Peltier fan + smart thermometer

[Tristan3030]

Hi all,
I have a lot of engineering experience and I have 3 wood burning stoves. I tried the aduru smart response gadget, but returned it as it was $**t - it was over complicated, expensive, and simply didn't do what I wanted, which was to be notified when the temperature dropped. I think the people behind that gadget got hung up on the optimum temperature and forgot about usability.
So I am going to make my own!
I am also considering setting up my own business and perhaps making this as a commercial product - I would really appreciate some feedback on features and pricing before making that decision.
I made a draft product spec sheet - have a look.

The basic idea is this:
A peltier powered fan also has a wifi module and a thermometer. It would let you know when the temperature goes too high (you've forgotten to turn it down after lighting!) or too low (you need to add more wood)

1. would you want one? do you think it would be useful?
2. are there any particular features you'd like to see in it? are there any problems you would anticipate?
3. do you know of any other solution that is already on the market? (apart from the aduro)
4. how much would you pay for it?
5. any other feedback welcome!
6. if you've made something similar as an arduino project and could chat with me or give a link to useful info that'd be great!

Thanks a lot - Tristan

 

[xman23]

Wireless temp to a coffee table display. Not the phone, Maybe 2" characters, so I can see it. To better know when to reload at night, we would move it to the bedroom. Battery life is important, as this should never be turned of. Same as my outdoor temp monitor. Maybe sleep CPU mode when temp gets low. Alarms, I don't need. but if there there just make them switchable on / off. Prefer nothing big on the stove, but do what you want to do with the peltier idea. Cost, make yourself some money. If done well it could be the must have stove tool. Price point will limit some sales. You not exactly competing with a $9 bi-metal stove top thermometer. But that's what I use.

 

[Tristan3030]

thanks for the feedback. the target market is certainly not the <$10 stove thermometer! i think the route to market if I go ahead with it is to use stove sellers/installers as distributors and the market would mostly be people who would have bought a $60 peltier fan anyway and can be upsold to a $100 smart fan.
it would recharge a battery/capacitor when the stove is lit - but would be set to a low energy sleep mode if the temp is eg <30C, so it could be on all the time quite easily. the calculations I've done show this is possible. even if the battery ran out, the charge would be enough to start it back up when the stove temp gets >90C for 5mins.

 

[jetsam]

You will need to go through your TEG datasheets carefully. I run my stove at 250°F stovetop for four months a year. It's not hard to find a mass produced TEG that will spin a fan blade at 250°, but you are adding to your price point considerably if you want to pull another 3w at that temperature (and also not be damaged at 800°).

Also, TEGs and Peltiers are not the same modules. You don't want a peltier for this application.

You are also going to want to put the whole thing on a chip to get it down to a nice-looking size. That probably means a good sized FPGA for development and a big need for investment for the first round of fabrication. Not that I've ever commissioned a run of my own chips, but I understand that even when you have your FPGA all set to go, you are still likely to need some help from a hardware guy.

I would include ports for plugging in a couple optional thermocouples and maybe a manometer input as well. Some users will want a cat probe and some users will want a temperature reading from a different location on the stove.

Remember that people expect that consumer devices will make an insecure connection to a third party server which will allow for them to get at the data from anywhere. There's always AWS, I guess. But the variable nature of this enterprise means you want updatable firmware for the above hardware, which means further complexity.

I don't want to turn you off from going after this, but there's a big space between a functional device made with a breadboard and a FPGA, and a marketable consumer device.

/random musings, going to sleep now

 

[Tristan3030]

Hi jetsam, thanks for your musings, they're helpful
on the hardware side I'm going to play around with a few things in the coming weeks. Although they are more or less the same, you're right that I should have said TEG not TEC (peltier) as they are built to be more efficient and able to withstand higher hotside temps.
i'll consider a 2nd thermocouple when I've got 1 working
server/data storage - yes you're right that these days it's not simple, esp if sold internationally, but I've some experience with this and it won't be a problem.