How many tons can this support?

I have 6 holes drilled 275 feet deep all holes are in solid rock.. only one of the 6 hit water or had water in it.. as I said they are in solid rock and have been grouted etc etc.. So my question to the BB is what in everyone's opinion would be the max tons this loop could support?
BP

 

Why do you have 6 boreholes and no heat pump? Are you going to build a house to match the loop field?

Bergy

 

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No I already have a heat pump and a house and a geo field with the 6 holes .. just wondering the max tons one could put to this field? Opinions?

 

Wrong approach

This comes up fairly often with conventional mechanical engineers - "what is my btu per borehole?"

Doesn't work that way.

Or if you want it to, how about 1,000,000 btu's for about 11seconds?


Lots of data missing. Ground temps. Pipe diameter. Heating and cooling load hours. Etc..

 

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I understand that there can be a spread.. but there has to be some rule of thumb .. for 6 bored holes 275 deep in solid rock .. 1.25" pipe diam.. 2 ton ? 4 ton ? 6 ton? 8 ton? 20 ton?

 

No rule of thumb

The only rule of thumb may be the 1 loop/ton, but that is for minimizing head loss.

We don't know if this is heating, cooling, what your climate is, etc...

So you can see why the question without details doesnt make sense.

Its like asking us what the mileage of the car is and only showing us a fuel tank.

 

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Look guys I am not asking for warranty here.. or is anyone going to be sued .. if you give a wrong answer,... I can see why there is a huge black art cloud than hangs over the geo world.


So you mean to tell me that no one can estimate what one 275" hole in solid rock with 1.25" pipe fully grouted can support tonnage wise? If the hole was moved to California would the tonnage be so different than the same hole moved to North Dakota?


I was hoping that some long time Geo installers would be able to at least hazard a guess.. like well I would think that 6 holes drilled 275' deep in solid rock would be able to support a 6 ton or 12 ton heating and cooling system?

 

In a real mild climate this might support 10 tons,

In a real severe climate maybe 4 tons.

Knowing where you are at will help a lot.

 

We drilled 5 each, 120 ft wells in Seattle, with 1 each, 3/4" U-bend. Clay. It supported 9 tons. Maybe 20 - 30 tons?

 

Here is what i can tell you is average in NJ.
I typically drill 180' with a 1" loop for ton. That is typically drilled in sandy slightly clay formations. You have 6 275' loops. In Jersey I would say a would be "8-9 ton ballpark". Now you are in solid rock which would lower the heat transfer. I am not going to ballpark your tonnage since I am unfamiliar with your formatin and climate.
I hope this helps you, but I'm sure is just gonna confuse/frustrate you more.
You did not mention ground temps, house info, grout mixture or anything so this is just a shot in the dark.

Dan

 

Dean thank you very much.. !!

 

Thanks very much

 

Wow! That is an average of 67'/ ton!
I wouldn't have tried that in coarse water bearring sand.

 

Nope this helps thanks

 

So what is the issue you are having with your system?
It seems like your having problems and don't trust your contractors or loop field.

 

I got a few replies from here to there.. which is all I asked for... there is no way that with the wealth of experience on this BB that this should be so hard .. it seemed like I was pulling teeth or something. Look I am not trying to be a smart A$$ but the Geo network in our Area which is the Okanagan Valley in BC Canada is a mess.. and I have snooped around on this BB and it seems others are having all kinds of issues as well. So I thought I would make a post out there sorta fishing.. seems I got some of the same attitude and elusiveness, (hence my black art cloud comment) that I have got from some of the local Geo companies.. some are no longer around..some are still around and what I know now is I know more than some of them.. I had a half A$$ friend of mine who did my drilling go belly up.. had 6 drilling rigs with full crews .. he was a full engineer etc etc but the down turn in the economy got him.. so the guy doing my tin bending got me up and running sorta .. not working ..not all his fault..



We have a 3200 square foot 1 level house with a 2600 square foot wrap apron deck .. we have been building it ourselves and we just moved in as of today ..after 4.5 years .. the house is concrete tilt up with 10" walls which we formed on site and had a tilt up crew erected for us. .. 2" concrete 8" foam.. but some portions have 2" foam and 8" concrete .. (strenght required for tilt up.. heaviest wall section was 22,000 lbs.. total wall weight 150,000 lbs ) concrete is to the inside of the house foam to the outside.. yes we have interior concrete walls.. so theory is I am hoping for some thermal mass .. we have 7" concrete floor with radiate 4 zone floor heating put on 6" spacing .. we have had a full heating and cooling load done .. by my drilling friend .. we have a huge amount of windows maybe 1/2 the house .. E glass 8 12 8 on some and 6 12 6 on others.. .. we are built on 70,000 lbs of steel hanging off a 45 degree cliff.. R52 insulation on the cantilever.. so pretty well heating and cooling every wall .. so wall insulation was est. at R20 I do have a curved roof portion that is R29 .. the rest is flat roof R40 ..



I am embarrassed to state how much money I have into the GEO system .. and it is an absloute mess.. my gut is telling me I am short a hole after playing with it..



