# Harman P68 room temp mode vs stove temp mode



## ninjarob (Dec 10, 2010)

As a new pellet stove owner/user, I was looking for some advice from those of you on the forum.

I have been using our stove in room temp mode since installation (Oct 2010) and until recently it goes on about 2-4 times a day (sometimes less) for about 10-15 minutes a shot and maybe a little more than that at night. We bought a model that heats 2000 + sq feet to heat an only 560 sq feet area hoping to save on pellet usage. It is a furnished downstairs, a large model train room that the stove is in, master bedroom, and a bathroom, all on cement floor (we used to have radiant heat in the floor but the pipes busted last April)

Just this past week, we have experienced the real first cold of winter here in NJ. The stove pattern now is on for the same short time (10-15 min) but then on again sometimes within the hour. The dealer informed me that running the stove like this makes it 'burn dirty' The downstairs that it heats is not well insulated so the stove heats it up to about 76-77 degree's and then it will fall to 67 (I currently have the thermostat set for 67-68) within at most 2 hrs to start the cycle all over again.

My question is, is my using the stove this way using more pellets and more wasteful than if I just put it on stove temp mode? How low can you make stove temp mode go on these stoves? Am I not using the stove in an efficient manner this way? I currently have the feed rate on 3 as per the dealer/installer.

Any advice? opinions are also very welcome! I hate to waste pellets on trial and error and am hoping someone else has some experience with this.

Rob 
Andover, NJ


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## Delta-T (Dec 10, 2010)

you will likely use a lil more pellets through the on-off cycles than you would if it just ran on low, but the unit is basically the same efficiency in either mode. Try the Stove Temp mode and set it at 1 and see what happens. The worst you could do is use a few cups of pellets, not bags and bags.


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## Mackdog (Dec 13, 2010)

We have the same stove and are going into our 3rd season with it. We started out using room temp mode which is good for fall and spring when the sun comes out and day time temps go up. However, in my opinion you do use quite a bit more pellets with room temp mode in the dead of whinter.  We have used stove temp mode consistently since then after 2 years of learning the in's and out's of the stove and what settings are best for our stove and our home. When it's really cold, a feed rate of 4 works best on our stove. The fire is a bit bigger that way and so ultimately a bit warmer without wasting or using too many pellets. I hope that helps and after some time, you will learn the best settings for you. Keep it really clean and it will work great for you. It is our sole source of heating and we have 2800 square feet.


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## aaronnoel (Dec 13, 2010)

[del]I run a p68 also and used to use room temp, I ran through alot of igniters that way so now I only run on stove and since then no new igniters and it seems like maybe less pellets run on 1 when in 40s-50s and 3or so when it gets colder.[/del]


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## aaronnoel (Dec 13, 2010)

[del]I run a p68 also and used to use room temp, I ran through alot of igniters that way so now I only run on stove and since then no new igniters and it seems like maybe less pellets run on 1 when in 40s-50s and 3or so when it gets colder.[/del][del][/del]


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## aaronnoel (Dec 13, 2010)

[del]I run a p68 also and used to use room temp, I ran through alot of igniters that way so now I only run on stove and since then no new igniters and it seems like maybe less pellets run on 1 when in 40s-50s and 3or so when it gets colder.[/del]


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## aaronnoel (Dec 13, 2010)

I run a p68 also and used to use room temp, I ran through alot of igniters that way so now I only run on stove and since then no new igniters and it seems like maybe less pellets run on 1 when in 40s-50s and 3or so when it gets colder.


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## ninjarob (Dec 13, 2010)

Thanks everyone for the replies, looks like I am going to try stove temp mode as it gets colder.

One more question if anyone can offer some guidance, so for stove temp mode, you need to adjust all three dials correct?  The blower rate, the stove temp, and the feed rate?  The dealer advised me never to move the feed rate from 3 so I was curious as to what you all may be using.

One more thing, my central vac is throwing fine ash all over, I had to order a Couger II for $185, is this normal?  What all are you guys using for clean-up?

Thanks again for all the info!

Rob


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## cac4 (Dec 13, 2010)

Harman (it seems) has gone to great lengths to make their stoves functioning as confusing as possible.  

manual mode isn't really "manual;"  The computer still governs things.

the "feed rate" isn't really the feed rate.  It is really a "maximum".  "no more than ___".   The owner's manual says to set it to 4.  That doesn't mean that its going to always feed at that rate.  It means that it won't feed any MORE than that;  even in "manual" mode, the computer decides how much to feed, up to that limit, depending on what it senses...whether its taking direction from the exhaust temperature sensor, or the room temperature sensor.  You'll see owners of other stoves talking about "how much heat" a certain brand of pellets puts out, and so forth...They can get an idea of this because their stoves can be set for a fixed input--fixed amount of pellets, fixed amount of air= if there's a difference in the output (air temp coming out of the stove), it must be from the pellets.  Well, we can never see that, because we can't "fix" the input;  if  one bag of pellets is burning hotter, the stove will simply adjust the input to satisfy its sensors, no matter what mode is set.  

The stove is going to run most efficiently in room-temp mode, IF its getting an accurate sense of the heat load on the house.  It won't get an accurate sense if the probe is too close to the stove, or sitting on the floor.  If there is another heating system still in use somewhere else in the house, the stove will get confused, and turn on and off the fans erratically as it tries to match the heat load.   In room temp, the stove isn't just going by a fixed temp, and turning up when the temp is too low, and down when its too high;  it is sensing the _rate of change_ of the temp.  A central heating system can change the temp so fast, the stove has to constantly react in the only way it can, which is by cutting off the fan.  (you can't make a wood fire disappear in an instant, like you can w/ gas or oil).  

Its "normal" for a "normal" vac to make a huge mess when trying to vacuum ash.  you should never do that.  You need a special fine-dust filter in whatever vac you use.  Lots of people use regular shop-vacs, but they must have a special fine-dust ("HEPA") filter.


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## tkasek (Dec 13, 2010)

I’ve been playing with these settings the last couple days myself. After only a couple I like running the insert on room temp with the igniter on manual. And at night I set the ignitor back to auto. That way the stove doesn’t turn on and off during the day. It hasn't been real cold the last couple of days, but I can see where stove temp will be an option when it gets cold.


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