Dodeca Domes

[Paul Kranz]

https://dodecadomes.com/photo-gallery 

Paul sends...

[Dx G]

Paul,

 Thanks for posting.  The PentDod has been overlooked for a long time, and has a lot of advantages for a small structure. Not only are all the panels all the same size, but all the dihedral angles are the same.  This really helps at fabrication time.  I don't see it on the radar screen on this site, but its also a good candidate for the creased diamond panel domes I've been working on.

 One thing I did not see on the site was any mention of venting for the wall cavities or home interior.  There have been a surprising number of dome failures due to the incorrect assumption that there was no need to design for this, as "air tight" does not eliminate moisture trapped inside nor stop condensation.

  There are a few dead links on that site that are not working on my end.  As is so often the case, they have a "contact" button that does not work. I keep beating web designers over the head about this. If there is a phone number or email address on the site, one can at least report it, but Duh, how to you contact a site about a bad contact button when the contact button is the fault?  It reminds me of the insurance company that sent a letter to a policy holder to inform them their coverage was being cancelled because they did not have an address for them. Duh, again.  What did they used to say? To err is human, to really foul up, you need a computer.   Sure, I like them too, but to have an entire web site, with a lot of really well done pages...and not one place anywhere on the site for a phone number, surface address, email address, nothing? Really. Well, if its there, and I missed it, please advise.

thx

Dx G

On Wednesday, October 16, 2024 at 9:55:23 AM UTC-5 Paul Kranz wrote:

https://dodecadomes.com/photo-gallery 

Paul sends...

[Robert Clark]

I think ideally, dome walls should be filled with spray foam or constructed from Structural Insulated Panels (SIPs) to eliminate any moisture condensation and mildew rot within the walls.  Also, install a through wall ventilation system with a ceramic regenerative heat exchanger to ventilate the interior of the home.  Lunos of Canada sells thru-wall HRV units that I have installed in my SIP clad home.

[Dx G]

Robert,

 Looks like a very interesting option.  I took a quick look at the heat recovery models, but didn't see any provision to handle the condensation moisture issues normally expected with warm air on one side.  I'll look further.  What do those things cost?

With respect to the foam, there are dozens of web sites and youtubes about managing the moisture with spray foam.  Its probably the usual problem, spraying looks easy and a lot of applicators don't do it right, which results in moisture/mold/rot problems.  Rather like those who say domes leak. Same issue.

thx Dx G

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[Robert Clark]

Just the fact that you are exchanging air inside with fresh air from outside is going to take care of almost all condensation or humidity problems.  The heat exchangers are sold in pairs. They act like lungs for your dwelling. One unit will pull in air from the outside while the other unit will expel air.  The two units alternate air flow direction every one minute.  It is recommended to place them on opposite sides of a living space.  They are installed by drilling a 6-inch diameter hole through an exterior wall, at about 1-foot below ceiling height.  They are very quiet. I never hear them running. The ceramic core acts as the heat exchanger.  It captures the heat of the air being expelled to the colder outdoors.  Then, when the air flow switches direction, the incoming cold air from outside absorbs the residual warmth from the ceramic core and is heated before entering into the home. They are supposed to be 85%-90% efficient.  I purchased two pair six years ago.  At that time, they were $1000 USD for one pair.  Now the price is about $1600 USD for a pair.  One of the advantages of this type of heat recovery ventilation system is that you do not have to run air ducts throughout the house.

[Dx G]

Robert,

 Thanks for the background.  However, there must be some way they deal with moisture. Maybe they heat up and burn it off.  Without something like that, the warm air on the output side will hit a cold surface bringing in the outside air.  That's how it warms up the incoming cold air. Where I live, that incoming air could be 25 below zero, while the outgoing air is well above 60.  Since that outgoing air is warm, it can hold a lot more water than the same volume of cold air.  So you get water on those cold surfaces that has to go somewhere, and it can be gallons per day (empty any dehumidifier, and you will see how big the collection buckets are.)    So if these are true heat exchangers, there must be something in the system addressing condensation...

Dx G 

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[Levente Likhanecz]

hi,
i have i very bad ventillation path layout through my home resulting condensation at certain pozitions (the walls made of cored bricks like attached pic).
https://www.amazon.com/Dehumidifiers-Made-USA/s?k=Dehumidifiers+Made+in+USA
these heatpump based dehumidifiers (i have several pieces, multifloor) works like a charm.
the airco inside consumes 300-500W (capacity depend), and it takes out water from the air, higher the temp in your rooms, more efficient removal.
cheers, lev 

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[Blair Wolfram]

To all you guys with advanced mechanical solutions for condensation issues, the moisture is coming from some source and almost always it's the shower and the stove. Simply close the bathroom door and continously run an exhaust fan for 20 minutes after you shower.

