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Garage_Hermit

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Reply with quote  #1 
[image]
PROJECT OUTLINE


(A)    Pneumatic side delivers warm air into Loggia
  • The interface is a simple plywood plenum that ducts the warm air onto the roller blind
  • The roller blind caisson is on the inside wall of the room and is open to atmosphere
  • A fan installed on the caisson can therefore drag air out of the façade, to heat the basement
(B)    Hydronic side delivers warm water to storage tank in Crawlspace, for DHW preheating
  • An open circuit is used, allowing drainback at end of collection session.
  • Cold water from mains passes through a HEX in the tank, before feeding the hot water heater
  • Potential electricity saving = 10% of bill

Advantages:
  • zero-energy design utilizing existing building fabric
  • maximizes benefits of south-facing aspect
  • vertical collector for optimal winter heat-collection
  • heat goes into basement where it is most needed
  • no outside changes to aspect of house
  • maximum economic gain for minimal investment
Could be adapted for other facade configurations.

More details to follow - all feedback & suggestions welcome !
(for enlarged view, click on the image, click SAVE, then click Ctrl +)

G_H

P.S. For interest's sake,  Mattie dug up a parallel application here: http://www.irishvernacular.com/building-plans.html
Picture

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

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Reply with quote  #2 
Yep, lets see the details.
Garage_Hermit

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Reply with quote  #3 
OK, here's a couple of shots of the plenum that I have mocked up, showing the main parts:

  1. Plywood plenum skin
  2. Batten to facade structure
  3. Rear attachment to soffit of patio-door reveal
  4. Neoprene seal on business end of plenum, for sealing against the roller blind.

I decided to make the plenum tapered, to hopefully ensure best extraction.

The air extraction slots in the facade frame will  be as numerous and as big as possible.

Will post photos of inside of room as soon as !

G_H Plenum mock-up_internal.jpg  Plenum mock-up-external.jpg 


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Garage_Hermit

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Reply with quote  #4 
Photos showing inside of room, with mock-up fan installation.

This is a 7-inch PC case fan, 3 speed (manual select), giving 60, 100 or 120 CFM.
I would place a second fan on the left side.

The white box is the casing for the roller blind.  The fan will be screwed to the casing, with a cut-out.  Another (big) cut-out has to be made in the body of the caisson (preferably without damaging the roller blind !).  Roller blind is manual (fire regulations prohibit electric motor on exit).

Regarding the curtain poles, please imagine they are actually 28mm OD copper [redface] (1.25 inch).
And that the green Coroplast is actually a fin...

I envisage that the copper manifold will occupy around 2 meters width of slates.

The air part is 2.75 meters, to correspond to the width of the patio doors.

All feedbck welcome as usual !

G_H
FAN INSTALLATION CLOSE-UP.jpg  FAN MOCK-UP R-H.jpg  PIPES MOCK-UP LEANING.jpg 
PIPES MOCK-UP HALF-INSERTED.jpg


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SolarInterested

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Reply with quote  #5 
G_H  is the water manifold at full pressure - i.e. plumbed into the feed to your hot water tank? Not that it makes any difference to your design - just curiosity on my part. You had mentioned about it being a drain back so it wouldn't freeze. Is that a seasonal thing where you would take it out of service over the winter?

As for the  pipe diameter I guess it's a question of trade-offs. More smaller diameter pipes would give more surface area/heat exchange per equal volume of water in the pipes. However that greater surface area translates directly into more copper, more joints and possibly more cost. Are smaller diameter pipes cheaper per unit of surface area than the larger pipes?

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Garage_Hermit

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@SolarInterested

Hello & thanks for the feedback !

I envision  having the hydronics on an open circuit, to a storage tank, so it is not under pressure at all, just the pump pressure on one side, to fill the collector, then gravity return of hot water to the tank.  I will infact probably use twin tanks, the feed out of the cool tank, return HW to the hot tank.

The preheat comes from having a steel (or aluminum) radiator immersed in the hot tank; the radiator feed is taken off the cold water branch feeding the DHW tank.  This is an approximation of the commonly found Danish "tank-in-tank'' system of DHW preparation

The idea is that when hot water is run off the DHW tank, instead of having cold water replenish the tank, the make-up water has been sitting in the solar tank, so should be warmer...

