Fireplace grate heat blower

[DEKE]

joebill - as our resident fabricator, I would like any input you can provide on this potential project

On cool nights, DW and I like to sit on the back porch and have dinner and talk.  The porch is covered but has only screened sides so it does not hold heat.  The fireplace doesn't put out much heat except what goes up the chimney, so if we have a couple friends over, it gets really crowded as folks try to press into the fireplace for warmth. 

My FIL had a Heatilator brand device similar to what I've linked.  It worked very well to heat their house.  A small fire, hot coals, and the air flowing thru this device puts out a lot of heat. 

link

Look at the fourth photo from the top left corner for the best explanation of what I want to build.  As design improvements, I think the combo grate/exhaust tubes should angle out a bit in order to push hot air to the left, right, and middle.  Also, I think the exhaust tubes need to feed from some sort of air circulation box in the back of the fireplace which could gather more heat and help ensure an even flow of air thru each tube.  I have an all metal fan I can use, build a fan exhaust funnel to feed air into a feeder tube, into the air circ box, and then out the exhaust tubes. 

Any comments, suggestions, derision, or plain old insults you care to make would be "grately" appreciated. 

[beowoulf90]

If you have room to build a plenum box (what I'm assuming you are calling an air circulation box)it would pressurize the box and force air out all the tubes evenly. The fan should be piped to the plenum box. I agree that you could turn or angle 2 air tubes left, 2 right and 2 center for a broader coverage, but most fireplaces don't allow for that wide of a design. Unless you extend the tubing and turn it

[DEKE]

Yes, Beowolf, plenum, good word, exactly what I was thinking but had forgotten that word.

I've found some one inch, threaded black pipe that I can quickly throw together to make a test system. I have no idea how much heat that pipe can handle, but I'm going to find out.

[Ozarks Tom]

A few T-fittings and elbows would make a fast assembly if you have the right length pipes, or a pipe threader. I can see where splaying the pipes would give better distribution.

Being lazy, I can see when it would be a PITA to clean out the ashes/coals. You'd pretty much have to remove the apparatus first.

Before we installed our fireplace insert, we used a "fireback" in the box. If I had to guess, I'd say it increased reflected heat into the room by an additional 20%.

[DEKE]

If I raise the grate 4 inches off the floor on metal legs, why would it be any harder to clean out ashes than the existing old fashioned grate?

Not arguing with you, just making sure I'm not missing something.

[Ozarks Tom]

Yeah, you could make a rake type scraper to get the ashes forward so as to scoop. The unit in the link was 2" off the floor, that would be tough to clean.

[DEKE]

good catch, Tom. It's seeing things like that help eliminate the rework.

[beowoulf90]

Have you considered using a raised fire grate that sits just above the pipe?
This would still allow the heat, but the grate would take the weight of the firewood. Thus maybe eliminating any sagging or warping of the pipe. Just thinking out loud.. Oh and as for the word plenum, I'm the draftsman/Commercial Plumbing estimator for a HVAC & Plumbing company.. Otherwise I wouldn't have ever heard or used the word..LOL

[paisley]

Window squeegee.
Replace the rubber with
A metal strip
I used plumer epoxe
To attach the Merle stop

Side note
My wood stove has something like what you are planning.

There was built are two sealed off chamber above the water tank in the back of the stove.

In the back is the blower.
Honestly I do not use it much ...but it does kick out heat.

My reason for NOT using it much....

Poor planning for the ele cord location.

[DEKE]

Dec 14, 2017 12:23:07 GMT beowoulf90 said:

Have you considered using a raised fire grate that sits just above the pipe?
This would still allow the heat, but the grate would take the weight of the firewood. Thus maybe eliminating any sagging or warping of the pipe. Just thinking out loud.. Oh and as for the word plenum, I'm the draftsman/Commercial Plumbing estimator for a HVAC & Plumbing company.. Otherwise I wouldn't have ever heard or used the word..LOL

And here I thought you were only good for programming hockey arena music. 

[beowoulf90]

Dec 15, 2017 1:48:18 GMT DEKE said:

Dec 14, 2017 12:23:07 GMT beowoulf90 said:

Have you considered using a raised fire grate that sits just above the pipe?
This would still allow the heat, but the grate would take the weight of the firewood. Thus maybe eliminating any sagging or warping of the pipe. Just thinking out loud.. Oh and as for the word plenum, I'm the draftsman/Commercial Plumbing estimator for a HVAC & Plumbing company.. Otherwise I wouldn't have ever heard or used the word..LOL

And here I thought you were only good for programming hockey arena music. 

Hey when you're good at something, you go with the flow..

[Thtwudbeme]

I am obviously unsure as to what kind of "deck" you have, but might not a chiminea-type thing help. Especially the not so modern looking stone/clay models. The original idea of those things is to have a lot of thermal mass built into the bugger. That way the fire heats the thermal mass which will then release the heat in all directions.

[DEKE]

Dec 16, 2017 13:53:04 GMT Thtwudbeme said:

I am obviously unsure as to what kind of "deck" you have, but might not a chiminea-type thing help. Especially the not so modern looking stone/clay models. The original idea of those things is to have a lot of thermal mass built into the bugger. That way the fire heats the thermal mass which will then release the heat in all directions.

It is a regular fireplace and chimney with a stone face at the end of a paver covered porch with a roof. Lots of stone to absorb heat but that doesn't warm bodies all that much.

[joebill]

I just noticed this for the first time, and the first change I would consider making to it would be to put the dang thing ABOVE the fire.
First, it gets a heckuva lot hotter up there than below the fire, and secondly, it would have no effect whatsoever on ash removal.

The second thing I would consider is going to one of those places where they make custom exaust systems with an exaust tube bender and show them your sketch or print of the tubes, walk out a half hour later with a smooth factory looking set of tubes already pre-bent from material that is prob'ly more suitable than black pipe for heat related operations, has lighter walls for a fast heatup, less weight to struggle with, etc.

A single properly sized holesaw would allow you to make holes in the plenum that fit the tubes, if my understanding that you want to feed the tubes cool air from the plenum (sorry, I just skimmed that part), and if your fan is the squirrel cage type, you can put a simple flat plate restrictor on the inlet side to adjust the air quanitity coming through the tubes.

Any kind of brackets or straps could be used to hold the harp (nuther new word) of tubes together and properly alighned, since it is a low to no pressure system and being pierced with self tapping screws will not cause undue leakage to the tubes.

OH, yeah, one more thing. The exaust tubing has those chrome add-ons you can buy that changes the direction of flow by maybe 15 degrees just as the air exits the tube, allowing a bit of customizing where the air goes in case one of the people in th room is i a cold spot or a too-hot spot in the case of my wife.

Here are some exaust tips, far more expensive than if they came from the local parts house, I'm sure;

www.summitracing.com/search/part-type/exhaust-tips

Anyhow, that is my peliminary design.....Joe

[DEKE]

There are commercial models that put the tubes above the fire, but I think there is more heat in the glowing coals.

I did think about a muffler shop and using their tube bender. My guess is that regular exhaust pipes are too thin and would burn through, but I don't really know what I'm talking about so it is only a guess. The heftier metal used on headers would be better.

Even though I am loath to give summit racing any more of my cash (I raced for a few years and it cost me waaayyyyyy to much) the exhaust tips are a good idea. They might help spread and slow the air if needed. I think I'm going to stick with the black pipe at least to start. That way me and my welder friend can do everything in his shop and make tweaks as needed.