The moisture isn't magically created because you're in a dome.

Blair

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[Levente Likhanecz]

hi blair,

unfortunately humans are water based mechanics.

an average adult breaths out half a liter of water a day into the air.

lev

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[Robert Clark]

I live in a small timber frame home clad on the outside with SIP panels. It is extremely air-tight. The first year I lived there, I had not yet installed the HRV units. The timber frame structure was still new and had high water content.  I had a lot of humidity problems inside my home that winter.  I would resort to cracking open some windows during the day and running a portable dehumidifier.  The next winter, I had the Lunos HRV units installed and the humidity problems all went away.  I live up in Massachusetts.  The winters aren't quite as harsh as Minnesota or Canada, but it does get cold.  Like Blair said, most of the indoor humidity comes from hot showers and cooking, also just humans breathing.  The simple solution is just getting fresh air into the house, but without losing the heat.  These Lunos HRV units do that.  I know, I've been using them for more than five years.  I usually turn it off during the summers because I have windows open.

Rob 

[Blair Wolfram]

So we agree this condensation issue has nothing to do with domes, although we disagree on the source of the water vapor

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[Dx G]

lev,

Thanks for the lead. The poroblock is interesting.  We have dozens of models of dehumidifiers here also, and they do take water out of the air. However, the main difference with an exchanger like Robert shows us is it brings in outside air, and warms it with the outgoing air, which has additional benefits. Anyone can open a window in the middle of winter and get the same thing, but your energy cost will increase. The heat exchanger transfers the heat of the warm outgoing air,  and transfers it to the cold incoming air to reduce the cost of reheating the cold incoming air.  This is done without the two air streams ever mixing. So, for example, if the outgoing air was full of smoke for some reason, the warmed incoming air would be smoke free.  This is the special benefit of a heat exchanger over other forms of humidification and ventilation.

Dx G

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[Dx G]

Several issues here:

1) Sources of moisture in homes

Yes, lots of them inside the house - showers, water from stove (both open flames and cooking), even leaky pipes, human secretion, etc.  Many others overlooked, such as damp basement.   Information on this has been studied, measured and published.  No need to debate the issue. 

2) Moisture in walls.  

These also escape notice. Roof leaks that go directly into walls.  Inadequate vapor barrier on the inside of walls and lack of house wrap on outside. Many more on this list.

In winter, warm air leaks out of the house, carrying suspended water vapor.  Ideally it disappears into the outside air, like a properly installed bathroom fan does.  Worse case, that moisture laden warm air makes contact with a cold surface and forms condensation (water droplets) or even frost when its real cold, which melts later.  This can rot inside walls, under siding and place nobody notices until you get odors, mold, even structural failure in serious cases. 

Here is the point I raised.  

A heat recovery ventilator (HRV) has a warm air stream, with suspended moisture, making contact with a cold surface. This is how the heat transfers without the warm air mixing with the cold air.  So one could get condensation or even frost on that surface, and some HRVs can even clog shut and fail due to the frost build up.  Many have a drain for the water, or even a defroster, to prevent that problem.

So, I was just wondering how the unit the Robert showed us handles that issue.  Likely they have a resistance heater or some system to do to it, I just don't see that yet.  More importantly, if they have some novel system of doing that, I wanted to learn about it. 

Hope that helps....

Dx G

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[Robert Clark]

I think the Lunos HRV handles the issue of moisture and frost build up by reversing air direction after just one minute.  I have never experienced any of these problems.  Actually, I hadn't really given it much thought till now.  It just does what it needs to do in a very simple manner.  It consists of only the ceramic core and an electric fan sitting right in front.  The fan has blades shaped to work in both directions.  It runs off 20V.  There is no heating element.  Just the ceramic core and the fan.

[Eric Marceau]

When moved into my first home, 30 years ago, I discovered that my furnace's heat exchanger was a large cube with 2-feet on each edge.

Inside, the construction was panels such as these,

tightly-packed or heat-welded, with the channels of alternating sheets being at 90 degrees to each other, giving half of the channels for one "stream", and the other half for the other stream.

The opening on one face provided the air intake from outside, feeding the house and furnace.

The opening on another face at 90 degrees provided the purging of internal air to the outside, taking with it some of the humidity.  

The remaining humidity dripped out of the unit, which was aligned such that the line thru diagonally opposite corners of the cube was vertical, giving the sheets a natural slope for drainage of humidity to a single drains spout, at the bottom apex of the cube.  🙂

Thought that might inspire some of the more adventurous in the community.

Eric

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[Levente Likhanecz]

in evaporative coolers i've seen these polycarbonate chambered panels.
there was some experimental result, that the channels must be around 5 mm high for effective heat transfer.
something about border layers, whatsoever.
it is common, to use them in dry heat recovery / exchangers.

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