WaterFurnace Series 7 – Total Cost Breakdown

[Real007]

Geothermal is very efficient - likely one of the best options out there. It must be evaluated on a case by case basis however.

I personally would not rely on relatively shallow (less than 100 ft) ground water sources for open loop systems as there's a good possibility you'll run the well dry / have it collapse in on itself and experience massive sand saturation. I also don't think closed loops are any where near as effective as open loops and have personal experience with both architectures.

In one of my homes (Virginia / North Carolina border) I'm using a GEOSTAR 121-060TR114N00A0 five ton unit -- open loop: approx (constant) 55deg water is pulled from one of the wells on the farm (@ aquifer) , sent to the unit, then discharged into a 1.5 acre pond -- system is unbelievably efficient and I DIY'd the runs from the well and to the pond -- cost was a trencher rental and the lines. Approx $17K invested and medium payback.

In my other home (PA) I'm doing everything from scratch -- including the site work (pond construction) and new well. The well drilling alone will cost $7500 (aquifer is deeper than 100ft) so the whole system (Bosch System formerly Florida Heat Pump) will be approx $25K and a considerably longer payback.

 

[AlyGreen]

@Real007 thanks for sharing your system experiences, all great ways to do geothermal and good information to share for those thinking about it. Definitely if you can do the work yourself it will save a ton of money as per your figures.

I relied on the contractor, not personally having the geothermal know how, drilling, mechanical skills & equipment, so it cost more. Still I am happy with the outcome but would have been even happier at your price points!

Regarding open v closed loop, again I relied on our contractor and driller's experience. Our water table is quite deep, at over 225ft (from being most of the way up a mountain) for the home's normal water well. I am not sure an open loop would have been a viable option for this situation or if there would have been enough water flow. They drilled two 375ft closed loop wells for 5 tons total.

I can see a use case for both types of system, depending on the ground situation. I have not researched relative efficiencies, or benefits of open versus closed loop, so you are more qualified to give an opinion, having installed both types of system.

Glad your systems are working well for you and thank you for contributing.

 

[x98myers7]

wow. thanks for the writeup. that all makes sense. I have been seriously considering an outdoor wood boiler, which is the most common form of off-grid heating here in MI. but, for a completely fuel-less system, this is tempting. the need to process firewood is what is prohibitive in wood boilers... and let's be real, doing that as I age isn't going to get easier.

 

[millsan1]

I have a GEO system, but I use a wood boiler for heat. My GEO is open loop, and the well is very deep (500'), so there is a 2HP pump down there, and it EATS energy. The GEO itself is very efficient, the pump to get water to it, not so much. I will be making this into a closed loop system this spring.

 

[AlyGreen]

@x98myers7 I hear you on the wood chopping, I had that in our previous home for just a pleasure burning wood fireplace. Chain saw bucking, chopping, stacking, hauling wood takes work. The mice always seemed to be most appreciate the luxury wood stack condominiums we built for them outside by the shed, where the wood was stacked to dry...

Not having to do that work is a relief.

If you don't want the extra cost of ground source, air source a relatively simple install with a majority of the efficiencies and benefits of ground source at a lots less money. Still having done both I still like ground for the efficiency levels and free hot water but the payback is much longer.

 

[AlyGreen]

@millsan1 Good points on the well power draw costs of open v closed loop. Which system is right for each ground condition circustance and homeowner aims, really does take some careful assessment. How much land is available, the depth of water table, quantity of water flow and whether the locality allows reinjection of water directly back into the ground all play a part in the decision.

 

[foggysail]

How long do you think all aluminum coil will last (unit has 8 year warranty)?
View attachment 187330
For the price difference you could probably finance 2 - 3 mini split total replacements.

How long do you think aluminum radiators last in cars?

 

[Supervstech]

How long do you think all aluminum coil will last (unit has 8 year warranty)?
View attachment 187330
For the price difference you could probably finance 2 - 3 mini split total replacements.

Back in the 70s and 80s carrier/bryant used all aluminum coils in their air handlers and condensers.
They switched to copper in the 90s to gain thermal transfer lead for energy standards, when they realized the copper wouldnt hold up to water flow, they all seitched back to all aluminum...
Those coils from the 80s are still intact.
Trane has used all aluminum in their condensers forever...

Aluminum lasts FAR better than thin copper.

 

[AntronX]

I meant to say aluminum coil with refrigerant as heat transfer fluid, not water. Aluminum tends to rot if exposed to water. Copper seems much more resilient. My 20+ year central AC condenser unit has those aluminum fins rotted away in some places while copper tubing is intact and holds pressure. I wonder what will happen when pressure tubing is aluminum.

 

[Supervstech]

I meant to say aluminum coil with refrigerant as heat transfer fluid, not water. Aluminum tends to rot if exposed to water. Copper seems much more resilient. My 20+ year central AC condenser unit has those aluminum fins rotted away in some places while copper tubing is intact and holds pressure. I wonder what will happen when pressure tubing is aluminum.

Yet, this is not true.
Copper coils rot and fail quickly, the entire hvac industry went through near bankrupsy replacing warranty leaking copper evaporator coils

 

[AntronX]

replacing warranty leaking copper evaporator coils

What was the root cause of leaks? Bad brazing?

 

[Supervstech]

What was the root cause of leaks? Bad brazing?

Nope, formicary corrosion.
PAPER THIN RIFLED COPPER in constant water environment led to 95% failure of evaporator coils.

 

[Supervstech]

Aluminum forms a tough oxidation layer that is nigh impervious to corrosion.
Far superior to copper in a wet environment.

 

[AntronX]

PAPER THIN RIFLED COPPER

Manufacturers tried to save money. Hopefully most failures were in warranty so they get a good lesson.

 

[Supervstech]

I have changed 50year old equipment out that was not leaking, with aluminum coils...
Cannot say that about any copper...

 

[Supervstech]

Even grade L copper for boiler supply and return piping fails in time.

 

[AntronX]

Aluminum forms a tough oxidation layer that is nigh impervious to corrosion.
Far superior to copper in a wet environment.

My Midea window unit had the bottom of condenser coil sit in water for 6 months (by design). Aluminum fins got corroded and a lot of aluminum oxide dust came off. I probably should have left the oxidation in place.

 

[Partimewages]

The lesson learned was how to manufacture units that last just past warranty end!

 

[SunDave]

AlyGreen, Awesome writeup. As you pointed out in a previous post, there are air and water combo units. I put in a Synergy 3D unit by waterfurnace (4 ton).

Works great for this house because it occasionally gets all the way down to -40 here. I use it for hydronic heat, domestic hot water assist, and air heat.

One item I didn't see on the awesome writeup was to isolate the vent system from vibration too if putting in a new unit. Relatively easy with some fanfold looking rubber as a small section of duct.

I have been on it since 2010. The pre-biden prices were pretty decent. 30k before rebates, and just over 20k after. It actually came out to match exactly a forced air system after rebate, and included in the 30k was a nice propane fireplace as a backup.

Not perfect. I have had a compressor replaced under warranty, but other than that, coming up on 14 years, and I would do it again, depending on the price. The calculation changes where air source heat pumps have enough heat to work with.

 

[NC_hydro]

Friend's parents are doing a Geothermal closed loop with the lines coiled and laid flat in the bottom of a spring-fed pond about 12ft deep. They tied it to rebar to sink it.