HVAC II, which one?

[buckeyefarmer]

I've only done a handful of geothermals, so I'm far from an expert, but from what I've seen, as mentioned previously, geothermal is the way to go if done properly.

However...



Helped a buddy who is an HVAC contractor put a dual fuel system in his house this past winter, and so far, even when it was 30 F degrees outside, he still didn't need to run his gas furnace because his heat pump was keeping the interior at 74 F degrees no problem (R410A system, over 9.0 on the HSPF).

Numerous variables to consider as far as the interior conditions go.

What you quoted is not showing up, but Air to Air is not a geo system. A heat pump normally puts out air cooler than body temp, so it feels cooler to the touch, but it will probably be in the 90's and warm enough to warm the space.

 

[Richard]

There are different piping layouts. You will need one loop per ton of unit. The length of the loop depends on piping layout, depth, pipe size, soil type, location, etc... The designer will use software to determine the lengths. I would recommend 6 to 8 feet deep for horizontal, but the depth is included in the length sizing,

Thanks for commenting on the build of the brand and pricing!

Regarding buried 6 feet or more, that is also what they say. I asked them (and here it is for the crowd)

Since I can dig down to 15 feet, is there any additional benefit from going from 6' down to maybe 12?

Also... if the recommended length is 600' of underground tubing, is there any benefit of putting in 1,000 or is it just a waste of money?

In other words, is 600' the "minimim cost, minimim performance' standard or would that number (if the accurate amount) actually be the right amount?

If I use the field across from the house, I'd be veery able to add what I wanted to be positive it's ok. Might even lay a duplicate field of same stuff for my wifes uncle who lives next door so if/when his 15/20 year old system dies and he wants to convert to geo, he'll already have the hard part done.

They came out yesterday and looked around. Regarding doing any 'calculations', they didn't take any measurements, no window counts, nothing... just came and looked at what I had and the layout, noting we might need an adjustment here, slide the (basement) refrigerator over there for more room, punch a hole through house to take pipe outside over here... but not the first measurement.

Can they even give an accurate quote if they don't go through that process or are they simply relying on the unit I already have and their experience in the business? (this place has been around for a while)

 

[MarkV]

Richard I am following your thread with interest. We are do for a new system and have considered Geothermal. I personally can't see dumping that much water everyday unless it was being dumped back into the aquifer. Have you investigated the possibility of drilling another well to dump the water in? I don't know how that would compare to the trench and piping closed loop price wise yet may be worth looking into. I also heard, could be urban legend, that the EPA looking at stopping vertical closed loop system due to possible water contamination.

MarkV

 

[2manyrocks]

When my house was sized, I know they measured exterior walls, doors and windows. I also think the calculations took into account the estimated R factors of all those surfaces. They also asked me how much insulation was in the walls. And they gave me a copy of their calculations.

As far as burying pipe is concerned, I think there are some established parameters for ground temperatures at certain depths, and going 12' probably just means you've removing twice the amount of material for negligible gain. You just want the pipe deep enough to be protected from damage and to be in the earth deep enough to get the ground temperature needed for your system.

The amount of pipe in theory should be calculated based on how much surface area has to be in contact with the ground to make the system work properly. Too much is too much. Too little is too little.

 

[Reg]

Addition: the reason I'm leaning on a closed loop is simply, I abhor the idea of pumping out say, 2,500 gallons water per day, ever day of the year forever more. Dumping said water into ditch and adding cycles to my well pump which is already say, 10 years old.

A closed system simply seems the "right" way of doing it.

Plus, once a closed system is closed you have included any/every thing in it that will be in it.
i.e. you will NOT be sucking in a new load of whatever is in the ground and relocating it to the ditch, though eventually I guess it would find it's way to the aquifer (polluted).
You could (at least in theory) fill a closed system with something other than well water, e.g. some solution better able to conduct heat. (I didn't say "Glycol")

I would be interested in seeing tables of pipe length/diameter required for given materials (copper ?, plastics ?) and flow rates, or the basis of the arithmetic used to derive the tables.

 

[moeh1]

I looked real hard at geo a couple years ago and would have had to go open loop.
Hard on your well
Hard on your pump
Hard on the heat exchanger if you have the wrong stuff in your water
Not all second wells have enough capacity to "sink water" as fast as they can pump water.
Open discharge is outlawed in many areas due to wasting water.
The cost of systems eventually drove me to a high end air source unit that does great done to about 10F, then I have to switch over to a backup system.
If you go closed loop, no advantage to going deeper once you get to a stable ground temp. They have some "slinkly coils" that might reduce the actual distance you have to trench. There are some past posts here. Techman? did an install in Pa.

 

[buckeyefarmer]

He guessed that the incremental cost from the pump/dump to a closed loop system (me doing the digging & backfilling) would be about $2,500 upcharge. By the way, the speculated price for a Climatemaster TSV-030 (Tranquility 27 series) was $6,000. He corrected that today saying it would be about $6,682 as a pump/dump install and if I added the closed loop, it would then go to about $9,182 with me doing the digging and backfilling.

This is the single speed model, the dual is the TT line which will run slightly more in cost, but could offer some long term energy savings

 

[Sigarms]

What you quoted is not showing up

Apologies, what did I quote, and where is it not showing up?

but Air to Air is not a geo system

Understood.

A heat pump normally puts out air cooler than body temp,

In heating mode, yes, a R22 unit will usually have discharge air at the registers in the mid 90's range. Not always so with a R410A unit.

Apologies, off topic.

 

[buckeyefarmer]

Since I can dig down to 15 feet, is there any additional benefit from going from 6' down to maybe 12?

Also... if the recommended length is 600' of underground tubing, is there any benefit of putting in 1,000 or is it just a waste of money?

As an Example:
(repeat, this is only an example) For my area, with **K heat load and **K cooling load, the TS036 would need 625'' of trench at 6' deep in damp silt/clay soil. At 12' it would need 510' trench. this is for a horz 2 pipe spaced 24" apart.
If I use Knoxville TN bin data, at 12' it is 570' and at 6' it is 705' trench.
A slinky, 8 ft/ft, 3 ft coil at 12' would be 355' and at 6 ft would be 440' trench.

This is just an example to show how the depth can shorten the trench & pipe somewhat, and different pipe layouts make a difference.

More pipe is OK, as long as it is not drastically longer. you will need to have an antifreeze in the pipe, which slows the flow, so the longer the pipe the more pump you need. There comes a point the longer pipe does nothing but add to the cost, as it increases the pump size and causes more circulation pump electric usage. The main point is 1 loop per ton, the loops MUST be the same length, and use a reverse return header. One common mistake is to use the wrong soil conditions, and you can easily be 50% undersized, if your soil turns out to be drier etc...

Yearly heat cost, at $.10 per khw is estimated at $440, cooling $289, another $269 for hot water generations (I included desuperheater in the estimate). 12' deep saves only $18 /yr on the projected total cost.

Again, just an example using some made up heat and cooling numbers. you need the manual J calculation to determine these numbers.

 

[buckeyefarmer]

Sigarms: When I quoted you, and you had quoted someone previous, what you quoted didn't show up in my posting. It's a problem with the BB software apparently.