Totally hypothetical question, never going to build one or anything like that. So also assume that cost is not a factor.

Let’s say I wanted to heat an outdoor space like a courtyard or beer garden, just so it is nice and comfy warm for people to stand about. I have abundant supplies of wood or charcoal to use as fuel.

I could have an outdoor fire pit or Chimeneas or stuff like that, but that tends to produce one little very hot spot and cold spots in between.

So I have come up with this idea. Have an enclosed fire box (with adequate air intakes) with a long tall chimney. But instead of having the chimney just go straight up, at a height of say 3 or 4 metres install a right-angle bend. Then have it run horizontal in a big circle or coil a few metres in diameter around the central fireplace, before getting to an end right-angle bit and another few metres of straight vertical tubing for the top. The idea being that people could mill around underneath the chimney and get some warmth as the hot gases heat up the chimney pipe.

What I was wondering is, would adding the horizontal section of chimney piping ruin the chimney effect of drawing the fire, or would it still draw the same as long as the top of the chimney is at a decent height?

party_pants said:

Totally hypothetical question, never going to build one or anything like that. So also assume that cost is not a factor.

Let’s say I wanted to heat an outdoor space like a courtyard or beer garden, just so it is nice and comfy warm for people to stand about. I have abundant supplies of wood or charcoal to use as fuel.

I could have an outdoor fire pit or Chimeneas or stuff like that, but that tends to produce one little very hot spot and cold spots in between.

So I have come up with this idea. Have an enclosed fire box (with adequate air intakes) with a long tall chimney. But instead of having the chimney just go straight up, at a height of say 3 or 4 metres install a right-angle bend. Then have it run horizontal in a big circle or coil a few metres in diameter around the central fireplace, before getting to an end right-angle bit and another few metres of straight vertical tubing for the top. The idea being that people could mill around underneath the chimney and get some warmth as the hot gases heat up the chimney pipe.

What I was wondering is, would adding the horizontal section of chimney piping ruin the chimney effect of drawing the fire, or would it still draw the same as long as the top of the chimney is at a decent height?

i believe that some people do this in their houses for the cold times. might need more maintenance to stop tar build up as the gases get colder.

party_pants said:

Totally hypothetical question, never going to build one or anything like that. So also assume that cost is not a factor.

Let’s say I wanted to heat an outdoor space like a courtyard or beer garden, just so it is nice and comfy warm for people to stand about. I have abundant supplies of wood or charcoal to use as fuel.

I could have an outdoor fire pit or Chimeneas or stuff like that, but that tends to produce one little very hot spot and cold spots in between.

So I have come up with this idea. Have an enclosed fire box (with adequate air intakes) with a long tall chimney. But instead of having the chimney just go straight up, at a height of say 3 or 4 metres install a right-angle bend. Then have it run horizontal in a big circle or coil a few metres in diameter around the central fireplace, before getting to an end right-angle bit and another few metres of straight vertical tubing for the top. The idea being that people could mill around underneath the chimney and get some warmth as the hot gases heat up the chimney pipe.

What I was wondering is, would adding the horizontal section of chimney piping ruin the chimney effect of drawing the fire, or would it still draw the same as long as the top of the chimney is at a decent height?

My guess: It might draw when hot, but it may not when cold – making the fire difficult to light.

I don’t know how efficient the chimney would be but I’d imagine most of its heat would go straight up, rather than warming those underneath.

Michael V said:

My guess: It might draw when hot, but it may not when cold – making the fire difficult to light.

Might need some sort of valve to redirect the flow for starting and normal operation.

Bubblecar said:

I don’t know how efficient the chimney would be but I’d imagine most of its heat would go straight up, rather than warming those underneath.

I was thinking some sort of shiny metal reflector over the top half of the pipes. But forgot to add that in.

You would be much better off putting in a wet jacket and circulating the hot water.

party_pants said:

Michael V said:

My guess: It might draw when hot, but it may not when cold – making the fire difficult to light.

Might need some sort of valve to redirect the flow for starting and normal operation.

Yeah, it’s an easy fix.

a hypocaust is what you want.

JudgeMental said:

a hypocaust is what you want.

He’d need a bigger salary.

Michael V said:

JudgeMental said:

a hypocaust is what you want.

He’d need a bigger salary.

pffft a couple of barbie plates and a few bricks and away you go.

JudgeMental said:

Michael V said:

JudgeMental said:

a hypocaust is what you want.

He’d need a bigger salary.

pffft a couple of barbie plates and a few bricks and away you go.

what could go wrong?

sarahs mum said:

You would be much better off putting in a wet jacket and circulating the hot water.

Hadn’t though of that, although it does add a layer of complexity.

party_pants said:

JudgeMental said:

Michael V said:

He’d need a bigger salary.

pffft a couple of barbie plates and a few bricks and away you go.

what could go wrong?

you could start a barbie plate walking business.. charge people to find their inner peace and walk across the bbq plates.

JudgeMental said:

Michael V said:

JudgeMental said:

a hypocaust is what you want.

