Low Draft Setting

Are you taking the reading from the right location (inside the fire box) while the fire is hot? What kind of gauge are you using?

A high reading at low fire can cause operational problems, and would obviously affect the efficiency. Did you try lowering the reading, by turning the screw near the ignitor status light on the control? I had a new unit that had high readings like this, and it adjusted down O.K.. Do the adjustment slowly, make sure you're at low fire while doing so, and recheck it. In the "test" mode, the blower will ramp up and down every minute or so. The manual says this adjustment should be done after the vent is installed, and in the "test" mode - so I interprete that to mean on a cold, non-running unit. I noticed the blower sounds louder at low fire, which can be confusing.

Tonyd, I did the test today with the same stove and meter. I had very high reading as well and I adjusted the screw counter clockwise and it didn't make much of a difference. I guess I'll play around with it once the season gets going and maybe it will be easier to adjust. I'm on the rule that if it's not broken don't fiddle with it. Two seasons now with flawless burning and I'm happy with the unit. I am going to change the ignitor since late in the season it was taking close to 10 minutes to auto ignite. I like manually starting the unit anyway so it's not a necessity.

LIpelletpig said:

Tonyd, I did the test today with the same stove and meter. I had very high reading as well and I adjusted the screw counter clockwise and it didn't make much of a difference. I guess I'll play around with it once the season gets going and maybe it will be easier to adjust. I'm on the rule that if it's not broken don't fiddle with it. Two seasons now with flawless burning and I'm happy with the unit. I am going to change the ignitor since late in the season it was taking close to 10 minutes to auto ignite. I like manually starting the unit anyway so it's not a necessity.

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A high draft reading will make ignition take longer, since the ignitor is being cooled excessively by the air velocity. Changing the ignitor may not improve this, in your case. Other operational problems might be a high flame, pellet overfeeding, or a long shutdown time - if the draft is too high. If you're sure about the venting being within specs, and you're in the "test" mode with the blower at low fire, then maybe the supply voltage is higher than normal? Otherwise I'd suppose Harman has overlooked some factors...

LIpelletpig said:

I am going to change the ignitor since late in the season it was taking close to 10 minutes to auto ignite.

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This is often corrected by just cleaning out the sand and ash from in and around the igniter. Pull the ignite out, clean it, clean up in and around the front of the burn pot and replace the igniter...with good air flow you should notice an improvement. If not, the igniter may be junk.

just for funnsies, check to make sure the intake flapper is moving freely. If that doesn't swing open you can get some excessive negative pressure going on.