View Full Version : Chimneys

Blue Wren
14th September 2003, 06:05 PM
Hi I am very new to this. We have a beautiful 100 year old house in need of lots of TLC. The house was moved 30 years ago and the chimneys demolished. We have a cavity where we had 2 back to back fireplaces. We have at the moment 1 fire (completely out of sympathy with the house) on one side. We want to get a fire box for each side that has 2 flues that go into a common flue so only one flue comes out the roof. When we ask the so called "experts" they just want to sell us their fire and tell us it has to have its own flue. If the darn chimney could accommodate 2 fireplaces, I can't see why "modern technology" can't copy. Can't get a chimney maker in this area, have already tried. Not sure if this is a question for this forum but seeing downlights were here, decided to give it a go. Don't care if we need to go interstate to get what we want. Seems to me, only need a boilermaker or whatever with a bit of nouse. Can anyone help with contacts where we might start?

14th September 2003, 07:11 PM
I am guessing you are talking about having 2 slow combustion fireplaces? If that is so then they do need their own flue, as the flue is tuned to create the correct draw for the fire while retaining heat.

14th September 2003, 11:53 PM
I agree.
If what you had before was two open fires, you must realise that the chimney for open fires works different from a flue for a modern slow combustion.
Open fires or any of the old type fireplaces, relay on a big volume of hot air/smoke going up the chimney and drawing fresh air from the room, enough to avoid smoke going back in the house, (with mixed success usually). No seals, hope for no wind and no guarantees.
Modern slow combustion have sealed doors and very small and controlled orifice for air to come in the fire. In order for it to work, the flue must be of a certain diameter typically 6 inches, metal and a minimum of 4 to 5 meters.

Having said this, there is nothing stopping you from having two slow combustion or built in fire places with their respective flues, going up a single brick chimney, ending just short of the end chimney giving the impression of just one old fashion brick chimney. Two 6" flues fit perfectly in an ordinary brick chimney. All is left is to build an imaginative hat to it.

Blue Wren
15th September 2003, 12:28 AM
Take your point about combustion fires. Not sure that that is what I am looking for. Just want the old cast iron open fires. Hubby is having a willy at cutting all that wood, so he is thinking combustion stove. Interesting about 2 only 6 inch flues fitting up regular chimney hole, however, just didn't want 2 flues above roof. Would look rather messy Have seen fibreglass chimney tops that Harkaway homes use but it appears they can only go on ridge cappings. Guess, if we have to have 2 flues right next to each other, we do. Thank you for your input, because at least you have given us a reason for having 2 flues which is more than the salesmen have.

15th September 2003, 05:50 PM
I am not sure if this fits your requirements but you can get a two-way slow combustion fireplace. It fits in a wall and has large glass doors on both sides. It only has one flue as it is essentially one large slow combustion fireplace. I have seen them advertised in The Weekly Times here in Victoria but not now winter is over. You might try house type magazines in the ad section at the back or even at your local fireplace store such as BBQ Galore.

15th September 2003, 06:59 PM
Im the xpert in this field, you know, the drip under pressure.
Im a brickie with 30 years xperiance.
2 into 1 dont go.
If you have 2 fireplaces into 1 flue, the thing wont draw.
In the old situation there would have been seperate flues.
Same chimney but different flues, seperated by midfeathers ( I Knew my schoolin would come in handy one day......lol).
Where did you say you live?
How much did you say ur willin to pay....................lol?:D

Cheers, Allan the Midfeatherer

re do 4 u
16th September 2003, 10:45 AM
how about running both flues side-by-side up to the roof and then sliding a 12inch section over them both, with a cap on top of the 12inch. it will look big, but it will be easy to get and do. maybe a section of metal formwork tubing will do, they even make it in an oval shape. hope this helps.

