Workshop heating question.

[Chris Head]

The property I'm moving to has much more potential to heat the workshop/s than my current one, it's going to be heated with a woodburner & warm air distribution system. I saw the air pump yesterday in one of the bricos with four outlets.

For the wood burner I have two options; use an existing small Villager type stove I have already or have welded/constructed a solid sheet type burner; which I'd prefer because it could be made to suit the purpose. I'd like to learn how to weld but for the moment I'm going to have to rely on someone to do it for me....or find someone to teach me?[:D]

How do I create a chamber or something behind the burner to collect the hot air for distribution? It's got to be as efficient and simple as possible as eventually it will be heating two workshops and possibly a showroom and hopefully I'll be using the piped warm air to accelerate timber drying processes during winter months.

I hope I've explained clearly enough....heating/ventilation isn't my subject!

 

[Nick Trollope]

Nor mine, but I've done this;

Take a length of thick-walled steel tube about 75mm x 50mm and weld up a continuous tube for the bottom of the stove (or build a stove around it). Set the fire on top of the tube and blow air in one side, other side comes out very hot. Works for me! Well, as an experiment anyway, but my welding is awful and it leaked like buggery and tended to make the fire burn too quickly (in a blast-furnace fashion). If you can find someone who can weld, it really will work.

[Anton Redman]

Whatever you do if you are experimenting with a one off flue design then fit carbon monoxide detectors.

[Gluestick]

Chris:

Nick's idea is excellent. If you look at the schematic layout of locomotive boilers (or reciprocating steam-powered ship's boilers) they use multi-tubes for the water in the firebox as the Heat-Exchanger. Thus any collection of tubes will work very well.

Welding: if you buy a MIG (Metal Inert Gas) kit, these are now very cheap. The filler is a continuous wire on a roll. The torch has a hollow tube surrounding the filler wire nipple and as the wire feeds out, the hollow tube surrounds the weld with inert gas (Typically Argon, C02 or Argon-C02 mixture) which precludes the metal oxydising and creating "Slag", or impurities in the fillet (Seam) which cause structural weaknesses and blowholes.

Simple welding using a MIG set is simply like any other craft skill; practice. Different thicknesses of mild steel require different welding current (adjusted on the box) and different feed speeds for the filler wire; and different gas pressures.

Practices makes perfect!

Another new challenge for you, Mate!

Anton makes a very good and critical suggestion!

[Chris Head]

The outlay in terms of time & cost seem p'raps too much at the mo Steve. Creating an efficient heat collection void behind the woodburner or Nicks idea might be a more achievable alternative at the moment; it's going to be one of the first things to do after power requirements.

Like the idea Nick, although I'm not 100% sure what you mean, at the moment the space is a blank canvas, something like that sounds ideal...could you expand or show piccies?

Good point Anton.

Thanks

[Nick Trollope]

This is what I did (I am no artist!)

[img]http://www.aplaceinfrance.com/images/misc/firething.jpg[/img]

As I said, it was made from box steel cut appropriately.... And inappropriately welded. It didn't survive to be photographed...

[Chris Head]

So I guess the 'fins' heat up and consistently warm the air as it passes through the box Nick? I can see the principle now; I reckon if you could combine that with collecting hot air from a void behind the heater you could generate alot of heat. I saw the price of the flexible alu piping the other day; about 11 euros for a 3m length....no way am I shelling out for that! I can see the first few metres might need the alu stuff given the possible heat involved but after that I'd thought of perhaps reducing to something of smaller diameter, at a guess there will be in the region of 50m of piping needed. Maybe the plastic water pipe which could easily be teed off and should no way get too hot at the extremeties?

[Michael]

Chris Why not design the heat exchanger around the flue pipe,you already have the villager type boiler ,so the spigot on the boiler must be at least 150 mm. Get yourself a metre of vitros or cast iron flue pipe the size of the boiler spigot. and make the exchanger  box to wrap around it with the tappings etc ,at the top end of the flue pipe make a flue stableizer,in other words a flap inside the flue to control the boiler air flow [also to slow down wasted heat up the flue]then connect it to the rest of the flue/chimney/register plate or what ever. Also the idea of this is that once its made if you do get a more efficient boiler any time it can be transfered on. I made this system some years ago for curing tobacco although it was on a slightly larger scale.Michael.

