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OK, so I may have this wrong (ducks and waits for the shells to arrive ) I'm starting this so that I too can learn...
As far I can can interpret, Domestic Installations are not coverd by the L8 guidelines
Also there is a special exemption from the Health and Safety Regs for renewable energy heated domestic Hot Water (DHW)
Heres' the document / legislation http://www.hse.gov.uk/pubns/priced/l8.pdf
and a recent report from WRAS New Page 2
and Preheated water report Sep 09
It would appear that the MCS standard also condones, not complying with L8
This artilce though rams home the messages and sanctioned loopholes' such as MCS etc with some good advice on how to control legionnella
Solar Video: Solar Legionella exemption. Cut Legionella risk in solar water heating in conventional twin coil solar cylinders. | Solartwin
and here:
Controlling legionella in solar-thermal systems - Modern Building Services
In summary if you decide controlling legionnella in a Domestic Environment is important to you then these would appear to be the solutions on offer:
(ful text of recommendations here http://www.solartwin.com/solartwin-features/technical/legionella-solar-water-systems-with-conventional-twin-coil-solar-cylinders
As far I can can interpret, Domestic Installations are not coverd by the L8 guidelines
Also there is a special exemption from the Health and Safety Regs for renewable energy heated domestic Hot Water (DHW)
Heres' the document / legislation http://www.hse.gov.uk/pubns/priced/l8.pdf
and a recent report from WRAS New Page 2
and Preheated water report Sep 09
It would appear that the MCS standard also condones, not complying with L8
This artilce though rams home the messages and sanctioned loopholes' such as MCS etc with some good advice on how to control legionnella
Solar Video: Solar Legionella exemption. Cut Legionella risk in solar water heating in conventional twin coil solar cylinders. | Solartwin
and here:
Controlling legionella in solar-thermal systems - Modern Building Services
In summary if you decide controlling legionnella in a Domestic Environment is important to you then these would appear to be the solutions on offer:
(ful text of recommendations here http://www.solartwin.com/solartwin-features/technical/legionella-solar-water-systems-with-conventional-twin-coil-solar-cylinders
1 – Zero cost and immediate:
The simplest is to stay clear of hot water spray. Take baths, not showers. ....
2 – Lower cost. (Usually under £100 if you already have an immersion heater in place)
Buy and fit a long immersion heater which is the full length of the cylinder and which will reach to the bottom.
Time this to come on at the end of the day to heat the whole cylinder to 60C.
3 – Medium cost. Requiring a plumber and electrician and keeping the cylinder: (£300-500) Have the twin coil cylinder fitted with a mains powered destratification pump which comes on:
Why? This will heat the cylinder daily to the bottom and complies with L8 guidance para 158.
- Every day so that it holds the water at 60C all the way down for one hour.
- At the same time as the water heating is turned on, whether immersion or other type of water heater.
4 – Higher cost. Requires a plumber only: replacing the cylinder with a safer one: (£500-£1000)
Replace the twin coil cylinder with another twin coil cylinder which has BOTH heat exchangers (solar and backup) at the bottom. Also time the backup heating to come on in the evening.
Why? Again this will heat the cylinder daily to the bottom and complies with L8 guidance para 158.
5 – Highest cost. Requires a plumber only: replacing the cylinder with a supersafe thermal store: (£1000-£1500)
Replace the twin coil cylinder with a thermal store. With a Solartwin installation, this has one heat exchanger to take heat out only. With conventional solar, some have a second heat-in heat exchanger thus reducing efficiency a bit. You may want to time the backup heating to come on in the evening.
Why? Having fast flowing, frequently replaced water of low heated volume at any one time super-complies with L8.