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Topic: Project feasibility and cost (Read 1 time) previous topic - next topic


Arduino experts,

I need to implement a little project, and I need your advise on:
a- Feasibility and level of complexity;
b- Tentative cost; and
c- Where to find someone who could help.

The project would "simply" be to send a signal from my computer in my office to my home via Internet, controlling the level of power used by my water heater, and receive a signal with the temperature of the water.

After reading some the posts, it sounds like this would be a pretty basic project for someone with the right expertise (definitely not me). I live in the Boston area and wonder what would be a good way to find someone to subcontract a project like this.

Thanks in advance,



The gigs and collaborations forum would be a better place for this post. I've seen threads here about arduino systems that controlled heating temps with a servo moving the thermostat, so it's not unsurveyed territory. Unless you have some unusual circumstance, I'd imagine that most of the time, you would be better off controlling the water temp based on time of day and day of week, possibly influenced by ambient temp,with the internet override used rarely, if at all. Parts for such an endevour would likely come in at under $150. Consulting fees - that's another story. Crossroads and Johnwasser are frequent posters from the Boston area who have been known to show interest in collaborative projects from time to time.


That is not a difficult project. The parts you need are:

Arduino Ethernet ($60)
SSR with high enough current rating for your water heater, perhaps SSR-40DA + heatsink ($9 on eBay)
DS18B20 or other temperature sensor ($6)
5V or 9V wall wart to power Arduino

+ cables, box to mount the Arduino in, etc. So about $100 in parts. More if you can't conveniently run an Ethernet cable between the Arduino (near the water heater) and your router, then you will need e.g. powerline network adapters.
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.


Thank you both for the feedback--very helpful.
I also take the point that the collaborations forum would be better suited--I will post this again there.


Sent you a PM about your project.


I'd be curious if this actually saves any money. I assume that you want to turn it down when no one's home at back up before shower time. While this seems logical. I think you might find that the energy used to maintain a constant (correctly set) temp is less than the energy needed to heat colder water back to hot. The key is correctly set. The best way to save money on your hot water heater is to set the temp correctly. Factory settings are usually higher than needed.

I work in a plastics extrusion plant and we have done studies to convince our maintenance department that it is cheaper to leave an extruder on than to turn it off and back on. We have situations where we run a line Monday and Tuesday and don't need it again until Friday. Our maintenance department kept turning the extruders off on us. Using power monitoring equipment , we were able to prove that it was far more energy efficient for them to remain on. I don't remember the exact numbers but it was significant. While the extruder is on, the PID loop is cycling the heaters at a fairly low frequency. When we turn it on, the heaters come on and stay on for over an hour. This would be similar to what happens in a hot water heater.


When we turn it on, the heaters come on and stay on for over an hour. This would be similar to what happens in a hot water heater.

True, and in an area where a kilowatt costs the same at 9:00 AM as at 3:00 AM, there is no savings in using energy at one time versus another. Boston is not such a place, however. The cost of a kilowatt depends on when you use it. So, while it might take twice as much energy to reheat the water (probably not, is the heater is well insulated), it can be cheaper overall to heat the water when energy is cheaper.
The art of getting good answers lies in asking good questions.


Good point Paul. In fact, we have the same situation here in Tennessee where there are peak usage times. I did not take that into account.


Using power monitoring equipment , we were able to prove that it was far more energy efficient for them to remain on.

I'm surprised to find that - I'd have thought that the electrical energy requirements were directly proportional to heat loss which (other things remaining constant) would be driven by temperature difference and time. In other words I'd expect that an extruder which was allowed to cool and them reheated would lose less heat than one which was kept hot continuously, and so would use less electricity. Is there some other factor here which makes the reheating process particularly inefficient?

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