"Shallow rock" affects vertical loop's capacity to heat?

Our driller gives us the cheapest quotes when he can hit shallow bedrock quickly. That way he has to do only minimal casing in the overburden. Rock has the highest conductivity, mandating shorter boreholes. Let me say this very clearly: In Western NY drilling into the bedrock costs the least per running ft, plus one needs lesser total ft because the conductivity is higher than in the overburden. It appears that the BS continues...

 

I do not know what I am going to do with all my spare time once this is resolved.... I think things like this PE slip-up of putting the REAL issue in writing (money, not the impossibility of getting through the bedrock) are going to hasten the resolution. Time will tell.

 

This ONLY applies when the driller is set up for air rotary and is expecting rock and anticipating the need for casing. If the driller is expecting a much deeper rock and using mud rotary drill then there is a difference.
A mud rotary drilling rig is set up to drill soft formations quickly... If rock is encountered then drilling is slower and typically requires different bits and more labor
The price for mud rotary drilling here in NJ is a good bit $/ft cheaper than air rotary ( rock drilling).
When rock formations are hit then use of a cement based grout is also required here in NJ too and is more expensive than bentonite based grouts.

 

This is what MNGHPA says, so I think that in MN drillers expect rock and the need for casing ( or they should be):

Also, on rock-bored applications, Minnesota law requires that a permanent well casing be applied to each borehole along any “unconsolidated” overburden (soil) between the bedrock and surface. While a casing is not required in unconsolidated only formations, depth to bedrock can often make or break a vertically-bored project due to cost.

 

Your statement about depth to rock is absolutely correct about make/break geothermal installs.

 

In Tamar's case, the driller had good knowledge of the geology, was already setup to air rotary, and obviously drilled through shale and bedrock, did the casing and used different grouting in the rock versus the overburden. In her case, there was really no reason not to drill deeper if more capacity is needed. Plus the PE's explanations is lame. It is absolutely normal in residential application to install, in residential applications, a system covering 98% of the load with geo, and use supplement heat for the remaining 2%. If I quote a system I make sure it is designed to work as promised. In Tamar's case, it appears that they started to cut a corner after the contract was signed.

So in her case, the driller appeared to have done a good job, but was simply installing the capacity requested by the installing company. They proposed an 8 ton system to her to cover 98% of a 95,000 BTU/H heatloss. They installed the 8 ton equipment, but now claim 2 years later that it was never possible to install the correct size loopfield supporting her load. Now the consultant to the installer chimes in and claims it would be a waste of money to have installed the correct size loopfield (after she invested $60K) and she should go back to have a large portion of the load covered by gas again. What am I missing….????

 

It amazes me in this information age that some arrogant jerks still thing they can BS somebody. Way better to say I don't know or even; no comment, the other guy employed me and you are case building.
On another site a PE insisted it was irresponsible for anyone to recommend a system that was not designed by a PE. This case was cited as an example where a PE definately did not help.

 

It's funny and little scary that I am holding my own (at least I think I am) arguing with the president of a big engineering firm.

Here's his latest boast: 90% of the vertical well fields that I have designed in MN are above the bed rock. I even designed where there are 2 loops in series to 150 feet to stay out of the bed rock.

To which I replied:
That's great, but do you know that rock has much better conductivity than unconsolidated material, thus allowing for shorter loops?

 

"Here's his latest boast: 90% of the vertical well fields that I have designed in MN are above the bed rock. I even designed where there are 2 loops in series to 150 feet to stay out of the bed rock."

This makes no sense. If he needed five 300' bores but rock was at 150' so he had to punch ten holes for the same amount of pipe in ground. Why would he put them in SERIES to create five 300' loops??? All he is doing is increasing the amount of pumping required to move the fluid.

Bergy

 

Really all he is doing is hanging his a$$ out in regard to how little of his cranium is filled with real geo application knowledge. I am sure he also has years of drilling experiance.......... Just more people who love to have meetings about meetings, worthless use of time IMHO.
Eric

 

If he knew enough about Geo loop fields he would have "designed" those differently also.
This is the classic engineer, over engineering something he possibly doesn't know enough about.
A little book smart knowledge is a dangerous thing (so is internet access too).

 

He is listed on the IGSHPA website as an A/E and CGD....

Dan I know you just said internet access can be a dangerous thing, but it certainly came to my rescue. Thanks again everyone for getting me this far!

The Climatemaster district manager is paying me a visit on Wednesday. He lives in Indiana, but is in town for a few days. He may bring the local distributor. I'm not sure what the outcome will be, but I am impressed that he wants to come.

 

I had a realllly bad experiance with the CM rep for the mid atlantic. That being said, stay positive, document everything and if possible record and witness their visit to your site. More data collection can only help everyones position at this point.
Eric

 

Thanks for the advice, Eric. Since I work out of my home, I will be hosting the visit and acting as tour guide. I'll make sure to take good notes.

The Climatemaster district manager reached out to me after hearing that I had started some discussion posts on LinkedIn that generated lots of interest, concern, and advice. He wants to come over and review the installation, even after I confirmed that the equipment itself wasn't likely the issue (though the breaker on the W2W is pulled because of the current control strategy). I think he is concerned that an installer would recommend removing the equipment.

I probably would not have taken notes without your advice, but given your experience I'll make sure to have pen/paper handy.

 

It will be very interesting to see what the CM district managers take is on all this, especially when the equipment is rebadged Carrier. One more level of separation from the customer?

One point I must bring up here is the misguided application of the HiTemp W-W in this installation. With CM claims of 145F output many specifiers jumped on board to apply this unit for higher temp systems. In reality, entering load temperatures are not any higher than 130F according to the spec catalog. In this case the highest system setpoint at the buffer tank would be 130F. This is not much higher than a typical W-W HP. Also, with 30F source temps and 130F load temps, capacity falls to just over 2 tons with a 2.1 COP with no higher capacity models available.

In this installation with an estimated 7.5 ton load and 2.17 ton unit capacity minimum, the HiTemp W-W is not going to do much when hydronic (radiator) priority over the forced air system is expected by the customer.

I believe that unrealistic expectations by the installer in the capabilities of the Hi-Temp unit is the failure here.

 

I believe Carrier refers all geo questions/issues back to CM. I did try to call Carrier's customer relations line about a month ago and was given CM's number when they heard that I was calling about geo units.

One email from the CM dist manager before we firmed up plans for him to visit mentioned they might have a different unit that would be "better suited for this application". I do not know which unit or what happens if there is a unit deemed better suited.

 

It is all about piping and what the radiators will radiate. Think BTUH.

The piping from the loop field to the machines must be correct.

I, like others have stated here, think the loop field can do more than it is doing. I will do the work after the lawyers are done.

While this goes on Tamar and her family are uncomfortable and spending more than they need to spend to not be comfortable.

Mark

 

Be aware, district managers are sales and marketing people, and might have limited technical understanding. I am not aware of a unit in the Cm arsenal which would be better suited for your scenario.

 

Thanks, Doc, I will keep that in mind. If the high temp has a poor COP when run at the highest temperatures, and the TMW medium temp units come in multiple BTU sizes, might a larger medium temp unit be better than the 3 ton high temp unit?

 

I agree, a 5 ton medium temp would have served you much better than the 3 ton. However, you would then need another unit to cover you for temps above 130F as a second stage. Yes, you have the 5 ton split, but now you don't have the flow and the loop to support you with 10 tons of heat, as least as far as we know now.