Confused by Manometer - changes when door is open vs closed

[Bigeejakes]

Hi Guys - so i've been running a englander 28-4000 for a couple of years and have a pretty good handle on how everything is running, and I'm getting it to produce great heat with around a 6 hour burn. I have been getting quite a bit of black crystal creosote, I would say 3-4 cups 2x per year on cleanings.

Setup as you go up the chimney: Stove- Manometer inserted (6" above stove) - Manual Pipe damper - Condar Probe thermometer - 90* elbow, 4ft horizontal through the masonry wall to T and then 28' insulated stainless liner through outside masonry chimney.

Manometer is a dwyer mark II, connected by 1/4" copper tubing (no connectors, just a hole drilled in the pipe and tube snugly fit.

Here's the goofy thing: My draft readings are running in the -.10 to -.15 range when the door is closed and no pipe damper being used (when stove is at operating temp... and if I open the door at that stage, I get a -.05 to -.07 reading. SO it seems that by closing the door it causes my draft readings to increase by about 2x.

Which one do I use? Based on how the stove burns and what I have read about the NC30 and the 28-4000 burn temps and air intake settings, I'm tempted to believe the door-open readings more than the door closed readings.

If i use the pipe damper to set it at -.05 with the door closed (this is a fully closed pipe damper setting with sub 30*F outside temps... I get a verrry slow burn, with some smoke smell coming into the house as the fire burns down (about 2.5-3 hours in).

Is this normal for my Dwyer Mark II... why would I get these larger draft numbers with the door closed?

 

[Dieselhead]

More vacuum with the door closed is normal. with it open the chimney has a unlimited amount of air, with it closed the chimney has to “pull/vacuum” the air from the stove.

 

[Bigeejakes]

More vacuum with the door closed is normal. with it open the chimney has a unlimited amount of air, with it closed the chimney has to “pull/vacuum” the air from the stove.

Do I use the door open or closed reading to set a damper?

 

[bholler]

Hi Guys - so i've been running a englander 28-4000 for a couple of years and have a pretty good handle on how everything is running, and I'm getting it to produce great heat with around a 6 hour burn. I have been getting quite a bit of black crystal creosote, I would say 3-4 cups 2x per year on cleanings.

Setup as you go up the chimney: Stove- Manometer inserted (6" above stove) - Manual Pipe damper - Condar Probe thermometer - 90* elbow, 4ft horizontal through the masonry wall to T and then 28' insulated stainless liner through outside masonry chimney.

Manometer is a dwyer mark II, connected by 1/4" copper tubing (no connectors, just a hole drilled in the pipe and tube snugly fit.

Here's the goofy thing: My draft readings are running in the -.10 to -.15 range when the door is closed and no pipe damper being used (when stove is at operating temp... and if I open the door at that stage, I get a -.05 to -.07 reading. SO it seems that by closing the door it causes my draft readings to increase by about 2x.

Which one do I use? Based on how the stove burns and what I have read about the NC30 and the 28-4000 burn temps and air intake settings, I'm tempted to believe the door-open readings more than the door closed readings.

If i use the pipe damper to set it at -.05 with the door closed (this is a fully closed pipe damper setting with sub 30*F outside temps... I get a verrry slow burn, with some smoke smell coming into the house as the fire burns down (about 2.5-3 hours in).

Is this normal for my Dwyer Mark II... why would I get these larger draft numbers with the door closed?

The door open readings mean nothing. Go by door closed

 

[Dieselhead]

^^Yep^^

 

[Bigeejakes]

Here's an update:

As I keep tinkering with the furnace, I decided to try a barometric damper, I got one of the calibrated units from field controls and set the weight to .06"

It opens when my dwyer markII reads about .1" with the door closed. When I open the door at that range (and the baro damper just starting to move) I get a reading of .06".

Anyway, now I'm confident my stove isnt going to over draft, and I'll be keeping an eye on the chimney for creosote buildup.

Stove is keeping us toasty... It does go through the wood at almost a face cord / week.

 

[trx250r87]

Is your manometer calibrated to the zero mark when the tube is disconnected from the flue? -.06" should be the max draft, I often run mine less.

Eric

 

[JRHAWK9]

Do I use the door open or closed reading to set a damper?

This depends, do you typically leave the door open when it's in use....if so then that's how you set it.

 

[brenndatomu]

It opens when my dwyer markII reads about .1" with the door closed.

You are still overdrafting that furnace then. Get it at/below -0.06" will help you heat your house using less wood...and help the furnace last longer...you are overfiring it now.
Nevermind what the reading on the Field sliding weight scale says, set it so you aren't going over -0.06" when you are at operating temp (stove door closed)
And yes, make sure the Dwyer is plumb/level, and sitting at zero when not hooked to the flue (good to check it when you are burning regularly too, as temperature of the gauge changes zero a bit too)

 

[Bigeejakes]

You are still overdrafting that furnace then. Get it at/below -0.06" will help you heat your house using less wood...and help the furnace last longer...you are overfiring it now.
Nevermind what the reading on the Field sliding weight scale says, set it so you aren't going over -0.06" when you are at operating temp (stove door closed)
And yes, make sure the Dwyer is plumb/level, and sitting at zero when not hooked to the flue (good to check it when you are burning regularly too, as temperature of the gauge changes zero a bit too)

Thanks! I've set it so that it's reading .05" at operating temp, I'm able to see nice lazy flames and lots of secondary action. Now I just need to keep an eye on the chimney and see if I'm getting a lot of buildup.

I really like the way a baro operates, so even if it means more chimney cleaning I think I'll be sticking with it.

 

[brenndatomu]

Thanks! I've set it so that it's reading .05" at operating temp, I'm able to see nice lazy flames and lots of secondary action. Now I just need to keep an eye on the chimney and see if I'm getting a lot of buildup.

I really like the way a baro operates, so even if it means more chimney cleaning I think I'll be sticking with it.

If you are burning dry wood, you will likely see very little change in the chimney deposits...maybe just a bit more/darker right at the baro.
Hopefully you have an insulated class A chimney, that will stay the cleanest.