earth tube drain freezing

We're building an ICF (insulated concrete forms), off-grid house, designed to be passive solar (full south exposure on a hill). We're using an earth tube (made with 5 pieces of 20', 8'' HDPE culvert pipe) with our HRV unit. The very end of the tube is capped, with a little drilled hole to drain condensation water. The air intake is a ~ 5.5' long PVC pipe, sticking straight up about 1' prior to the cap. There were several f-ups during the installation - we were under the impression the builder would only dig the trench for the tube, and we'd be able to spend time sealing the pieces properly prior to back-filling. Instead, we came to a fully buried tube one day. There was NOT much rejoicing (https://www.youtube.com/watch?v=yciX2meIkXI).

Our soil is very clay-based and is SOAKING wet for months now. As in - we're on a little hill (~ 15 feet from the house to the bottom of the hill); the hill side has little springs coming out of its entire side. We know there's a fair bit of water going out of that earth tube, most likely water that is coming in through the seams between the tube pieces. I've been kicking myself for not going with PVC (due to toxicity concerns), since glued PVC would likely not have this issue, but hindsight is always 20/20. In the spring, we're planning to put a diverting ditch above the tube to reduce water logging and also unearth the tube and re-seal it.

In the meantime (here's my actual, pressing issue) we've had fairly cold weather (almost -20C a few nights in a row) and the bottom part of the tube (from the cap and the drainage hole and at least up to the air intake spot) is completely filled with ice, so our HRV air intake was completely busted. Yesterday we put a bunch of epsom salts and hot water down the air intake to thaw some of it out. It somewhat worked, but I'm guessing only till next time. This is only the beginning of our winter, so we really need to find a good way to keep it from freezing in the next 3-4 months, until we can fix 'er up for good. Right now it's covered with styrofoam, but that's hardly going to do anything. Any ideas??

I am not sure if this is a "self build" or a contracted job, but it sounds like there maybe a number of challenges that did not get properly designed and or addressed. Before even starting this type of project I would have:

1. Completed at least a cursory hydronic and soils survey of the building site, referencing and list clay types, depths, bentonites present, expansion rates, local soils angle of repose, etc.

2. Both CAD and physical modeling of this type of fossorial architecture is warranted to properly plan for drainage.

3. We do not use ICF as there are to many challenges with them in the builds and future issues, some work, many do not, and there are other natural methods (as well as commercial) that are more sustainably manufactured and designed...

The above is what I would have suggested to a client on the short list of what I would recommend have taken place first...

As for the current challenge, the pipe needs to be taken up, properly sealed and the trench it is placed in needs to have been designed and excavated properly with the correct slope and gravel drainage backfilled...not clay soils...

Regards,

j

salt, hot water, and a bilge pump are pretty much your options until a good thaw. IF you can get the intake end dug out, you can add a drywell to take some of the moisture. This problem is why many suggest the pipes slope TOWARD the house, so the drain sump is inside heated space.

IF IT WERE ME, I would shut down the HRV until you can do the corrections and fire up (or install) a wood stove for this year.

Sounds like an impossible setup to clean too. Earthtubes are prone to having toxic bio growth on the interior surfaces of the tube. Cant you abandon it for now (preferably for good) and just draw in outdoor air thats not through the earth tube?

Well...I keep coming back to this post because I am so frustrated with my first post here...I don't like sounding "negative" to folks trying to build naturally...So I apologize for that if I do...

Now...to my chagrin...Brian Knight has joined in, and yet again I feel even more unsupportive as I must really agree strongly with his points...!!

I really love natural and traditional building, yet when these "new age" designs try to take traditional or ancient concepts and "reinvent them" inevitably...well...it usually gets all screwed up...BIG TIME. The concept behind ET or “Earth Air Heat Exchangers” (EAHX) is awesome and founded on some vernacular concepts...Unfortunately I see very few that are:

1. Well researched for the area they are employed...

2.. Well designed.

3. Well modeled and tested.

I could keep writing for some several long and technical paragraphs, but suffice it to say, if what I have suggested thus far hasn't been done...(plus more I haven't even gotten into) then I would cap these until weather permits redoing them properly...

Sorry to be such a stick in the mud on this one...

