feeding pellets during shutdown? The stove that doesn't stop

[smirnov3]

I have had some wierd experiences with my accentra. Several times, when I turn down the temp setting for the day (ie I ran the stove for the night. indoor temp is 65ish). I set it to 55. the distribution blower goes off, the combustion blower stays on. All normal

but the stove keeps feeding pellets. what gives?

Also, at this point if I turn the distribution fan (which is NOT running) to off, it turns back on!

I tried unplugging the stove for 20 seconds & re-plugging it, to see if it was a software glitch, but it kept doing it.

is this normal?

 

[pelletheat]

The stove will continue to feed pellets, at very minimum of 7 seconds per minute, in shutdown until the ESP temperature reaches 250 degrees. This will allow the stove temperature to drop safely during shutdown. There is no preset time, only temperature, that determines when the feed shuts off.

 

[smirnov3]

WHY IS THIS NOT IN THE MANUAL?!?

I paid over three grand for my stove. would it be so difficult for Harmon to tell me how to operate it / what to expect when operating?

Sorry for yelling. I just had to let off steam.

 

[HarryBack]

well, the manual doesnt actually go into all the specifics of what the stove does when it shuts down....much like your car manual doesnt actually tell you how your engine runs, but the manual DOES tell you how to actually shut the stove down.

 

[begreen]

Why is it feeding pellets during shutdown? What is the intent of this design? I would think this would be a good thing to include in the manual. An informed owner helps avoid service calls.

 

[MikeS]

could be to avoid thermal shock--slow cool down. Although, for thermal systems I have worked on, we cut the fuel but leave the process air on to evenly cool the process train. I would think this would be OK for such small process as a pellet stove also...any other ideas? maybe they need a sooooooper slow cool down?

 

[stovemanken]

The Harman underfire system has more pellets in the burnpot at any one time compared to top feed designs. This gives a compact, dense firemass that also gives the visual effect that makes the fire more pleasant to look at than most "blowtorch ambience" pellet stoves. Also note the fact that your can see and feel the infrared glow of the embers, someting that is not seen/felt with a confined burnpot.

This design makes it desirable to slowly allow the firemass to burn down. Steel stoves will cool much more rapidly than the all cast iron Accentra free standing. Your Accentra Insert is about the middle of the pack.

Your dealer and/or installer should have mentioned this feature to you.

SMK

 

[begreen]

That's a helpful explanation. I learn more about stoves every day. Sadly, I haven't seen infrared, eyes must be getting old. Stand in front of a Quad "burnpot" and you'll feel it though. That is how my son started out every day before school. It's a real nice warmth radiating out from the glass.

 

[stovemanken]

First of all, I mispoke. No one can "see" infrared, unless you are an "X" man. Anytime you see glowing embers, one can assume that that is the source of infrared heat, which can definily be felt.

If your Harman doesn't impress you with its heat, I am amazed. Please be sure you have the feed rate at 4 or better. As I have said may times on this forum, low feed rates do not save pellets!

SMK

 

[SoCal65]

If your Harman doesn't impress you with its heat, I am amazed. Please be sure you have the feed rate at 4 or better. As I have said may times on this forum, low feed rates do not save pellets!

SMK[/quote]

Please point me in the right direction, which posts should I look for. I want to learn more about the pellet feed rates and if room mode or stove mode can actually slow down the pellet consumption. I'm a new owner.

 

[stovemanken]

Harman pellet stoves feed on 1-minute cycles. The portion of the time the stoves "feeds" or "rests" is determined by the feed rate setting.

A setting of "2" might mean 20 seconds of feed and 40 seconds of rest. A setting of "4" might mean 40 seconds of feed and 20 seconds of rest. Obviously either example adds up to 60 seconds.

It is important to note that 20 seconds of feed in the above example is the MAXIMUM time the auger will feed, under ANY circumstances! The same would be said for the 40 second example.

My point is this: If the heat loss in the room exceeds the amount of heat 20 seconds of feed per minute can generate, the room will be cold.

By far and away, ROOM TEMP mode is the way you want to go. The room probe reads the temperature in the room, and adjusts the fire to maintain the temperature selected, plus or minus 1 degree. A Harman can modulate the amount of air passing through the fire (combustion air) the amount of air blowing into the room (distribution air) AND the number of pellets that are being fed. In ROOM TEMP mode, a Harman will NEVER burn ONE PELLET more than is needed to maintain the temperature selected. This is because the room probe is EXACTLY measuring the thermal loss in the room through the walls, ceiling, doors and windows. As the room approaches the desired temperature, the drapes, furniture, walls, etc. are achieving equilibrium. The control board is looking at a 7-minute trend in the room to anticipate a fast warm up (sunny day) or a fast cool down (doors propped open bringing in groceries) and adding or subtracting from the fire.

Please note: The 40 second feed rate a "4" setting represents can and will decrease as the room reaches the desired temperature. It will, in all probability, decrease to below the 20 second rate a "2" setting represents. If it feeds at 15, or even 10 seconds per minute this will save pellets. This happens seamlessly, even though the feed rate is set on "4".

Don't forget that if the stove ran for hours at a 20 second feed rate, the room may NEVER achieve equilibrium, meaning that it would remain cold, and the feed rate could never back off to below 20 seconds because the room never got warm enough to allow it. THIS WASTES PELLETS!

STOVE TEMP mode is a manual mode that is useful for continuous output. It is useful if the dog ate the room probe, or in those rare instances where a steady-state output is desired. Sometimes you might just want to look at a fire. Maybe the stove is used to heat a wood working shop and the door is often opened and closed so cranking out a lot of heat is desired. The stove will not slow down or modulate regardless of room temperature. In 90%+ of the time this is more inefficient than using ROOM TEMP mode.

I hope this is clear.

SMK

 

[Kenny1]

SMK and pelletheat - thanks for the explanations.

I had thought that it was a bit odd that my P61A would continue to feed pellets as it was shutting down. Now I know why.