MPD Vs Primary Air

scalabro · Post by **scalabro** » Wed. Jan. 06, 2016 3:47 pm

These past two nights were in the single digits here in western mass. I have found on my Crawford that I can use the MPD as a "throttle", if you will.

I set the primary air shutter wide open, then set draft to achieve barrel temps.

For instance

.01 = 300 +or -

.02 = 450

.03 = 525

.04 = 575

Anybody else do this?

ddahlgren · Post by **ddahlgren** » Wed. Jan. 06, 2016 4:14 pm

Seems like a rather bizarre way to get it done. The higher the draft the more goes up the chimneyy

Post by **Lightning** » Wed. Jan. 06, 2016 4:21 pm

Heat up the chimney is inevitable either way you do it. Theoretically speaking, with a tight stove neither would be more efficient than the other. (Primary vs MPD)

freetown fred · Post by **freetown fred** » Wed. Jan. 06, 2016 4:23 pm

Scott, are you workin or off for the winter?????

Post by **Lightning** » Wed. Jan. 06, 2016 4:26 pm

Fred wishes he woulda thought of that lol :bag:

KingCoal · Post by **KingCoal** » Wed. Jan. 06, 2016 4:27 pm

scalabro wrote:These past two nights were in the single digits here in western mass. I have found on my Crawford that I can use the MPD as a "throttle", if you will.

I set the primary air shutter wide open, then set draft to achieve barrel temps.

For instance

.01 = 300 +or -

.02 = 450

.03 = 525

.04 = 575

Anybody else do this?

yes you can do it that way. as you have found, primary and stack draft is a balancing act with these stoves.

the precautionary side is that, if you have the primary wide open and the draft held at .025 or more and get unexpected high wind where is your barrel temp. going to stop ?

as a safety issue you are much better off using your MPD and primary to get about -.025 /-.03

play around and you'll find that at most any Mano. reading you get from a specific MPD setting you can drive the Mano. up by closing the primary more. OR, you can drive the Mano. down by opening the primary more.

it really is a balancing act and i'd always go for the safest side of the process.

.02 worth

tcalo · Post by **tcalo** » Wed. Jan. 06, 2016 4:28 pm

Why don't you keep the mpd closed and adjust the primary air?

scalabro · Post by **scalabro** » Wed. Jan. 06, 2016 4:32 pm

I think I was misunderstood

This is with running the primary fully open.

I have not recorded numbers but it seems the stove will only accelerate out to "X" temperature for any given draft number with a fully open primary.

I have not had the balls to run wide open primary air and .06 draft

Oh and my draft numbers will not change via primary settings....until the stove heats more and creates more draft. Stove draft is primarily a function of MPD setting.

scalabro · Post by **scalabro** » Wed. Jan. 06, 2016 4:35 pm

freetown fred wrote:Scott, are you workin or off for the winter?????

Went in today @ 0330, so I'm kinda loopy

freetown fred · Post by **freetown fred** » Wed. Jan. 06, 2016 4:41 pm

I keep my MPD 3/4 closed all the time in cold weather--even while tending. I've got no mano, no baro, no thermo's -- what I do have is an 1800 sq. 200 yr old farm house that the old HITZER keeps at 72*. So much for my scientific feed-back.

scalabro · Post by **scalabro** » Wed. Jan. 06, 2016 4:49 pm

Mostly that's me too Fred, except while tending the it's wide open MPD

But no worries I never leave the stove unattended with the primary wide open. It's just something I noticed these last couple days so I figured I'd ask....

michaelanthony · Post by **michaelanthony** » Wed. Jan. 06, 2016 5:08 pm

My basement box stove has both, a mpd and a baro, the primary leaks but I don't care it's 35 yrs old and runs like a champ. I run it with the primary closed, (for what it's worth it looks closed), I too play with my mpd, I know I made a funny

...anyway I use the mpd to adjust the draft reading on the mano and to set the baro so it falls but will flutter gently with the slightest breeze. I can also tell what the stove temp will be with out the ir gun within 10 - 20 degrees. It's a fun head game I play when I'm moving coal in the basement and no one to tell ...it feels good to get that weight off my chest.

Sunny Boy · Post by **Sunny Boy** » Wed. Jan. 06, 2016 5:10 pm

Try that on my range and you'll be setting the CO alarms off for sure. Been there !

The fire WANTS to breath. If you don't give it the chimney YOU WANT, it will find another ...... which might be through any and all leaks above the firebed in the stove and seams in stove pipe - all leading to inside the house.

And incase anyone has forgotten, carbon monoxide poisoning is cumulative. Almost lost a friend to a leaky car exhaust system one winter.

Paul

scalabro · Post by **scalabro** » Wed. Jan. 06, 2016 5:10 pm

That's the first step Mike

scalabro · Post by **scalabro** » Wed. Jan. 06, 2016 5:12 pm

Sunny Boy wrote:Try that on my range and you'll be setting the CO alarms off for sure. Been there !

The fire WANTS to breath. If you don't give it the chimney YOU WANT, it will find another ...... which might be through any and all leaks above the firebed in the stove and stove pipe leading to inside the house.

Paul

Well if my baseburner had four miles of gas path I would expect that! Wink, wink