DSM 1400 Secondary Inlet and Outlets

Post by **Lightning** » Wed. Dec. 25, 2013 9:31 pm

rberq wrote:and hope that DS had practiced intelligent design rather than random creation.

I'm guessing they probably designed the secondary air to be just enough to prevent puff back at their recommended running pressure, which I think King said was -.06 ....

KingCoal · Post by **KingCoal** » Wed. Dec. 25, 2013 9:36 pm

Lightning wrote:
rberq wrote:and hope that DS had practiced intelligent design rather than random creation.
I'm guessing they probably designed the secondary air to be just enough to prevent puff back at their recommended running pressure, which I think King said was -.06 ....

i believe this to be true, although I have never had a puff back in this stove even when firing as a batch heater at 125# stove top and -.03 WC.

somethings going on here, like in the baseheaters that we haven't seen clearly yet is all.

oliver power · Post by **oliver power** » Wed. Dec. 25, 2013 10:40 pm

The secondary air also acts as an air wash for the glass.

MarkV · Post by **MarkV** » Sun. Dec. 29, 2013 11:37 pm

Lightning wrote:
rberq wrote:and hope that DS had practiced intelligent design rather than random creation.
I'm guessing they probably designed the secondary air to be just enough to prevent puff back at their recommended running pressure, which I think King said was -.06 ....

First, thanks to the earlier posters for pointing out something I never knew about my DS 1500. Had no idea those secondary air holes drew air from the outside--I mistakenly assumed, based on a conversation I had with someone at DS Machine that the source of that air was from under the fire...i.e., from the thermostat-controlled air intake.

When I saw the pics posted above, I looked with a flashlight through the metal mesh on the sides of my stove, and sure enough, there are the secondary air inlets.

My question: If these stoves are designed so the secondary air prevents puff-backs, why is DSM selling anti-explosion louvers? Those are the rectangular cast metal pieces that take the place of two firebricks, and have a downward-facing louver to channel more air into the firebed. DS Machine told me when I bought my stove last year they were still testing them. I was so freaked out by the pinned thread on puffbacks I went ahead and ordered a pair for around $75 for two of them.

I haven't had a puffback (yet) and assumed it was due to the louvers. Now I'm wondering if I wasted my dough, and would have been fine with the secondary air inlets as is.

Post by **Lightning** » Mon. Dec. 30, 2013 1:48 am

MarkV wrote:Had no idea those secondary air holes drew air from the outside--I mistakenly assumed, based on a conversation I had with someone at DS Machine that the source of that air was from under the fire...i.e., from the thermostat-controlled air intake.

Your stove has "independent" primary and secondary air. The primary controls heat output and is adjustable via the controlled air intake. The secondary air which is fixed thru the drilled holes, lets air in over the fire to burn volatile gases on top the coal bed.

MarkV wrote:My question: If these stoves are designed so the secondary air prevents puff-backs, why is DSM selling anti-explosion louvers? Those are the rectangular cast metal pieces that take the place of two firebricks, and have a downward-facing louver to channel more air into the firebed. DS Machine told me when I bought my stove last year they were still testing them. I was so freaked out by the pinned thread on puffbacks I went ahead and ordered a pair for around $75 for two of them.

I believe member "I'm on Fire" installed the louvers because he was having puff back problems. He also has a very weak chimney draft. Its very possible you could run the stove without the louvers. Hard sayin..

The louvers use some of the primary air to bypass the coal bed and become more secondary air. A technique I like to call a codependent secondary air system since they depend on the primary air control. Personally, I'm not fond of these style secondary air systems. It actually caused me a lot of grief with my furnace. But seems to work well for others that have a more effective grate system.

oliver power · Post by **oliver power** » Mon. Dec. 30, 2013 6:57 am

Harman has air coming around it's glass in the Mark-series stoves (maybe others). They call it an air wash for the glass. Slows down the fly ash build up on glass. It also could be considered secondary air for burning. Take your pick. Most likely wouldn't affect burn at all. A stronger primary air adjustment, I think would overcome that little bit of secondary air. Just my thoughts.

rberq · Post by **rberq** » Mon. Dec. 30, 2013 8:38 am

MarkV wrote:
rberq wrote:and hope that DS had practiced intelligent design rather than random creation.
My question: If these stoves are designed so the secondary air prevents puff-backs, why is DSM selling anti-explosion louvers?

Their first pass was random creation, the louvers are intelligent design?

I think the secondary inlet channel and the number of holes are the same for the smallest (1300) circulator to the largest (1600). On the face of it, that does not seem reasonable. My 1300 has 9. I would think the larger firebox would need more secondary air.

MarkV · Post by **MarkV** » Mon. Dec. 30, 2013 8:45 am

Lightning wrote:
I believe member "I'm on Fire" installed the louvers because he was having puff back problems. He also has a very weak chimney draft. Its very possible you could run the stove without the louvers. Hard sayin..

