Solar Thermal From Scrap...AGAIN!

[Onoff]

Started on the CADCAN!  (As opposed to CADCAM....)

 

Who knew? When you stack 150mm high 440ml Fosters cans you lose 2mm as they interlock:

 

[Onoff]

Now THIS is a cool home made tool for forming short tees and saving on fittings. I can't for the life of me see how it works though! How does the J not just pull through? Surely it needs to rotate to form the cylindrical female stub?

 

http://www.builditsolar.com/Projects/SpaceHeating/KenSolShed/TeePuller.htm

 

[SteamyTea]

I was told that you should never use a soldered joint on solar thermal.

May be just on high temperature or pressurized systems though.

[Onoff]

12 minutes ago, SteamyTea said:

I was told that you should never use a soldered joint on solar thermal.

May be just on high temperature or pressurized systems though.

 

Good shout. Though if I get to temperatures hot enough to soften / melt solder I'll be a happy chap as I reach for the compression joints!

[Nickfromwales]

Nah, just braze them then. 

[Onoff]

On the subject of heat damaging components I'm still a bit concerned about this American obsession with using 'foil faced poly iso" i.e PIR to insulate their solar thermal panels. They reckon it's the best thing.

 

I was under the impression it would melt/catch fire at the sort of temperatures achievable but maybe that's EPS?

 

If not then 50mm of Wickes finest, on offer Celotex will be going on! It'd mean I could ditch the reflective aluminium sheet I've used before above the Rockwool / under the can stack. I'll probably insulate around the perimeter too this time.

 

 

Edited April 27, 2017 by Onoff

[Nickfromwales]

How shallow an angle can you mount these at?

[SteamyTea]

Generally speaking. PUs don't catch fire these days, they have a retardant in them as part of the mix (remember the Manchester Woolworth's fire 1979).

 

If the celotex, or similar, is not in direct contact with the cans/tubes, then there will be little distortion/melting.

http://www.talkcomposites.com/22732/celotex-in-a-composites-oven

Edited April 27, 2017 by SteamyTea

[Onoff]

20 minutes ago, Nickfromwales said:

How shallow an angle can you mount these at?

 

You can lay it flat if you like but the flatter you go the less the principle of "hot air rises" applies and you'll maybe be losing heat back off of the panel.  (You only have to consider how hot a black surface like tarmac gets). A lot of the Americans mount their space heating ones vertically on the SIDE of the house.

 

I take the lead from the PV panels and aim at about 45degs generally only because it'll likely end up on a house roof.

 

I'm mulling that if I did one on say a shallow pitch roof like a shed I'd take the cans into a length of 110mm soil pipe or similar steel ducting if I could get it (maybe even a run of Party 7s ). The duct would be parallel to the ridge of the shed. I'd cap one end and draw hot air from the other via a PV backed 12V fan. 

 

 

[SteamyTea]

I don't think that heat losses from convection are much of a worry.

[Onoff]

Something like this I guess for a shallow pitch with an "apex" take off pipe? Cans painted black under glass (blue), draw up from the bottom into the larger collecting tube at the top suitably insulated. Ply carcass (brown) with a lead cap (black). Lets be honest, if you were clever you'd build it into the shed roof design from the start and save on a bit of felt  No reason why that bottom 18mm board couldn't be the OSB shed roof itself. You could then draw heat DOWN via a 110mm T:

 

 

(Good luck getting magenta soil pipe though..........  )

Edited April 27, 2017 by Onoff

[Onoff]

Another brain fart:

 

[SteamyTea]

Don't you want the glass to cover the top, stops rainwater pooling at the lower edge.

Or you could just mastic on a second sheet of glass to totally cover it.

[Onoff]

12 minutes ago, SteamyTea said:

Don't you want the glass to cover the top, stops rainwater pooling at the lower edge.

Or you could just mastic on a second sheet of glass to totally cover it.

 

I've just shown a lead flashing (as in if money were no object  ). Figured a run of sealant between that and the "glass". Not sure where it would pool?

 

Only playing with it tbh.

 

EDIT: I'll get bored soon!

Edited April 27, 2017 by Onoff

[Nickfromwales]

Liking it, but the shed roof would need to produce wet thermal heat to warm my TS's ? Got me thinking of an 'active' roof now made at a steeper angle out of 30mm box section steel......

? Back to work. 

[Onoff]

40 minutes ago, Nickfromwales said:

Liking it, but the shed roof would need to produce wet thermal heat to warm my TS's ? Got me thinking of an 'active' roof now made at a steeper angle out of 30mm box section steel......

? Back to work. 

For some reason I thought you wanted to just space heat the shed. 

 

So.....could you take the hot air stream thru a coil in the tank instead of the usual water in the coil? Would the temperature lessen as you reduced the pipe size?

 

As you can guess I'm firing on random today!

[Onoff]

And continuing the mad musing after a beer and armed with a craft knife & pair of scissors:

 

The "clip fin" design solar thermal panel is where black painted aluminium (or ideally copper) fins are attached to a copper pipe matrix to heat water. With ali it's important they are held tight to the copper. Yes, I know you can buy them (or at least could) and tbh they should be thicker sheet......but.....

A 440ml Fosters can yields a nice piece of aluminium. I think about 0.25mm thick:
 

 

 

 

Add a pipe clip as a former and run it up and down:

 

 

 

Looks like a clip fin to me:

 

 

 

Except it springs out of shape when you take the clips off:
 

 

However.....the metal is so thin I reckon you could stick it to foil backed PIR with foil tape to keep the shape? Or maybe make a full length clip out of something?

[ProDave]

I knew I should not have read this thread.

 

DIY Beer can UFH spreader plates anyone?

[Onoff]

16 minutes ago, ProDave said:

I knew I should not have read this thread.

 

DIY Beer can UFH spreader plates anyone?

 

if it's for @AliG's 504sq.m ground floor I might need some assistance emptying the cans! 

[AliG]

Haha. I was wondering how I came up in this forum.

 

21275 cans according to the measurement shown in the pic!

 

I just paid for the tiles today, Foster's cans may have been cheaper!

Edited April 29, 2017 by AliG

[Nickfromwales]

10 hours ago, Onoff said:

 

if it's for @AliG's 504sq.m ground floor I might need some assistance emptying the cans! 

 

 

[richi]

...or just come get these three old-skool tube panels:

http://forum.buildhub.org.uk/ipb/topic/2494-free-solar-thermal-panels-x-3/#comment-39425

 

[Onoff]

21 minutes ago, richi said:

...or just come get these three old-skool tube panels:

http://forum.buildhub.org.uk/ipb/topic/2494-free-solar-thermal-panels-x-3/#comment-39425

 

 

Tempting if I had a truck! You're 70/80 miles from me.

 

How big are they btw?

[richi]

I guess the shorter dimension is ~600mm (I'm looking out the window at them at the bottom of the garden)

[Onoff]

10 minutes ago, richi said:

I guess the shorter dimension is ~600mm (I'm looking out the window at them at the bottom of the garden)

 

Would they fit in the back of a Focus Estate?