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Looking to determine whether gas water heater is on
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Looking to determine whether gas water heater is on

by Corwyn on Sun Feb 03, 2013 9:01 pm

I am working on a arduino based solar hot water system. One little side project is to determine whether the hot water I am getting is heated solely by solar, or whether the Bosch Aquastar tankless hot water heater has turned on to boost the temperature.

My first thought was to use a CdS light sensor, appropriately placed to see the light of the gas flame. The readings I am getting are too widely fluctuating to work based just on a threshold value.

Anyone have any ideas for a better way to determine whether the heater has kicked in?

Thank You Kindly,

Corwyn
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Re: Looking to determine whether gas water heater is on

by zener on Sun Feb 03, 2013 9:08 pm

PIR sensor. The kind they use in motion sensors. You will still get a fluctuating output but it should be usable. I never tried it though. You could also use a thermocouple I suppose. Or even a bimetallic temp switch "thermodisc".

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Re: Looking to determine whether gas water heater is on

by franklin97355 on Sun Feb 03, 2013 9:21 pm

Seems this is a great use of a thermocouple.
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Re: Looking to determine whether gas water heater is on

by Corwyn on Sun Feb 03, 2013 10:24 pm

Thanks, I may try that. I do worry that getting close enough to the flames to be able to differentiate hot water from flames will be closer than the thermocouple enjoys being.
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Re: Looking to determine whether gas water heater is on

by zener on Sun Feb 03, 2013 11:02 pm

If it has a flue exhaust fan then you can sense that.

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Re: Looking to determine whether gas water heater is on

by adafruit_support_bill on Mon Feb 04, 2013 7:31 am

Or a even a flue exhaust damper should be detectable.

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Re: Looking to determine whether gas water heater is on

by Corwyn on Thu Mar 21, 2013 1:19 pm

It has neither. No electrical connection at all. Thank You Kindly.
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Re: Looking to determine whether gas water heater is on

by zener on Thu Mar 21, 2013 4:31 pm

Did you try any of the other ideas?

There is also this from Home Depot

"Honeywell-Replacement-Thermopile-Generator-750-Millivolt-CQ200A"

I could not post the link because I got this message which I am not making up:

"Your message contains banned spam words. Please rephrase your post without the following words : xxxxx6986" where the xxxxx was 20318

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Re: Looking to determine whether gas water heater is on

by tastewar on Fri Mar 22, 2013 8:26 am

Sheesh, another guy trying to peddle that honeywell thermostat again! Will it never stop?! Guess we'll have to add "honeywell" or "thermostat" to the banned word list...

:wink:
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