Mini-excavator for geotherm trenching, need recommendations!

[toolnut]

Hi all,

I have a small landscape business and want to "experiment" a little with doing geothermal loop installs as a sideline. I'm planning on starting on my house first, to get a better idea of time and problems involved. Basically I need to trench between 6 and 8 ft deep, 18 - 24 inches wide. A typical job would involve at least 600 ft of trench. We have a compact NH tractor (33TC), but rather than invest in a BH, I'm thinking that an used mini-excuvator would be the right tool.

OK, so now the questions... Minimum size machine that folks would recommend? I'd like to keep it as small as possible to get started, under 5000 lbs if feasiable. Soil conditions are mostly shale (I've only dug footings to 4 ft or so, not too bad that deep). If I hit a big rock I'll just have to stay above it or go around. I know a smaller machine will be slow, but I have a lot of learning to do, and I'd rather scale up later if this works out.

Any specific things to watch out for? I've checked out the auctions, and it seems feasiable to get a useable machine in the 10k range, basically my budget.

Rubber or steel tracks? From what I've read, steel is actually easier on the lawn (if you're gentle on the turns). I do plan on having to work in established yards (starting with my own...

And finally, any comments on specific brands? I'm OK with a wrench, so main consideration is probobly parts availability. From what I have seen, older Yanmar's and Takeuchi's are common and priced right, but I really have no experience with this type of equipment.

thanks in advance for your comments...

Craig

 

[Botabill]

I have a new KX41-3 Kubota that would do the job you are talking about quite nicely in my soil (Hard clay with lots of rocks). I can't say how it would behave in shale though. The KX41 is a 2 ton machine with rubber tracks. The rubber tracks are better if you have any travel to do on concrete or pavement. This machine also has tracks that can expand or contract to get into narrow areas. As far as ruts in lawns are concerned it is more the way you drive than what type of track you have. I would suggest you rent a machine and try it out.

 

[Birdhunter1]

I wouldn't wory about cutting up the yard too much, a few months after you're done there gonna have to do some grading work anyway when the trenches start to settle.
Get a machine that will dig into the 9'-10' range instead of 8' as the max.

 

[jgh]

20060807

With your uncertainty about the shale, etc, definitely try out in depth (NPIntended) b4 buying, as it is not that hard to max out a 5K machine. Frankly based on the experience I have with my Bobcat 430 (about 8500 with my new cwt tail), I would not recommend anything lighter for the job you describe. You did not fill out your profile so I don't know your geography, but the size trench you describe is far more than GT HVAC folks do here, being more like 4-5 ft deep and not quite so wide.

Not meaning to be nothing but negative, just helpful, and hope I have been,

Jim Hardwick

 

[toolnut]

Thanks all... I appreciate your comments, yes, I'm not sure about the optimal trench profile, there are different trenching/slinky layouts depending on soil conditions, etc. I really should probobly rent first, but I'm assuming it will take me a few days just get reasonably proficient with the machine... then the "experiments" will start with different trench configuretions, etc. It's the kind of project that will take me a month of "spare" time at least.

-Craig

 

[plowrup]

You might want to look at the John Deere 35 ZTS Series-

 

[jgh]

20060808

I believe Deere's OEM is Hitachi, which local teacher in heavy equipment says is not high on his list, but YMMV.

The wt on that one is about the same as mine and I would definitely stick with zero house swing like that one and mine (Bobcat 430). If not for ZHS the rear on mine would not be nearly as factory fresh. Think about how many Bobcat and other small trackhoes you have seen with war-zone-looking rears. And think about what they hit each time a scrape went on there!

But let me also point out that ZHS impacts capacity since it compromises the counterwt effect. I added a big bulky cwt which has left me with better capacity but a tail door that has to be slammed hard and leaned against hard to open. Win some lose some.

Again, if it does turn out that you have to dig 8 ft and wide trenches all the time, I would seriously consider a heavier model provided transport wt is not an issue. I would not want to use mine all day long for such deep and heavy digging. Day does not pass that I do not wish for something like a Cat 330 for some jobs!! Only divorce and financial ruin stands in the way.

Have you spoken to other contractors doing these installs? I know Albemarle Heating & Air in Charlottesville VA has done this, could ask for you. Owner and his son hunt our property.

J-

 

[toolnut]

Thanks J, I've asked around a bit, but to be honest there is not much geothermal activity around here right now, which is kinda surprising considering the price of oil. It seems there were a number of closed loop geothermal heat pumps installed around here in the early 90's, and they didn't live up to expectations. Of course...heating oil was 25 to 50 cents a gal also!

Anyways, I've been researching trenchers as another option. If I could get to say 5-6 ft (and say 6" wide...) I could install one run of pipe at the bottom of the trench, of course you would need more linear ft, probobly twice that compared to putting slinky pipe in bottom of wider trench. All part of the experiment.... does anyone have any experince with trenchers?

-Craig

 

[Teabagger]

kubota kx91 would do the job nicely. its not to small but not to big. hope this helps.

 

[sandman2234]

No experience with excavators, but from a homeowners point of view...

Rubber tires, simply because anyone that is going to let you dig up their backyard, realizes you will tear up the grass. Most of them don't want to pour concrete when you have to drive over their sidewalk or driveway and it tears the concrete up.
Smaller not only transports easier, but what about getting between the house and the garage, or that huge old tree you better not kill, etc. Too small and it eats up the profits with extra time.
Have you done your homework with the geothermal people? If it isn't working right, it won't matter how good the explanation is, your going to have problems with the word of mouth putting you in hot water.
Good luck,
David from jax