How "Low" Can You Go? (Pix)

In an attempt to gain longer burn times out of my stove, I've been playing with adjustments, to see if I can "reap" any rewards. I've finally gained enough confidence (with the help of the manometer), to close my MPD completely. My draft dropped from approx. .06-.07, to as little as .02-.03. Not knowing what to do with the Surdiacs thermostat, I opened it just a "tad" more to maybe help support the fire. At this setting (but with the MPD set open about 10-20 degrees), my longest burn (with-out scraping or poking) is about 6-8 hrs B4 the coal bed is almost completely out. With the MPD totally shut, my burn time hardly made a difference at all.
However, the plus side of this is that it appears the coal consumption was reduced somewhat. I'm still watching this to make sure there aren't other variables influencing it. But my question is, on your stove, how slow can you make it burn, yet keep the coal bed hot enuff to keep it from going out? I know it's like comparing apples to oranges, and all we have to go on is temperature readings. (which we all take differently). But how about the appearance of the fire? I don't know if computer pix are a good indication, but here is what my coal bed looked like on the lowest setting I "think" I can achieve, from my stove.


Compare that to this pic of when it's hotter.


Like I said, maybe pictures aren't a good indication, but I'm trying my best to get this thing to go longer with-out poking, yet still produce enuff heat, so I won't be waking up after less than 6 hrs to a "luke' warm' stove.

joeq wrote:But my question is, on your stove, how slow can you make it burn, yet keep the coal bed hot enuff to keep it from going out?

Like you mentioned, theres many variables.. I've been able to get 24 hours between shake downs easily during warm spells. When I shut down in January it took 36 hours for it to burn out. I've read of some getting 48 hours without tending and managed to revive and rekindle the fire .... Coal fires are able to be choked way down to barely burning for long periods of time. Usually its maintaining the draft that becomes the issue when choking the fire down. During warm spells I've seen .005 - .01"WC of draft pressure which is low, but as long as there is any negative pressure carbon monoxide can't escape.

How's this?

The Glenwood Base Heater in the living room can be operated at around 180 degrees for an indefinite period of time. Due to the high efficiency of the internally suspended fire pot, the fire bed temperature never cools to below its ignition point. It will simmer until all of the coal is reduced to a fine talcum like powder.

I agree with William. A deep round fire pot that loses little heat will survive a low fire with the least air and burn the coal most thoroughly.

To get a longer burn in a Surdiac, take out the hopper and build up the front of the fire box to take a deeper bed of coal. Will have to be run as a batch loading stove.

Smitty, what is that? 1 piece of coal burning? will it stay lit all nite?

Removing my hopper, and trying your method, FB, might happen sooner than later, if my hopper keeps deteriorating as quickly as it has.

The Golden Bride can idle 90*F for 12 hrs between ""refills"". The right stove for the right place.
The Sunnyside can run around 200*F and probably lower, I will have to make some tests to see how low it can idle the 12 Hrs runs.
Both stoves have round fire pots. Very easy to work these stoves.

Joe, we discussed in another thread about your Surdiac being very similar in design and operation to my old Franco-Belge 10-175. Top load, hopper feed to rear of fire bed, etc. I can give you some input from my long experience with the Franco.

The thermostat on the Franco went, I believe, from 0 to 7 or 8. I generally set mine at 3.5 to 4 on average winter days, as high as 5 to 5.5 on coldest days, and as low as 2.5 on warmer days. I had an MPD and a baro in my setup. Usually had my MPD about half closed, sometimes 2/3 closed on windy days.

Judging from your pix, your fire is burning as hot as my Franco would be on the 5.5 setting. When burning that hot, it would only maintain that temp about 4-5 hours, then start to cool down. It definitely needed a shake around the 5 hour mark to keep it hot. Sometimes, on single-degree or lower nights, I'd shake the stove at 11 pm, then set my alarm to get up at 4, to shake it again and keep it hot. If I left it go for 8-9 hours on that setting, there would be mostly ash in the firebox, and the fire would have started burning up into the hopper. In that state, there were usually enough hot coals that if I shook it down carefully, and left the ash door open, I could recover the fire.

