We are building a new home in Augusta, Kansas.  The home is a modular home.  It will have 2x6 exterior with R-21 walls and R-50 ceiling.  It will be build over a full basement, with 1948 sq. ft not including the basement.  Windows are energy star Pella windows.  As for HVAC we were thinking geo-thermal.  The home is on 20 acres, so we bid out for a horizontal closed loop system.  No large body of water to go that way.  The following was from a local HVAC contractor:

Equipment:
   
   1-climatemaster Genesis GSV036 Water source heat pump, 3 tons;
   36,000 Btu cooling/36,000 Btu Heating; 16.3 EER
   1-Factory hot water generator built in w/ all tie in to HWH
   1-Air Pad installed under unit to absorb sound/vibration
   1-I-230 QFC Non Pressurized Circulating Pump Kit w/ flow center connector kit
   1-AGL10A--10Kw Electric Heater
   All closed loop piping, excavation, gycol charge, valves, etc as required for complete Closed Loop system
   1-Honeywell TH832OU1008 Digital Touch Screen Theramostat w/ Outdoor Sensor

Options:

   1.  Upgrade to Factor Hot Water Generator installed                                      included
   2.  Upgrade to genesis w/ variable speed blower 19.3 EER                           add $655.00
   3.  Upgrade to Tranquility 27--2 stage w/ variable speed blower 27 EER      add $2230.00
   4.  Install General 1042LH Humidifier                                                              add $390.00
   5.  Install High efficiency Trion Air Bear media air filter                                    add $255.00

Installation:  As per our design layout.  Excavation expense included.  Custom sheet metal fittings as required to complete tie in to
                     integral supply and return air duct system--(supply and return)**The modular home comes with all internal ductwork
                     using the 1/2" foam ductwork.

Plumbing:  All closed lop piping, valves as required, gycol charge, pump kit as required is included.

Electrical:  By others---not included in HVAC pricing

Warranty:  One year free service.  10 year compressor and refrigerant circuit parts warranty.  5 years other parts.

Total Cost $12,530 incl. tax.




Questions:

1.  From your experience, is the base price of $12, 530 a good price.

2.  I will already be renting a Ditch Witch to trench in 2" piping for rural water supply to go 1/4 mile onto the property.  It has a backhoe attached as well, and I should, if time permits, be able to do the basic trenchwork for the geo thermal as well.  They will be digging 2' x 250' and will loop back on itself with 2' of dirt each loop.  An additional 125' trench will also be done.  If it is a simple 2' x 250' and 125', is this something that could be done by me, or should I let the experts do this?  The contractor estimated (since he outsources the digging and looping) to save about $1000 in just pure excavation.

3.  for only $655 more a variable speed blower and increase to 19.3 EER from 16.3 EER seems reasonable.  Correct me if I'm wrong.  But would the 2 stage variable speed blower 27 SEER system really be worth an extra $2230.00?  What kind of cost saving would this really add up to?

4.  Correct me if I'm wrong, but the humidifier would also help by possibly allowing us to keep the thermostat a bit lower and feel just as good.

5.  The Bear filter is changed annually at $43.00 per filter and also seems the better option.  Again correct me if I'm wrong.

6.  They had an identical quote for a vertical closed loop system (200 ft.) for $14,470.  I have been told these are slightly more efficient, but if the cost differential is $1,940, and it may save $10 per month (it would take 16 years for the ROI) to $20 per month (it would take 8 years for the ROI), this doesn't seem worth the extra money.  I have 20 acres and the horizontal won't be a problem for space.  It would be more understandable if we were in a neighborhood.

7.  Do you see any problems with the type and or brands recommeded for the installation?

Any and all responses would be greatly appreciated. 

Chris

Chris,

How often will you have to add to or change the gycol antifreeze for the horizontal loop.  What will this cost over the lifetime of the unit.  It seems to me that a vertical system properly sized would not have to include gycol.

Sorry Alton, but I need to disagree. Both vertical and horizontal systems need freeze protection.

Chris, the prices you have been quoted seen very reasonable. The contractor should be able to tell you difference in operating costs between the 19 EER unit and the 27 EER. Then you can decide how long the payback will be.

I would go $655 for the variable speed blower and 19.3 EER.

Digging that much trench with a Ditch Witch will take a long time. It might cost you more than $1000 in rental costs.

Alton,

I was not aware of the need to recharge the glycol.  I was under the impression that like the antifreeze in other AC systems, as long as it doesn't leak, since it is closed loop, there's no need to exchange it.  I have emailed the contractor to get a response as well.

 

Chris

Chris,  this is my understanding as well.

Alton,  if you have info about glycol needing to be replaced periodically please let us know.

anti- freeze will need to replaced every once and a while 5-10 years as it breaks down it will turn acidic and can damage piping or equip. at work I recomend a ph test anualy, but every 2 is fine

Geo Fan,

I agree.

I guess I forgot that Chris was building in Kansas.  So far, here in the Southeast, my projects with vertical loops have not used antifreeze.  I prefer additonal loop length versus using antifreeze since water-to-air heat pumps are so reliable.  Homeowners never call for service unless the unit quits working.  Preventative maintenance is not practiced much here.  As long as it runs, leave it alone seems to be the attitude here.

