Benefit of connecting 2' above the stove?

[emt1581]

We had the installer over the house last night and he said we CAN do a direct connect from the back of the stove to the wall, but that he recommended coming up 2' from the stove and then elbowing it into the wall. He said it would increase the draft. I'm curious if it matters THAT much and if it was good advice?

Ideally, we'd like to direct connect so you don't see any pipe.

Thanks!

-Emt1581

 

[SKIN052]

What type of stove? A initial rise would certainly seem to be the best way to go, easier to get the draft going.

 

[emt1581]

What type of stove? A initial rise would certainly seem to be the best way to go, easier to get the draft going.

Avalon Arbor

http://www.avalonfirestyles.com/TravisDocs/100-01190_003.pdf

So without the "rise" would I have trouble with the stove or what?

Thanks!

-Emt1581

 

[My Oslo heats my home]

I own an Oslo and have 4ft of pipe running directly up before elbowing. Never had a draft issue since the install

 

[Renovation]

We had the installer over the house last night and he said we CAN do a direct connect from the back of the stove to the wall, but that he recommended coming up 2' from the stove and then elbowing it into the wall. He said it would increase the draft. I'm curious if it matters THAT much and if it was good advice?

Ideally, we'd like to direct connect so you don't see any pipe.

Thanks!

-Emt1581

Hi EMT,

It's an interesting question, and here's my understanding, submitted for consideration.

As I understand it, draft is produced by a temperature difference (like between a stove's outlet and outside air) across a given rise (not distance) of pipe--your overall chimney height.

Clearly the overall rise is the same regardless of where the elbow is, so when everything is hot, elbow location makes little difference in overall draft.

The performance difference comes when lighting a fire.

Before you add flame, the flue has an initial amount of draft, produced by the difference between temperatures inside and outside your house. When you start the fire, the first chimney section it heats--and the first to potentially add draft--is the section closest to your stove. If that section is vertical, the height and temperature difference across the section nearest your stove produce additional draft, and your fire take off right away. If that section is horizontal, there is no extra heated height to product draft, and draft will not pick up until the area *after* the horizontal section heats up. This slows startup, and can cause smoke leakage and make lighting a fire more challenging.

So IMO your installer knows of what he speaks.

That's my understanding anyway, for discussion and correction.

I HTH, and good luck!

 

[shawneyboy]

I have a 4 foot rise before the 90. I would think the taller the rise the better, for as previously mentioned, the draft.

 

[snowtime]

Out the back is fine just make sure the installer puts a slight rise to the "straight" pipe coming out the back.

 

[emt1581]

Out the back is fine just make sure the installer puts a slight rise to the "straight" pipe coming out the back.

Do you mean angle it or what? I don't understand.

Thanks!

-Emt1581

 

[Mcbride]

I would say go up at least 2 feet first as the installer suggested, better drafting.

Merry Christmas

 

[SKIN052]

What is the plan for the chimney? From page 10 of the Avalon Installation guide.

Rear Vent Configuration
The rear vent configuration is only for masonry fireplace installations (hearth stove). All steel chimney
applications require the top vent configuration.
The vent (chimney connector) may be directed to the rear of the appliance when installed into a masonry
fireplace. See Figure 5 for details.

 

[Stephen in SoKY]

I'd be concerned that my thimble would be too low for the next stove I purchased with a direct rear vent on your present stove. Two feet up to a ninety would cover a top or rear vent stove in the future I would think.

 

[emt1581]

What is the plan for the chimney? From page 10 of the Avalon Installation guide.

Rear Vent Configuration
The rear vent configuration is only for masonry fireplace installations (hearth stove). All steel chimney
applications require the top vent configuration.
The vent (chimney connector) may be directed to the rear of the appliance when installed into a masonry
fireplace. See Figure 5 for details.

Hmm...totally missed that part. I appreciate you pointing it out. No one mentioned that before.

Thanks!

-Emt1581

 

[emt1581]

I'd be concerned that my thimble would be too low for the next stove I purchased with a direct rear vent on your present stove. Two feet up to a ninety would cover a top or rear vent stove in the future I would think.

This is why we've decided on the 2' of pipe method. Well that plus, as pointed out in the manual, we don't really have a choice. But I want to build a nice hearth in the future and probably add a back-splash (is that the right term?) on the wall behind the stove. Connecting it behind the stove would seriously limit my height capabilities plus any stoves we got in the future, not that I plan to buy another one, would have to be the exact same height or shorter. Putting it two feet above, all I have to do is shorten the pipe a bit and I'm good to go.

Thanks!

-Emt1581

 

[LLigetfa]

This is a verbatem reply I gave in another similar thread.
https://www.hearth.com/econtent/index.php/forums/viewreply/755080/

There is no one-rule-fits-all and I am somewhat confused with BeGreen’s advice. My advice seems to run completely opposite.

If going up first and then horizontal introduces more turns, you need to count those turns as reducing the overall flue height used to determine draft. If flue height and flue performance results in marginal draft, you could have even less with additional turns.

A through-the-wall exterior chimney running up through cold space is already at a disadvantage and your draft may be marginal. You might want to sacrifice some of the heat that would be extracted with an up-and-out setup by reducing turns. If you are confiident that there will be adequate draft, Up-and-out may be OK. If you prefer the look of up-and-out, consider double-wall smoke pipe to preserve some of the heat the flue may need to maintain adequate draft.

A straight-out through-the-wall install would mean usingf more expensive class A pipe and it would put the cleanout on the Tee closer to the ground possibly making it harder to do botton-up sweeping.

I have a severe aversion to through-the-wall installs and will always advise a straight-up through-the-roof instead where possible. It puts more of the class A inside a warm chase and with no horizontal sections, there is no place for creosote to drop and collect only to later ignite. I’ve experienced a chimney fire in a Tee and my father’s house burned to the ground because of a chimney fire in a through-the-wall chimney.

 

[Renovation]

we've decided on the 2' of pipe method.

-Emt1581

Yay! Don't forget--two 45 degree connectors should be used instead of a single 90, for a more gradual turn, better airflow, and better draft. Double-wall connector pipe is recommended for a better draft and cleaner flue.

Good luck!