So i was told that you would need about 400 - 600 linear feet in a horizontal setup for every ton of heating you would need, does this sound about right? If my house is about 4000 sq feet basment and main floor 2000 each and all done in ICF wouldnt i need less tons of heat? and if you had to guess how much would i need? i live in Utah

also, with these closed ground loops, horizontal or vertical, do trees and roots ever pose a problem?

I would recommend a program call HVAC-calc and go ahead and do a accurate manual J calc. He offers a $40 single use license and the input is very straight forward. That way there is no need to guess and you can get some pretty accurate estimates. I have a 4500sf ICF house and a 6 ton unit on 2000lf of horizontal closed loop.

Hi,

The amount of pipe needed in the ground varies according to the depth, soil composition, pipe configuration, average ground temp and a few other things.

You are right about not needing as much heat in an ICF block house.

How do you have 4000 sq ft in the basement and 2000 sq ft on the main floor?

Trees and roots are not a problem for a buried loop.

You don't want to guess on how the size of the heat pump or ground loop. Too much costs you a lot of money, too little and you house will not be comfortable.

Figuring the heat load for a house is pretty straight forward and then sizing the heat pump can be done by a dealer.

I also live in Utah. I can help out if needed.

wnbrandt<

Good call on HVAC-calc.  I use that program and it is great. 

Is that 2000lf of trench or 2000lf of pipe?

How is the pipe laid out?  Slinkies, 2 pipe, 4 pipe?

I have a 4.5 ton heat pump with 6000lf of pipe laid out in slinkies and 700 lf of trench.

2000lft of pipe in four 2 pipe runs so that there are no buried connections, they all start and end in the basement.

wnbrandt,

You should really look into Direct Exchange geothermal for your system. It can save you a lot on the installed price. www.ecrtech.com
I'm also in Utah.

Look into DX Geothermal LINK. In a trench loop system, you have typically 1-1.5 loops per ton [200 ft. loops] The system is much simpler in design, less maintenance than a water-source system , more efficient since there are no water to refrigerant heat exchangers and they have the best warranty in the industry. Energy [heat] is transferred directly to or from the refrigerant circuit. It needs no water pumps and uses copper loops versus high density plastic loops. Copper is a much better conductor of energy, plastic is actually an insulator.

Tree roots can in fact damage loop systems. Deep rooting trees can mash and restrict the loop causing reduced flow rates and reduced system capacity. A good rule is to keep loops away from the drip line of trees.

As mentioned, an accurate load calculation is critical. System selection is equally important. I have an ICF house with approximately 6600 sq.ft. with a 3.0 Ton DX system conditioning it. I also used an energy recovery ventilator for fresh air exchange since the home is extremely tight. You will probably need to do the same. I will not do an ICF or SIPs house without air exchange.

Dakers,

Where are you located? The 6600 sq-ft heated by a 3 ton unit sounds small or your located in a mild climate. Can the DX go into wells? I ask because if the well is in a water table that has movement, you have the efficiency of DX with nearly in-exhaustable source.

Patrick T

Patrick,

The system is sized properly according to the load calculation performed. That is my point. 95+% of most systems installed today are oversized, some as much as 200%! This is also testimony to "green building".

The project is located just North of Charlotte, NC. We are in a very hot and humid climate in the summer but somewhat tempered in the winter. It still gets into the teens yearly. This system was maintaining 74° IDDB @ 101° ODDB.

This system was installed using vertical loops [7 loops 50' deep]. The ground in fact does have a shallow water vein where the loops are located. However, my other installations are exhibiting the same performance. There is a picture of the install at LINK if you what to see it.

D

Dakers,

 

Nice web site. We are building an ICF home 5800 sq-ft on a bacement. Just a few more questions;

Can DX systems be used with radant heating in combination with AC air handler? I have looked into Geo thermal using a split system, some tonage devoted to Radant heating and some tonage devoted to air. In extrean cold spells, both the Radant and Air systems would provide heat, but under normal Winter needs, 100% Radant. With the AC needing the air portion, thus the system is split.

Do you know of any installers in the Bloomington IN area?

Do you know of any well driller using "small rig" technoligy in Bloomington IN or will to travel? So far all I can find is water well drillers and the price reflects the size of the equipment!

