Fireplace heater

[Pete]

What type of piping/material would I use to build this fireplace heater? I would like to do it without welding. Maybe cast iron? Are there metals that would give off gases when heated? The fire is built on top of the grid. Air is pushed by the fan through the heated pipes. The heated air escapes through the openings in the front of the pipes and is pushed out into the room. My family had one of these when I was a kid and it worked too good. We had to open windows to adjust the temp. Problem is nowadays this thing costs 450 dollars.

[cute fuzzy bunny]

I'm not entirely sure which way the air is supposed to flow, but my first thought was 'carbon monoxide'.

I think I'd use stainless steel but iron would work too. Basically consider anything that goes into a furnace or bbq grill.

[d]

no carbon monoxide problem as it simply takes room air, passes it by the fire within the tubes, and returns it to the room

[cute fuzzy bunny]

Oh I understand the principal, but when you're blowing air in the vicinity of a CO producing fire, its plenty easy to carry a little of it into the room. I can detect CO within a foot or two of the front of my fireplace when its in use, but most of it ends up getting drawn back in and up the flue.

I've seen a number of the passive versions that use the curved tubes that start at the bottom and end at the top...and they're often recalled for CO issues.

I'm not sure if putting the air under pressure with a blower would make it better or worse.

Fireplaces are just such awful heaters, efficiency-wise. You pull a lot of conditioned air up the flue and between the cost of wood and the electricity to run the blower, an efficient furnace would be a better choice.

Unless that fireplace is all you've got to heat the room with.

[stoopwallace]

Pete:

Interesting product. As I too was curious, did a wee bit of googling.

How to make a fireplace grate blower??
How to make a fireplace grate blower?? - DoItYourself.com Community Forums

Black galv pipe seemed to work on his project -- after [very important] 'burn off'. Particularly like the low-budg idea of hair dryer fans... probably wouldn't pass the 'wife acceptance factor' though.

Let us know how yours turns out!

- Stoop

[Pete]

Thanks for the help so far. I also thought about using some of the computer fans I have. Some push quite a bit of air, draw low amounts of current, and are quiet.

Here is some stuff I found about welding or burning galvanized:

When zinc vapor mixes with the oxygen in the air, it reacts instantly to become zinc oxide. This is the same white powder that you see on some noses at the beach and the slopes. Zinc oxide is non-toxic and non carcinogenic. Extensive research into the effects of zinc oxide fumes has been done, and although breathing those fumes will cause welders to think that they have the flu in a bad way, there are no long-term health effects. Zinc oxide that is inhaled is simply absorbed and eliminated by the body without complications or chronic effects. Current research on zinc oxide fumes is concentrated in establishing the mechanism by which zinc oxide causes "metal fume fever," how its effects are self-limiting and why zinc oxide fume effects ameliorate after the first day of exposure even though the welder may continue to be exposed to zinc during subsequent
days ("Monday-morning fever").

[Pete]

Quote:

Originally Posted by stoopwallace ...probably wouldn't pass the 'wife acceptance factor' though. Stoop

I'm lucky. My wife has been on board with the Ultimate Cheapskate ER methods and is now reaping the benefits with me at 47.

[HFWR]

A fireplace insert is a good choice, but definitely more expensive than a homemade grate/heat exchanger. One example:

WINTER WARM Cast Iron Catalytic - Large Insert Fireplace Inserts | Wood Fireplace Inserts by Vermont Castings

[haha]

Quote:

Originally Posted by Pete Here is some stuff I found about welding or burning galvanized:...

Why would you want galvanized anyway? Just use black iron. Any of it will likely burn out fairly quickly, that is why fire grates are made of cast iron.

If you really want heat from a fireplace- a dubious proposition at best- get a cast iron wood stove insert, or better yet a conversion that sites the iron stove in front of the fireplace. This will be safe, and it will come with its own blower, and it will give you a lot of heat.

The thing in your diagram will put heat into your room, and but likely also suck it up the chimney out of the room, and cause cold air to be drawn into the house to replace the hot air going up.

