hacking a rinnai hot water system..

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mark.duyvesteyn

Member
i want to have a play round with hacking my rinnai continuous hot water system.

My flatmates like to have long long showers, and the power bill is suffering as a result.

My idea is that after the hot water has been running for 10 minutes to decrease the temperature to as low as it will go - about 37C at the head. Not cold, but not really enjoyable so you will get out.

I plan on wiring reed relays to emulate the pressing of the buttons on one of the controllers and using the "flame on" LED as an indicator of the shower length interfaced with an LDR.

The controller has only 2 wires connecting it to the main gasburner out side, and the voltage across these wires is 12v DC.

Would i be able to run a voltage reg off this same line to power the picaxe, or would that interfere with the signal that is going back up toward the gas burner??

any thoughts or suggestions? here something that someone has done similar. http://jon.oxer.com.au/blog/id/264
 
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Dippy

Moderator
Blimey Mark, I think most people will say Don't Do it!
Asking real basic qustions like that suggests that maybe you should start on a safer newbie project.

OK, you are determined.

Without knowing the ins and outs of that boiler, the answer is: I don't know.
Those 12V lines could be signal lines, or going to the buttons via resistors. Any load may affect the voltages etc.
Or it may not.
Without a circuit diagram , or without a boiler engineer, I couldn't say.
And I'm NOT going to guess.

I suggest you just make an alarm, if something goes wrong you (or someone) could be dead and/or you could be in court.
... this sort of stuff, done by novices, is asking for trouble.

But good luck... someone may help.

EDIT: DON'T DO IT MARK. This potentially LETHAL. In the nicest way meant: I hope no-one suggests anything.
 
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hippy

hippy

Ex-Staff (retired)
One would need to know a lot more about the system, how it is wired and how it is controlled, before even contemplating making any modifications. If there are just two wires to the gas burner it seems unlikely to me that they would be an always-on power supply.

It may be worthwhile contacting Rennai as they may have a ready-made solution to such problems.
 
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lanternfish

Senior Member
SYMBOL A = Do you own the house?
SYMBOL B = Do you have adequate insurance cover?
SYMBOL C = Do you have previous electronic experience?

IF NOT A OR NOT B OR NOT C THEN "Don't do it!"
 
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moxhamj

New Member
I have a Rinnai but it is one of the older ones without a remote. How popular would you be if you broke the remote by hacking it?? Also, would your flatmates notice the hack and 'unhack' it?

It still is a problem that needs solving though. How about a large bucket of icy water that you rig up above the shower with some ropes and a little solenoid and with a picaxe controller, and after 10 minutes it dumps the water on the recalcitrant flatmate? You could take bets on who can get the closest to 10 minutes without looking at a clock...
 
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KMoffett

Senior Member
How about just using a PICAXE to monitor, log, and time stamp the power consumption by the heater and portion out the power bill accordingly. :)

Ken
 
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mark.duyvesteyn

Member
i own the house, and a new remote is only around $100 dollars, so not too expensive.

I only plan on "pressing" the buttons using the little relays ( i have used the same method to "press" buttons on cell phones and it worked fine) this is no different then standing in the bathroom and manually adjusting down the water temp by pressing the buttons with my fingers.

I can get the power supply from from somewhere else, i was just wondering if any one knew anything about transferring data and 12v on the same lines and if a voltage reg would effect this. I think they are doing something similar in cars now for lights e.t.c.

I appreciate the concern re: insurance and house burning down etc as far as i can see the only problem this little project could have is maybe a bung controller.. or am i missing something?
 
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hippy

hippy

Ex-Staff (retired)
If the use of the lines is unknown it's not wise to use them for something else, you just don't know what affect that will have. Presumably the 'mod' would be in the control unit and there should be a 0V/+V of some sort in there. Without a detailed discription though it's all guess work; so far we know there's some controllers, a gas burner, and two wires. I suspect there's more too it than that :)
 
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Dippy

Moderator
If you simply intend to bypass the buttons with relays that will make life easier.
But sending signals along the power wire requires extra bits and pieces.
I don't enough about that boiler to say if it can upset things.

A separate power supply triggering relays is the simplest option.
And that information is available in Manual 3.
I assume you will be using sealed relays?
But novice electricals and gas... oohh.

Are you a complete newbie as far as electronics/electricals and programming is concerned?