Patrick T

Patrick,

These are split systems and can be used with radiant heating systems. You have to decide which you want to perform the heating primarily. It can be installed to provide radiant heating until the load becomes to much for the system capacity where auxiliary heat is needed. This can also be designed to operate as such automatically.

There are some drillers using compact drilling rigs in that area. I will see if I can get some more information and forward that to you. The size of the rigs typically do not determine the cost of drilling, rather the labor and cost involved. In some instances from my experience, some larger rigs operate cheaper than smaller rigs. It is basically determined on a case by case basis. Depending on the location, drilling costs vary from $8-$22 per foot. Some include grouting, some don't.

I'll try to get that information to you tomorrow.

D

Dakers,

Good to confirm split system. I would devote as much of the heating system to Radant as could be allowed yet still having the cooling capacity. Depending on the local condition, this would varry. Here in the mid west, Indiana, we have hot steamer Summers and Cold Winters.

I need to do a heat load anlysis to get a better idea. My biggest fear is an over sized cooling system. Resulting in cold damp conditions!

Patrick T

You've done your homework Patrick,

Oversizing is one of the most common issues facing our industry today. Oversizing the system causes comfort issues, additional installation costs, shortens system life expectancy, increases energy consumption....etc. This system, combined with an air handler with an ECM motor and humidity control works great. It will "rip" moisture right from the air.

You can have a load calculation performed and determine what size system you need. Size the unit to meet the heating/cooling load, which ever is greater. You do not want to oversize either load by more than 30-40%. DO NOT ADD SYSTEM CAPACITY AS A "SAFETY FACTOR". This is a common mistake.

I have asked Jim to post the driller information here. Hopefully that will help you.

D

You write as if you're looking at the system capacity to be the sum of the radiant and air portions. It doesn't need to be. It can be all one or the other, or any combination of the two. You can run both at once if the heat pump is connected to a water module and the water is run through both the air handler and radiant tubing.

If you include a storage reservoir in your system over sizing won't be near the problem it normally is. That's because you can separate the heat pump side of the system from the house load side of the system. An oversized heat pump will just heat or cool the reservoir quickly, but the energy transfer into/out of the living space can be made to match the load.

A couple of other options to kick around. One, put your radiant tubing in the ceilings and use them for cooling also. You'll get a lot of naysayers come back and say "not practical" because of condensation issues. Condensation will be a problem only if the system is running water below dew point through the tubes. Cooling by radiant is being done every day in the SW and Europe. The SW is dry, Europe isn't. You will need an ERV if your house is tight. You can combine a cooling coil into that system for humidity extraction if the outdoor air exchange with the ERV doesn't take care of it. It's going to take some thinking, and a cooperative HVAC contractor, to do it, but it's a feasible option. One good place to start info hunting is www.bekausa.com. Follow the link for Dedicated Outdoor Air System.

I was going to do ceiling radiant using a DX heat pump in the house I'm building, but instead have opted to go the other option I want to suggest. That is a Daikin air to air heat pump. Reason, cost and efficiency. Cost over rules my 30 year desire to have radiant heating in a house. Efficiency gives me a choice that will be nearly as energy saving as a DX would be. The Daikin VRV-S outdoor unit will extract heat from outdoor temps down to 10F with a COP of 3. The Daikin system is a multi split system, meaning one outdoor unit will serve up to eight separate indoor units. I'm expecting my installation w/ the Daikin to be at least $5k, maybe even $8k, less than a DX/radiant system. That's basically what it would cost me for the wells for the DX loop. Daikin is at www.daikinac.com. The tubing, plates, manifolds, etc., of a radiant system aren't cheap, and depending on your particular situation, may be somewhere around the cost of forced air ducting. If you are pretty much committed to having a forced air AC system regardless of whether you do radiant or not, definitely take a look at Daikin. Mitsubishi offers a similar system but it switches to auxilliary heating under 32F. I don't know of any other mfrs of variable refrigerant volume (or flow) systems in the US that will perform down to 10F.

Patrick,

You should contact Mike at Hoosier Energy Associates in Warsaw, IN. He has very extensive knowledge and background with DX doing radiant, forced air, and domestic water heating, all from one heat pump unit. He also has drillers available for the DX systems. Click on dealer locater on the LINK website. Click on IN. He's the sales rep for the area.