hughpinder
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| posted on 26/3/10 at 11:58 AM |
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Advice on water tank please
I have one of those 'straw burner' heaters for my central heating. One of the problems you can get, if you fuel it with wood (I use broken
pallets) is that the bed of embers keeps suppling heat even when the thermostat cuts the air of to the heater, and this can cause it to become a
"boiler" rather than just a heater . It seems the usual solution is to fit a large insulated water tank as a thermal store. I can't
fit a standard tank without a major moving exercise, so I want to fabricate one (well get one made anyway). It would be 3m high, 1.5m wide and 700mm
deep. Does anyone know what thickness of steel I should use and what internal bracing (if any). It will be open to atmosphere, so no pressure rating
required.
Thanks for any input
Regards
Hugh
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tegwin
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| posted on 26/3/10 at 12:11 PM |
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That is an enormous volume of water!! I assume you are putting this on the ground floor?
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hughpinder
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| posted on 26/3/10 at 12:19 PM |
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Yep, It'll be on a concrete base outside (next to the heater). For reference, the heater itself holds about 800l of water, and the boilers
rated at 120kW when burning wood. I would fill the tank to 2.5m (about 2500l), and have about 500l of expansion space.
I always seem to manage to boil it this time of year (too entheusiastic with the amount of fuel after all the cold days) - its quite exciting as it
vents through at 22 mm overflow pipe and makes a good plume of steam!
Thanks
Hugh
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Liam
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| posted on 26/3/10 at 01:28 PM |
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When our workshop guys have to make a tank for a big model, it'll usually be a timber and ply construction then lined with fiberglass. Would be
the locost diy solution.
Liam
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907
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| posted on 26/3/10 at 02:17 PM |
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Hi Hugh.
To eliminate the need for internal bracing I would make it round. The material can also be thinner as the tank supports its self.
The normal thing to do is design around the size of the sheet to be used, less welding etc.
For instance:-
Two 3 x 1.5's plus a 2 x 1m.
3m rolled would give you 950mm dia.
Two of these would give a tank 950mm dia x 3m high, with a capacity of 2126 Lt's.
Assuming mild steel then to factor in a corrosion allowance I'd say 4mm thick.
The 2 x 1 would be cut into two flat discs for the top and bottom.
(Bottom cut big to allow a fillet weld inside and out, rather than an outside corner weld)
HTH
Paul G
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Liam
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| posted on 26/3/10 at 02:41 PM |
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^^^ I'm assuming he has a space he has to fit it into, otherwise he could just pick from a large number of plastic/metal tanks on ebay or
wherever.
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907
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| posted on 26/3/10 at 03:14 PM |
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quote:
Originally posted by Liam
^^^ I'm assuming he has a space he has to fit it into, otherwise he could just pick from a large number of plastic/metal tanks on ebay or
wherever.
No doubt that ebay would be the cheapest option Liam.
Paul G
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big_wasa
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| posted on 26/3/10 at 06:27 PM |
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Just find an old 600gallon oil tank.
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hughpinder
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| posted on 26/3/10 at 07:03 PM |
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Thanks for the ideas
Unfortunately the gap to the side of the dragon is only 900mm wide (hence 700 deep tank + 2*75mm insulation).
I suppose I could get away with less capacity in a 700 dia rolled tank, I'll have a think about it.
Regards
Hugh
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907
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| posted on 26/3/10 at 07:26 PM |
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It doesn't have to be round. Think of road tankers.
Oval? Like some petrol tankers.
Then there's the maxi tanker. They have slightly curved sides, top and bottom, with a sharper radius at the four corners.
The main thing is to get away from flat surfaces as these will bow and stress the joints.
Paul G
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