Regular Guest
Your analysis for the cost of funds, pre vs post tax etc is all sound unfortunately that is the easy part to figure. But you've assumed is a $400/mo savings and that isn't at all clear.
Remember I'm comparing geo with air sourced heat pump. And your analysis can't be generalized for anywhere (in my case it's Portland, OR) but is good only for where the installation going to be. For us in the NW our mild winters it just isn't clear at least without a detailed how efficiently each system will perform. I'm sure someone can sit down and do it but it is not a simple thing when you really get into the process.
Luckily there is a reasonable shortcut. You find installers and manufacturers who will disclose the COP for real systems that have been properly instrumented. The European companies more open to providing this information than domestic suppliers, I suspect because with their much higher cost of energy they don't have to puff the numbers to make them compelling. The answer I get is around 3.3 and that is on the best case side of the range (meaning the field has been generously sized so it isn't heavily loaded under worst case conditions).
Perhaps that number is low, so try plugging in any number you want and then compare it with the full system COP for the air sourced alternative (again in Portland). I couldn't find the saving to justify the capital cost to suck the heat out of the ground instead of out of the air.
But I'm happy to be proved wrong, but so far no geo person has run any numbers that do so. Mostly they compare their systems to resistance heating (and ignore gas heat) because otherwise the numbers don't pencil out. Hey, that's Ok, its called marketing, but I'm an engineer and I like to deal with the problem at hand which is to compare the cost of heating with gas, air sourced heat pump and geo heat pump as against the capital cost of each.
Professional Member*
Exactly!Originally Posted by 4l530
The cost of the loops system is the big kicker, and is hugely variable.
The best candidates for geo systems are new construction, people with large properties, and people that live on lakes.
For most of us that live in suburban areas, the cost of drilling, even if the property is accessible enough for it, makes geo systems prohibitively expensive.
Regular Member
I had the same experience. Even with the 30% tax credit on the ENTIRE geo install versus the $1500 max on the high end DFHP, I came up with a geo cost almost 3 times the DFHP with a generous manufacturer rebate. You have to look at you energy life style. On our larger home,our entire energy bill has been running about $15-1600/year. Guessing that maybe $1000 is for heat/AC/hot water, it takes a very long time to get a payback. Maybe on a new house with an expected long occupancy, the geo could work. You have to do your own numbers. Make sure you include all of the local/state/utility credits in your area.
I was very gung ho for geo. The numbers didn't work for me.
Regular Member
Gosh, VK. I sure would like to see those numbers in more detail. I could be wrong but I am having a hard time seeing how a 5 ton+ geo can be operated in the dead of winter for $200 when you used to burn through 1000 of propane on a 93% efficient furnace previously. Seems like magic to be able to go from $2400/yr to $300/yr. I would enjoy seeing how one does that trick.
Also, $2400-$300 = $2100 savings/yr. If you could get that kind of savings/yr, the payback might be possible in 8 years. Just having a problem seeing that kind of percentage drop in costs.
Professional Member*
The Waterfurnace dealer I knew told me that if natural gas is available in a particular area, they will not even consider to target that location.
Always here
Regular Member
I'm lost here. Are you saying that's $347/mo * 12 mo/yr * 20 yrs = $83,280????!!!!
Regular Member
Sounds like a heating scenario. Here in NW Arkansas, I had a geo contractor say that the geo well temp can get into the 90's, as I recall, during the cooling season. Does this sound right? If that's right, isn't it kind of hard to cool against that well temp?Closed loops remain fairly constant on the temps, Typical depths are 5 feet down. ( horizontal) The surface temp of the soil makes little difference at five feet. Find a good loop contracter in your area or find someone from loop master to help you. the soil temps vary from region to region. At my house it can have 6 inches of snow on the ground and be 25 degrees and my loop is 48 degrees. The spacing between the tubing will determine thermal transfer rate as well as type of soil and length of loop circuit. Check out www.igshpa.okstate.edu/ this is a good web site for ground loop and geo info. One of the best
Regular Member
SBE, your posts are pretty old, but I hope that you are still around. I would like to give you a very high compliment for your logic and clarity. Your advice is tremendous.
