I have a Lennox EL296UHV furnace (2-stage, variable speed). About a month back it started showing code E229 Ignition on high fire. Some times it proceeds to heating/blowing after a couple attempts, some times it "waits" for a while before trying again. When it runs, it starts in stage 2 (high) and within a few seconds, switches down to stage 1 (low). I had the furnace maintenance done by a professional a week ago. He said everything is in perfect condition, but the issue continued.

Previously, the furnace always started in stage 1 and some times would kick into stage 2 toward the end of cycle. I remembered changing the fan setting from "Auto" to "Circulate"about a month ago (this coincided with when the code E229 started). Last night, I changed the fan back to Auto and the furnace now starts in stage 1 and ends in stage 1. No more E229 or kicking in high at start. My uneducated guess at this point is that the Circulate mode is some how causing a condition that makes the control board think the low pressure switch is open (may be when the fan is still running when the thermostat calls for heat?).

Did anyone else experience this with their furnace (with the fan in "circulate" mode or similar mode)?

 

Sorry.... can't help you directly with your problem but the blower fan has no connection to the draft inducer and pressure switch. The pressure switch should not care if your blower is running or is in low speed or in high speed.

 

Might just be a dirty pressure switch tubing port on the furnace side of the tubing.

Most techs do not measure vacuum at the pressure switch.
You must use 2 tees to check 90 percent furnaces.
I use two 3/16 x 3/16 x 1/8 inch tees when checking 90 percent furnaces.

On a side note the flame rectification on that furnace measures slightly erratic.
The flame sensor voltage is very low ( less than 4 volts).

When a Lennox communicating stat is used with that furnace it can display flame rectification at the stat in test mode... Very impressive.

 

I'm seeing initial readings of 1.48 inches water column, 1.64"wc and, 1.36"wc in my notes for 3 EL296UH furnaces that I checked Nov 15th.

Did your tech list your readings on your invoice?

 

https://tech.lennoxintl.com/C03e7o14...h2uV/1125p.pdf

From the manual...

Since it fails to start sometimes I think it is the low pressure switch. ( option 1 )

 

Houston204. great information. Thank you!
It's good to know the E229 code is information only. I am guessing the furnace kicks on high fire when when fan is active to compensate for the extra cooling effect the fan might have had on the heat exchanger (kind of like pre-heating the oven before putting the turkey in!). No more E229s since the fan mode was changed back to Auto. I don't hear the draft inducer anymore and no sudden rush of air in the vents. It looks like the furnace now starts in stage 1 like before.

I have the iComfort communicating stat and will look into the diagnostic mode. I just watched a great video on flame rectification. Yes, very impressive the stat can detect such small current in test mode. I will look into that later.

The Tech never gave me the invoice, said he will email it later. This was done through my American Home Shield service plan. I am following up with AHS for the report.