Cold Air Return. Do I Need It?

Any chance of getting some pictures posted?

Only for a couple more days and then cold returns.

For today, only, here's what I think I'm doing.

I'm cleaning everything out real good and putting it back together and lighting the fire to see what I got.

Analyzing and getting ready to make a return.
Hopefully, I can have something in a day or two.

Any suggestions or caveats are always appreciated.

Let me see what I can do.
What would be informative?

larryfoster wrote:The short horizontal run from the furnace to the chimney only has a very slight elevation to the chimney.
Not much.
Is that enough?

Yes.

larryfoster wrote:Preliminary results are not good.
My grate is full of clinkers. Big unburned lumps.

So you attempted burning some bit coal?

larryfoster wrote:But the worst was the flue was packed full of soot.
There couldn't have been any draw.

Yes bit coal is very sooty. Without draw (I believe you mean draft) it wouldn't have burned at all, or smoke would have been coming out of the furnace into the stove room.

larryfoster wrote:If I clean this out will it come back now that I'm not using the wet wood?

Do you mean, Will the soot come back? It will likely leave creosote residue in the flue pipe and chimney.

It's recommended to use an 8 inch flue with bit coal because of clogging by soot, but others here use a 6 inch and clean it often enough that the soot is not a problem.

larryfoster wrote:I'm cleaning everything out real good and putting it back together and lighting the fire to see what I got.

Good, get back with your progress

Thanks, Lightning.

I was looking at my manual (imagine that) and saw that they recommend cleaning every two weeks

Yes, I am using bit coal.

I wish Hot Blast would have said about the 8" flue.
It would have been easy and not much more money to have done that in the beginning.

I had the stove sitting idle in the basement for a couple years.
I guess I need to get a brush to clean out my chimney, too.

After the cleaning, I got a roaring fire.
It was hot enough that I couldn't lay my hands on my pipe.

And I found one place where I can't put my return but my second choice should work.

I think I just may not have been firing enough

In another thread I asked if I need to be a rocket surgeon or a brain scientist to do this.
Maybe, or I'm just really thick.

BTW, this is pretty long.

I'll start off by, once again, thanking all of you who offer suggestions while I sort out my issues.
Your patience and willingness to type really slow is greatly appreciated.

This is an update of my experience after 2 months.
Along with some more questions.
Always more questions.
I had no idea this would be so complicated.

There is some good and a lot of frustration.

The really good news is I'm saving a lot of money on propane.
Even with the low cost of propane right now and having to buy a load of wood, I'm projecting to save up to $1000 this winter.
That is net after wood and coal purchases.

Now, the frustrations and questions. In no particular order.

1. Walls are black. Or really dirty.
My wife likes the heat and saving money part but doesn't like the dirty walls.
And she's guessing our clothes and other stuff are the same.
In our house, if momma's not happy no one is happy.

2. Soot in the chimney continues to be a problem.
2 weeks is the max I seem to be able to go.
I cleaned the whole thing 5 days ago and am sure that it's still building up,

I would gladly take Berlin's suggestion and yank the 6" stainless liner if I wasn't concerned about the safety of my deteriorated existing chimney.
I'm not being cantankerous just to be ornery and contemptible.

I don't know if there's an answer but I am puzzled about this (and, obviously lots of other things).
As best I can tell, the chimney is installed to spec as well as the furnace.
Except for cold air return

My buddy who has been servicing and installing furnaces for 30 years and sweeping chimneys, probably, 15 years claims he has a lot of clients with a 6" chimney and they only clean their chimney once a year.

3. Hotblast insists that all the problems in the universe are caused by my lack of a cold air return.
They blame it for soot buildup in the chimney as well as poor heat in the house.
I could see the possibility of the second but not the first.

4. My fire is hotter when I burn wood than coal.
This is true even with the new hotter burning coal I got. Coal definitely burns a lot longer.
I thought there were more BTUs in coal.

When I am burning only coal, my burn temps are around 300 maybe a little higher.
With wood, I get upwards to 400 and this morning, close to 500.
I have a Rutland magnetic thermometer mounted just above the load door.
Even with that high temp, my house wasn't that warm.

I have the spinner draft on the ash door wide open.
The vent on the load door is 1/2 way open.
My manual damper is wide open.
My baro is sealed off with aluminum foil at the recommendation of the furnace guy.

Thank you for allowing me to continue to ask my questions.

I'll add #5.
Am I just dumb?

larryfoster wrote:Am I just dumb

You used to be, but not anymore, you are learning fast.

Berlin is the expert on burning bit in this forum. When he recommends 8 inch pipe because of soot problems, it is a concession that burning bit in a hand fired is dirty. That smoke and soot is where your heat is going. It is unburned fuel.