[Chris Head]

Again, I sort of think I understand Michael...I'm no engineer; it sounds quite simple though?

Thanks

[powerdesal]

[quote user="Chris Head"]

Again, I sort of think I understand Michael...I'm no engineer; it sounds quite simple though?

Thanks

[/quote]

Very eco friendly Chris, a sort of waste heat recovery unit, just like we fit waste heat recovery boilers to gas turbine exhausts.

[Jonzjob]

Hi Chris, this air pump you saw sounds like the type used to suck the damp air out of French houses? If it is then make sure that the air going into it is not too hot because they are designed for damp ambient air from bathrooms and kitchens and may not take too kindly to heat???

I think that the main reason these fans are needed so much here is because of the amount of petrol (parafin to us) that's used and chucks bucket loads of water into the air!!

One of the most efficient air blowers I have seen was in a pub and it was a tubular fire grate. Cold air was blown into one side and red hot air came out of the other side. It heated a very large public bar very well! If you have a way to fit one in the bottom of your stove you could fabricate one from large bore water pipe with screw elbow fittings. Then all you would have to do is to cut the in and out holes and hook up you ducting to the out. You could use a single port, sqrirrel cage blower to blow in the cold air with no problems of the blower overheating?? The only welding needed would be around the in and out pipes...[8-|](well warm really?)

[Michael]

Powerdesal .Now you are getting a bit technical for this thread!!we are now getting into the the area of flash steam vessels to run low pressure heating systems etc but my concept is on that track.If we hear of a boiler in space then we will know that Chris has not cracked his problem.Regards Michael.

[Chris Head]

Couldn't we continue this chat at my place? (dont forget the tools!)

[powerdesal]

[quote user="Michael"]Powerdesal .Now you are getting a bit technical for this thread!!we are now getting into the the area of flash steam vessels to run low pressure heating systems etc but my concept is on that track.If we hear of a boiler in space then we will know that Chris has not cracked his problem.Regards Michael.[/quote]

Not really technical, your idea was a relatively simple method of extracting heat from the flue, ie heat that would be wasted ergo - waste heat recovery. My units fitted to gas turbine exhausts are just that much bigger and are not in fact flash steam units but standard water boiling medium pressure (18 bar) boilers. I dont think Chris (or anyone else here) really wants a treatise on the use of flashing steam units as applied to multi-stage flash desalination.......I can oblige if there is demand [:P]

ps. MED as well if you wish, or even RO membrane technology.

[Weedon]

There is lots of info about stove construction here:-

http://journeytoforever.org/biofuel_library/ethanol_motherearth/me4.html

I know it's waste oil stove construction but I guess the collection and distribution of warmed air is the same principle.

[Chris Head]

Going to look at a second hand insert tomorrow, I think a combination of creating a specific & efficient space behind the insert to gather the heat with a heat transfer thing is the simplest solution. It's hard to imagine working in the warm in winter!

 

[Jonzjob]

[quote user="Chris Head"]

Going to look at a second hand insert tomorrow, I think a combination of creating a specific & efficient space behind the insert to gather the heat with a heat transfer thing is the simplest solution. It's hard to imagine working in the warm in winter!

 

[/quote]

Oh dear Chris, are you getting old? Joining us wot like to be warm? Getting soft???[6] If so then I for one don't blame you. I had my fill of working outside in all weathers and hours in the R.A.F. Now I like to keep my arthritis nice and warm!

That site on the oil burners is great Weedon. One of those would keep your new building project lovely a warm for nowt! I think that the basic problem over this side of the pond is that all if not most of the water heaters are copper aren't they?

[Chris Head]

Oh dear Chris, are you getting old? Joining us wot like to be warm? Getting soft???

Yes, maybe & definately not!

Seriously guys, thanks a bunch for the help, I sort of have an idea of what I'd like to achieve now and how to go about it...ish, also using heat that's already there to spedite drying of timber may well knock a few years off drying processes too which is seriously exciting!