Too many HVAC customers are fixated on a particular solution for a complex situation, whether it be geo, HP, or whatever. As you point out, all cost effective solutions are LOCAL. You have to decide on your priorities and preferences and run the numbers so that you have the real facts in front of you before you decide on a very expensive solution.
SBE, maybe I have worked with too many engineers when trying to design an effective solution, but I appreciate your engineering mentality when it comes to acquiring one of the most expensive systems that a HO will attempt.
THUMBS UP, SBE!
New Guest
Your comment about high first cost is an often heard complaint - do you know there are three methods of earth coupling for geothermal? Closed Loop, Standing Column Wells and Open-diffusion wells - Closed Loop will be the highest first cost for the earth side of the system by a factor of three or four. alway get a clear definiton of these three earth coupling options, each have advantages and disadvantages. With the 30% Federal tax credit your pay back should be very quick - with a positive cash flwo from day one.
Regular Member
Carl, not sure I know exactly what you are talking about. Here in NW AR from my experience they propose vertical closed loop almost exclusively. Have heard of horizontal closed loop but it messes up the yard and you need a lot of acres. Using running water or ponds or other water isn't a very likely scenario for most HO's as I see it.
PS: I was reviewing some of the previous posts and find such scenarios as 10 tons needed and $900/month "power bills" a bit off the wall. If I needed or had either, I would freak. Sounds like that person should invest a lot of money on the house envelope before proceeding with any HVAC upgrades.
Professional Member
Standing Column is hardly a viable option for a residential installation. You did not to mention DX.
SR
Professional Member*
Since you don't have a real summer (what 800 cooling degree days? compare with Miami 3500) and are drilling in rock, it is not surprising your simple straight line payback looks so bad. The numbers don't lie, your right! Good for you that you did your homework.
Best payback is going to be to insulate and tighten your home and use less of what you are using. Use that same approach to review that and other equipment choices.
You are a good customer to deal with. The numbers will sell you if the approach is right.
What's the sense of being a New England Yankee without that common sense.
Too bad you have that unfortunate association with a team called the Patriots or Parrots or something
Professional Member*
PS do a blower door test to see how much infiltration you have. The sealing and extra insulation should be available through a good insulation contractor.
Be sure to have an HVAC guy who understands ducts engaged as well. The insulation guys only understand duct leakage and not airflow. Two different things
Regular Guest
Yep still around. Glad you found the advice useful. BTW I am an engineer.
The "problem" is as you note that determining the lowest cost system is quite simple, IF you just run the numbers. Of course very few people actually do that and most suppliers won't volunteer them either (for a whole host of reasons).
My own experience highlights the problem. I determined the a ground sourced heat pump didn't make sense in the Portland OR climate so I decided to go with air sourced.
One of the hidden costs in any niche technology (which ground source heat pumps certainly are) is market inefficiency. They just don't have the volume to drive costs down the way a more mainstream product does. Another is installation cost inefficiency. I'm not talking about the additional cost of additional work, like the buried lines, but costs associated with the low volume of work which means less money to focus on driving down costs.
Well if ground source heats pump are niche, the air sourced (to water) are a niche on that niche. I went in with my eyes open and because I was getting the equipment for a fraction of the retail prices I figured that would leave some room for more labor and still come out Ok.
Wrong. Everything begins to change once you leave the mainstream. Manufacturers with low volumes don't have the resources that larger companies building hundreds of thousands of units have to pour into design, testing, support and that allow them to get all the details right. At low volumes you may get a solid product, but it isn't going to be plug and play.
While I don't regret the decision and I'm having fun this kind of system is not for the faint of heart. Even the best installer is not equipped to engineer a design and it is my experience that this can become necessary since each of these is a one off due to difference in the installation.
This is not to say its a bad thing only something to be aware of. Everyone knows how to install a furnace or an air to air heat pump. If it croaks, anyone can fix it. A ground source heat pump is a whole different animal. You need to get it right and doing so exacts a cost.
