Will This Chimney Draw Well ?

[maple1]

Re. the OP & question - a chimney that tall should draw well, yes. But there are other factors that also influence that I don't think were mentioned - like internal dimensions & lining/insulation details. An all-brick/clay largish external chimney might not do as good as you'd think a chimney that tall would do.

Plus other things that can impact draft - like the surrounding landscape and nearby tall trees & buildings, etc..

 

[Simonkenton]

You are correct sir my fireplace uses 4 to 5 times the wood of my Jotul.
However, it is a good heater and will continue to heat the house for 24 hours after the fire goes out.

 

[bholler]

You are correct sir my fireplace uses 4 to 5 times the wood of my Jotul.
However, it is a good heater and will continue to heat the house for 24 hours after the fire goes out.

Only if you burn long enough to heat the whole structure which has to take quite a bit of time and wood. And that wont work for the op with an external fp

 

[Rearscreen]

I'd build a correct Rumford if an open fire was a necessity.

 

[bholler]

I'd build a correct Rumford if an open fire was a necessity.

Pryor fires are even better or go with an ahrens fire with the precast firebox. They are slightly more efficent than a stasndard open fireplace

 

[Rearscreen]

Priorfire. Bhboiler I noticed some recent misspellings. Has someone switched keys on you as a practical joke? All I came up with was Richard Pryor burning himself up.

 

[bholler]

Priorfire. Bhboiler I noticed some recent misspellings. Has someone switched keys on you as a practical joke? All I came up with was Richard Pryor burning himself up.

Not recent my spelling has alway been horrible. But i should know how to spell chris's last name by now. And i was right with the prerogative thing. That is how it is spelled

 

[Ashful]

Bhboiler I noticed some recent misspellings.

Who's "Bhboiler"?

Irony.

 

[Jan Pijpelink]

Who's "Bhboiler"?

Irony.

He is new on this forum, he installs water heaters.

 

[BrotherBart]

Oh great. It took us 17 years to get spelling Nazis.

 

[bholler]

Who's "Bhboiler"?

Irony.

I am pretty sure that was on purpose. At least i hope so if not yeah it is pretty funny

 

[jetsam]

Oh great. It took us 17 years to get spelling Nazis.

I am actually both a spelling Nazi and a grammar Nazi, but I restrain myself from sharing my corrections with others. I do sometimes make involuntary noises such as "urrrRrrrrnnngh" while reading, though.

Don't hate us; it's actually a rather difficult condition to live with if you spend much time on the internet.

 

[jetsam]

He is new on this forum, he installs water heaters.

He's over on the oil-fired hydronic boards right now arguing that the old systems where you pour buckets of oil in the firebox are just as good as the fancy new kind with tanks and nozzles.

 

[Quincy Fivelos]

Thanks all. We have two open wood burning fireplaces in our current house and quite enjoy them. Yes, this is for ambiance only, no expectation of producing any heat and with knowledge that a bunch of heat will, unfortunately, be going up the chimney. We looked at a bunch of ZC and similar options and simply don't like them as much.

Make up air units will pre-heat incoming air. Our HVAC contractor prefers to heat the air to 38-50°f with an inline electric heater (Electro) and then feed it in to the return air duct for further heating by the gas furnace. This has worked fairly well in our current house though we do sometimes get a bit of smoky smell. I've wondered if this was directly from the fireplace (not all going up the chimney) or if the MUA or natural air leaks might be sucking smoky smelling air back in from outside.

 

[maple1]

Make up air units will pre-heat incoming air.

That is done with outgoing air - but outgoing air going up a chimney won't be able to do any pre-heating.

 

[Simonkenton]

I have to burn a roaring fire in my fireplace for 5 hours to heat up the rocks. As someone noted, mine is an internal fireplace which means that the back wall of the fireplace is the inside wall of the bathroom.
After five hours I let the fire go out and shut the damper. That back wall gets up to 105, of course, the massive masonry of the firebox is really hot never bothered to measure that.

The firebox is a modified Rumford and it really throws heat while burning, we had to move the sofa back 2 feet on about the third fire, 21 years ago.

This is the best heating fireplace I have ever seen and the ambiance of the open fireplace is something else. It will throw good heat for 24 hours, so you burn it every night for 5 hours you will heat the house around the clock.
Still, for practical heating it is no match for a wood stove.