BTW, I know a few old welders with emphysema. I think I would job out any welding chores, unless you are really going into it and want to become an expert yourself.

Ha

[samclem]

If appearance isn't an issue, you could just use a cast-iron automobile exhaust manifold under the grate that holds the wood. Push the air in through the end that used to be hooked to the exhaust pipe, it flows through the pipes and exits (through the openings that used to hook on to the cylinders) into the room. If you want more pipe surface area, you could mate the cylinder-side of two exhaust manifolds, have the single inlet pipe and the single exit pipe (into your room).

A leisurely stroll though your nearest auto junkyard looking under a lot of hoods will probably turn up something shaped right for your fireplace. I don't know what they'd charge, but it probably wouldn't be much. And, you'd be recycling! And, getting those rusted bolts off the exhaust manifold in the wrecking yard will count as strength training.

JC Whitney also sells flexible stainless steel spiral-wound tubing that you might be able to use in this project. An Example. 35 bucks for 5 feet of 2" diameter stuff. I don't know if I trust that this non-solid tubing is truly tight against CO, so unless I learned it was truly gas-tight I'd only use it outside the fireplace to connect the fan to the solid pipe inside the fireplace. If it really IS gas tight, you could just buy as much as you want, paint it flat black with some stove paint/header paint, and put zig-zags of it under your wood rack. Push the air in from the outside, and have the exit pipe somewhere outside your fire box.

No matter what, invest in a good CO detector and use it all the time in your house. Get one with a digital readout. Saving a few buck on heat isn't worth it if you get CO poisoning and can no longer remember your name. Be careful out there.

[Free To Canoe]

I have been looking for some ideas on how to do this for a while. I have an odd shaped fireplace and cannot find a commercial one to fit. Besides, they want a whole lot of money.
I don't have a welder. I was thinking steel conduit but black pipe sounds much better. Hair dryer or bath exhaust fans are also good ideas.

Thanks,
Free to canoe

[TromboneAl]

Hey Pete,

I did this in a very simple way about 20 years ago and here's how I did it and what I learned.

I bought 4 pipes with threads on the end, and the elbows that let me send a pipe to the back of the fireplace, across the back, U-turn, back across the back, and out to the front. Like this:

FireplaceHeater.jpg


I don't remember what kind of pipe -- heavy stuff from the hardware store. Outer diameter about 1.5 inches.

Hooked that up to a hair dryer, IIRC.

You can save yourself trouble by avoiding complicated arrangements with many pipes. The pipe is going to get very hot, and you'll get a lot of heat from it.

It took a long time to get rid of the smell/gases when first using it. It was pretty horrendous. Had to open all the windows and doors. I don't remember for how long.

I think I ran the hair dryer on a motor/dimmer dohickey, but it was still pretty annoying.

It's a great idea in theory, but I don't think I used it for long.

[TromboneAl]

Quote:

I have an odd shaped fireplace and cannot find a commercial one to fit.

Ask about options at the wood heating forum, and you'll get tons of answers.

[Westernskies]

Buy a cheap welder (Harbor Freight or used) , and the heaviest-wall pipe you can find (I 'd go for schedule 160 if you can find it, schedule 80 if you can't.) Socket weld fittings are easier to weld, but you can get a good butt weld with a backing ring. Threaded fittings are difficult to seal, and will burn out fairly quicky. Pressure test the assembly for leaks. Oterwise, it will draw smoke into the airstream via venturi action.
Thinwall conduit and/or flexible pipe will begin to distort the first time you build a good hot fire. They will collapse eventually.
Carry the exhaust end of the tubes well beyond the firebox.
Install a carbon monoxide detector and a smoke detector.
Keep a fire extinguisher handy.
Make sure your Homeowners Insurance is paid up.
A hair dryer is too noisy, and isn't designed for constant duty.

Don't ask me how I know this...

[Free To Canoe]

Good stuff!
Thanks!