Ideally I'd like to see a mainstream system that is as plug and play as a air to air heat pump in air to water but there isn't really anything like here in the US yet.
So if you are looking at a ground source heat pump and you want to run the numbers it shouldn't be that hard, except for one little problem. You can look up the cost of natural gas vs electricity. You can estimate the heating days. But you never really know what the COP is going to be. You know what the manufacturer tells you it will be, but I've yet to see any supplier that will guarantee a figure for an installation. Few people if any instrument their system so they don't know how well its really performing so any payback calculation is almost certainly fatally flawed because everything hinges on that COP being what it needs to be.
Just so you don't think this issue is merely theoretical I spent a fair bit of time researching what measured COPs were for actual systems and, surprise, they are significantly lower than what suppliers tout. This isn't surprising marketing being what it is, but it points out once again the absolute necessity of running the calculation and doing so with actual verifiable numbers for COP that one can expect for your installation. Since this requires one to figure in the size of the system, length of loops, depth, type of material, DX vs water, number of heating/cooling days, type of soil, wetness of the soil among other variables it will, it has to be performed by a competent unbiased person skilled in the art. That rarely happens.
One final note and remember this comes from someone who has just spent an enormous amount of time and energy putting in a heat pump system. I wouldn't bet on ground source paybacks getting better but rather that they get worse. There is growing glut of natural gas and there isn't the political will to tax it so I'd venture there is a higher chance that gas prices will stay stable or head down over the next 5-10 years. Electricity is the opposite. There is resistance to new plants especially nuclear and coal so prices are likely to head up. Within reason, this is politically acceptable as it is supposed to encourage conservation (which it does for lighting, but not for heat in that it discourages a move from gas furnaces to air sourced heat pumps even in the south where they are a screaming good idea). What this means is that for better or worse to the country as a whole the lowest cost fully loaded for those in a heating dominated climate with access to natural gas other than people with very cheap electricity is almost certainly going to gas. I know I said you have to run the numbers and you should but don't be surprised if this is the way they come out.
Professional Member*
Like I always say...this is directly from the mouth of a WaterFurnace rep,
"If natural gas is there, we do not target that area"
Always here
New Guest
ALL this discussion AND NOBODY has brought up Reverse Cycle . . using heat pump - compressor technoplogy AND a heat exchanger coil to give COP's of 2 @ zero degrees. Check out The Aqua Products Co. on line I think they Build the ORIGINAL one!
Regular Guest
I think if you check my posts you will see that I am talking about exactly that. My installation is two heat pumps each with its own reverse cycle chiller...from Aqua Products.
BTW I'd like to see test results validating the whole system COP at zero degrees (or any other temperature for that matter). Is this something the company is publishing now?
Professional Member
Personally, I'm with SBE.
Getting a professional to setup & service these systems is critical!
One service call could wipe out a lot of savings.
I see a lot of high SEER equipment running by the skin of it's teeth! Savings???
Regular Guest
Actually what I was saying is that once an installation moves beyond cookie cutter then costs skyrocket. The problem is that anything that isn't absolutely plug and play will almost certainly require a lot of extra attention and because that work is only amortized over a single system it gets very expensive.
Its not that anything is "wrong" its just the nature of doing a one off job. Ideally what happens is that new and better technology becomes mainstream and standardized so that its cookie cutter driving down the installation cost and making it competitive.
We are beginning to see that with one of my favorite products a high efficiency furnace with heat pump. Its a complete system including the controller that automatically choosing between heating with gas or using the heat pump based on the outside temperature. That seems like a very good idea and it shouldn't add but a small amount to the equipment cost and nothing to the installation.
Regular Guest
Work a few decades in a manufacturing area and you learn you don't want a special product. You want something that is made by the millions. There is a lot of time and effort in quality control and design on large run products.
Spare parts are easy to fine. Manuals for repair exist. Etc, etc. One off designs are great if you like to tinker but never worth is if you pay someone else to do it.
Friend of mine bought a house with a wind mill on the property. I though it was pretty cool. He told me there was a huge maintenance required every 5 years that cost more than all the electricity it would produce.
Posting Permissions
Reply
! -George Carlin