In a colder climate I understand that antifreeze is needed and probably costs less than drilling more wells.

How much is the duct? Why isn't that included (of course at a higher price)? Surely you're not just going to use the modular home's duct for the basement and upstairs, right?

geo fan....on another thread you stated  "have not yet touched water source".   Does this mean that you have not installed a water source heat pump?

Please tell us what your background and experience in geo systems are.

Tuffluckdriller,

As far as the duct work, my understanding is that the HVAC contractor will install duct work to tie into the existing duct work of the house.  As far as the duct work in the home, I am not sure, and will need to check and verify what is included.  It will be an unfinished basement, but I don't know if the modular manufacturer will install vents to the downstairs if the basement plans are known.  I am going to call today to find that out.  Again, I am brand new to this, and I am trying to gather as much info before going forward.  Thanks for your insight and questioning.

 

Chris

Alton,

I just called the HVAC contractor and questioned him on the glycol recharging.  He said that used to be needed, but they are using a newer glycol that is very stable and doesn't need to be replaced periodically.  I didn't think of asking the chemical makeup, but he seems very knowledgable when speaking to him.

 

Chris

Chris,

Thank you for getting back to me.  Although I try to stay up-to-date, with so many items used in homes there is no way that I can.

Some installers use ethylene glycol while others use propylene glycol.  Both can be harmful but propylene is less so.  Make sure no pools of either are left around for animals to drink.

The older glycols that I knew about were subject to breaking down and becoming more acidic thus more corrosive.

I have never heard of a modular home manufacturer putting vents for the downstairs.

For comfort's sake, please don't just plan on using the modular home's duct. It works for the main floor, but if your installer puts holes in it for the basement, you'll be VERY unhappy with the performance. The smarter thing would be for the modular manufacturer to not install any duct, and have your HVAC guy size, design, and install the correct duct for the home.

Propylene glycol is a food additive and is completely not toxic. I bet most of you ate some today. I have asked four geo experts about the need to change out glycol. They all say there is no need.

Tuffluckdriller,

I called the manufacturer and they do the vents for the basement when going on a basement.  The modular flooring design is a truss system with compressed foam/aluminium rectangle ductwork.  The size and place the ductwork according to where the HVAC is going and its tonage.  The vents are run in the trusses and are only cut for the upstairs.  The basement ducts will be "T"'d off the main trunk, but are shut off until the basement is later finished.  Hope that makes sense.

 

Chris

Mr. Dean,

Yes, propylene glycol is a food additive.  It is considered safe in food and on skin because exposure is usually very limited.  However, according to the Propylene Glycol Safety Data Sheets, care should be taken when working with propylene glycol.  My concern is that some of this material might be spilled while being added to the geo loop.  If this happens then be sure to use soap and water to remove it from skin and keep the pets away from pools on the ground.  I have included Section 3 of the emergency overview below.  If this helps one person then it is worth it.  I am not saying not to use it - just be careful.

                 **** SECTION 3 - HAZARDS IDENTIFICATION ****

                              EMERGENCY OVERVIEW
Hygroscopic.

Potential Health Effects
    Eye:
         Causes mild eye irritation.  Contact may cause irritation, tearing,
         and burning pain.
    Skin:
         Causes moderate skin irritation. Contact with the skin may cause
         erythema, dryness, and defatting.
    Ingestion:
         May cause gastrointestinal irritation with nausea, vomiting and
         diarrhea. Low hazard for usual industrial handling. May cause
         hemoglobinuric nephrosis. May cause changes in surface EEG.
    Inhalation:
         Low hazard for usual industrial handling. May cause respiratory
         tract irritation.
    Chronic:
         May cause reproductive and fetal effects. Laboratory experiments
         have resulted in mutagenic effects. Exposure to large doses may cause
         central nervous system depression. Chronic ingestion may cause lactic
         acidosis and possible seizures.

As long as the duct is sized properly for the total tonnage of the home, you'll be ok then. Just make sure they don't short it.

I'm with Clark, duct is everything here. Remember code is 6" square of return for 1KBTU (loosely 24x10). That's more than I see in all but the largest modulars. Your price quoted is cheap! I'm not familiar with 1/2" foam duct work do you mean duct board? Is this a manufactured home (or modular)? The advantages to the TTV are R-410 refrigerant, variable speed fan, 2 stage, cheaper quieter operation, and a standard MERV 11 filter. This means your price difference (by skipping the Air Bear and vari fan) is about $1,300. That's reflective of the actual dealer price difference, fair; and I think worth it.
Regarding the antifreeze employed I suggest you yield to your installer and -don't drink the water.
Joe

joe,

On the Tranquility 27, you said it comes standard with a "MERV 11" filter.  Is this the same as the BEAR filter.  I was told by our installer that the BEAR was a 5" filter changed yearly at a cost of ~$45 per filter, they filter better than the monthly filters, and in the long run are more cost efficient.  Can you tell me the difference in the MERV 11 and the BEAR?

On your comment about "...-don't drink the water".  Were you saying not to drink water from the same well as the closed loop system is located, or not to drink from any well on the property if also drilling for a closed loop system.  Our plan is to dig 3 200' wells (1 for each ton) and a separate well for drinking not located less than 50' from the 3 wells. 

 

Chris