Thanks for all your replies! Jay C. White Cloud, I'm not sure if I should say that you should never move to New Brunswick, as you'd be horrified at the level of 'swinging it', or if should should move permanently, so that we finally have some decent, cross-your-ts and dot-your-is type people. The whole house (walls, roof, floor, rough-in plumbing) was done by a builder, a pretty decent one too, which is terrible, considering that, for example, our vapour barrier got torn to shreds, the vapour barrier holes for the chimney and radon pipe never got taped, infloor heating pipes were placed completely off what we wanted, etc...

The earth tube toxic gick concerns seem to stem from either tubes with not enough slope or tubes corrugated on the inside. Prior to deciding on it, we talked to the director of Canadian Passivhaus Institute, who has one installed at his house and is happy with it. The main reason we went with it is that the HRV would require too much electricity to pre-heat the air, if we didn't have the tube in place. Being off-grid, we couldn't afford that. The pipe can be cleaned by putting vinegar (or soapy water or bleach, if you're into that) down the pipe every now and again.

Freezing-wise, the salt and hot water (and mild day a couple of days ago) did the trick for now. We do have a wood stove, but with what is supposedly a fairly tight house (we did tape the living crap out of that vapour barrier!), lack of fresh air becomes a concern after a while.

I'll keep in mind all the good advice for when we unearth the damn thing and dry to make things right...

Youve taken the criticism very well and we really hope you stick around to tell us more about your project and how it performs over time. Other folks are sure to benefit from your research and postings.

In such a cold climate, I would probably be attempting the same thing with the HRV, earthtube intake but I would be prepared to abandon it too. I dont think your solution of pouring stuff into the adequately sloped tube is enough to solve the main problems with them.

Humid air can condense moisture on the entire surface of interior walls of the tube, not just the bottom. Dust and pollen will stick to this moisture and provide the foundation for the concerning lifeforms that put the air supply at risk. Pouring stuff into the tube will not address the sides and top of the tube.

The only way to properly clean the interior surfaces is to mechanically remove it. This means a pig, plug or brushes that you can pull through the tube to clean the entire inside. When you rebuild the earthtube, it would be wise to provide a means of doing this.

Curious if the passivehouse facilitator did anything similar and be aware that it could take several years for the interior earthtube problems to become apparent.

I second Brian's advice and too thank you for sharing your project with us and hope you continue to.

As any that read my posts on "natural building" and traditional methods I am not a fan of modernity, and practice traditional/natural methods whenever possible for architecture...

However...I am also a professional builder with 40 years of experience and understand well the different realities that can take place on many building projects today. Mixing modern methods with traditional/natural is not easy to achieve...nor good practice if the facilitators are not well versed in both modalities. As Brian can contest to...today the market is flooded with "experimental and theoretical" systems, like ET technology. This just has not been around long enough to understand fully and the research is limited at best. Can it be done well...perhaps. I would never design a system however that was not complete backed up by at least two others and fully capable of augmenting these systems easily and also there servicing should be of little effort. If they are not designed this way...well...they are simply wrong.

Because this project also has so many modern building elements (ICF, et al.) I would also...very much...look into a HRV system or a similar form and understand it well and how it works. This structure by its nature is going to be "air tight" (and I don't like air tight) but if that is the design...It must be fully incorporated in the way these systems are meant to work...that means air filtration with hepa filters and Heat Recovery Ventilation, and back up systems...

Regards,

j

Hi, I am looking to Build an earthship in the STL MO area out in the MO Bottom area 63114. I want to do earthtubing as my heating/cooling. The house will be 2400 sq ft (2 stories). I was thinking of using 4" or 8" x 20 ft. SDR17 HDPE Pipe (High Density Polyethylene Pipe). For heating I was going to use a cast iron stove and a fireplace as well. For the cooling I was going to use a dehumidifier to help with moisture in the tubing. From what I understand, a dehumidifier is essentially an air conditioner as well. I have been reading into your forums for little tips and tricks for actually installing the piping. What I was more so curious about was how many feet deep should I go into the ground? How many feet of pipe would be ideal to use. Is the soil in that area good for what I am trying to do? Is this ideal for MO area? Would it actually make a significant difference?

Hi Gabe...

Its late...so I apologize for the short reply...

I would start my own post thread...and then ask these questions. That way we don't confuse this conversation...

With Earth Tubes...sorry to say...if not a professional builder, and not able to answer or already know the answers to these questions suggest to me not to use this system...or at least not with out a designer with at least 20 years experience (and success.) It is very experimental with lots of "bugs" to work out before really understanding. Yes it can be done...it is not easy...

We look forward to you starting another post about your project....