Blue Wren
16th September 2003, 10:26 PM
Hi, I know that as a bird I should know about midfeathers, but I don't. I am guessing that they are some sort of baffle in bricks. So help me out here. You will need to explain very simply.....its a girlie thing. Have seen the fires with one flue but as I don't want glass doors, they don't do the trick. Only want the old victorian or federation fireplace fronts. Yes, we are rapidly coming to the conclusion that the two flues have to go up through the roof and then put something around them. Have found out you can get fibreglass chimneys made. Not sure how they attach to the roof yet, but will get there. It is a long way up 12 foot ceilings and about the same in the roof and the slope on the roof is 60 degrees. Northern N.S.W. is maybe a bit far to come to build a chimney but our weather is pretty good. Isn't it frustrating when you know what you want, but need to jump through so many hoops for what should be a simple thing. Thanks guys for being so patient!

16th September 2003, 11:15 PM
If you knew how much pollution you get in your home, carbon monoxide and different toxic fumes with an open fire, as much as I like them miself, you would go combustion every time.
Have a look at the two way combustion they do exist and they are hot!

re do 4 u
17th September 2003, 03:46 PM
so i gather that you want a brick chimney built on top of the roof. which part of the chimney was demolished when the house was moved?? was it just the part above the roofline, or was it the brickwork inside the house??
if it's only the part above the roof, you could build a steel frame and clad it in thin bricks, the ones they put on the outside of fibro houses that look like real brick veneer.

Blue Wren
17th September 2003, 05:25 PM
No, they demolished the whole of the chimney inside and above the roof to move the house. Nothing left there but a hole and as we have pressed metal ceilings, we need to stick with the size that the chimney was. We already have a glass door fire on one side. Just need the other room at the back. Can't say I like glass doors as they seem to restrict a lot of the heat and if the fire has glass doors they need to be shut as otherwise it smokes. Yes, I did try it open.........it was cold! Still will look around and see what else is available. Used those slim bricks when they first came out and found them a pretty good alternative for creating a brick wall without all the massive support you need for a real wall. We are pretty green on most things breeding organic meat but I don't think I want to know the "nasties" of an open fire. I have survived this long and have to say one of the pleasures of winter is curling up to a crackling fire. At least I can die happy and warm!

20th September 2003, 02:05 PM
I have got an old house with the two into one chimney thing.

They don't work.

We have a woodstove on the kitchen side and a wood heater (slow combustion) on the lounge side. They both have (had) full six inch flues going all the way up the chimney. The two into one section of the brickwork made it a nightmare to get the flues through, and the kitchen one blocked up at the bend so often I have pulled out the top section. It now only goes up to the junction point. It does work better.

The bends involved and the sharing of the draught means both fires perform poorly. It is quite variable, one day it burns fine, the next day burning the same wood it just won't get going brightly and smokes like blazes.
I have had a woodstove installer look at it, they say the flue is the trouble.
I have had similar slow combustion heaters before with a single flue, they burned much better and never smoked inside the house.

Do what you are being advised, have two separate flues.
And slow combustion heaters will save you lots of pain - they get much more heat from the same wood, can have a fan for better heat circulation, and don't let smoke back into the room.
People get all romantic about those cast iron fires, but they are a pain to use. If you reallly want one, get a gas fired one.


21st September 2003, 09:59 AM
And if the thing still doesn't draw properly you can get a fan assisted unit that creates an updraft for you.

Blue Wren
21st September 2003, 02:16 PM
Interesting results with your chimney that was standing. After all your responses and good advice, we would be foolish to go any other way than the 2 flues. The one thing we have learned going through this life is that it is better to learn from someone elses mistakes than make them yourself. Thanks heaps for your input.

29th January 2009, 01:40 PM
I am renovating our family home as the second generation. I have just done the best thing ever. Demolished the double fireplace/chimney between the kitchen and lounge. My mother was always cold in this 10' tin ceilinged house because of the open fireplaces being so inefficient. The combustion stove keeps the kitchen relatively warm and I guess the open fire in the lounge was not too bad, just you couldnt leave it unattended, and no heat got to the rest of the house. My old setup sounds just like yours, and yes internally, the one lange exterior chimney was divided into two by brickwork. With the high ceilings and fairly pitched roof it was about 20' of brickwork. So now with the whole thing gone plus a bit of dividing wall removed, I am going to install one wood heater sideways and in the ceiling above install an air movement system to draw the majority of the heat off and away to other rooms.