The cleanest and most efficient way to burn wood is in a pellet stove. This is because the pellet stove feeds small amounts at a steady rate with a set rate of combustion air. With a wood stove loaded with a large batch of wood the release of gas is too fast for the available air to burn it and we get smoke and creosote. If there is enough air we get a monster fire but a clean one. Once the gas burns and charcoal is left the needs change again and it burns clean with modest air.

Bit coal is the same sort of challenge. With lots of air well mixed you get a scary big fire. If you restrict the air or mix it poorly you get smoke and soot.

The antique stoves that did the best job with bit used a round fire pot and introduced heated air in quantity just above the fire to better burn that smoke. A stoker, like the pellet stove feeds small amounts steadily so the air supply can cope with both the gaseous stage and the remaining coke.

Saying all this does not help you very much except maybe to clarify the problem. Feeding little and often in a smaller fire box would certainly help. Perhaps adding a better over fire air system as well. The maker of the stove can't help because they probably don't have a clue either.

#5... No . Well, maybe you were a little dumb to have bought the Hotblast in the first place ,but you took them at their word when they labeled it as a wood/coal burner. Very few units that say wood/coal work well with both.I know little about burning bit coal,if you want to burn bit,the best thing to do is to go to the bit section & learn all you can about how best to make it work in the less than best unit you have OR if $$$ are available to upgrade to a unit that will properly do the job,& you will have to decide whether you go with bit or anthracite & the proper unit to use for which ever way you go. Or burn wood in your current wood furnace.

Thanks, francob and windyhill.

Especially for reassuring me that I'm dumb.

I accept Berlin's status here and any opposition to his advice is purely practical for safety.
And< I think, the only thing I have quibbled on was removing the liner.
I have gone through the Bit forums fairly extensively trying to pay the most attention to Hotblast users.

I would probably not consider anthracite due to it's lack of availability in my area or the cost if it were available.
It would defeat my purpose for getting this unit.

I have wood but it's not ready this year due to poor planning on my part.
Just got back with a pickup load of wood for $95.
I bought the last coal for $100/ton but only paid $50 for the load which I'm sure was close to a ton.
But the wood I buy isn't very seasoned.
I bought a load a couple weeks ago for $80 and you could still feel the sap. Guy said it was split in September.

As you can tell, I'm having a hard time reconciling this based on my long ago experience burning coal.

I'm doing an experiment right now.
Just checked and my temp was 300.
I put only a log on and will check in a little to see.

Any suggestions on why the heat in the house is not very correlated to the heat in the stove?
Somewhere, in one of my posts, I mentioned that this furnace is oversized for my house and it should cook me out

Would it be practical or helpful to mix the wood & bit coal ?Both of those fuels need mainly over fire air,seems the mix might help to burn hotter & cleaner ? 300* just doesn't seem like a very high temp for a furnace to be able to draw enough HOT air from.

First thing I will say is that I am not a bituminous coal burner but everything I have read on here about it says that you need over fire air for it to burn properly. In your posts you have said that you have the air intake in the ash drawer fully open and the one in the load door only partially open. Have you tried the reverse, having the load door damper more open and closing the one on the ash door? I know when I burn wood in my cook stove, it does not put out much heat if I use the under grate dampers... I have to use the above air ones for the fire to burn properly. It sounds to me that you need more over fire air to burn off the volatiles that are creating the soot issue.

Randy

Thanks, windyhill and Randy.

There is so much conflicting info.
Randy, you said

says that you need over fire air for it to burn properly.

I don't remember where I saw, read or heard that coals burns from the bottom up so it needs under fire air and wood burns from the top down so it needs air over the fire.

I have been trying to use a little wood with my coal, windyhill
When I do, temps go up over straight coal.

I mentioned my little experiment with a log only on the hot coals.

In a little over 1/2 hour, the temp went up 50 degrees

300* just doesn't seem like a very high temp for a furnace to be able to draw enough HOT air from.

Before I found this forum, there was a YouTube video from a Hotblast user that says he keeps his burning range from 250on up.
My furnace guy said 450.
It's hard to keep it at that.

larryfoster wrote:Thanks, windyhill and Randy.

There is so much conflicting info.
Randy, you said

says that you need over fire air for it to burn properly.

I don't remember where I saw, read or heard that coals burns from the bottom up so it needs under fire air and wood burns from the top down so it needs air over the fire........

Hi Larry, with all due respect don't confuse "Anthracite coal" with "Bituminous coal", anthracite needs under fire air, bituminous needs both but a hell of a lot more over fire air.

Yup, that's why I said to reverse the settings, close down the under fire air so it is just barely open and open up the above fire air more. Bituminous burns more like wood than it does anthracite coal.

Randy