New Build in 2018: Geothermal vs NG/conventional AC

[Rustyiron]

I knew it was commonly used to pre heat, and getting ground water half way there is great! I took his post as his GT made his dhw alone.

 

[Erik M]

There are many different GT manufacturers and it is important you get one optimized for your needs. My two Nordic GT heat pumps are made in NB and are focused on heating vice Cooling. Parts if needed are locally obtained and winters are comfortable. I have a 5 ton water to air unit in the house using the existing FA ducting and the shops are heated with a 3 ton water to water unit via radiant heating in the floors.

My house was built in 1912 and has modern windows and lots of insulation in the attic but the walls are not insulated to modern standards. However, mold is never a problem and no air exchanger is required in my home so not a problem. I have a wood furnace as backup heat in the event I lose commercial hydro as my little 5 kw generator will run the furnace blower, well pumps, freezers, etc. Though it is a two stage unit, I have yet to ever need the second stage and I have seen -27 with high winds on top of that. Yup, GT is awesome if you can afford the significant upfront costs.

 

[Dadnatron]

In one of our clinics we have Mitshibushi Mini Splits that have the ceiling tile air handlers and wan can control each room independently.

As I have been looking at options, the Mitsubishi mini splits keep popping up over and over. I like the ability to alter each room or groups of rooms separately. Especially since most of the time it will just be my wife and me. I don't like the appearance of the 'wall' units, but the ceiling units are OK. I think this might be my wife's biggest complaint, and might derail this as an option.

But looking at the options for mini splits, I like the thought behind them a lot. 300% efficient vs 500% for GT... while it isn't as good, it is far superior to a regular NG forced air system. I am going to try to get in to see some local HVAC guys this week and see what they have available, recommend, etc for my needs.

 

[Erik M]

If you don’t need the highest efficiency because you don’t get real cold very often, the mini-splits are a good choice and cost far less than a GT system.

 

[MacLawn]

Oh me, I've researched this stuff for years and still don't know! Old Red, Eddie, etc. who said insulation are right though. I'm currently totally rebuilding a 2,000 sq. ft. two story 1900 built house, torn down to studs now. Located in Missouri, so cold and hot. Son in law who is a builder and has a lot of experience doing old houses, is doing the work. I wanted geo but he said spray foam insulation would be where to spend money. If mini splits, I'd need about 3-4 at least, even with one unit doing two inside units. It's in city, so geo would have to be drilled, not long loops. For now, I've decided on insulation!! It'll have everything new except the studs, roof, and foundation! Everything. A total rebuild.

 

[Erik M]

With enough insulation you are likely fine with the minisplits and some EBB for the coldest days although a gas fireplace has advantages if the power fails. I was not going to rip all the walls apart here, but if the house burned down tomorrow I would rebuild very differently.

 

[MacLawn]

Boys, I'm a geezer, and acronym deficient. Please use words. I missed a lot because I simply don't know what in the world you's guys are talking about.

 

[Erik M]

Ebb = electric baseboard heaters
Dhw = domestic hot water
CW = cold water
HW = hot water
GT = geothermal
FA = forced air heat
NG = natural gas

 

[buckeyefarmer]

Ebb = electric baseboard heaters
Dhw = domestic hot water
CW = cold water
HW = hot water
GT = geothermal
FA = forced air heat
NG = natural gas

FART = forced air rank thermal

 

[s219]

Will G/T make 120* dhw or just do the lion's share of preheating prior to a "normal" hwh?

My geo system hot water generator has settings for 120F and 150F. I believe that rating is based on an assumed input temp and a certain amount of runtime at stage 2, and of course the pump speed is changed to get one or the other so you get more volume of hot water at the lower temp. I have it set to 120. No idea what the "actual" output temperature is other than when I put my hand around the brass elbow on the output fitting, it feels a good bit hotter than a very hot shower temperature, so it's probably in the 110F range.