Short Burn Times with EBW-100

[maple1]

This is the type of damper I have. When the chimney is cold and a piece of paper is held against, it is blowing away from the damper resulting in a heavy downdraft.
(broken link removed to http://www.fieldcontrols.com/rc.php)

Now I"m way confused. I can't imagine how a chimney that tall can have backdraft like that.

 

[SIERRADMAX]

stack effect?
(broken link removed to http://www.thechimneysweep.ca/2stackeffect.html)

 

[NE WOOD BURNER]

I see you have an exterior chimney?
Is there a cap on your chimney?
Do you have pictures of your install?
Your back draft is at idle? does it draft well when the boiler is burning full out?
May have missed this but do you have clay tiles in chimney or a SS liner?

 

[NE WOOD BURNER]

nice explanation there.
That is where I was heading!

I have a similar setup. In fact the back draft will pull from my other two flues and fill the basement. I am working on a cap with dividers to help that situation.

 

[b33p3r]

Econoburn 150 recommendation was a draft of .02-.05. I installed a Barometric damper and had to max it out to get the proper draft on a 13' 8" pipe. If you read the installation guide, I believe somewhere in there states you may have to install 2 dampers to get the proper draft. Please don't quote me on any of this. I don't have a great memory. I posted it to give you ideas.

 

[brenndatomu]

I believe somewhere in there states you may have to install 2 dampers to get the proper draft.

Huh! I've never heard that recommended anywhere before, but it makes sense. I have a 8" x 30' insulated SS liner in an external masonry chimney and a 9" BD adapted to an 8" tee (don't ask) and I still get too high draft readings during really cold windy weather, with BD laid out wide open!
My Yukon furnace calls for -.03" WC draft, if I hold the BD closed, draft goes to -.1" or so, flue temps go way up but the supply plenum temps climb slower than with a -.03" draft, even though there is a ROARING fire.

 

[SIERRADMAX]

Yes, chimney is entirely on the outside and has a 1 piece stainless chimney cap.I core drilled through my foundation to include an 8" thimble for the wood boiler, a 6" thimble for the oil & two 6" cleanouts. Any thoughts on moving the B.D. to the cleanout opening?
(broken image removed)
basement

 

[SIERRADMAX]

Econoburn recommends .02-.05 draft setting. Also, outside combustion air??? From Econoburns manual:
COMBUSTION AIR SUPPLY
Air inlets of at least 200 square inches free area must be provided to the room occupied by the
wood fired boiler.
These fresh air inlets must provide or allow free access of fresh outside air to the boiler.
At no time, or under any circumstances can a wood burning boiler be starved of combustion air.
The boiler must at all times be able to maintain the approved stack draft. The barometric draft regulator
must be installed on the boiler smoke pipe in the same room or at least in such a way that
there is unrestricted free passage of air between the combustion air inlet to the boiler or burner
and the barometric draft regulator.
It is important to provide adequate combustion air to the boiler, a minimum 200 square inches
free area. It may be necessary to add a ventilator to an exterior wall of a closed boiler room or an
airtight basement.
Operating a wood or oil fired appliance with inadequate combustion air could be hazardous.
5
OUTSIDE COMBUSTION AIR MAY BE NECESSARY IF:
1. Fans that are installed in the fuel storage area create negative pressures in the room where
the solid fuel-burning appliance is located.
2. The solid-fuel-fired appliance does not draw steadily, smell, experiences smoke roll-out, burns
poorly, or back-drafts whether or not there is combustion present.
3. Any of the above symptoms are alleviated by opening a window slightly on a calm day.
4. The house is equipped with a well-sealed vapor barrier and tight fitting windows and/or has
any powered devices that exhaust house air.
5. There is excessive condensation on windows in the winter.
6. A ventilation system is installed in the house.

 

[brenndatomu]

My Yukon manual shows that putting the BD on the cleanout door is a no go. Yukon took this drawing directly from Fields install info.
Also, this is how they recommend doing the make-up air supply. My furnace is about 140k BTU. My make-up air pipe is 6". It's more than adequate with a 8" chimney.

 

[SIERRADMAX]

Update: It took a while for UPS deliveries with the holidays. But bottom line, I installed a barometric damper, a Dwyer Manometer & stovepipe thermometer.

I have to block the barometric damper upon startup. I noticed smoke billowing out (w/ cold chimney) even after trying to warm it up with some crumpled newspaper. When up to temperature, Manometer is reading .05 when at idle and between .06 & .08 when the blower is on. Damper is almost wide open! I guess when my chimney is warm, it pulls like a mule. Stovepipe surface temps around 150 degF.

I'll post results with an overnight burn but I suspect I will see much longer than 3 hours.

 

[SIERRADMAX]

Last night...Average temps between 18-20 degF. Both thermostats set to 71. Burned and maintained 188 degree water for 6 hours on a partially loaded stove. Nice feeling sleeping with a thin sheet in the winter. I would assume by lowering the thermostats a bit and tightly packing the stove, 8 hour burntime seems attainable.

Still pulling .05-.08 on the manometer. Maybe two BD's like b33p3r mentioned?

 

[maple1]

Two BDs might be something to consider if you can get the second one in without too much trouble. If you're getting those readings on calm days, the wind can ramp it up to yet another level again - wind gusts are likely the thing that starts more flue fires than any other thing, can suck the flames right out of the firebox right into the chimney if not careful (less of an issue with a clean burner like a gassifier though).

