID-19 travel restrictions were reduced.
• Travel-associated Legionnaires' disease accounted for most cases (59.4%) during the period 2017 to 2022, consistent with previous years. During 2020 and 2021, the proportion of travel-associated cases was less than community-acquired cases, reflecting reduced travel due to lockdown restrictions.
• Between 2017 to 2022, there were nine deaths in Legionnaires' disease cases equating to an average case fatality rate (CFR) of 5% and a range of 0% to 15% in this period. In Europe, CFR for Legionnaires' disease cases was reported to be 9% in 2021.

The risk of contracting legionella domestically is so small, one has to question the levels of hysteria associated with it. Plenty of other interesting ways of dying that no one seems to concern themselves about. Then there are the mundane preventable deaths that hardly ever get a mention - e.g. Deaths from road accidents which seem to kill a disproportionate number of younger people.

Thanks only read the headlines, not the detail.

It's an even smaller risk domestically than headline 44 clearly - but the OP - as a Scottish landlord - has to comply with having the check or doing own assesment every 2 years.

It's not a user generated "hysteria" but a government mandated one arguably.

One which HSE has applied to commercial firms for years - and considers landlords as link above subject to.

That landlords guidance link looks like uk wide, the need to formally document it every 2 years - possibly Scottish only - not sure as I'm not a landlord ?

JSHarris

Scot_39 said:

FreeBear said:

Scot_39 said: Checking Scot gov website there were seemingly 44 recorded cases last year in a population of over 5 million - which was up on Covid and precovid levels - but no breakdown of likely domestic vs industrial sources. 

https://publichealthscotland.scot/news/2023/august/slight-increase-in-legionnaires-disease-incidence-in-scotland-in-2022/

Some takeaway points from that report -

• Legionnaires' disease cases were observed to peak in Q3 (July to September) of each year from 2017 to 2022. This was driven largely by travel-associated cases, highlighting the peak travel season over summer months. This trend was also observed during quarter three of 2020 and 2021, during which time COVID-19 travel restrictions were reduced.
• Travel-associated Legionnaires' disease accounted for most cases (59.4%) during the period 2017 to 2022, consistent with previous years. During 2020 and 2021, the proportion of travel-associated cases was less than community-acquired cases, reflecting reduced travel due to lockdown restrictions.
• Between 2017 to 2022, there were nine deaths in Legionnaires' disease cases equating to an average case fatality rate (CFR) of 5% and a range of 0% to 15% in this period. In Europe, CFR for Legionnaires' disease cases was reported to be 9% in 2021.

The risk of contracting legionella domestically is so small, one has to question the levels of hysteria associated with it. Plenty of other interesting ways of dying that no one seems to concern themselves about. Then there are the mundane preventable deaths that hardly ever get a mention - e.g. Deaths from road accidents which seem to kill a disproportionate number of younger people.

It's an even smaller risk clearly - but the OP - as a Scottish landlord - has to comply with having the check or doing own assesment every 2 years.

It's not a user generated "hysteria" but a government one.

As some view the Scottish requirements on interlinked heat and fire alarms in multiple rooms, rather than individual units.  So £50 - maybe 4 for for a 3 bed - rather than a couple of cheapish sub £20 battery ones advised in rest of UK - unless of course a private landlord.

It is a government created hysteria, as the risk from domestic hot water supplies is vanishingly small.  There are around an average of 250 cases of Legionella in the UK each year, and it has a typical mortality rate of about 10%.   None have ever been traced to domestic hot water supplies.  Most common sources in a domestic setting are hot tubs.  Other than that the cause is mostly from public buildings and places of work, usually associated with commercial scale air conditioning systems, plus some cases where there are people that are more vulnerable, like care homes and even hospitals.  A good example of the large scale water system risk is the recent Legionella case on the Bibby Stockholm barge moored at Portland.  This had been out of commission for months before being towed there and set up to house migrants.  In that time Legionella had got into the systems on the barge and multiplied as soon as the conditions were right (Legionella multiplies in water that's between 20°C and 45°C).

The main reason that Legionella tends to thrive in larger, commercial scale, systems has to do with the combination of dead areas in pipework and water storage, as well as open access (via vents, open tanks or evaporative water coolers etc).  Domestic hot water systems usually have water flowing through them regularly, and most modern systems are effectively sealed from the open air so the residual chlorination in most mains water supplies tends to inhibit Legionella growth, even if they don't get to a high enough temperature to kill the bugs off.  

The exception to this would be a hot water system that's been left for a week or two, say when people are on holiday, when there is a small chance that Legionella could multiply, but then there has to be a means for legionella to get into the system in the first place.  The primary mechanism for allowing Legionella into a plumbing system is homes with an open cold water tank that supplies the hot water system.  Homes with closed domestic hot water systems (i.e. combi boilers and homes with pressurised and sealed hot water tanks) don't have a path for Legionella to get into the system in the first place.  It's not going to get in via the disinfected mains cold water supply, so with no open transmission path such systems are very unlikely to ever become infected.

