we have received quotes for replacing our oil fired boiler and window a/c with geothermal. We've narrowed it down to 2 proposals. 1) is for waterfurnace envision with horizontal loop for $16,150. 2) is for hydroheat megatek with vertical loop for $16,880. Both qoutes have no hot water, me providing electrical svc, duct work labor, and removal of old system.

megatek guy says the horizontal loop can freeze the ground and make the system useless so he uses a vertical loop.

waterfurnace guy says his horizontal loop has 2X length of pipe (2400' for 4 ton unit), works fine, and has 55 year warranty on loop.

waterfurnace has a 10year parts and labor warranty on all system components. megatek contractor says they will match 10yrs but parts only.

the $700 difference isn't a deciding factor, we are trying to pick the best system. We don't personally know anybody that has one of these in sothwest Michigan.

Does anyone have thoughts on vertical vs. horzontal ? I've seen a few bad reviews for megatek and none for water furnace but I'm keeping an open mind because I know sometimes poeple only write in if they had a bad experience.   
 

2400 ' of pipe for a four ton system seems a little short for a 4 ton unit. How cold does it get in your area?

I have 6000' of pipe for my 4.5 ton system. I live in Salt Lake City Utah

Freezing the ground is a real possibility if not enough pipe is used. This is not a real problem unless the frozen ground will cause damage to a nearby structure. However the heat pump will lose some efficiency at lower loop temps.

Ask the Waterfurnace guy if he will guarantee that the loop temp will not drop below 32 degrees.

Mine never drops below 40 degrees.

Most horizontal loops are 4 times as long as vertical loops, unless the water table is high and the pipe is in wet ground all year.

Just from the loop standpoint, the vertical system is a lot better deal at almost the same price.

This might be a case of going with the contractor that seems to be most reliable.

outside temp usually does't get below 0F . The water table is high except late summer and the soil is a sandy clay.

as far as the most reliable contractor , trying to decide.. Waterfurnace guy has more experience and its his specialty but diddn't spend a lot of time with us. Megatek guy admits he dosen't have much experience but presented load calcs, residential balance point analysis, etc.

our circa 1970 tri- level home is 2000 sq' with new windows, r13 wall and r30+ attic insulation and proposed possible future master bedroom addition (240 sq'), . both contractors say thier 2 stage units will compensate for current sq' and future expansion. waterfurnace proposed 4ton, megatek proposed 3ton.

If the WF guy can provide good references, go with him. Experience is everything.

It matters little if the WF loop drops below freezing so long as the loop has antifreeze mixed with the water.

You'd also be well served by adding the desuperheater option for hot water - it should only add a few hundred dollars to the unit price. However, desuperheat is nearly useless without a separate upstream preheat tank into which it stores the recovered heat - don't do a desuper without preheat tank. Even if it adds $1000 it is worth it since domestic hot water is 15-25% of total residential energy bill and a desuper can cut that by 50% or more. Free all summer, cheap in winter.

You definitely don't want a geo system installed by a guy who "admits he doesn't have much experience" unless you have the stomach and desire to learn along with the installer. Been there, done that - I enjoyed it as an adventuresome engineer, but it is not for the faint of heart.

Though we shouldn't rely on rules of thumb for sizing , my instinct suggests that a 30+ year old 2000 SF house in Michigan needs 4 tons, especially if the unit is 2 speed and additions are planned. 3 tons will work but will more often require use of more expensive strip backup heat.

Waterfurnace home is near you in Fort Wayne, for what that is worth. WF is more of a mainstream brand than Megatek, and Envision is their latest, most efficient unit. I have a 3 ton and it works well.

Just be aware that all heat pumps will either shut down  or fail if the loop temp gets too cold.  For the envision the limit is 20° F.


What type of horizontal loop is the WF guy proposing?  Slinky?  2 pipe trench?  4 pipe trench?

thanks fot the input geodean and engineer! I'm not sure what type of loop WF has in mind I'll have to ask him monday, after the holiday. the loop would go under our garden area 60' X 150' I'm not sure how much he can cram into the area but it sounds like the more the better.

WF desuperheater was additional $750 (water heater tank not included) and can be added later for the same price- now I know what that means -thks engineer
Meg Tek direct hot water was addtional $2,666.00 and had to be decided before installation.

Our $ is alittle tight right now -3 month old Brooklyn is always hungry!! We were thinking to get somthing in place before winter and save 1 tank of fuel oil money to add desuper to WF next year.

I'm skeptical that a desuper can be easily added later. Desuper is in refrigerant loop so system would have to be recovered, desuper brazed in a very tight space, triple evacuated and then precisely recharged. THEN waterside plumbing additions, including a pump and controls would have to be added. Unless I'm missing something, I wouldn't plan on it.

Maybe the desuper heat exchanger is included at manufacture and only the pump, plumbing, and controls are added later - still a PITA, but not as bad.

With regard to low temperature cutout, my Envision docs indicate it occurs at 15 F for a closed loop (assuming anti-freeze, of course)

good call on the desper- it was the humidifier that could be added later. WF said add $400 to unit price for desuper then $350 to connect it later if desired. so might as well do it now and get it over with.

WF proposed loop is (4) 100' trenches W/6 pipes per trench. +300' round trip from house to field. I asked him if adding more pipe would boost performance. he says 2400 is plenty especially for our moist ground conditions (blueberry country).
I figure if the warranty is 10yrs pts & lbr that will give it time to prove its self. I asked for referances and he provided a list- some with vertical and some with horizontal- seems they go with vertical only when there is no room for horizontal

I live in Halifax, Nova Scotia, Canada, on solid bedrock, in the city on an average size house hot. My house is only 1600 sq. feet. I presently use an oil fired furnace and force hot air. I have to go with a vertical bore hole but don't have the space for multiple holes. Does anyone know if there are advantages or disadvantages to a single bore hole at a great depth (more than 500 feet) compared to multiple holes at shallower depths?

It's hard to believe you don't have room for an EarthLinked DX vertical loop. For a 4 ton loop, it would take a 10' diameter circle's area. For a 6 ton, it'd be 14'. If you have a driller available to go diagonal, you could even have a surface footprint of only an 8' circle.

we were originaly interested in the EarthLinked system. We scheduled an appt. with the closest contractor to us and he was a no show so we moved on. I've read several posts regarding the DX system and renewed my interest. I contacted the next closest contractor (40min away) turns out he lives in my home town and will stop out tomorrow -thurs. Any specific questions I sohuld ask?

Maybe find out how many he's done. How long has he been an EarthLinked dealer? I'd like to point out again, though, that with the EarthLinked system, a dealer doesn't need to have done very many to be an expert. Rather, he should have a good HVAC background. If so, he'll be a great choice.

1.  The warranty offered by waterfurnance is very misleading.  I have a waterfurnance Geo unit in my house and I have had nothing but problems with it.  Installed in May 2005, Evap went bad in Oct 2006 waterfurnance paid a small portion of the repair.  In May 2008 the evap once again went out and waterfurnance is giving me the runaround on paying for an obvious facto defect.  Buyer beware....  After they sell you the unit, they want to move on to the next victim...