NA: Direct wiring furnace induction motor for the weekend

Huckster79

Huckster79

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Huckster79
Well it appears the relays went to crap on my furnace circuit board. Used the multimeter checked all components, and its sending 6 volts to the induction motor. The induction motor is 115v AC unit.

Now I can get a whole board for $130 but won't be here till monday. Or I can get the two relays and resolder them in for $20 with express shipping to get them tuesday.

Either way, need heat for the weekend. No part of the furnace will operate as the induction motor spools up before anything else will go on, and being it is 115v AC unit, I do not see any reason for temporary I cannot go get the right connectors at the hardware store in morning, and run that baby direct to an outlet... Do You?

Sure it will run 24 hours a day, so a little more wear on it, big deal its a weekend. But it would spool up and stay running so the rest of the furnace will operate...

What say you?
 
Better than freezing in the dark. :D

Is the furnace firing the burners on thermostat signal though? Or does it need to know the relay to power the induction motor is closed first?
 
GRG55 said:
Better than freezing in the dark. :D

Is the furnace firing the burners on thermostat signal though? Or does it need to know the relay to power the induction motor is closed first?
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Absolutely nothing happens, as part of the self check cycle is the pressure switch check, it doesn’t directly look for the induction relay itself. But induction motor turns on as part of that process to see if pressure switch closes as it’s a “normally open” switch... when the induction motor doesn’t turn on the self check cycle fails as the pressure switch never gets kicked to close... So it doesn’t go any further steps...

If the induction motor is running it should pass the rest of the self check... at least as far as I can think it through it will... lol. Guess I’ll see once TruValue opens up..
 
Get a new board, I think you will solder the new relays in and find the board is crap. Did it work?
 
NEW BOARD ORDERED

Plan did not work... Two problems with the plan I did not foresee, though the temp attempt did confirm induction motor good- furhter confirming board is bad.

Problem with direct plug in was running the induction motor from the get go closes the pressure switch so it set that error off, evidiently it checks to see if the "normally open" switch is closed before the induction motor fires up, then it checks to make sure its closed. So I thought I would try timing it out and give it a second to check that then plug it in... Eureka for a moment, more things started to happen that way...

Then it shut off and errored out no flame... Well it now looks like the control board isn't sending 120v to the induction motor NOR the igniter, so Paul very correct that the board is shot, I highly doubt both relays as they are seperate failed at same time, however they have some connection over to the fancy stuff on a board I wouldn't think of touching- evidently something is bad over there and not sending the signal to either relay.

Good news is its confirmed as all get out in my mind its the board, other good news is Amazon Prime will have it here Monday for $135....

Bad news is we are going to spin the electric meter a bit extra this weekend keeping the house from going full cold...
 
You might yank the existing board and check for cold solder joints. A Carrier system in my parents house did exactly what you're describing. After replacing the board, I looked at the old one and found a couple of bad solder joints on the relays.... Causing the induction motor issue. Hit the solder joints with a hot soldering iron and the board came back to life.

Couldn't return the new board so they ended up with a spare.
 
wsuffa said:
...Couldn't return the new board so they ended up with a spare.
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I live out in the boondocks, in a sometimes harsh climate area (presently -3 F outside) so keep a spare board, spare ignitor, spare gas valve and a spare pressure switch for my home heating boiler. In the 8 years since I finished building and moved in the only thing that has failed on the boiler is the induced draft fan - of course the one significant part I didn't have a spare for. :dunno:
 
GRG55 said:
I live out in the boondocks, in a sometimes harsh climate area (presently -3 F outside) so keep a spare board, spare ignitor, spare gas valve and a spare pressure switch for my home heating boiler. In the 8 years since I finished building and moved in the only thing that has failed on the boiler is the induced draft fan - of course the one significant part I didn't have a spare for. :dunno:
Click to expand...
For the same reason the buying a snow blower means that it won't snow that year.... :D
 
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