geothermal standing column well capacity

[Dunfudgin]

So geo designers, what tonnage can this well support? I'm looking for 7.5t of HEATING if I can get it. Cooling is much less critical we are on the coast and rarely use the ac.
Well is not used for domestic water, but is used for irrigation in the summer.
good disposal available for bleed water.
The standing column well capacity numbers I have seen run from 46ft/ton to 100ft/ton thats quite a range.

boston area 52f water temp
bedrock well
510' hole
6" diameter
20.6'static
drawdown test pumped at 7gpm for 4 hours results below:

time (min) dist to water ft
0 20.6
15 35.8
30 41.2
45 55
60 61
75 65
90 68
105 74
120 78
135 80
150 84
165 86
180 88
195 90
210 92.5
225 94.3
240 97
255 99

obviously if the hole can support my tonnage i would not redrill it or frac it.

Thanks
D

[ISOTHERMAL]

Just a couple of thoughts here, 7.5 ton takes a lot of water per minute. If you draw down the water level in the well you will need to over come the lift (feet of head) meaning it will require a sizable pump. Properly sized your unit will probably run constantly in the coldest part of the year = draw down of water level. Also you mentioned you have good disposal area for your water, hopefully this is a dry lake area cause it's gonna make a big puddle that may freeze when the od temp is low enough. BTW I don't design geo loops open or closed. And I'm not trying to talk you out of a geo unit.

Looks like you may already have considered some things, and done some homework ,just wanted to share some thoughts,

iso

[aircooled53]

Most of our wells , vertical are 220-300' per (1) ton of a/c spaced min. 10' apart and ranges are different on lift by pipe size/pump gpm.

Might want to call Tom Willis at:
http://www.earthenergytech-supply.com/

He has always help us in our wells and been drilling geo's for years.

[ISOTHERMAL]

Normally in our area closed loops are around 200' per ton, But my understanding is the OP is planning on a pump and dump geo. Water quality would be a big issue, most pump and dump systems around here have problems with strainers, HX, and flow valves failing because of clogging. Also the cost of operating the pump will offset some of the savings. And a dry spell may affect the water levels of the well.

[tecman]

Figure you should have 20-25 GPM for that sized unit. At 200' lift head that is close to 3 HP. That will be a lot of power just for the water, assuming the well can support that type of flow.

paul

[fsq4cw]

Without going into all the issues regarding open loop systems, at 7.5-tons, you will need to pump at least 18gpm, minimum. However – consult the installation manual specifications for the specific WSHP you intend to install, that will be the final authority on your requirement.

Consult a professional well driller or knowledgeable geothermal installer/designer to verify the capacity of your well.

SR

[fsq4cw]

I wish to correct my last post. 7.5-T = 24USGPM min. Consult manual & professionals.

IMO

SR

[Dunfudgin]

consult professionals:

thats why i am here. nobody here seems to know much about scw heat exchange capacity. just looking to check my pro's #'s before dropping big bucks on a geo.
wall of shame is not a fun place to hang out.


D

[geodude]

is this a commercial system or two units on a residential building?

[Dunfudgin]

its 2 in a residence.

D

[jpsmith1cm]

WildWillT

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[jpsmith1cm]

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