This may sound odd but ive made something

[edubcee]

hi
im new here so first of all hello to every one
im a bit of an avid engineer and decided to make myself a saw dust pyrolising burner
the problem i now have is it works so well i want to plumb it up to my central heating system as a passive heater
the unit i have built uses saw dust as fuel but turns it in to charcoal producing a gas which then burns at the top of the burn chamber (it produces a flame 50mm high and measurung 100mm diameter)it is temprature controlled (fan driven) and switches on and off like any regular gas boiler
i was thinking of using a copper coil 28mm in diameter placed in the body of the heater above the burn chamber (not directly but around the heat soak area ive allowed) and splicing this into the 22mm flow pipe of my gas boiler with an extra circulation pump so that the heat is passed to the radiators before returning to the gas boiler allowing me to keep the gas boiler functional and to use either one or the other or in tandem which is what i really desire
my heating system currently has a gas boiler feeding a hotwater cylinder with triple valve and a hot water tank in the loft
just wondering aside from my lunacy if this will work to heat my house
kind regards
eddie

 

[RigidRaider]

Would copper tube survive at that temperature?

 

[Weedrip]

If it’s producing more energy [and more importantly] effort to keep it going and remove ash etc.....
I presume the sawdust is a by-product? And you have lots of it, can store it to keep it dry.....
Is it better than the existing waste wood burners? If so.... by this time next year you’ll be a millionaire.... only teasing.
I would have thought a steel tube would last longer, piped in the return to preheat the gas boiler to then kick it up to a usable temp.
There a number of tried and tested schemes for plumbing a dual fuel system out there so yes it’s possible. Whether it worth it, only you can really judge it would depend on the heat-output available to ensure a safe interconnection with the gas boiler.

 

[Porque223]

What is the "heat of combustion" or "heat value" for sawdust, in BTUs?
Over here the average house needs 6 BTU per square foot per Heating Degree Day with a tight house taking about 2.

 

[ivixor]

Why not find a faulty boiler on ebay or something and pinch the heat exchanger out of it?

 

[Onetap]

Why not find a faulty boiler on ebay or something and pinch the heat exchanger out of it?

A Range Powermax cylinder might make a good heat exchanger, like a domestic water cylinder with 8 or 10 fire tubes up the middle. Not the later Potterton Powermax, those are different. Lots of them are being ripped out. It's not copper, but some harder alloy, a bronze maybe. Try a few scrappies, leave a card.

The gas generated is mostly carbon monoxide, utterly lethal stuff if it should leak.

 

[Dan Robinson]

How How many kw's are we dealing with? What kind of physical height?

Might have just the thing.

 

[Dan Robinson]

Marvellous

We get a good excentric invention that peaks my interest and he bugjers off before the thread has even got started.

Come on fella.... I have a suspicion I have exactly what you need sitting in my workshop.

 

[JohnD]

this kind of burner was used in great numbers in the Soviet Union to run trucks when they were short of oil.

 

[Dan Robinson]

Well I have a couple of stainless hat exchangers comprised of a spiral of 15mm OD tube with lots of fins. It can absorb 40Kw and is encased in a stainless steel wrap with two probe mounts at the top (for gas ignition and flame detection probes).


The burner is bolted to the bottom tray and is designed to burn horizontally, with a fan pushing the fuel air mix up through some turbulators; but I am sure that can be changed to suit.

Joining the flow pipe is a little tricky, but you can buy (and i stock) gasket kits.

 

[edubcee]

hi
the burner is still in the development stage at the moment and im playing with flame detection for the safty cut off for the fans
it is a small unit the main burn chamber being a 100mm pipe capped at the base with drilled holes top and bottom of the side profile, this is then sat in a 125mm tube with a fan at its base.
once lit the first burn creates hot embers, once this is acheived the next load of saw dust is added via a push tube fed by an auger feed from a small hopper outside (simlar to a pellet stove) the mass is then forced air through the 125mm tube as it passes the inner tube the gas produced at the bottom of the burn chamber is sucked through the holes in the bottom of the burnchambers wall and pushed back out at the top where heat and air allow it to ignite.
it is a bizzar thing to watch, each load of saw dust burns for roughly 6 minuits as it only take a handfull of dust each time and as soon as its added there is a tiny puff of smoke then ignition
The unit im fitting to my house is being built inside a cast iron vitorian washing machine not sure if any one has seen one but it fairly attractive and in keeping with the house the only thing is i have upturned the bowl to create a void inside approx 400mm round and 450mm deep this is lined with refractory cement allowing me enough room for a coil of 28mm tube from an old heating cylinder i had measuring 300mm across and 270mm deep.
this was dry destruction tested and survived, so i think i will stick to the copper as it is so easy to work with (plus i have a few of these coils incase anything goes wrong)
The main problem im having is what pipes do i plumb it to on my boiler its a baxi solo so im assuming the flow is the top pipe from the heat exchanger and if i put my copper coil inline on the flow as it comes out of the boiler with its own circulation pump it will travel to the rads before going back to the boiler pre heating the water for the boiler and when not in use act as a radiator/thermal store.
any help will be greatly recieved

 

[danplumb]

Would love to see that working, could you make a video ?