Just be blooming careful and I'd still say don't do it - but that's up to you of course.
You could really mugger up your insurance if there is , hippy forbid, an accident.
 
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boriz

Senior Member
If it can be done without any direct interfacing with the system (no soldering, no removing of covers), EG: Light sensor looks through same window as human, and servo-press-button. AND if it can fail safely in any possible configuration, then I see no problem with experimenting with this idea. Otherwise forget it.
 
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BeanieBots

Moderator
mark.duyvesteyn said:
Would i be able to run a voltage reg off this same line to power the picaxe, or would that interfere with the signal that is going back up toward the gas burner??

any thoughts or suggestions? here something that someone has done similar. [/url]
Click to expand...
Unless YOU can PROVE categorically that it won't, then it WILL.
The need to ask says DON'T DO IT.
 
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manuka

Senior Member
As a fellow Kiwi I should point out that NZ mains wiring regs. are very liberal - much to the disgust of some Australian states where a sparkie is required to even change a fuse. Both countries have identical mains sytems too, but here we can legally do all manner of 230V tinkering- fatalities are LESS than Australia as well. However I'd draw the line at gas water heating, especially since flatmates may engineer unsafe workarounds. All manner of regulations in fact apply here to gas appliances, & simple servicing on the likes of stoves & room heaters can NOT be legally done without extensive (re)certification etc. This of course relates to both the explosive nature of gas & CO issues - neither are to be taken lightly.

A home owning reality is that flatmates winter showers may be prolonged- they're a morale booster- & perhaps this is cheaper overall than running heaters/raiding the beer fridge/ having to readvertise for new flatmates. Perhaps put in a small hotbox electric sauna ?

Failing the classic "shower with a friend", you can always put in a simple annoying timer that cuts in after 10 mins. Few "Gen.Y" flatmates could stand the likes of Frank Sinatra singing "I did it my way" either!

THOUGHT: Humidity sensor? Hope RF make a nifty HH10D => www.picaxe.orconhosting.net.nz/hopehum.htm
 
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lanternfish

Senior Member
We are fortunate in NZ that we are able to do some basic 240V electrical work. We are not, however allowed to do work on gas lines (or sewerage/foul water).

And if you are only renting a house, etc, then the liability for any damage to that property and neighbouring properties falls squarely on the you as the tenant. So not a good idea to muck around with something if you have limited experience. Or limited information on what you are hacking.
 
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BrendanP

Senior Member
thread hijack, attention Stan.

I need a humidity sensor for my incubator project Stan. Any tips on the q/reliability of the hope item?
 
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BrendanP

Senior Member
I have to admit Stan is long suffering

I have to admit Stan is long suffering, but as he got me into Picaxe he has to cop it on the chin! His mate Andrew, father of the kiwi patch is also to blame.
 
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manuka

Senior Member
Total disclaimer - no commissions from anyone! However I'm always open to free samples,an occasional beer- & even the likes of a ROW airline ticket.

Brendan- see this months (June 2009) SiChip humidity article in fact. Wayne & I rustled this up in conjunction with MicroZed. Wayne did all the hard work, & my contribution pretty much was just at the colouring in level. We've yet to L O N G term test these sensors, but none have failed over the past few months. At Aust $13 each they're certainly worth having a crack at. Stan
 
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premelec

premelec

Senior Member
Mark, I'm interested in your concern... one of the reasons I _don't_ have an on demand DHW unit is that there is a minimum flow rate [corresponding to input line temperature and minimum gas flame BTU] and another is that "never run out of hot water" mentality [they don't mention runing out of money...] - They also take about 75 watts electric while running [a figure I got from Rinnai not that I've measured].

Assuming the unit is running above the minimum flow rate [ca > .4GPM] you might be able to fake the cold output by adding cold proportionate to run time rather than messing with the Rinnai's guts. Note that there are commercial flow restrictors called 'dole valves' that could be used to keep excessive volumes from flowing in conjunction with appropriate plumbing with attention to pressure drops et al. A PICAXE and temperature sense unit could control a proportional flow valve on some downstream cold addition... good luck!
 