I have to size the system so that sufficient preheated water is available - means finding a radiator of the right size.  I prefer using an off-the-shelf radiator, to messing around with coils...

The idea is, when the pump is turned off at the end of collection, the collector manifold should drain back to the tanks...  This is to prevent freezing in winter... (We generally get down to minus 4°C a few times over a normal winter) and below minus a few more times than that...).  The system is designed to pick up heat year-round, but especially in winter [cool]

The idea is that I could keep the system running over the summer, for DHW preheating... since the collector is vertical, it ought to perform less...

I agree about the trade-offs with the bore of the copper...  I wanted to utilise the maximum "thickness" of airspace available in the facade framework, and I suspect that part of my reasoning is, desire to keep mumber of brazed connections to a minimum....  I started off looking at 16 mm PEX, and basically worked my way UP from there !  I suspect that big bore is better, & since I intend to use a variable speed pump, I hope to "manage" the flowrate to give optimal time for water to heat up...  Will post my preliminary calculations when I have formated them some more for "public consumption"!

Actually, had not compared the cost of different pipe diameters, I  have been working basically on heat requirement, and available area of slate collector, and amount of water required to hit my desired temps... so it will be interesting to compare "price per heated liter of hot water per square foot of slate", for different tube diameters!

More later when I get the chance !

G_H


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Garage_Hermit

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Reply with quote  #7 
Have not finalized my numbers yet, but have hopefully cleared up another problem - namely, how to get long pipes into the left-hand part of the facade, when the garden level is so high...

The VSF will accept pipes 193 cms long, but there is only 145 cms of clearance below the frame.
Which means a lot of lost potential...

Therefore will excavate garden somewhat, for comfort.

Then will build the collector in two halves - upper and lower, each nominally 1500 tall.

For assembly, the top half is inserted as far as possible into the glove slots, then temporarily locked in place, until the lower half is soldered up.

Then the lower half is inserted some, until the top is in abutment.
This leaves the major part of the lower half exposed by approx. one meter.

The pipe connections are then made to the thru-wall stub fittings into the basement, using flexible hose.

The exposed part of the manifold is then covered over with an add-on structure built to resemble the existing slate facade.

So at the end of the day, I gain an extra 1.8 sq.meters of slate collector !

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  #8 
It's been a long time... How is it coming along?
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Willie, Tampa Bay
Garage_Hermit

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Reply with quote  #9 
Hi, Willie !

Still in the planning / standby phase !

This VSF is one component of my full system -- based on using my crawlspace as a  heat store...

So it's the CS dig-out that's getting all my attentions at the moment - rather a long & heavy job, but progressing...
(I am intending installing my floor datum point this very evening !).

For my morale, I occasionally check the facade temps : today is 18°C Ambient (= 64°F) and the facade internal temp is 42°C (107°F) - not bad for 7/10ths stratocumulus with bright sun between...

http://www.google.fr/imgres?imgurl=http://eo.ucar.edu/webweather/images/cloudchart.gif&imgrefurl=http://eo.ucar.edu/webweather/cloud3.html&h=352&w=504&tbnid=IoPj4RaGCnbckM:&zoom=1&tbnh=118&tbnw=169&usg=__i9MomPYfN3K5To3L9N18BkwWu3M=&docid=mW51DXr3amL99M&client=firefox-a&sa=X&ei=tO9MVJS-OoWqPKffgdAB&ved=0CCUQ9QEwAA&dur=3016


[cool]
Otherwise, our recent discussion about a FP HEX for your Aretha, had me thinking about trying one for my facade...
I would need a flattish one, as Idon't have much space to play with.

Per a recent Mattie LINKS  posting about coil calculator, I should need 1.5 sq.ft of exchange area, to warm one of my tanks (I am planning on having three).


It's all go, otherwise, even if I don't post as much as I'd like to, try & get some photos posted this evening !

Best regards,

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  #10 
To be honest, I think trying to get a heat exchanger into that void looks like a lot of work. Why not bring the heat to the HEX instead? I'm thinking shove a length of pvc sewer pipe up there and suck the hot air out with a fan. Run it through the HEX of your choice, and return the (still warm) air to the void space with another piece of sewer pipe, to be reheated. Just a thought.
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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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