Legionella, should I be worried?

[SMB]

I have a standard indirect vented hot water cylinder(gas boiler to coil & top mounted electric immersion heater) with a new covered & vented cold water tank in the attic.

We had solar pv panels fitted a couple of years ago and have just come across the IBost system that will divert excess electricity to the immersion heater.

This seems to produce almost all of the hot water that we need, but it only heats the top 1/3 to 1/2 of the cylinder. The lower section obliviously does not get heated at all.

So in these circumstances are we at risk of legionella problems?

If so, what is the answer.

Cheers.

SMB

 

[PlumbBobBob]

no, as long as you keep the tank stat at 60 degrees you will be fine. is your boiler still heating the water as well or just the immersion?

 

[SMB]

no, as long as you keep the tank stat at 60 degrees you will be fine. is your boiler still heating the water as well or just the immersion?

If the sun heats the water enough, most days, no the boiler is not used to heat the water.

 

[SMB]

no, as long as you keep the tank stat at 60 degrees you will be fine. is your boiler still heating the water as well or just the immersion?

thanks for your reply

The boiler is not used very much, as the pv gives us enough hot water for most of the time.
hence the tank at the bottom could be cold for several weeks.

 

[Dotty]

And in all honesty because of the frequency with which a domecile's hot water system gets used the likelihood of legionella developing is greatly reduced.

 

[townfanjon]

My aunty works for a social housing association , and has recently done an intensive course on legionella,
her conclusion to the course was , my team , huddersfield town have more chance of winning the European cup before somebody caught legionella through a domestic hot water system.
As said keep it at 60 degrees and you will be fine.

 

[GB123]

Post above is spot on, dont worry mate.

 

[AWheating]

if you wanted to be 100% cautious get a eco 7 cylinder and put bottom heater on a timer so once a week it def hits 60.

 

[chris watkins]

The posts above are what I thought until I started to do some reading on this a while ago.

Unfortunately just having the top part of the cylinder at 60deg C does not guarantee that the bugs that are able to live, grow & multiply at the base of the cylinder will be killed as they pass through this band, it has been found that the contact time is just not enough to do the job.

Add to this the unpredictable heat source which could often mean that the top goes cold but water is still drawn and there is I believe a danger.

 

[mooey]

Te posts above are what I thought until I started to do some reading on this a while ago.

Unfortunately just having the top part of the cylinder at 60deg C does not guarantee that the bugs that are able to live, grow & multiply at the base of the cylinder will be killed as they pass through this band, it has been found that the contact time is just not enough to do the job.

Add to this the unpredictable heat source which could often mean that the top goes cold but water is still drawn and there is I believe a danger.

Tbh I ve done a few course s this and it also depends on your age smoker or not and how good your respiratory system is, but for the avarage joe you ve got more chance of winning the lottery your body has to be in just the right condition and the droplet stroje spray would need to go straight into you lung without hitting anything at all

 

[mooey]

I work in a hospital and this is a high ridk area we have one guy that flushes taps all day every day.

 

[Reg Man]

I have air source heat pump heating much lower temperatures, so every Friday night the hot water gets boosted on the timer to reduce the legionella risk.

 

[Ermintrude]

I use crystal meth on all outlets once a month. Nothing left

 

[Reg Man]

Fatality rate is between 5-30% so why take the risk, to save money and having insufficient hot water. If you are worried about scolding, fit blending valves.

 

[Ermintrude]

And use copper pipe, bleach shower heads & hoses . Blend at point of use and get rid of tanks

 

[Dotty]

I use crystal meth on all outlets once a month. Nothing left

Ahhhhhhh!

THAT explains why you do what you do in your mother-in-laws wetroom. ....

The lack of control over your bodily functions should've been a giveaway.

 

[DrainMedic]

Is it a possibility for you to install a longer immersion element to heat more of the cylinder?

Apparently, legionella is dead in 30 mins at 60 deg, and in 2 mins at 65 deg. With this in mind, why not crank your cylinder temperature up and install a tempering valve on the outlet to reduce scalding risk.

Im not quite sure why, but mines set at 'steam' and has been for years. Thankfully, we've all got the reaction time of a traffic warden, so it's never been a problem.

 

[SMB]

Is it a possibility for you to install a longer immersion element to heat more of the cylinder?

Apparently, legionella is dead in 30 mins at 60 deg, and in 2 mins at 65 deg. With this in mind, why not crank your cylinder temperature up and install a tempering valve on the outlet to reduce scalding risk.

Im not quite sure why, but mines set at 'steam' and has been for years. Thankfully, we've all got the reaction time of a traffic warden, so it's never been a problem.

Can't fit a longer element, but will change the cylinder that has the element at the bottom.

Many thanks to all for your help.

SMB

 

[DrainMedic]

It would be cheaper to install a boss at the bottom for another element. I'll work out how to put a link up and do it in a minute.

 

[DrainMedic]

Toolstation.com part number 38614 (roughly £12)

Thats a mechanical immersion boss, where you drill a hole in the cylinder and bolt the thing in place.
There's another version, for soldering into place, depending on how good your soldering is. Either way, it would be advisable to remove the cylinder and drill/fix the boss outside where you can fill it afterwards and check for leaks etc without flooding the place.
Someone on here posted a pic a while ago of 6 immersions mounted in a cylinder, presumably using something similar to the above product. Don't go that mad, but an extra one will do no harm. You could always keep the original in there or even remove it and blank it off.

It's a nice Sunday project for you!

All the best

Dave

edit: I forgot to mention. If you do end up adding an immersion, don't drill into the cylinder where it might foul the coil inside.