On the average winter day when I had it set back to 3.5 or 4, the fire wouldn't burn as hot as your pix look (more unburned coals on top), but the fire would burn 8-9 hours, and a good shakedown would keep it going. On the warmer days, with the thermo set back to 2.5, I still only got around 9-10 hours of good burn, because opened my MPD more, so more hot gasses would be getting up the flue to maintain the draft.

Bottom line, this type of stove just doesn't have a big enough, or deep enough, firebox to maintain a really hot fire for more than about 5 hours, no matter what you do. The best I could do, after 28 years with two Francos, was keep the fire going at a moderately warm temp with a minimum of three shakings a day. If I wanted to keep it very hot, I planned on shaking every 4-5 hours.

Incidentally, the very longest my Franco went without shaking, and still was recovered, was about 17 hours. The wife and I left at 8 am one December day when temps were in high 30s. I'd turned the thermo way down to keep the fire low. Planned to get back around 10 PM but make it till just after 1 AM. Thought the fire was out, but found it had burned completely into the hopper, and about eight or ten hot coals were still burning--barely. Shook it very gently to get the coals back into the fire box with a little new coal on them, then left ash door open for almost an hour. The coals heated up and ignited the new coal. Didn't have the full firebed burning again till next morning, but I was still on the first match.

Thanx for your very "detailed" response MV. I can agree with all your efforts with your franco, and results, but why or "how" can the manufacturer promote 6-24 hr burn times in their brochures with a straight face? I also work with an individual who operated a Surdiac in the 80s (tho not the same model), and said he also got "long" burn times, with very little fuss. He also "emphasized " the fact the manufacturer stated it was imperative his had a baro-damper. It'll be a last attempt to install one, because, at this point, I don't recognize a draft problem to warrant one. Did you have one installed to your Franco?

joeq wrote:Smitty, what is that? 1 piece of coal burning? will it stay lit all nite?
......

Yeah, that night it was pretty much one piece of coal burning. That was close to a 40 hour burn - got home late that night. Saved the fire too if you can believe that one. Would've been quicker to just start over - that took FOREVER to get going again.

joeq wrote:He also "emphasized " the fact the manufacturer stated it was imperative his had a baro-damper. It'll be a last attempt to install one, because, at this point, I don't recognize a draft problem to warrant one.

The baro keeps the draft pressure regulated but doesn't do it perfectly.. I have mine set to start opening as the draft pressure exceeds a .02"WC.. But in times of extreme cold and/or wind it will stay a steady .05"WC or higher.. Thats where the MPD does its magic and I can choke it down to a .03-.04 while the baro keeps it regulated there.

But overall, I don't think the baro will improve your burn times since you are keeping the draft at bay with the MPD.

Smitty thats hysterical

Deep, round coal bed does have a huge advantage and the baseheaters have the added advantage of maintaining the heat/fumes around the combustion chamber for incredible performance at the lowest settings (of course some will argue they loose radiant ability for this advantage ) but I agree with the previous poster the Surdiac just does not have the attributes to preform like this no matter what you do to it.

Am I the only one who is cold and doesn't care about how low his fire is? I want to be warm, so I turn it up.

I'm On Fire wrote:Am I the only one who is cold and doesn't care about how low his fire is? I want to be warm, so I turn it up.

No way man! We be cranking lol

I'm On Fire wrote:Am I the only one who is cold and doesn't care about how low his fire is? I want to be warm, so I turn it up.

I understand where you're coming from. I have no problem making heat when I'm able to be around the house to constantly scrape the grates every 2-3 hrs. My complaint is when I go to bed, and wake up to a stove almost out, and not producing any heat. My twisted way of thinking is that if I can slow the burn rate down at nite, the coal consumption will be reduced, and while we're all under covers(staying warm), there won't be as much ash accumulation to clog the grates.