Guidance needed - Can you educate the educators?

[aslqkschools]

 We are a small group of students with teacher support that are trying to embark on a sustainable energy project. We aim to provide and build a solar powered hand washing facility in our school playground . We need to keep it simple , cheap and practical. We meet for an hour once a week and have 10 weeks to do this in ( including sourcing funding ) . We are researching solar panels and water tanks and making preliminary drawings .

Any advice ?

[wyleu]

Decide how big your tank will be based on user demand and then work back form there. Investigate how much the 'average' user will use it. Remember there will be much inital interest and the resource will be limited. Inform people of this element. That way you look presient for predicting performance rather than inconsiderate dealing with complaints throu' overuse.

Also investigate things like BPEC to consider scalding and how you control this.

How will you pump things and who will do the electrics and sign them off? You may not do this but at least understand the processes involved and if possible consider how people will be protected in the event of the worst possible electric failure ( Live conductor making all the water components live). Investigate the calculations made to ensure it will be safe if the fault repeats.

Then cover it in one-wire sensors and link it to a PC

[martin]

Crib what we used as a "demo" at festivals - solar panel, insulated tank, gravity fed with cold water from a small storage tank with ballcock - TMV on the hot tap to save scalding - no electrics, no pumps - job done! (just use a simple "scaffold" to hold the tanks.......) - the order (from the top) is cold storage tank, insulated storage tank, solar panel (s) - taps below the level of the bottom of the storage tank - THAT simple!

[wyleu]

Excellent advice, but from an educational standpoint it's worth looking at the electrics if only to reject them throu' complexity. Try to demonstrate you have made considered choices and assessed risks.

[Alan]

When used in a public place you will need to take on board the possible
implications of. Legionnaires’ disease?

Info taken from Health and Safety Executive web site.

What is legionella and Legionnaires’ disease?
Legionella are bacteria that are common in natural (rivers and lakes etc) and artificial water systems, eg hot and cold water systems (storage tanks, pipework, taps and showers).

Legionella can survive in low temperatures, but thrive at temperatures between 20oC and 45oC. High temperatures of 60oC and over will kill them.

Legionella bacteria can multiply in hot or cold water systems and storage tanks and then be spread, eg in spray from showers and taps. Although the generally high throughput and relatively low volume of water held in smaller water systems reduces the likelihood of the bacteria reaching dangerous concentrations, you must still carry out a risk assessment to identify and assess potential sources of exposure. You must then introduce a course of action to prevent or control any risk you have identified.


Are conditions right for the bacteria to multiply, eg is the water temperature between 20oC and 45oC?

Are there thermostatic mixing valves that set a favourable outlet temperature for legionella growth?

You will need  thermostatic mixing valves to limit the temperature in the system.

Regards

Alan

[Justme]

Take a look at the self contained systems on Navitron site. Make sure its an SFD & not an SFA.

http://www.navitron.org.uk/product_detail.php?proID=121&catID=116

You only need a mains pressure water source.
That can supply the header tank to keep the store full & also the mains pressure to feed the hot water coil & the TMV to lower temps to safe level.

No need for:-
pumps, electrics, sensors (unless needed for data logging)

Plus as its a thermal store with mains pressure hot water coil the L risk is non existent as the water volume is so small (you only use whats in the coil, whats in the tank has inhibitors in it) that minimal use will keep the water turning over. Prob set up a flush so after holidays it gets run through before use.
(not much of an issue in summer as the system will get very hot.

[Baz]

Cold water not good enough for the little darlings nowadays?

[martin]

Unfortunately not - went out with Bronco, floggings and PT masters compulsorily having to be "of dubious proclivities"

[welshboy]

What about protection from frost ?

[dhaslam]

[wyleu]

I can't look at that without thinking Saturn 5.

Don't forget to work out how much those two tanks actually weigh.

[EccentricAnomaly]

I can't look at that without thinking Saturn 5.

Looks a bit like a Saturn 5 but the engineering's more like a Shuttle.

[Alan]

Sorry to be the provider of more Doom & gloom.

Are the tubes Football proof.
What happens if that Stone lands on the glass.

I know it sounds Boring.
How about an electric P.V. Panel and grid inverter.

[martin]

hefty chicken wire.......

[Ivan]

I kid you not - Wyleu has volutarily tested the football-proofness of Navitron solar panels. That avatar's there for a good reason, you know.