The louvers use some of the primary air to bypass the coal bed and become more secondary air. A technique I like to call a codependent secondary air system since they depend on the primary air control. Personally, I'm not fond of these style secondary air systems. It actually caused me a lot of grief with my furnace. But seems to work well for others that have a more effective grate system.

Thanks for the explanation. I recall reading IOF's posts last winter, possibly in the pinned thread.

My draft isn't the strongest either, so I'll probably wind up keeping the louvers in.

MarkV · Post by **MarkV** » Mon. Dec. 30, 2013 9:03 am

rberq wrote: I think the secondary inlet channel and the number of holes are the same for the smallest (1300) circulator to the largest (1600). On the face of it, that does not seem reasonable. My 1300 has 9. I would think the larger firebox would need more secondary air.

Good point. Same here, my 1500 has the 1" square inlets on either side, and nine holes inside the glass. KingCoal probably nailed it in his post above...

KingCoal wrote:by some feat of engineering or magic MY stove alters the amount of air it pulls into the secondary tract according to the amount of over fire draft present. more when draft is low, less when draft is high, no explanation, just happy, steady, even, economical heat.

I can't argue with the fact that the 1500 just keeps throwing plenty of heat with minimal bother or attention from me, except during warm/damp weather.

I'm On Fire · Post by **I'm On Fire** » Mon. Dec. 30, 2013 9:48 am

Lightning wrote:
MarkV wrote:Had no idea those secondary air holes drew air from the outside--I mistakenly assumed, based on a conversation I had with someone at DS Machine that the source of that air was from under the fire...i.e., from the thermostat-controlled air intake.
Your stove has "independent" primary and secondary air. The primary controls heat output and is adjustable via the controlled air intake. The secondary air which is fixed thru the drilled holes, lets air in over the fire to burn volatile gases on top the coal bed.

MarkV wrote:My question: If these stoves are designed so the secondary air prevents puff-backs, why is DSM selling anti-explosion louvers? Those are the rectangular cast metal pieces that take the place of two firebricks, and have a downward-facing louver to channel more air into the firebed. DS Machine told me when I bought my stove last year they were still testing them. I was so freaked out by the pinned thread on puffbacks I went ahead and ordered a pair for around $75 for two of them.

I believe member "I'm on Fire" installed the louvers because he was having puff back problems. He also has a very weak chimney draft. Its very possible you could run the stove without the louvers. Hard sayin..

The louvers use some of the primary air to bypass the coal bed and become more secondary air. A technique I like to call a codependent secondary air system since they depend on the primary air control. Personally, I'm not fond of these style secondary air systems. It actually caused me a lot of grief with my furnace. But seems to work well for others that have a more effective grate system.

Man was I ever getting explosions. I do have a very weak chimney and need to use a draft inducer 24/7 all winter. I installed the louvers because the explosions I was experiencing were so intense my house shook and at times I'd get blue flamed shooting out of the thermostat and sides of the stove where the secondary air holes are. The louvers have pretty much eliminated the puff backs. When I experience them now they are much less spectacular. I've also changed how I shake down the stove. I don't touch anything. I don't open the MPD, adjust air settings.

I think the louvers were one of the best buys for the stove last season.

slinger100 · Post by **slinger100** » Mon. Dec. 30, 2013 10:04 am

I believe the puffbacks has much more to do with each particular situation i.e. draft. My 1600 has never had a puffback yet. It is installed in the basement in a center of the house masonary chimney about 35 feet tall so draft is no problem. The secondaries do work as sometines I have blue flames shooting out of them that almost looks like a gas burner. I'll try to post pictures the next time I see them.

KingCoal · Post by **KingCoal** » Mon. Dec. 30, 2013 11:03 am

hmmm, this is interesting. and seems to contradict my theory of more secondary draw at low draft and less at high draft.

you no doubt have at least as good of chimney draft as I do (which has been called industrial) and I have only had flames at the outlet holes once, when I first fired up the stove with out the hopper in it.

slinger100 · Post by **slinger100** » Mon. Dec. 30, 2013 12:19 pm

I keep draft at .03 on the manometer using a baro and mpd to keep the baro from being wide open all the time. The chimney definitely has plenty of draw. This setup works very well in my application.

KingCoal · Post by **KingCoal** » Mon. Dec. 30, 2013 1:10 pm

.03, hmmmm, well that's another story altogether isn't it ? and would rather seem to support the theory that these stoves pull more secondary at lower draft. very interesting.

slinger100 · Post by **slinger100** » Mon. Dec. 30, 2013 1:34 pm

That may be. It would be a matter of the air taking the path of least resistance. The baro being set to .03 I would think that as the grates get covered with more ash it would get easier to pull more air from the secondary air which is unblocked by any ash. When I purchased the stove I did think it was odd that the secondaries were not adjustable. But if the baro is set to a constant draft it should pull the same no matter what the bimetallic primary is doing. So I'm guessing that if the primary is wide open and the grates are clean most of the air comes from there. As the stove reaches it's set temp and the primary closes the manometer doesn't change so the air has to be coming through the secondaries more. Does that help or make it worse? Lol