 

[bholler]

Thanks all. We have two open wood burning fireplaces in our current house and quite enjoy them. Yes, this is for ambiance only, no expectation of producing any heat and with knowledge that a bunch of heat will, unfortunately, be going up the chimney. We looked at a bunch of ZC and similar options and simply don't like them as much.

Make up air units will pre-heat incoming air. Our HVAC contractor prefers to heat the air to 38-50°f with an inline electric heater (Electro) and then feed it in to the return air duct for further heating by the gas furnace. This has worked fairly well in our current house though we do sometimes get a bit of smoky smell. I've wondered if this was directly from the fireplace (not all going up the chimney) or if the MUA or natural air leaks might be sucking smoky smelling air back in from outside.

Why would ypu preheat air that will be used for the fireplace? That is a waste of heat just supply air to the firebox where and when it is needed. And shut it off when not needed.

 

[Simonkenton]

I agree, a waste of heat, to preheat fireplace air. Let's see, paper burns at Fahrenheit 451. Paper is made of wood.
So the temp in a fireplace might be 600 degrees, maybe more.
Outside air is, let's say, 20 degrees. What benefit is there to using electric heat to warm the outside air to, what, 90 degrees? Tje bad ass fireplace will heat it up to 600 degrees in about 3 seconds.

The numbers don't add up, it is a complicated waste of electricity.

 

[maple1]

Make up air units will pre-heat incoming air. Our HVAC contractor prefers to heat the air to 38-50°f with an inline electric heater (Electro) and then feed it in to the return air duct for further heating by the gas furnace.

This does not make any sense to me, at all. Unless it is cheaper to heat with electric resistance heat than gas. In which case you should do all your heating with resistance electric.

Also, make-up air, is to replace air that is being used by combustion and sent up the chimney - it doesn't go to return air ducts.

 

[Quincy Fivelos]

So, 800 CFM up the chimney means we'll need 800 CFM of combustion/MUA. Right? You can do two 6" passive intakes directly in to the fire box (unheated). I believe a 6" passive is good for 75 CFM (@5pa differential to outside)? So two is 150 CFM leaving us needing at least 650 CFM MUA in to the house?

In MN make up air is nearly always brought in to the return air duct. Outside air could be as low as -30°f. HVAC installers here consistently say that the heat exchangers in residential gas furnaces should never have air below +40°f. Theoretically this is due to the potential for creating extreme condensation. I have never seen anything from a manufacturer saying anything similar though.

So, the air being brought in from outside is filtered, pre-heated to between 38-50°f before being introduced in to the return air duct from where it will enter the furnace, be heated to room temp and then distributed throughout the house.

I'm not an engineer of HVAC person so mostly just spitting out what I've read and been told by HVAC folks and builders.

 

[bholler]

So, 800 CFM up the chimney means we'll need 800 CFM of combustion/MUA. Right? You can do two 6" passive intakes directly in to the fire box (unheated). I believe a 6" passive is good for 75 CFM (@5pa differential to outside)? So two is 150 CFM leaving us needing at least 650 CFM MUA in to the house?

In MN make up air is nearly always brought in to the return air duct. Outside air could be as low as -30°f. HVAC installers here consistently say that the heat exchangers in residential gas furnaces should never have air below +40°f. Theoretically this is due to the potential for creating extreme condensation. I have never seen anything from a manufacturer saying anything similar though.

So, the air being brought in from outside is filtered, pre-heated to between 38-50°f before being introduced in to the return air duct from where it will enter the furnace, be heated to room temp and then distributed throughout the house.

I'm not an engineer of HVAC person so mostly just spitting out what I've read and been told by HVAC folks and builders.

But why not bring the right ammount of air to the fireplace instead of using air that you already paid to heat? You are not limited to 2 6" ducts to supply air to the fireplace.

 

[Quincy Fivelos]

I believe you would need eight 8" ducts to provide that much passive MUA. When you get below that then you begin depressurizing the house.

 

[bholler]

I believe you would need eight 8" ducts to provide that much passive MUA. When you get below that then you begin depressurizing the house.

What size flue will it have? What size is the firebox opening?

 

[Quincy Fivelos]

Opening is 42" w x 30" h. I believe it's a 14" flue.

 

[bholler]

And how tall is it?