Geothermal heat pump install with crawlspace encapsulation

[buckeyefarmer]

My design came out to 500' per ton which created a 62' slinky. I have an extra 100' each way to get to where the slinky is buried, so I actually have 200' straight into a 500' slinky, per ton. The design software lets you easily change type of loop, and it automatically calculates it for you. you use less total pipe for straight loops, but you dig a lot of trench. A slinky uses just a little bit more pipe, but pipe is cheap, and the digging for slinkies is much much less.

 

[BobRip]

My design came out to 500' per ton which created a 62' slinky. I have an extra 100' each way to get to where the slinky is buried, so I actually have 200' straight into a 500' slinky, per ton. The design software lets you easily change type of loop, and it automatically calculates it for you. you use less total pipe for straight loops, but you dig a lot of trench. A slinky uses just a little bit more pipe, but pipe is cheap, and the digging for slinkies is much much less.

My builder had a time getting all of the air out of a slinky (not at my house). He had to bring in temporary bigger pumps to push all the air out.

 

[cre10]

My builder had a time getting all of the air out of a slinky (not at my house). He had to bring in temporary bigger pumps to push all the air out.

That's normal with loops with an underground manifold. On commercial jobs large pump trucks have to be used to purge and fill them. If you do an inside manifold with a non-pressurized flow center then you can purge and fill your loop field using the standard system's circulating pumps.

 

[cre10]

My design came out to 500' per ton which created a 62' slinky. I have an extra 100' each way to get to where the slinky is buried, so I actually have 200' straight into a 500' slinky, per ton. The design software lets you easily change type of loop, and it automatically calculates it for you. you use less total pipe for straight loops, but you dig a lot of trench. A slinky uses just a little bit more pipe, but pipe is cheap, and the digging for slinkies is much much less.

Some of the design software can be a little scary. Engineers and software designers can be brilliant in certain areas and naive in others. Quality contractors typically know what works and what does not in the area for feet of pipe per ton. Homeowners should never be afraid to ask the contractor for references on previous jobs. It never hurts to have extra pipe in the ground. I would error on extra pipe than too little especially for super cold or super hot summers that aren't normal. The larger the loop the better water temperatures you will have which will save you more money on operating costs. Extra pipe within reason won't hurt with pumping efficiencies and Reynold's numbers.

 

[tkappeler]

Sorry if this seems like a hijack and I do not mean it to. I am enjoying this thread as I want to consider geothermal in a year or two. Wells would be most likely given the amount of trees we have. Has anyone heard about Agreenability's Twister piping? They claim that you get more BTU exchange per hole due to 4 loops in a single bore, thereby cutting down on the number of well holes needed.

I have no stake in the company. I am interested as 3 wells 300' are about $6,000. If I could cut down on the number or depth, it would be a savings. Of course, if the pipe is that much more, it could easily offset the well savings.

 

[MacLawn]

That twisted pipe stuff looks good Tom! I've never heard of it, so in a few years when I plan to install geothermal, I'll show it to my installer. This is not an easy decision!

 

[Redneck in training]

Wow, red, I wouldn't have thought that! We lived in Japan about 30 years using those so called mini split systems, so I know them well. A huge problem with them is you need one for every room! Or at least one outside unit that can handle maybe 2-3 inside wall mount units. We never used that kind in Japan. We had five in our last house in Japan. At $1,000-$2,000 or so per unit, and our house here would need at least 8 inside units, I don't see how they could be cheaper than geothermal. Our house is small, only about 1,500 square feet now, but duct vents even in walk in closet! Could not do that with Japanese heat pumps (that's what we call them there, just heat pumps).

We spent close to 40000 for our geothermal system with heat exchanger in the pond. The Halcyon unit for two rooms was 2000 plus 1000 for installation. Looking at the guys who installed it is easy DIY job. The single room unit were about 1500 USD plus about 150 for baseboard electric heater as backup. I am not saying splits are for everybody but it is an alternative.

 

[DKCDKC]

I put in a 2.5 ton WaterFurnace geo unit when I built my home in 2001. I'm in the middle of my 120 acre farm, so we just buried the pipe in trenches outside - random pattern. Now wish I had added another half-ton - failed to account for the big windows my wife put it the design. But overall it works like a champ, and for a lot less power than I used with a much larger house earlier with a high efficiency conventional HP. I did encapsulate the crawlspace, although my contractor thought I was nuts. That works too. Floors are warm. The crawlspace floor is just a few layers of plastic over the dirt - with a vent under the plastic to vent any radon gas. I think the geothermal unit has paid for itself already. Maintenance has been minimal. I made sure I had a really strong dealer before I even went with geo. It's too complicated for some.

 

[Country Geek]

Not much happened for a few days because of rainy weather. However they attempted to resume digging trenches on Friday and had to give up after about a half of day. There are two main problems that they are encountering:

1. Cave-ins: the trenches have been caving in. This is mainly because of the wet weather combined with my soil composition. Understandably, a man doesn't want to get down into a six foot trench to put in piping if it might cave in. The first trench had a few minor cave-ins and they were able to complete it. They had hoped that was only a problem for that corner of the pasture, but the second trench was much worse so they stopped.

2. Buried junk: in probably the worst decision I ever made, 15 years ago I allowed my grading contractor to bury the stumps of the trees that were cleared for the pasture, in my pasture. I thought I knew were all the burial sites were and had helped them lay out the trenches to avoid those sites, but they have run into more and also found some buried stuff (like old plastic barrels and just plain brush that was supposed to have been burned) that I did not authorize to be buried. The original plan was to detour around any of these if they were found, but combining that with the cave-ins has just been too much. Btw I should be angry about what the grading contractor did, but I can't because he died of cancer about 10 years ago.

So today plan B starts: The rest of the piping will be put in using horizontal boring. They have brought in the boring machine and are currently digging two shallow trenches, one at each end of the pasture, which they will bore between. The pipes will be bored in 10 feet deep, to get under any other bury pits that have yet been found, and as an added bonus deeper means more constant soil temp.

The good news is that a lot less of the surface of the pasture will be disturbed. My horse will appreciate that. Looking back on it this is probably what I should have done in the first place.

No pictures yet but I'll have some in a few days.

 

[cre10]

Sounds expensive. Make sure they grout or you won't have good contact with the soil for heat transfer.

Are they tying the original two trenches into the bored ones? If so make sure each circuit is within 5% of the total length or you won't have a balanced flow.

That's what's nice about a pre made slinky, you bench out the header pit then you drop the slinky in the trenches and don't have to be in them.