Need Help Setting Damper/Optimizing Performance, Napoleon NPS40

[becasunshine]

Hi, Everybody!

We have a Napoleon NPS40 (freestanding) stove and this is our second season. Last season we thought we'd found the stove's "sweet spot" in terms of settings: feed setting of 4 (right in the middle of their "optimum" range) and a damper setting of 2.

Last year we had a couple of major home renovation projects going on, so if the stove was producing heat at all we were happy. We kept it clean and full and running and otherwise our time and minds and hands were occupied elsewhere in the house.

This year I'm all about optimizing our stove's performance, i.e. wringing every last btu out of those pellets.

Our Napoleon has basic, manual mechanical controls.

I've done the damper thing I saw described elsewhere on the forum- push the damper in until the flame gets big and lazy, then pull the damper out as the flame gets more compact, intense and whiter. When the flame stops changing you have, according to this explanation, found your optimum damper setting.

Our Napoleon has a horizontal exhaust vent out of the adjacent wall with one 45' elbow inside the house behind the stove and a short distance to travel to the outside. (The stove is positioned on an angle in a corner.) We have a professionally installed OAK. That OAK intake tubing also travels a very short distance. We have NO PROBLEM with an outside air feed to the burn pot. As I extract the damper rod the flame just gets tighter and tighter and whiter and whiter all the way to damper wide open. I can actually get a Bunsen burner flame with blue at the base.

So do I just stop extracting the damper rod at the point where the flame gets white and tight? Because that's actually a little lower than 2. It's more like a damper setting of 1, with "Low" being the lowest and 5 being the most wide open. Does this make sense given the above scenario?

We also use a box fan pointed at the stove to facilitate natural convection. That seems to work quite well.

Last year we burned Hamer's Hot Ones, plus several bags of Lignetics that we purchased from a private seller who didn't need them. This year we are burning O'Malleys.

I want to burn at the most efficient setting and I want to avoid sending excess heat out of the exhaust vent. Where is our damper best set and is there anything else we can do to optimize performance?

GREAT FORUM, btw. So much good information here!

 

[imacman]

Welcome to the forum, becasunshine. Lots of nice and friendly people here to get help & info from, and some laughs sometimes too.

As for the setting, I'll give you what I believe to be the best setting for most any pellet stove that has an adjustable air control like yours. (this comes straight from the Travis Indust. (Avalon & Lopi) manual:

The best setting is the one where the burning pellets are "dancing" a little on the bottom of the burn pot....if their not moving at all, open the air a little...if their jumping out of the pot, close it a little.

BTW, we all love pics of stoves, especially burn pics...hint, hint. :cheese:

 

[jtakeman]

Welcome becasunshine,

There are a few way you could do it.

One is to watch for the pellet dance as they say. Turn or advance the damper setting until the pellets just start dancing about.

Two is with a temp probe or thermometer to watch the heat exchanger air temp. Move damper slowly until you reach the hottest temp.

To much damper will only send the heat up and out the vent. Not efficient in anyway.

Check here:

https://www.hearth.com/talk/threads/46929/

One other way to judge if you have went to far, Is the flame will vary from high to low. Try to keep the flame consistent or as consistent as possible

have fun with it.
jay

 

[becasunshine]

Hi, Macman and Jtakeman! Thank you for your prompt responses. I snapped a few pictures of the burn pot in action and I tried to upload them. They were too big, so I tried cropping them and I'm still getting upload error messages. I need to work on editing the pictures to a small enough size for the forum. I will do that in a little bit; I have to do something else right now. BRB with pics!

 

[eschills]

I have an NPS40 and do the same as far as pulling out the damper setting until the flame is no longer lazy. At 3 -3 1/2 it seems to stop changing. I can set the feed rate at anything but never have to change the damper. I do not have an OAK.

 

[becasunshine]

M'kay, thank you for your patience!

Here are some pictures of the stove.

Current settings:
Damper 1
Feed 4
Blower 4

Household temp 72'F, outside air temp 36'F, adjusted for windchill 30'F

Burn time since cleaning approximately 9 hours

O'Malleys hardwood pellets

The large view picture shows the stove with the divine glow of inexpensive heat in its belly. I think it's rather inspiring and artistic, don't you?

The back of stove picture shows the short excursion of the exhaust vent pipe and the outside air intake hose.

The next several pictures show a "cycle of fire" (wow, I rather like that phrase, "cycle of fire") in the burn pot, ranging from the previous pellets almost spent through the delivery of fresh pellets to the greatest excursion of the fire beyond the burn pot.

The ash build up in the pot is about typical. We get a bit of ash but no real "clinkers." We do clean the stove every day so that probably mitigates some clinkers.

We used to keep the damper set at 2. I have to say, closing the damper to 1 seems to have made a significant difference in the temperature inside the house. The temperature in the house is warmer. When we had the damper at 2, the inside air temps stayed in the mid to upper 60s, especially when the outside air temps were near freezing. We've been burning O'Malleys this year with the exception of one bag of Hamers and today is the warmest we've had in the house.

Last year wasn't a great test of the stove because we had some exceptional circumstances. We tore out our kitchen and laundry room, down to the exterior brick wall and to the subfloor in some places. That end of the house was a drafty construction zone. Blocking the doorways helped some but there was an insane temperature gradient. Anyway, like I said in my previous post, in the middle of that mess we were simply happy to have heat.

Do you think that the short excursion of the exhaust pipe and the outside air intake have something to do with us needing to keep the damper closed down to prevent our heat from blowing out through the exhaust pipe? The stove doesn't seem to need a wide open damper.

Or am I running the stove with too little air?

 

[becasunshine]

Hey, Eschills, nice stove! That might be the most handsome stove I've ever seen!

Our flame changes, no lie, between Low and 1. I swear, I think it's the short excursion of the exhaust pipe and the OAK to the outside.

Is that a vertical exhaust pipe behind yours?

Maybe the OAK is making ours a little blast furnace.

I dunno. I'm warm. I'm happy.

 

[becasunshine]

Burn pics