Geothermal Commercial experience?

[marauderx]

Who has worked on a geothermal project for a commercial site? What did you do?

[DocHVAC]

Start with an engineer.

[mainteng]

I'm interested too! While working for a consulting engineering firm I put in a proposal for a review of a commercial site. 250 Florida Heat Pumps in a retirement home. 10 years old. 1/2 had been replaced...
Then I broke my ankle (tib/fib) and lost my job.
Site was in Milton Ontario and they were having their problems. Don't believe they had adequate capacity, or perhaps inadequate heat transfer.
Site had been modified in the 10 year period with boilers and cooling tower added.

Regards,
Dave (iron ring ;-) )
Ontario Canada

[marauderx]

Start with an engineer.

That would be me.

Let me ask more specifically - what was your role in the project? Did you install the geothermal loops, size the piping, pour grout, or size the system? How big? Where? Was it connected with a cooling tower system?

[Texasgrand]

I've put in verticle wells, lake loops (slinkies) verticle runs and have an open system on my farm for the last 15 years. I use the waste water on my farm for irrigation.

Most of the commercial systems are verticle wells with about 1 borehole 250 to 300 feet deep per ton. If there are many tons, the site should be tested. I put in one commercial system with a slinkie loop in a lake.

If you get the earth condenser right, and the geology doesn't saturate the ground with heat, the rest of the engineering is old school. If the ground heat exchange is out of ballance you can put in a drycooler to cool it down in the winter with free cooling like a wet economizer.

[mainteng]

I've seen a system locally (250 heat pumps) that wasn't grouted well, and the heat pumps weren't disconnected by the installer when they flushed the piping prior to startup. Two issues--too little capacity, and 1/2 of the heat pumps replaced in 10 years.
Working for a consulting engineering firm then. Broke my tib/fib and lost my job, so I don't know the outcome at that site (where I repsonded to a request for proposals.)

Original system--many vertical wells; no boiler, no cooling tower. Boilers and cooling tower had been added by the owner, who also used city water for heat transfer in the kitchen/freezer! :-(

Regards,
DaveL

[fsq4cw]

My advice would be to hire a professional engineering firm with a geothermal specialty.


As mentioned previously, an in-situ test borehole must be drilled (with results good for that depth only!). I would also seriously look at and consider the effects of adding thermal storage to the geothermal equation (calmac.com). Should your project involve processes that involve freezing, such as skating arenas, then Ice Kube is likely the product to use (icekubesystems.com). This would be a sensible starting point.


Should your projects involve various levels of government, be prepared for long waits, a slow process and potential disappointment.


SR

[flange]

i have been involved in several large scale projects, both with and without towers. we are a service cmpany and work with several plan/spec contractors. we have not installed any systems, but serviced a lot. in most cases, they have been designed well, but the atc is the weak link. we have seen many problems associated with atc. for example, compresssors running with no water flow on weekends, poor control of primary pumps due to cycling units on mild days, and poor response from the bas, while these may seem minor, they can wreak havoc on large systems. think about manually resetting 300 high pressure switches because the computer geek doesnt understand. on tower systems extended range units may be in order depending upon connected load, supplemental heat or not, etc. think about small units loads. they may be problematic, as many manufacturers use oversized compressors, and in some cases require control logic to bypass the low pressue control at startup, and for maybe three minutes or so. these can drive service guys nuts.

[mikeweber3]

Mara,

I am not an engineer, but have designed, serviced, and installed many systems. I have done horizontal, vertical, open loop, closed, cooling tower, liquid cooler, and boiler assisted for over 20 years.

Do you have a specific question or job you need help with?

Mike

[MADHVACTECH]

I work as in house tech for a company that a campus that is almost all geo. We are running Trane water sourced heat pumps, with about 800 making our main load. But these all feed from ERV's that also are the geo loop. I belive this the largest geo system going in the area, that just finsihed drilling a new well field of an additonal 400 wells. We are in our in 3rd phase of building with 5 buildings planned.

[FlewtheCoop]

It sounds like your just getting started in the process of design or are still trying to make an application decision. We do a lot of these at my office, with the whole "green is great" fad these always end up on university or public money wish lists. We start by ball parking the required area of well field:

In most of our jobs we wind up with anywhere from 2.5 to 2 tons per well. That's with a 400 foot vertical. If you have an idea of the size and occupancy type of the building you can square foot a tonnage and get an idea of how many wells. Then figure to keep them about 15 feet apart per well. Remember to keep room for your mains in and out of your vault, and vault size and location or quantity depending on your required capacity.

Then cost, in the NE they've been coming around 6 to 7.5k per well with 1.25" wells

If it fits and they want to spend the money get a test well drilling to test ground conductivity and determine drilling conditions. There are specialty contractors out there that offer this service.

Also look into design software such as GLHEPRO that Trace 700 can directly export to. I dunno about HAP though. GLHEPRO will design the field for you once your building loads are calculated and tell you exactly what you need.

I try to push chillers on these people rather than these fields. Just cos they're sooooooo much cooler. In my opinion that is.

[geodean]

We have done drilling and loop installs on about 20 schools and office buildings

[daliti]

Just visited your website with live data with the vertical slink coils: how do you remove the air out of the coil? You each time have an upper part in each turn?
What was the reason you installed it this way and not in a flat position?

[tomnor]

J how do you remove the air out of the coil? You each time have an upper part in each turn?
What was the reason you installed it this way and not in a flat position?

In residential systems like this the circulation pump pack comes with purge ports. These ports isolate the heat pump and provide means to connect the ground loop to a purge cart. Essentially it is a open water vessel that pumps water into the loop and the return line dumps back into the open tank, therefore you get a solid water column in your ground loop.
The pump in the purge cart moves the water at high velocity and gets all the air out.

[Texasgrand]

We used a trash pump mounted on a two wheeler with appropiate fittings, valves and quick connects. Add a plastic barrell.