Thanks for your support, Brian and Jay. Yes, the Passivhaus facilitator strongly suggested we string a rope through the pipe as we put it in (which we did), so we do have a means of taking a sponge or rag through the pipe. We do have an alternative air intake, straight through the attic wall, and we can use that, capping and bypassing the earth tube. But that, of course, means colder air in the HRV. We do plan on measuring the intake air temp, just to compare to outside air - the pipe isn't as deep as we would've liked, so we have been curious about how much it tempers the temps.

Jay, I'm all for natural buildings and highly experienced builders. Problem is, neither was available to us. Doing quick math, we decided that ICF was harder to screw up than a regular construction, and that a builder would be less likely to mess up than if we did it ourselves. If we had people available to us, we would've snatched them in no time. As it was, the decision was to either spend 40 years to learn how to build a proper home ourselves, or do as best as we could under the circumstances. And yes, we do have a proper HRV unit, filters and all. That's what the earth tube plugs into.

So far had to dump another couple of buckets of hot water into the pipe after a ~-25C night. A crude and annoyingly repetitive solution, but it seems to work for now. Waiting for spring to come

Would it be possible to use a UV light to sterilize anything that would pass through the intake?

Glad to read you are progressing along with the challenges S Usvy ,

I feel for your frustration, sincerely. Often I am called..."after the fact," and I feel so bad for folks. They, like you, try there very best to make the best decisions yet many in this field of construction still let them down...

I think you have done grad "plowing with the horses you have...instead of the ones you don't." We are here behind you should you need any guidance or just want to bounce and idea of someone.

Regards,

j

Hi; First post at Permies;

We built a house in 1980 with an Earth Tube.. a brilliant (and ancient) concept, and it was off to a fine start, but had some key errors that required addressing.. and before we could do it there was a divorce and several graduations and relocations.. ah well! Just the same, I feel that the energy available from the ground a scant few feet beneath our feet is far too great to ignore or shrug off. It does, however, require a renewed attention to the engineering realities that have been brought up.

Key to all this for me is that we make a very similar mistake with all our household mechanical systems, and build them into the house-system with 'nails, glue and rivets', so to speak, as if they were permanent fixtures not requiring the kind of modular accessibility that we take for granted in our cars and our computers. I want all the moving parts and the flows in my house attached with screws or bolts, and routed through dedicated mechanical access channels which will allow me and future owners to inspect, maintain, repair and replace these vital conduits whenever necessary via access hatches, not with shovels and jackhammers. I don't pretend that moving our current design expectations to such a standard would be easy, quick or cheap.. but I do think that this goal is well worth moving towards, and every step I take on that route has convinced me that it is.

I do appreciate the ancient wisdom that we've inherited with classic building tools and materials.. but with Plumbing, Air Handling, Electricity, Communications and Heating/Cooling Systems, there is just too much tech development and system maintenance involved to bury these things 'permanently' behind plaster or under a slab. With so many of our energy and mechanical systems, we have hidden and shushed everything like they were back in the servants passages of the old days, and tried to live like these tools and forces ('energy slaves'.. as sometimes described) were best kept invisible and inaudible, hardly touching our awareness, at best.

Sorry for the soapboxing.. but the point for me with this topic is that these earth-tubes should be re-installed and rethought a bit, basically as others have said, with an eye towards that accessibility (and with the micro tech we have now, 'pipe pigs' for cleaning isn't a bad idea, really.).. and the proper designing of drainage, and I'd say a good bit more surface area/air-volume, within soils that you can also Insulate to whatever degree is possible, but without sacrificing a good thermal mass of soils in the process. Yes, it would be a 'lot', a helluva lot even.. and will certainly be called out as uneconomical under conventional building cost expectations.. but I think the long-term value of such a system would regain all of the investment, as big a hump as it would be to hurdle initially.

Lawton's video on the greenhouse in Canada, which put their Annual Geothermal EarthTubes right under the core of the slab makes great sense to me, while that system also reheats the soils in the summertime with the solar gain of the greenhouse as well... ideally I would just have also kept an access hole at each end of the tube-trench, if not made a cellar trench that ran alongside these pipes, in order to be able to access this key mechanical system into the future. As with many renewable type systems, the startup costs might seem simply ridiculous to consider.. but taking the longest view you can, thinking of 'redigging' .. as you now must weigh into your own plans.. and similar barriers to fixing and improving an installed system, I have to suggest that it would be the right thing to work towards, no matter what today's beancounters will say.