Kansas 2 ton vertical loop

Not having the best go of it with my new geothermal system. Two days ago when we had the first real cooling day of the season I noticed my entering water temp was 87 degrees in early evening. So today after system was dormant for a while I lowered temp setting from 73 to 71 to get the system running. It started with 60 degree ewt but in 8 minutes was up to 70 degrees and in 15 minutes was up to 74. Two 200 foot wells are drilled. Not sure if header pit done incorrect or grout not right but clearly seems like heat transfer is not good. Any ideas? Driller says it is system but I don't see how. Delta t set to 9 degrees on tranquility tev026.

 

I am just a homeowner,

First thing that comes to mind is, Was the loop flushed properly? It may only be utilizing 1 of the 2 wells.

ChrisJ

 

Would that really be the case if not flushed properly that it would only be using one of wells? How could that be but that does seem like it would explain how this thing has acted even going back to winter. It was installed in late winter so didn't have much heating time but eat quickly dropped from high 40s to low 30s in winter.

 

What does the pump think it is doing?

 

Not exactly sure on the question. The pump is set to delta t 9 degrees for cooling. It seems to be putting back out water temps 9 or 10 degrees higher than entering ones. If there is more specific info you are looking for let me know and I will get.

 

Can the system tell you how much water you are moving?

You need 3 GPM per ton of cooling, so you need 6.

 

Well this is the new climatemaster with vflow. You can set it to fixed and when I have set it to fixed at 90 percent it has been running in the high 4 gpm.

 

I do not think you are moving enough water. You are 2 gpm short running at a fixed 90%.

What happens if you let the pump do what it wants to do?

What size are the loop pipes in the wells? Are the wells 200' down and then back up? How are the loops piped together?

What is the dirt around the wells like? Did the driller make a log? Where is the high point in the loop system?

Mark

 

When vflow is on it varies but is usally in the 3's for gpm. Less than the 90 percent fixed. They are 200 foot down and up so 400 pipe per well. I think it is 3/4 inch hdpe but will double check. I don't know how the loops are piped together. I need to get that info. I don't know about dirt around wells. Don't know about log and couldn't tell you what the high point is so I have some questions to ask. Just he is being difficult and saying it is fine. But lines come back up a foot or so when entering foundation. I guess it is possible first well is sitting in a little bit of a u loop with house on one end of u and second well on on other end. Would that create flow issues?

The other thing I will add is water pressure differential in vs out is low. Would that indicate moving too little water?

 

Air will stop water flow in a hydronic system better than a ball valve.

The piping will give us the high spot. An air bubble there will stop most flow of water and therefore heat transfer.

Since you see the issue with your system and taught me about it, I think your driller may be more than difficult. He may not know what he is contracting to do. MHO

Mark

 

Your are certainly short looped, since your EWT swing from at least 60-87F means that not much loop is connected well to the ground. It is possible that the loop is locked due to air? But more information is needed. Lets do the math. If you have 3 gpm/ton flow, 6 gpm total, and you have 9 degrees delta T, and Heat rejection is HR=9F x 6 gpm x 485= 26190 BTU/h, assuming that your refrigerant circuit is performing as specified, which is likely, given the amounts of heat injected into the loop..
This means your have around 3.0 gpm/ton flow and are right on target. The 14F increase within 15 minutes would not concern me, but your loop going up fast to 87F that early in the cooling season is indeed disturbing. May be your grounting is not done well, your water level is very low in the borehole, or other things (air cavities for the grout...).
Where are you located? Did they drill in rock? how did they grout? Grout conductivity? Pipe diameter?

 

In spite of what your driller says, your loop is not working as it should. Did you hire the driller or did the HVAC contractor? Hopefully he will step up and make it right.

 

My vote is on air/grout. I can't believe 400' of utubes is not adequate for the load in any diameter. It is not the equipment.

 

I agree. My vote is also that you have air cavities due to not well done grouting. Some drillers cut corners by not grouting the entire borehole. Not saying that this is the case here, but obviously your geo pipe is not well connected to the surrounding ground.

It is weird that he driller points at the system, when the system is putting heat in the ground, what it is supposed to do, but the ground cannot handle it.....

 

I have some questions out to driller and will respond. The one thing I will point to is this is the climatemaster model with vflow so it is not always 3gpm per ton. The flow varies to achieve that delta t of 9 degrees. The flow has overall, not per ton, has been running in the 3's. I can set it to fixed and have done so but flow still doesn't seem to reach the gpm level it should when i do that. No drilling in rock and I am in Kansas outside of Kansas City. I thought they used a bentonite material in grouting but will confirm. I hope not poor grouting because air bubble seems way easier to fix. We will have some high 80's days later in the week and I will be paying attention to entering water temps during those days. Thank you for all the help.

 

If you have disabled the vflow and set it to manual max and you are still not getting the correct flow rate, my vote is for incorrect piping or a air bound loop, or a piping schedule that the vflow or circ pump can not produce due to friction or head.
Eric

 

The assumption was that the delta T is constant, and even at higher compressor stage the delta T is 9F. Even at less flow, 3 gpm, the BTUs rejected are similar than at higher flow. So low flow would not explain you quick swinging loops.
Your loop does not reject the BTUs to the ground, and swings quickly, meaning your heat transfer to the soil is not sufficient. Either one of your loops is air locked, not likely if you indeed reject around 26KBTU/h max. 3 gpm and 9 delta T give you 13 KBTU/H,, something you would expect a 2 ton unit would do in 1st stage. Even if one of the 2 loops is air locked, and running in low stage, one 200ft borehole to be enough. But that is not the case, your loop runs too high, too quick.

 

Thank you for that info. It does seem like it is a heat transfer issue more than flow. I will say it is harder for system to hit the delta t of 9 When ewt temps get high. Related to flow though I switched to fixed tonight and ran the unit. Fixed only lets 90 percent of max gpm and I would expect the system to run in the low 5s but seems to run in the low 4's most of the time sometimes getting a little higher when cool stage 2 is on. I measured the water pressure in and out tonight and they seemed really low. 3psi on the out and 5psi on the in. I took the digital gauge out to one of my car tires just to make sure it was working correct and it is. What should I make of these numbers? A 2 differential seems okay but those are very low psi numbers.

 

You need the cut sheet for your unit. There is a chart that equates the difference in ewp and lwp to the flow rate for your unit. another easy DIY diagnostic. I am curious what it will tell us.
Eric

 

Here is some info. Thermostat one is from last night after I ran the unit for a little while. Was on fixed vs vflow. Speed 90 percent of max setting. Psi readings I took seem really low. This makes it seem psi should be up over 50 in winter months at least and perhaps a little lower in cooling months not 5 and 3. What does the ft mean in the water pressure drop section of table?