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Discussion Starter · #1 ·
I have a Olsen Duomatic gas furnace with a Honeywell igniter board and Honeywell gas valve set up to be a downflow furnace. The old inducer motor died so bought new one with exact same specs. Also replaced the Inducer Relay; ignitor board, spark ignitor. Now when power is turned ON the inducer motor does not start but ignitor lights pilot, then gas comes on, burners light...and flame blowback happens - all w/o inducer motor making a sound of life. Connections from inducer have been checked and are in right place. what is going on here? Inducer should fire up at start before anything else happens!
 

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You have a very dangerous situation on your hands.

There should not be power applied to the ignition/gas valve circuit without the inducer on.

The inducer failure uncovered another problem.

In all likelyhood your pressure switch is stuck closed or there's a short in this circuit, bypassing it. disconnect it and ohm it out.

New furnaces monitor this and won't let the furnace start up with a stuck closed switch.

Correct that before dealing with the inducer.

Post a model number and clear picture of the schematic on the blower access panel.

pressure switch:

 

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You probably have some mixed up wiring.

If it is a very old original Olson it is 30+ yrs old and they did not have a integrated circuit board but a S86 system.

Check all the wiring and make sure the inducer relay is wired in properly.

You may have also bypassed the pressure switch and sent power directly to the S86 module.

Find the pressure switch and remove the wires from it and make sure it has a open contact when the unit is not running.

I suspect some mixed up wiring as you have more than one problem and pressure switches never stick closed. Open yes, closed, not that I have seen in over 35 yrs of working on them.

If you can take a pic of the burner area and post it on photobucket or imageshack and put the link here it will help. After 5 posts you can attach pics here ( anti-spam feature ) and you reply to the email they sent you when joining.
 

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Until you get this figured out, any further troubleshooting should be done with a meter. Fuel supply needs to be turned off for obvious safety reasons.
 

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Discussion Starter · #5 ·
I should add that the old draft inducer i replaced did not have a stem or valve for the pressure switch to be attached, rather the switch was attached via its tube to the furnace manifold....whereas the new inducer motor has a stem/valve for the pressure switch to be attached. Otherwise the new motor has exact same specs (hp/amps/rpm) as the old. I tried pressure switch connected to new motor & then to furnace manifold both with no results of new motor coming on. Do I need a switch that has 2 tubes to connect to both motor and furnace now?
 

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Discussion Starter · #6 ·
Another possible factor is that this Olsen furnace was installed upside down to be a downflow furnace. Would this require the new draft inducer motor's direction of spin to be changed from CW to CCW?

I will post the schematic of the furnace shortly. Olsen 405070 D /HW8204 IID...with...Honeywell Ignition S8610M and Honeywell Gas Valve VR8204M (I have not been able to find a manual of this Olsen online)
 

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You cannot flip that furnace. It was designed for downflow. Has to be UL and CGA certified for upflow or downflow. Some can be used sideways/horizontal but not flipped.

There is no manual as they went out of business 20+ yrs ago. Used to be a well known Canadian company. They name got sold to someone else a few years ago but they don't have manuals or parts for the old furnaces.

Even if you post the schematic we don't know what you did to the wiring and may not be able to help.

Follow it exactly and make sure none got mixed up.

Post a pic of the old inducer and new one. Sounds very strange to me. Usually they are made by Fasco and have identical fittings to attach the pressure switch tube on.

It can be EXTREMELY dangerous if that is hooked up wrong. The furnace was UL and CGA certified with it in the original spot. Very rarely does that change as there are legal ramifications.

Lennox does it but they supply their own parts and certify the change.

You may have the wrong inducer. The amps and RPM is not the issue, the amount of air it moves and size of inside wheel is.

It should still try to start unless it is wired up wrong or the inducer relay is shot.
 

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The inducer isn’t the direct issue. The unit should NOT try to light without the inducer running and pressure switch closed.
Do you have and know how to use a meter? You’ll have to pull it out and start picking through the wiring
 
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