Is your thermometer a probe? An accurate themometer can also keep tabs on your HX & turbs getting dirty & needing cleaning - if temps start rising for no other apparent reason things are likely getting dirty. I wouldn't regard anything except a probe as being accurate.

Always good to read of some progress!

 

[willworkforwood]

... I have to block the barometric damper upon startup. I noticed smoke billowing out (w/ cold chimney) even after trying to warm it up with some crumpled newspaper.
...

Glad to hear that you appear to be making progress on keeping the heat in the house. But IMO there is something still not quite right with your system. I've started many cold-chimney fires in the past 6 years with my 150, and never get even a wisp of smoke from the BD, much less a billow. And I'm also inside and pulling with a tall chimney. It seems logical that at start up, the hot smoke would be even more willing to be pulled up what should be a colder chimney.
Is the BD door swung partially open during start up, and does the door position change as the smoke begins to flow? I'm not sure if that even matters though, because I could hold the BD door wide open on mine, and still get no smoke into the basement. Is the BD installed right next to the thimble? Maybe a pic would be helpful.

 

[SIERRADMAX]

Here are some pictures.

(broken image removed)

Currently -10 outside and still keeping the whole house at 70 but is eating a lot of wood. Feeding the boiler roughly every 5 hours. Chimney is pulling .1!
(broken image removed)

 

[Fred61]

I believe you should be measuring your draft upstream from the BD. It appears in the photo that your manometer probe is inserted near the thimble which actually doesn't read the draft your fire is seeing.

 

[brenndatomu]

Fred is right, gotta measure somewhere between the BD and the fire. Nice lookin setup!

 

[maple1]

Can't tell exactly where the Dwyer probe is mounted in the pipe. It might be OK if it's in close to the boiler breach. I see you have a kep damper in there too - did you try closing that down a bit too to get your draft to where it should be?


EDIT: Ah wait, is that it I see close to the wall? If so, Fred is right. You need to get the probe close to the boiler for a good reading of what your boiler is seeing.

 

[brenndatomu]

Since the key damper is after the BD, I wouldn't be comfortable using it to regulate the draft. If it was upstream, yes. The way it is, you are just asking for smoke spillage out the BD, and backpuffing.

 

[maple1]

Posts are coming fast & furious.

Another good point on the key damper.

Can you rearrange things to get the baro up close to the wall, and the key damper between it & the furnace? Put a cleanout cover where the baro currently is? I had both a baro & key on my old one, and the key was between the baro & boiler - had forgotten that.

Then put your mano probe on the boiler T maybe.

 

[SIERRADMAX]

I've seen a couple people mounting the BD out of the smoke stream, hence it's location in my setup.

 

[maple1]

It might be OK the way it is - but you should get the mano probe in close to the boiler outlet for a good reading of what the boiler is seeing, and leave the key damper open. As mentioned above, if the key is closed some, that would increase the chance of some smoke coming out the baro under certain low draft conditions as it is quite close to the boiler and would see reduced draft from the key being closed up some. If it will work the way it is, it's a good location for it since it would also make for a good cleanout spot - you could reach in & get some ash right thru the baro opening, or even stick a skinny vacuum hose in as far as you can. Also makes for a handy inspection point - just look in with a light & check for ash.

 

[SIERRADMAX]

The keyed damper has always been left "open". still gets some smoke billowing. Usually occurs just when the fan ramps up.

 

[NE WOOD BURNER]

I would elbow off the appliance then install baro tee with baro then to chimney.

right now your boiler can exhaust both directions. to chimney and to the baro.

 

[brenndatomu]

My flue pipe setup is almost identical to yours sierra, and it is arranged like maple describes in reply #44. Baro is installed in a tee right next to the elbow at the wall. (this allows you to take advantage of some heat coming off your flue pipe this way too) Then I have a key damper directly upstream from the tee. I originally put the KD in just in case, now I'm using it the regulate the draft.
Last year I just let the baro do its thing, but when I cleaned the chimney this past spring, I found some stage 3 creosote in the elbow and my chimney liner tee. The Yukon furnaces have a huge secondary heat exchanger and I figure there just isn't enough heat left in the flue to offset the cold air from the baro, especially when it is layin flat out wide open during cold weather (I have a 25' chimney that would suck up small cats if not for the baro!) So what I have done this year is to set the baro to a higher setting so that it still works when it's windy, but I set the draft that the furnace normally see's using the KD. Seems to be working, I guess I'll know for sure when I clean the chimney next.

The setup you have now should be fine if you don't mind a lil smoke spillage as you described, but with the manometer sampling the the downstream draft, that is not representative of the draft over the fire. You will find lower readings if you move the manometer tube to the flue outlet of the boiler (upstream of the BD)
The way it is now, you can't accurately adjust the BD. You can just put a piece of foil tape over the lil ole hole that the manometer tube is in now.

 

[willworkforwood]

As others have already suggested, I would also move the BD to be next to the thimble. That's where mine is located, and I believe it will eliminate the smoking at startup, and may extend your burn times a bit as well. But OTOH, loading every 5 hours during this period of time isn't too bad, because a 5F daytime high along with -13 F overnight low certainly is design day here in MA, and I'm sure it's the similar where you are in RI (you guys living in the North Country may now chuckle if you wish).