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D n T

Senior Member
long hot shower and Stan and the humidity sensor

With all this stress over modding the system ( I would leave it intact), all this discussion about the new hope humidty sensor and the fact that stan does a lot of research and shares it with us, why not use a bit of each?
Leave the poor defenceless hot water system alone and get hold of a humidity sensor, connect it to an alarm or and sit it in the roof above the ceiling vent or near the extractor fan. The longer the shower, the more humidity, hit the threshold and the alarm goes off. You could even use a hoperf module set to make the allarm remote ontrolled
If you feel like it you could "get a licensed plumber to" install a solenoid in the hot water to the shower supply pipe and instead of the alarm , oh gosh the water is cold, and the hot water system is not touched and it thinks you have turned off the tap. Make it reopen the solenoid after 2 or 3 minutes so you can have a shower. You might want to set the solenoid so that without power it is open and allowing flow, with power, no flow.
You could install a second remote in your room or shed for remote vengence
OR, HANG ON!!!

You own the house, tell them you will up the rent on them

DON'T play with the rennai please. They measure electricity frequency in hurtz because if it goes wrong it hurtz
 
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ad8bc

New Member
Wow. We have it great here in the 'States. In the past week, I replaced some sewer drainpipe, did some electrical wiring, and hooked up a friend's gas dryer. All by myself. No permits, no inspections, not illegal.
 
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manuka

Senior Member
Well it's assumed you know what you're doing (& are not colour blind!). Just like Australia,not all US states permit such DIY utility tinkering of course- NYC for starters apparently insists on certified installers...

But back at the showers -don't forget Frank Sinatra's voice is an industrial strength Generation Y room clearer! Many of that '80s-90s vintage say his songs would probably even unclog drains. I've a teaching mate who torments miscreants in detention with Frank's classics- the kids HATE it!

Apparently some urban malls even play Frank's tunes to drive seedy youths away from such hangout spots as shop doors and dark alleyways. It's cheaper than cameras or security guards, & of course the music tends to appeal to just the sort of older customer that they want. How's that for selective marketing!
 
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papaof2

Senior Member
ad8bc said:
Wow. We have it great here in the 'States. In the past week, I replaced some sewer drainpipe, did some electrical wiring, and hooked up a friend's gas dryer. All by myself. No permits, no inspections, not illegal.
Click to expand...
That does vary by location. The county I live in allows you to do almost anything, as long as you get a permit for new work and have it inspected. Most maintenance is not regulated. The inspector did have one question about the wiring in the room I added: "Are you an electrician?" No, I'm not - but everything was done according to the National Electrical Code handbook. I gathered from his comment that many people have no idea what they're doing with building construction or electricity. If the TV show "Renovation Realities" runs in your area, you'll find that some people start big projects with little or no knowledge of what they should or should not do.

John
 
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Dippy

Moderator
"In the past week, I replaced some sewer drainpipe, did some electrical wiring, and hooked up a friend's gas dryer. All by myself. No permits, no inspections, not illegal."

- yeah, but you didn't tell us if it worked.. or blew up :)

Has the home insurance got a wriggle-out clause for damage relating to DIY?
 
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mark.duyvesteyn

Member
ok, so i did it...

Using an 08m, a few little relays and a feed off the LED flame indicator on one of the controllers in the bathroom.

There is a 5v voltage regulator on the board so i am just feeding the power for the axe off that.

if the water runs for more than 10 minutes, it turns off and cant be turned back on for 1 minute.

If the water is run for between 3 - 10 minutes then once it has stopped it cant be turned on for 1 minute.

If the water is run for less than 3 minutes it can be turned straight back on.

After the water has been turned off, the controller powers down, if you want hot water again then you need to press the on/off button. This is quite good because it means that you only use hot water when you need it, not just turn the tap on for a few seconds and only heat the water in the pipes.

my hotwater system uses 55KW of gas (winter full flow), at 8c/KW an hour, therefore hour long showers, sometimes twice a day were adding about $150 a month to the energy bill!.......
 
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mark.duyvesteyn

Member
yeah wasn't me with the hour long showers

a couple of my flatmate's just stayed in there for ages and ages, and there other flatmates where getting annoyed with having to subsidize their habit.
 
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SgtB

Member
As the owner of the house, I'd just tell them to hurry, or chip in on the bill. Social engineering is the quickest route. :)
 
premelec

premelec

Senior Member
Coin op...

There are coin operated valves I've encountered in National Parks - you get in the shower with a fist full of coin and get 5 minutes per - added income can be had with a drain screen that allows coins through and trap below :) cleaned coins! [car washes are famous for these as well - and the nickel lock toilet gate is an abomination...]
 
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