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HauteGaronne

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Posts: 9
Reply with quote  #1 
Thank you for all inspiration on this forum.
I have spent many hours here getting up to speed and feel that I am now ready to embark on my first build.
I need to have the inlet and outlet at the same end of the collector so I am thinking about a U shaped downspout collector.
However I am having trouble finding those rectangular aluminium downspouts which everyone in the US seems to have used. I am based at the foot of the Pyrenees mountains in the south of France.
We have round zinc downspouts readily available here with 8 or 10 cm (3.15-3.94 inches) diameter. 
They probably have more mass than the aluminium downspouts but would they still be ok? 



gbwillson

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Reply with quote  #2 
Welcome HauteGaronne!

Having both inlet and outlet at the same end can be problematic. Will the unit be directly attached to the home? If so, a U-shaped collector is a good choice. However, if the unit will be placed either next to, or in front of the home, you can build units with duct ports at BOTH ends. You simply need to route the duct(s) to the home. My collectors sit next to my home and I route both ducts into the same window. 

Steel or galvanized downspouts are generally thicker and won't transfer heat as well as aluminum downspouts. You might look as using insect screen or mesh instead. It's cheaper, lighter and makes for an easier build than downspouts. It's also very effective in almost any size and configuration. And if you are a glutton for punishment, you could consider using aluminum beer cans. With cans you can make thin aluminum tubes for almost no cost. But it is very labor intensive as you have to drink(I know, tough work), wash, cut, and glue the cans together. 

Greg in MN
HauteGaronne

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Posts: 9
Reply with quote  #3 
Thanks Greg for your reply, 
It will be attached straight to the wall of the house for aesthetic reasons.
I have been choosing between downspouts or Zero Pass collectors. The reason I am leaning towards downspouts is that I have not yet seen a successful turnaround/U-shaped ZP, while there are a couple of successful downspout collectors. 
If anyone has made a successful Turnaround ZP build then please let me know the details.

I am also struggling to find a polyiso substitute here. The closest I have found is this chimney protection:
https://www.leroymerlin.fr/v3/p/produits/panneau-en-laine-de-roche-firerock-rockwool-1x0-60m-ep-30mm-r-0-7-e164808
My French is almost non-existing but Google Translate does a good job in describing it as: "Rigid rock wool panel with reflective aluminium vapour barrier, reinforced thermal insulation of chimney hoods". It is 30 mm thick.

Are there any other French/European builders out there who can suggest good substitutes?

/Andreas
gbwillson

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Reply with quote  #4 
Andreas-

A few ZP-style collectors have been built where the path of the air returns to the same end as it started. There has also been some where the path of the air snakes around to a different location than where entered the collector box. The ZP is a very flexible design. The biggest issue with a ZP build is that it usually needs a LOT of airflow in order to keep the temps moderate so you don't waste heat through the glazing. Having a higher speed and volume of air will also help keep the air between the layers of screen and away from the glazing.

The coated rock wool insulation you linked looks fine to use. Just be sure to seal it completely so none of the rock wool fibers can enter the air stream. I wouldn't want to breath it. It should be fine once it's installed against the house.

What is the size and shape of the collector you where planning on building?

Greg in Minnesota
HauteGaronne

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Posts: 9
Reply with quote  #5 
I am looking at a 1 x 2 m (3.2 x 6.5 feet) collector as this is the only twin-wall size I can find.

I have already bought this fan:
https://www.amazon.co.uk/Blauberg-UK-TURBO-125-Turbo-Extractor/dp/B01M10DGCU
I hope it will up to the job

It will be used to heat up a non-heated garage section of my ancient house. This is just a trial to see whether it will be worthwhile to make a bigger collector later connected to the living areas. That would involve making holes through the walls and as they are 4 feet thick stone walls I want to make sure first that it is worth it.
The garage has a small window which I will use. I will do a lot of data logging to see which temperature gains I will get.

Do you remember the names of any documented successful ZP turnaround builders so I can search for them here on the forum?

Is it ok to use normal silver duct tape in collectors to seal up the rockwool? Ie, can it stand the high temps?

Thank you for all your help to me and others!

gbwillson

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Reply with quote  #6 
HG-

The small size of the unit you will be building will be limited to heating a small room, but not much more. It will, however, help you see the benefits of solar heating. The size of the glazing pieces shouldn't limit the build size. My collectors have more than one piece of glazing. Glazing manufacturers often sell parts to join two or more sections together. Or you can design a way to seal the butt-joints.

4 foot thick stone walls? Sounds more like a castle ready for a siege. But I can understand the desire not to put holes in the stone wall without careful thought. The tape often used is not what traditionally called duct tape, which has a plastic surface and uses a rubber-based adhesive. Tape made of aluminum foil is preferred. It has a strong, usually acrylic-based adhesive and can handle the heat with no problem.

The mixed-flow fan you purchased is a great fan, but a bit too powerful for the size of the small collector you plan for your test unit. This can be easily remedied by adding a speed control to slow it down, if needed. But hold off on adding any speed control until you get things up and running, as your collector/ducting may end up needing such fan capacity if you make a larger unit or have long duct or winding duct runs.

Here is a link to the most recent ZP-style collector(s) that aren't linear. Jake built two of them. I don't recall the names of the other non-linear builds, but there are a few. You could try a search using ZP as the search parameter.

Be sure to check out the link to his site where he logs the data for the two units. Very interesting, to say the least. 
http://simplysolar.supporttopics.com/post/jakes-solar-north-of-50-9446061?&trail=10



Greg in MN
HauteGaronne

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Posts: 9
Reply with quote  #7 
As my proposed size is only 20% less than the common 3x8 foot I had hoped that it would heat more than a small room.

I think I know which tape you are talking about. Is it used for chimney joints?

Thanks for the link to Jake's build. Interesting reading indeed
HauteGaronne

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Posts: 9
Reply with quote  #8 
You are right that my proposed unit is quite small. I might double the size straight away. The intake window has bars restricting the size of the ducting to 4 inch. I might have to use 2 inputs and 2 outputs if I double the size of the collector.

I think I know which tape you mean. It can be used to seal chimney tube joints right?

Thanks for the link to Jake's build. Very interesting indeed.
gbwillson

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Reply with quote  #9 
Just to be sure you have the correct tape:
https://www.menards.com/main/heating-cooling/ductwork/ductwork-accessories/intertape-polymer-group-aluminum-foil-tape-2-x-50-yd/p-1444436063246-c-1455981638766.htm?tid=2237643660227122999&ipos=4

You don't need the expensive tape. It's thicker foil and is rated for higher application temps. You'll also likely need 100% silicone in a caulking tube. You can't paint silicone, so it is one of the last things to do on a collector box.

To give you an idea of the output you can expect at a given collector size, a basic 32sf 2-screen collector in full sun will give you roughly the same BTU output as a 5,000 watt electric heater. In most cases, if you double the square footage, you double the BTU output. The ZP being the exception as it produces quite a bit more heat at larger sizes, but it also needs much more airflow to run efficiently. How large is the area you are trying to heat, and is it insulated?

Greg in MN


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