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stmbtwle

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Reply with quote  #21 
I might be missing something but I don't see why you need the second heat exchanger. You could just pump the water from the wheelie bin to the DHW HEX, which would give you your isolation.
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Willie, Tampa Bay

Garage_Hermit

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Reply with quote  #22 
Hi, Willie,

Yes, I agree with you !

Basically, I have a choice between two types of system...

  • The FP HEX approach involves a lot less infrastructure, and delivers hot water direct to the DHW tank. It is a real-time "on demand" system and does not provide for any backup storage...  Sizing such a system would be far trickier...
I guess it is plain to see that I am still seesawing between the two ideas [frown]


G_H

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(1)  "Heat goes from hot to cold, there is no directional bias"
(2) It's wrote, "voilà" unless talking musical instruments...
stmbtwle

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Reply with quote  #23 
Have you already installed your air heating system? If so how well does it work? Can you tie into it for your water heating? If so it will save you a lot of work.
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Willie, Tampa Bay
Garage_Hermit

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Reply with quote  #24 
Hi, Willie,

No, the air system is still on hold - it has to follow my sequence of works...

Namely, the Crawlspace has to be viable... (sine qua non)

Then my 1st obstacle will be... getting the fascia board off the roller-blind caisson - I need a plastic spatula [mad].
I have only done this operation once before (around 4 yrs ago), and it worked OK, but I cannot find the tool I used...

After that my work steps are:
  • test 220VAC - 12-VDC transformer (= fan supply) (obtained in a swap - I am nervous of testing it on a good fan - any ideas ?) (? light bulb off car?)
  • cut hole for fan air supply
  • mount fan
  • configure power supply
  • build plenum and install onto slate facade bottom board
  • test fan
  • if test OK, remove fan, install fascia panel then install fan as definitive mount on fascia panel
  • run system and check air temps in basement lobby
  • configure Whole House Fan inside Crawlspace
  • run WHF simultaneous with facade extractor, and check temps to see if it was all worthwhile
I get your point: IF the air system runs OK - try tying it in to water heating like you suggest:
could save not just a lot of work like U say, but also a LOT of money [redface]

G_H

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(1)  "Heat goes from hot to cold, there is no directional bias"
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stmbtwle

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Reply with quote  #25 
I think what you really need is a round tuit. They're always in short supply here! [smile]
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Garage_Hermit

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Reply with quote  #26 
Agree !  (they are a great cure for analysis paralysis !)

G_H

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(1)  "Heat goes from hot to cold, there is no directional bias"
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Garage_Hermit

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Reply with quote  #27 

After encouragement from members, I have (finally) decided to concentrate on AIR initially…

 Yesterday was a good sunny day so I experimented at extracting from the VSF, using a simple plenum and fan.

Despite the rudimentary experiment, results were encouraging :
For 19°C external ambient, the stagnation temp was at 44°C and I read 30°C at the fan outlet.
(I used a 125 cfm 220-volt AC PAPST fan).

 This somewhat low value was no doubt due to the fact of neglecting to seal the façade (which is full of exploratory slots and holes…).

I also neglected to record the slate surface temperature, for reference… So the test needs repeating…

 Still, one thing is clear: I do not want an air offtake plenum  running along the bottom of the façade: it looks pretty unsightly…  
(at the top of this thread, I considered such a plenum, feeding in to the roller blind caisson, but this is looking more & more impractical;
I therefore considered the same plenum, but with an extraction stack, but his involves feeding through the half-open portico door, and I have finally discarded this as Bad Design…).

 =====

 So my next task is to define the OPTIMAL way of getting maximal heat out of the façade, using AIR but without a long bottom-mounted plenum.

 I finally came back to this idea…

http://www.simplysolar.supporttopics.com/post/prefabricated-copper-manifold-for-slate-facade-6251821?highlight=aluminum+rule&trail=23

 I think that these aluminum channels could be adapted to improve air collection, but would appreciate any ideas !

  •  ·         A “radiator” comprising several of these channels would be inserted inside the façade cavity.
  • ·         The idea is to have the maximum wetted area of aluminum, absorbing heat, therefore 12 channels x 180 cms
  •      This equates to over 50 square foot of aluminium, soaking in HOT air...
  • ·         The channels are connected to a sealed 5-inch dia horizontal PVC duct fitted with an offtake fan.
  • ·         Air is pulled down the channels and discharged into the basement, via an open window.
  • ·         So by definition, aeraulics is now on the left part of the façade
  • ·         (And by serendipity, hydraulics will be on the RIGHT, which makes for easier pipe penetrations…) (via garage)
  • ·         The “naked” sections of aluminum down the unslated façade will be covered with a prefabricated slate façade, providing a further collection area and temperature boost…
  • ·         The duct also is also clad with a mini slate façade, to prevent heat-loss.
  • ·         The duct terminates in a 90-degree elbow, pointing towards the window.
  • ·         The offtake fan is installed inside the elbow, and an extra shroud section is added to avoid system effect.
  • ·         After collection is finished, an end cap is put onto the duct, to keep damp & foreign bodies out…
  • ·         The window can now be closed.  (it is generally open most of the time anyhow).
  • ·         The basement should be warmer…

 All feedback welcome as usual !

G_H


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(1)  "Heat goes from hot to cold, there is no directional bias"
(2) It's wrote, "voilà" unless talking musical instruments...
stmbtwle

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Reply with quote  #28 
Can you go directly through the wall ABOVE the roller-blind casing, from the inside?  That would keep your ductwork out of sight from the street.  If there's an attic behind the facade you might even be able to hide everything in there.
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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Garage_Hermit

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Reply with quote  #29 
Hi again, Willie:

Quote:
Can you go directly through the wall ABOVE the roller-blind casing, from the inside?


Fraid not - the casing is firmly in the angle between the ceiling and the fascia (which is in fact concrete blocks) (I guess it must have reinforcring steels in it, in order to form the span ??)
(knowing my luck, if I tried to drill thru it, I would hit steel every time... [redface])

the casing occupies the entire fascia (latter being 10 inches deep x 10 inches thick).  The fascia is 8 foot long and forms the "upper rear sill" of the door reveal.  The soffit of the reveal = the facade wall ( also = 10 inch thick blockwork....) (this place was apparently built to last...) (I am told it was a Canadian architect...)

The equivalent part of structure in the garage is identical: floor-above and fascia, the front face of the fascia being the... facade.
The garage facade (fascia) is covered with 60 mm of external wall insulation.
the patio fascia is not - it has a 12-cm slate box instead...
So the slates project forward by 6 cms in relation to the neat line of the garage fascia.

What the fascia does, is drop the free (room) height from 232 cms, to 205 cms, which takes standard joinery in these parts.

So to cut a long story short, I guess I am leaving this area Well Alone...
At least until we have roofing repairs done in (perhaps) 10 yrs time (a slate roof is supposed to last 40 yrs in these parts...)

G_H


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(1)  "Heat goes from hot to cold, there is no directional bias"
(2) It's wrote, "voilà" unless talking musical instruments...
stmbtwle

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Reply with quote  #30 
"Well enough alone" seems like a good plan. One of the ideas behind DIY solar is that it's supposed to SAVE you money. This doesn't appear to fit with that. Bummer! [frown]
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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
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