He’d need a bigger salary.

pffft a couple of barbie plates and a few bricks and away you go.

It was a Roman illusion.

party_pants said:

sarahs mum said:

You would be much better off putting in a wet jacket and circulating the hot water.

Hadn’t though of that, although it does add a layer of complexity.

you can run heaters off it.

This is a big subject and well researched.
In industrial applications the flu gases are often used to preheat the product being heated by the furnace.
Ideally the flue gasses would leave the flu at atmospheric temperatures having given up all their heat to the process but that is not practical because of draught considerations.
But yeah your idea is quite feasible.

party_pants said:

Totally hypothetical question, never going to build one or anything like that. So also assume that cost is not a factor.

Let’s say I wanted to heat an outdoor space like a courtyard or beer garden, just so it is nice and comfy warm for people to stand about. I have abundant supplies of wood or charcoal to use as fuel.

I could have an outdoor fire pit or Chimeneas or stuff like that, but that tends to produce one little very hot spot and cold spots in between.

So I have come up with this idea. Have an enclosed fire box (with adequate air intakes) with a long tall chimney. But instead of having the chimney just go straight up, at a height of say 3 or 4 metres install a right-angle bend. Then have it run horizontal in a big circle or coil a few metres in diameter around the central fireplace, before getting to an end right-angle bit and another few metres of straight vertical tubing for the top. The idea being that people could mill around underneath the chimney and get some warmth as the hot gases heat up the chimney pipe.

What I was wondering is, would adding the horizontal section of chimney piping ruin the chimney effect of drawing the fire, or would it still draw the same as long as the top of the chimney is at a decent height?

generally with any fire you help the carbon monoxide (and dioxide) rise, any way you can, using any heat you can to do that, so you need consider worst case situation, which generally is when fire dies down, mostly hot coals left. Reason I mention it is that it’s one of things you need consider of any slow combustion, whether the gas can in fact reverse with flue cooling.

anyway you’re outside, so not such a worry maybe

transition said:

party_pants said:

Totally hypothetical question, never going to build one or anything like that. So also assume that cost is not a factor.

Let’s say I wanted to heat an outdoor space like a courtyard or beer garden, just so it is nice and comfy warm for people to stand about. I have abundant supplies of wood or charcoal to use as fuel.

I could have an outdoor fire pit or Chimeneas or stuff like that, but that tends to produce one little very hot spot and cold spots in between.

So I have come up with this idea. Have an enclosed fire box (with adequate air intakes) with a long tall chimney. But instead of having the chimney just go straight up, at a height of say 3 or 4 metres install a right-angle bend. Then have it run horizontal in a big circle or coil a few metres in diameter around the central fireplace, before getting to an end right-angle bit and another few metres of straight vertical tubing for the top. The idea being that people could mill around underneath the chimney and get some warmth as the hot gases heat up the chimney pipe.

What I was wondering is, would adding the horizontal section of chimney piping ruin the chimney effect of drawing the fire, or would it still draw the same as long as the top of the chimney is at a decent height?

generally with any fire you help the carbon monoxide (and dioxide) rise, any way you can, using any heat you can to do that, so you need consider worst case situation, which generally is when fire dies down, mostly hot coals left. Reason I mention it is that it’s one of things you need consider of any slow combustion, whether the gas can in fact reverse with flue cooling.

anyway you’re outside, so not such a worry maybe

flue length/restriction also matters when first light fire too

party_pants said:

Totally hypothetical question, never going to build one or anything like that. So also assume that cost is not a factor.

Let’s say I wanted to heat an outdoor space like a courtyard or beer garden, just so it is nice and comfy warm for people to stand about. I have abundant supplies of wood or charcoal to use as fuel.

I could have an outdoor fire pit or Chimeneas or stuff like that, but that tends to produce one little very hot spot and cold spots in between.

So I have come up with this idea. Have an enclosed fire box (with adequate air intakes) with a long tall chimney. But instead of having the chimney just go straight up, at a height of say 3 or 4 metres install a right-angle bend. Then have it run horizontal in a big circle or coil a few metres in diameter around the central fireplace, before getting to an end right-angle bit and another few metres of straight vertical tubing for the top. The idea being that people could mill around underneath the chimney and get some warmth as the hot gases heat up the chimney pipe.

What I was wondering is, would adding the horizontal section of chimney piping ruin the chimney effect of drawing the fire, or would it still draw the same as long as the top of the chimney is at a decent height?

> What I was wondering is, would adding the horizontal section of chimney piping ruin the chimney effect of drawing the fire, or would it still draw the same as long as the top of the chimney is at a decent height?

I ought to be able to answer this, based on fluid dynamics.

There are two sources of pressure loss – from the length of pipe and from the two right angle bends.

The pressure loss from the pipe length can be calculated from the Moody chart.

!!

The pressure loss from the bend is encapsulated in coefficient k_b.

For actually doing the calculation: my consultancy rates are reasonable.

mollwollfumble said:

For actually doing the calculation: my consultancy rates are reasonable.

thanks, I’ll be in touch :)