Arduino HW control project

[Greenbeast]

What started as a simple cylinder monitoring project is slowly expanding in scope.

I'm intending to use an arduino to read 5 (or more) 1-wire sensors on my cylinder and display the results on a little LCD.

Then i got to thinking i could do a little maths with it and use it to tell the misses how many showers would be available depending on how many sensors were at shower temperature.

THEN i got to thinking, could i use the arduino to turn on the immersion or boiler for long enough to generate water for a given number of showers (1 or 2) for example??


Can someone assist me in thinking through this little project.

This year we had to rely on immersion but with my new boiler going in soon i expect we'll rely on that when there's no sun.

If i select '1 Shower' i'd like the arduino to fire the boiler up until sensor1 is at the predetermined temp, if i select 2 showers, fire the boiler until sensor 2 is about a predetermined temp.

does this sound crazy?
is someone just going to suggest using 2 tank stats in series?

i'm assuming i need a relay that can be switched by the arduino to make the mains connection

[Jonathan]

It sounds a good project 

In my house you'd need different settings for:-
a) Daughter arrived home late from work and going out in 10 mins therefore 1 min shower.
b) Daughter got all the time in the world and washing hair therefore 30+ min shower - Boiler, immersion and full sun can't keep up.
c) The rest of us, 2-4 mins each.

regards Jonathan

[Greenbeast]

lol

There's 2 of us and we use roughly 5-7 minutes each, misses take longer occasionally.
I've got two approaches to working out the figures, install the sensors and use experimentation (which we're getting good at with the the single TDC3 sensor at the top) or work out how much water we need and work out how much water is at a give temperature.

I think it'll probably experimentation and i'll probably set it up for 1, 1.5, 2 and 2.5 showers (the 1.5 and 2.5 for when the misses wants longer), as its only a little extra code

[wookey]

This has long been on the list of features to add to my set-up. Because whilst 'tank top temp' is a metric of sorts what you actually want to know is 'is enough water hot enough for a bath/shower'. As people have pointed out that's a rather variable target but in this house 42C is the critical temp for showers (40 at a pinch). And 50C for baths. If ther 2nd sensor down (about 20l) shows those temps then you are good to go. OK, a 25l bath is a bit stingy and 40l is a lot better, but it does the job.

The maths is trivial, so even on an arduino it's straightforward. I'm still stalled on rewiting my logging backend and putting in a nice GUI.

[ericw]

THEN i got to thinking, could i use the arduino to turn on the immersion or boiler for long enough to generate water for a given number of showers (1 or 2) for example??

It might be worth checking that the cylinder will heat in a stratified manner. Quite often the convection currents from the boiler coil stir things up so much that it heats up the whole cylinder.
If it does then is only a matter of checking that sensor X is above the 'shower' temperature - the lower down the sensor you choose the more showers would be available.
 

[Greenbeast]

This has long been on the list of features to add to my set-up. Because whilst 'tank top temp' is a metric of sorts what you actually want to know is 'is enough water hot enough for a bath/shower'. As people have pointed out that's a rather variable target but in this house 42C is the critical temp for showers (40 at a pinch). And 50C for baths. If ther 2nd sensor down (about 20l) shows those temps then you are good to go. OK, a 25l bath is a bit stingy and 40l is a lot better, but it does the job.

The maths is trivial, so even on an arduino it's straightforward. I'm still stalled on rewiting my logging backend and putting in a nice GUI.

This is spot on what i'm thinking, i've had my arduino for a week now, and i figured this is a fairly straight forward project for it

It might be worth checking that the cylinder will heat in a stratified manner. Quite often the convection currents from the boiler coil stir things up so much that it heats up the whole cylinder.
If it does then is only a matter of checking that sensor X is above the 'shower' temperature - the lower down the sensor you choose the more showers would be available.
 

like i said i'll probably run with just sensors for a while to assess how well it stratifies

[stephendv]

I see you've already got the arduino so assume you're comfortable doing the soldering and ancillary circuits required for the relay, push buttons etc.  If I were to do another arduino project I'd defintely go for the "Electronic Brick" system developed by these chaps: http://www.seeedstudio.com/depot/electronic-brick-c-48.html

Plug and play with a large number of sensors/displays/buttons, no more soldering 

[Greenbeast]

Yes i had seen those products but i wanted to display more information that those 16x2 lcds can display (at least to read comfortably) and also needed a small temp sensor that i could get onto the copper of my cylinder.
So they didn't seem to fit the bill that well

[Alan]

A two line 40 character L.C.D. gives you eight three digit displays. You could loose one space between readings and still have room for a on / off thingy at the end.



http://steamboilers.homecall.co.uk/LCD1.jpg[/img]


Best to use solid state relays.

This one is good for 50 amps. It can be turned on / off direct connection to the micro port pin at five volts. They are optically isolated so your five volt switching / micro processer is completely isolated from the mains.

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=4914868

If your only switching 13 amps cheaper relays are available.

One day I will get to grips with taking pictures in focus.

Regards

Alan

[Alan]

General gist about one wire. Up to 64 devices on a  Pic 16F84

Build cost about 10£

http://www.anotherurl.com/therm/Default.htm

http://www.anotherurl.com/therm/schematic.htm

Regards

Alan

[Greenbeast]

I made a bit more progress, i've posted a write up for Desperate:

http://www.navitron.org.uk/forum/index.php/topic,9852.msg109978.html#new

I'm taking the project a little further than Desp needed and haven't quite finished my code yet.
I'll post it up when i've finished getting it to control the boiler.

[Greenbeast]

video evidence!

http://www.youtube.com/watch?v=Bzjp8KM3nvc

[daftlad]

I missed this one, seems interesting, how is going? have you got it in a nice shiny box with shiny buttons? Can the "bread knife" work it?
ta ta

[Greenbeast]

i got a simple sensor in a nice box a few months back but i've not been actively pursuing this recently.
I really need to get in gear, got another straight sensor version to make for someone and also work on my more advanced version.

it should be fairly straightforward to operate when done.