BikingBud

JSHarris said:

Scot_39 said:

FreeBear said:

Scot_39 said: Checking Scot gov website there were seemingly 44 recorded cases last year in a population of over 5 million - which was up on Covid and precovid levels - but no breakdown of likely domestic vs industrial sources. 

https://publichealthscotland.scot/news/2023/august/slight-increase-in-legionnaires-disease-incidence-in-scotland-in-2022/

Some takeaway points from that report -

• Legionnaires' disease cases were observed to peak in Q3 (July to September) of each year from 2017 to 2022. This was driven largely by travel-associated cases, highlighting the peak travel season over summer months. This trend was also observed during quarter three of 2020 and 2021, during which time COVID-19 travel restrictions were reduced.
• Travel-associated Legionnaires' disease accounted for most cases (59.4%) during the period 2017 to 2022, consistent with previous years. During 2020 and 2021, the proportion of travel-associated cases was less than community-acquired cases, reflecting reduced travel due to lockdown restrictions.
• Between 2017 to 2022, there were nine deaths in Legionnaires' disease cases equating to an average case fatality rate (CFR) of 5% and a range of 0% to 15% in this period. In Europe, CFR for Legionnaires' disease cases was reported to be 9% in 2021.

The risk of contracting legionella domestically is so small, one has to question the levels of hysteria associated with it. Plenty of other interesting ways of dying that no one seems to concern themselves about. Then there are the mundane preventable deaths that hardly ever get a mention - e.g. Deaths from road accidents which seem to kill a disproportionate number of younger people.

It's an even smaller risk clearly - but the OP - as a Scottish landlord - has to comply with having the check or doing own assesment every 2 years.

It's not a user generated "hysteria" but a government one.

As some view the Scottish requirements on interlinked heat and fire alarms in multiple rooms, rather than individual units.  So £50 - maybe 4 for for a 3 bed - rather than a couple of cheapish sub £20 battery ones advised in rest of UK - unless of course a private landlord.

Most common sources in a domestic setting are hot tubs. 

I often wonder what else is growing in the primordial soup of hot tubs!

JSHarris

BikingBud said:

JSHarris said:

Scot_39 said:

FreeBear said:

Scot_39 said: Checking Scot gov website there were seemingly 44 recorded cases last year in a population of over 5 million - which was up on Covid and precovid levels - but no breakdown of likely domestic vs industrial sources. 

https://publichealthscotland.scot/news/2023/august/slight-increase-in-legionnaires-disease-incidence-in-scotland-in-2022/

Some takeaway points from that report -

• Legionnaires' disease cases were observed to peak in Q3 (July to September) of each year from 2017 to 2022. This was driven largely by travel-associated cases, highlighting the peak travel season over summer months. This trend was also observed during quarter three of 2020 and 2021, during which time COVID-19 travel restrictions were reduced.
• Travel-associated Legionnaires' disease accounted for most cases (59.4%) during the period 2017 to 2022, consistent with previous years. During 2020 and 2021, the proportion of travel-associated cases was less than community-acquired cases, reflecting reduced travel due to lockdown restrictions.
• Between 2017 to 2022, there were nine deaths in Legionnaires' disease cases equating to an average case fatality rate (CFR) of 5% and a range of 0% to 15% in this period. In Europe, CFR for Legionnaires' disease cases was reported to be 9% in 2021.

The risk of contracting legionella domestically is so small, one has to question the levels of hysteria associated with it. Plenty of other interesting ways of dying that no one seems to concern themselves about. Then there are the mundane preventable deaths that hardly ever get a mention - e.g. Deaths from road accidents which seem to kill a disproportionate number of younger people.

It's an even smaller risk clearly - but the OP - as a Scottish landlord - has to comply with having the check or doing own assesment every 2 years.

It's not a user generated "hysteria" but a government one.

As some view the Scottish requirements on interlinked heat and fire alarms in multiple rooms, rather than individual units.  So £50 - maybe 4 for for a 3 bed - rather than a couple of cheapish sub £20 battery ones advised in rest of UK - unless of course a private landlord.

Most common sources in a domestic setting are hot tubs. 

I often wonder what else is growing in the primordial soup of hot tubs!

Many years ago I remember going up into the loft to replace the float valve in the cold water tank (which had a plastic lid over it) and discovering the remains of a bird at the bottom of the tank.  Goodness only knows how it had first got into the loft and then found it's way into the tank.  Wasn't pleasant thinking that we'd been showering, washing dishes, etc, in that water.  None of us got ill though . . .

MultiFuelBurner

For safety if you have a water tank then scorch that water if you have a sealed system you can laugh at the high temperatures and energy wastage people go through for the miniscule risk of Legionella.

Legionella burn set for every two weeks on our invented system and only to 55oC for 2 hours in the afternoon for maximum heat pump efficiency and at the weekend when generally tracker prices are low. Reason being heat pumpers no auxillary backup inefficient electric heaters required infact our system can get the water to 57oC without backup help (just for info for anyone interested)

matelodave

watch this - https://www.heatgeek.com/hot-water-temperature-scalding-and-legionella/

Reed_Richards

So perhaps when you have finished taking a hot or warm shower you should turn the temperature to cold to flush out any warm water remaining in the shower head?  Personally, I would get out of the way when doing this but some say a brief exposure to cold water has health benefits.