UPS with Auto-Shutdown of Stove During a Power Failure

[Pelleting In NJ]

UPS with Auto-Shutdown of Stove During a Power Failure

I built and installed this on my Ecoteck/Ravelli Elena stove, using the convenient wires of the hopper lid switch. I believe all the Ravelli stoves have a hopper switch, which allows easy access to connect this device. This can be used on any "top feed" stove, by just wiring the relay contacts in series with the auger motor. I would not try this on a "bottom feed" stove, like a Harman, because I think the shutdown sequence of a bottom feeder is more complex than just stopping the fuel auger.

Please be aware that you are connecting to hazardous 110VAC voltages....I am not responsible for the outcome of your attempts to do this modification.

 

[kenora]

Can you reference an appropriate latching relay please?

 

[Pelleting In NJ]

page 2 of the PDF has a parts list and schematic...…...

 

[kenora]

Dooooh....I never got to page two....thanks

 

[bill3rail]

Great deal. Thank you for the idea. For $10.00 in parts that is an amazing idea.

Just curiosity here, but don't some UPS' have a shut down circuit to shut down a computer?

Thanks,
Bill

 

[zrock]

Yes you can get a ups that will trigger a shutdown on the computer. The one i have triggers via the usb port but done through software

 

[Mt Bob]

And most Harman stoves have built in programming for a "soft" shutdown.

 

[bill3rail]

I am not a huge fan of technology, however, an auto shut down could help the end user from replacing smoke damaged home furnishings.
I wonder if pellet stove manufacturer's are considering this? Should not be too complicated to add wires to the shutdown button for external control.

Bill

 

[whit]

Been using a variation on that theme since being advised on it here in 2011. It's been flawless:

https://www.hearth.com/talk/threads...ce-for-when-a-pellet-stove-goes-on-ups.75156/

That's with an older Santa Fe where there's no switch on the lid.

 

[alexH]

waking the dead of a good thing.

I'm making this right now, pretty simple yet awesome.

I considering adding a capacity and resistor to the feed current, if the power just fluctuates for a couple seconds, the cap will keep the circuit alive.

$22 all in.

 

[Pelleting In NJ]

Yes, I have been meaning to add a large cap (maybe 1000uF) across the relay coil so that the shutdown circuit does not react to very short powerline dropouts, where the stove would continue to operate without problem.

 

[alexH]

I know about 10% of electronics, but i'd be happy to do the same and test it.

i just need to know "how" to do it. aka: where to put a cap and/or resistor.

 

[Pelleting In NJ]

No resistor needed, just a cap.

1000uF 10V cap, Digikey pn = 1189-1072-ND
51 cents each

Connect it across the output wires of the 5V power supply/adapter. You must observe polarity (or the cap will rupture):
1) Connect negative 5V adapter lead to the negative cap lead that is marked "-" (marking on cap body).
2) Connect positive 5V adapter lead to the positive cap lead (no marking on cap body).

If you don't get enough powerline drop-out immunity time, you can add additional caps across the first one, connect with the same polarity.

 

[alexH]

Got it. raided a old power supply for caps to test times.

 

[alexH]

after testing: I went slightly different route with the shutoff.

even with a 1000VA cyberpower UPS, it still took up to 20 minutes to completely shut off the pellet stove.

instead i went with a high value resistor in parallel with the control knob. if power goes out for more than 8 seconds, it closes the relay and adds the ohms to the "off" setting. that immediately puts the stove in shutdown mode and its fire-clean in about 10 minutes.

i'll share my version off the schematic soon. (did it on the fly, so need to draw it)

 

[Pelleting In NJ]

What kind of stove do you have?

 

[alexH]

pelpro pp70 Reading their tech docs, the control knob has a 10kohm high value for "off"

from service manual : RESISTANCE MEASURED ACROSS BLACK & WHITE WIRE FOR DIAL: 10K OHMS TO 0 OHMS (OFF TO HI)

 

[alexH]

I'm stuck, prototyping this for the 10kohm value to the control knob isn't working
i thought i could just use the NO side of the relay to put the 10kohms on the knob.

its not the end of the world though.

 

[Pelleting In NJ]

Try connecting the 10K resistor and the relay like the attached diagram.