ridgeracing wrote:I have turned stove temp down to 325 past 24hrs and have had a draft of .03 with mpd closed 100%. Opening mpd 100% and closing bi/metal intake I now read .04. I no that with increasing temps in next 2 days I will have to open mpd a little to sustain a descent draft. It is about 45deg outside, 72-74 inside
thank you. stove has .04 leakage from secondary over fire air bleed holes designed in. mpd open. not at .06 yet. if then open manual draft can you get .06 reading, mpd open. mark that spot. problem most draft is over top fire, not under. reduces main draft control effect. fixed drilled bleeds steal control from main draft knob. .04 with mpd open, dont really need mpd. I'd block few fixed air bleeds & come down .01-.03 leak test, transfer control to main draft. new stoves are emission EPA regulated. lots of secondary air in flue, to make legal sellable for EPA. remember air pumps on 1970s cars. same deal pumped air in exhaust manifolds EPA mandate. bleeds create .04 draft then needs mpd to reduce it when main draft opened. no bleeds=no mpd, just draft control. old stoves over fire air was adjustable, today EPA mandates it must be fixed. you can experiment there. question- whats mano reading main draft wide open, mpd wide open?
on my DSM 1400. right now, mature fire, 6 hrs. past last tending. stove top 325*. both lower and upper MPD's fully open, bi-metal flap fully closed. Mano. reads .06 WC..
if i reopen the intake flap to the former position, 1/16" open and holding, the Mano. reads .07 WC.
if i leave the intake flap open that far and close the lower MPD the Mano. reads .05 WC.
if i close the upper MPD 45* the Mano. reads .04 WC and if i close it the Mano. reads .03 WC.
because of this i can't fully support the reference to .04 WC fixed air bleed from the secondarys. BUT, i do have experience that will support the idea that you can alter the balance of how much air enters the stove from under the fire and over the fire by blocking some of the secondary openings. i have proved that conclusively here with my set up.
the infinite variability of the bi metal intake and the constant feed of the hopper is a set of factors that have to be experienced to understand their true impact on all this.
so far my take is that these stoves pull MORE secondary air at lower factors of -WC than they do at higher. i'm not saying i know how, but i have logged the diff. in stove out put a variety of ways and the most transfered heat is at -.05 / -.06WC, secondarys wide open, lower MPD fully closed, no matter what stove top is being held.
no brand or damper axe to grind, just sharing perspective.