Geothermal/well planning

[David G]

I am planning a geothermal installation at my home in RI. Ground water temperature is about 50*. It will use a well as a source and exit into a pond. I want to get heat, AC and DHW. I want to heat with the existing radiant floor.
The well is a 500', 6", 15 GPM existing(new) well with a head of 15' approximately 40' from the location in the basement where the GSHP will be which is at the elevation of the well head.
The house is well insulated and sealed and will need a 3-4 ton unit. There is existing hydronic radiant floor heat, 1/2 above floor(climate panel) and 1/2 between joists with heat plates. It is plumbed Primary/secondary.

The AC evaporator will be in the attic 24' above the GSHP. This will feed into existing Space Pac 3" duct work system which is already installed.

I need help determining the size of the well pump and type of controls. Should I run directly to the GSHP as posts on this site suggest or use a pressure tank or CSV? What effect is high Iron and manganese and possible brackish water(with a Cu/nickel exchanger)? Some on other sites suggest a buffering tank after the GSHP what do you think and how does one size it?

Does the evaporator get fed direct well water? or through the GSHP? Can I use anyone's evaporator or have to use the one from Space Pac?

Whose GSHP with a cu/ni exchanger do you recommend which would work most efficiently for me. What kind of specs should I be looking for? Should I use a 3 ton which is on the small side as suggested here and depend on the boiler kicking in to supplement it on very cold days?

Any help would be appreciated and please point out anything I am missing here.

 

[Valveman]

Hi David
You can hit the search button with words like "heat pump" and "geo-thermal", and gets lots of stuff to read like this one.

https://terrylove.com/forums/showthread.php?t=22560&highlight=heat+pump+valveman&page=2

Do you mean that the static water level is 15' in a 500' well? And will this level pull down when you start pumping?

 

[Sponsor]

 

[David G]

I mean that the water level in the well is 15' down from the top. Since I have not used the well I do not know anything about the drawdown.

 

[David G]

I did read that thread and concluded that a simple 1/3-1/2 hp pump direct to the GSHP would work. That still leaves several questions I was not able to (clearly) find on the site after a couple of hours of looking.


What effect is high Iron and manganese and possible brackish water(with a Cu/nickel exchanger)? I am cosidering a pellet chlorinator on the well head to precipitate iron to the bottom of the well.

Some on other sites suggest a buffering tank after the GSHP what do you think and how does one size it?

Can I use anyone's evaporator or have to use the one from Space Pac?

Whose GSHP with a cu/ni exchanger do you recommend which would work most efficiently for me. What kind of specs should I be looking for?

Any help would be appreciated and please point out anything I am missing here.

 

[Valveman]

I don't have a water quality issue with my heat pump. However, I did install cut off valves and flush ports to use for cleaning the heat exchanger should a build up ever cause a flow restriction. Maybe Gary will chime in and help with the water quality issue. An HVAC guy with experience with these type systems would probably be best to recommend a brand of heat pump and evaporator.

 

[Speedbump]

The only two things I would be concerned with are:

1. A pellet chlorinator is the worse thing you can do to your well and I highly recommend you don't do it.

2. Water with a high iron content can and most likely will plug the heat exchanger quite often and your going to have to figure a way to keep cleaning it or the whole process will quit working completely until you do clean it.

I know a lot of people want to save money and think this is the way to go, and it may be with pristine water, but I had one at a house I once owned (it was there when I bought) and I wouldn't give you a nickel for a truck load of them. I had .5 ppm of iron and that thing would quit working every six months. Then there was the solonoid valve that would keep sticking on. And on and on and on.

Just my two cents.

bob...

 

[David G]

Is it the poor operation of the chlorinator that you object to or that it does something bad to the well. What does it do???
How Can one rig the plumbing going in and out of the heat exchanger to allow it to be cleaned periodically?

 

[Speedbump]

The pellet chlorinator spits pellets of chlorine into your well. Chlorine eats anything including plastic if left long enought on the plastic. Metal doesn't stand a chance. I have seen the whole side of a 4" casing eaten away where the pellets were hitting. The rest of the casing was so bad down below the pump couldn't be moved.

The way I cleaned mine was to inject 90 lbs of air into a 315 gallon galvanized tank and let it fly through the entire system. The water would ordinarilly dump into a pond. After clearing it with air, half the pond was gold.

bob...