The field is hooked to the following



Climate master GSW060AGC00CFCS (for under slab)\



Carrier 50YDHO72PCA301 ( FA ac / heat)



We have two 40 gallon holding tanks with plumbing which is not 100% right so it is all being ripped out and we are going to start over..



4 years ago I knew nothing about Geo and trusted way to many people... with the re-do I am having pressure gauges and also temp gauges put on every where..



Our temp range is plus 40 c to -20 C .. two months hot and maybe two months cold.. with the average cold being maybe -5 to -10 .. can have two months of plus 35 c the rest is average ..



We had a cold snap this Christmas and we stayed in the house .. thank goodness I went and bought a $250.00 NG construction heater to supplement the heat.. hooked it up on my fire place . embarrassing .



hydro cost here is for the first 1370 KHW .00670 after 1370 cost goes to .096 from Dec 1st to feb 1st burned up 7754 kw with the bill being 768.97 .. this with the heating strip turned off and also still running NG heater.. wouldn't mind paying that much for a warm house..



air temp out of register is 80-82 F I know low and slow .... but cannot keep up...but I know the whole system is wrong.. so will see what happens after the re-do .. my sons NG reg is 120 F



I am more than likely going to have to supplement the expensive geo system with some form of NG. the house is 100 feet long so I have the hot water system split in two and I am using a Nav instant how water at each end.. thinking about maybe using one of those to run a coil/condenser in my duct work .. or help with the under slab heating to help off load the geo system..



My brother in-law... 4500 square foot house Minus 30 .. uses an NG NTI ( NY Thermal Inc.) for his under slab.. domestic hot water , and hooked to a Hi-Velocity model # 150 .. once again NG .. 1/2 the price for heating than me so far... and probably 1/4 the cost to install.. one small box for the whole *%# house



I have a friend building a massive house and he is going to try the new Mitsubishi source air heat pump that is now good to minus 30 .. also had Geo before .. this was not available for me at the time.. I may end up still having to install one .. ahhhh..

NG is so cheap right now .. for us anyway.. some of you in the USA may not have access to it or as cheap as us.. but I could heat my whole house with this cheapo 50,000 BTU for probably 200 -250 bucks a month.. so as of right now I see no reason at all to go Geo .. in our area anyway.. power is going up and NG is going down.. yes this may change and yes when it was 9 bucks instead of 2.20 it may have been a good idea but not right now IMO..

I hate coming on a GEO BB and stating something like this .. but allot of Geo so called Geo guys do not know what they are doing.. they drill less holes than they should to try and get the deal keep the cost down.... they tell you no more NG bills or heating oil bills but forget to mention the HUGE power bills.. even worse when the heat strip kicks in.. and I have seen others on here complaining about high power bills as well so I believe I am not making this up ???

Sorry for the rant and please excuse the bad grammar and bad spelling.. and thank you to those that gave some input with out making a new poster feel like an idiot..

Just 100% frustrated with Geo!!

 

Ouch

You are in my area, sorta (I'm out of Kamloops). If you had supplied that information initially, you may have got an actual useful result.

There is no secret society here. But we are honest when saying your location (and all the other details we asked for) matters. I know all the other guys are now scrambling haven given you a guestimate and now finding out you're in Canada.

At the end of the day, the most useful piece of information you could supply us, is missing.

The heat loss/heat gain on your house.

I wouldn't move any further on anything until I knew that simple bit of information.

You could plumb and patch to absolute frustration and not get anywhere at the end of the day.

Your GSW unit for example: 3.5kwh x 720 hours/month x 0.07$ = $176/month if that unit ran full time, non-stop (which is highly unlikely).

Your Carrier unit is likely similar. So that would be the max bill per month associated with geothermal. You may get something like that if were running the equipment while the house was being insulated in winter. The additional electric costs are associated with supplemental heat coming or big screen TVs for all we know.

My gut tells me you have way more than enough capacity in the geo, including the units to heat your house. But that doesn't help if the controls, plumbing, etc... are not done correctly.

 

Well both units did run 24-7 .. hence the 700 power bill.. the math may work on paper but in real life I am telling you that is what I paid .. very little other power during the test two months so to speak.. have T5 dimmable Ballast lighting .. no oven and or the like was used.. actually used the Bar b- que for the turkey.. LOL ( on NG of course)


Part of the problem is what I am figuring is wrong size piping into the GSW .. so to keep the delta (right term? ) down between the return on the holding tanks I had to lower the under slab heating .. so forced air running way more than it should.. just a real mess all around.. hey I am not an expert or do I claim to be but the people I gave money to .. did .. and this is what I am dealing with now .. the home owner shouldn't have to teach himself on a Geo install .. this is all I am saying .. and if others are reading maybe they can learn from my very very expensive schooling!! For one ask to see 3 other installs and talk to 3 other customers.. first before go ahead and ask to see their power bill!!

 

Radiant plumbing

Just in case...

Your radiant plumbing supply/return feeds the buffer tank.

Your geo supply/return feeds the buffer tank.

If, by chance, your radiant return feeds in to the heat pumps, you are going to have problems. Conventional boiler guys tend to plumb geo this way and it is wrong. I'm not sure who did you instal, but your delta T comment made me think this may be the issue.

If you end up in town here, I can walk you through one of our mechanical rooms to give you an idea.