sure sounds like you need a few more loops... or larger circulation pumps.
John

You didn't mention if this has been going on since day one or if it just came up all of a sudden. I'm assuming your repair guy is a competant individual with vast knowledge and experience with your type of system. If he is just a regular everyday handy andy repair guy thats your first problem. If he is in fact an honest to goodness HVAC tech and he's been stumped this long it is time to call in the manufacturing reps. It'll probably cost you but one would tend to think that after 5 years of aggrivation it would be worth the money.
Was the system engineered and installed to specs?

Re: swattdoc

Do you mean 30ºf or -30ºf? What are the minimum specs for ELT & LLT of your GSHP?
What Âfixes has your repair guy tried; how qualified is he? Is your repair guy your installer? Have you contacted the manufacturer directly? Has the antifreeze level in the loop fluid been verified? Have the systems been flushed, purged and pressurized properly?

Sounds more like it maybe a problem related to Freon charge level than whatÂs going on in your liquid ground loops though. Start by changing your Ârepair guy and speaking with the manufacturer.

What make & models are they? If youÂve been having this problem right out of the box with BOTH HPs, then something is probably wrong with the original installation. Your system should be ÂIDILINGÂat 30ºf!!!

Where are you located? In Pa we usually use somewhere around 150 ft of borehole for each ton. So for a 6 ton house 900' would be typical. You have 1050 ft. Each area has a little different geology though.
In the winter time you are removing heat from the loop and then the earth is supposed to warm it up. What you are experiencing seems to indicate that you are removing more heat than the earth can replace. In cold climates electric heat is usually needed to supplement the geothermal but you didn't mention that.
Having someone confirm water flow and refrigerant levels is the first step.

fsq4cw wrote:

"Your system should be ÂIDILINGÂat 30ºf!!!"

Not necessarily - it depends what the design temperature was. If the unit was sized with 30f outside temperatures then it should be running continuously at that point. There wouldn't be any point sizing it for 0F if his climate doesn't get that cold - if it was sized that way then it would probably be oversized for cooling. The only way to know is with a proper load calculation. He did say his house has no insulation - it could be that his heat loss at 30f is of the order of 70kbtu/h.

He should check to see if his system can be configured to work with sub-30f loop temperatures - my systems have a jumper which sets the leaving water temperature alarm point at either 32f or 10f - we have ours set to 10f. Of course, a "3 ton" system won't have a full 3 tons of heating capacity at an entering water temperature of around 30f. I'd definitely check to see if his system has these jumpers. Sub-32f loop temperatures are fine so long as the circulating fluid has antifreeze in it.

Paul in Montreal.

Problem has been with me since day one. The hvac guys come out and say its a loop problem and then the loop guy attempts to fix it by : Checking antifreeze level. Adding water to loop. adding valves to prevent backflow. At one time I had the system hooked up to my water heater drain and was told to add a little water when the system would shut down. This actually seemed to work. So then I was told I had a leak. They replaced all the connections they could access but it still kept shutting off. During this time (2001-present) I was never charged for the work performed. This year I decided to switch companies. (I am wiiling to pay someone to get it right) They did a flush fill put something in the water to seal any leaks and checked the units. They were also stymied. I then showed them some picture of the loop setup that I took during construction. They said it looks like things were hooked up improperly. something about "first on last off" as the principal that was not followed. They state that they either need to dig up and change connections or add pumps. The guy said he would talk to the engineers and get back with me. I'm still waiting.
Thanks a lot for everyone's post. I can email pix of the loop configuration to anyone that's interested.
Thanks again.
Tom
I'm in southern Indiana. And the loops were placed through limestone bore holes. we hit stone after about 30 feet.

A picture is worth a thousand words. We need to see pictures. If you really have that much hole. and the metrics are the same as stated, then somethin is wrong.

Send picts to the experts to get the ball rolling. I am not an expert on geo. I am an advocate.

First find (and hire) an installer through the link below. Tell them you Âthink your ground loops are hooked up in parallel. Ask them if they know what a Âreverse return header is; if they donÂt, thank them very much and keep calling till you find an IGSHPA installer who does (they all should!).

SR

Here is a link that might be useful: International Ground Source Heat Pump Association (IGSHPA)

It should be very simple to determine if you have a leak. You have a closed loop system. You should not have to add water to your system. I am assuming you have an expansion tank. Close any make up water connection. Check your loop pressure and write it down with the date. Check the pressure every few weeks. If your pressure starts dropping you have a leak.
It's quite possible the wells aren't piped correctly and you are not using all the wells.

here are some pix of the loop connections.

I do not have an expansion tank.

My installer was listed on the IGSHPA web site.

Thanks again for everyone's help.

Tom

Here is a link that might be useful: Loop Pics

From the photos, it really does look like the loops are hooked up in parallel. If this is the case, no wonder you're having problems.

Paul.

Re: pyropaul

Hi Paul, from your comment, are we to infer that parallel loops are inherently problematic; if so, why?

Re: swattdoc

Just a comment and a question regarding your pics. Are your headers the same diameter all the way through? I canÂt tell for sure from the pics. It looks like there is some reduction (as there should be). My comment is that sharp right hand bends should be avoided where possible.

Your installer should be able to puzzle your problems out. Keep us posted.

Steve

Steve wrote:

>> Hi Paul, from your comment, are we to infer that parallel loops are inherently problematic; if so, why? Water flow is very much like current flow. If the impedance of the parallel branches is not the same, then current (i.e. water / antifreeze) will flow preferentially in the loop with the lowest resistance. This is almost certainly not what is wanted and could explain the low fluid temperatures the original poster complains of. If most of the flow ends up in one loop, it will be "overloaded". To guarantee equal flow in all the loops, they have to be in series, though, of course, the pressure required to drive the water will be higher due to the greater overall resistance. The electrical circuit analogy is pretty much perfect for this kind of fluid flow.

Paul.

Paul,
Can this be remedied with more pumps or do the piping connections have to be redone?

Thanks,
Tom

Re: Paul

Paul, I disagree with your analysis. True, lower impedance will result in higher current draw, however, in an electrical circuit you certainly can have parallel branches feed from the same B+ drawing virtually the same current irrespective of their position relative to the B+ power supply.

The same is entirely true for parallel vertical ground loops. A properly designed header is a self-balancing manifold so equal flow is achieved in each borehole. Large commercial, industrial or institutional installations are invariably parallel installations. Series would make no sense on many different levels.

True, to split hairs, if you measured current draw in an electrical circuit with a Fluke there would be nominal differences in the micro or milliamp range, but in the real world they would be irrelevant. The same holds true for parallel ground loops, probably measurable but in reality irrelevant. Personally, for any system 3 tons or larger, I prefer parallel.

Steve

Re: swattdoc

A number of things trouble me about your installation. You seem to have leaks for one. Second, living in southern Indiana with 175-foot boreholes (ground temperatures near the mid 50Âs) and outside air temperature of 30ºf, how are your loop temperatures dipping into the 20Âs? Has the flow rate and pressure head been verified? Has your loop pump been thoroughly (internal visual if need be) inspected? Are there air pockets in your loops? Have your compressor and refrigerant circuits been verified? Is everything that should be, insulated and covered in Armaflex? Is the system drawing current according to specs?

Describe in greater detail your two Âsplit systemsÂ. What make and models as well as the nature of this Âsplit arrangement; pictures could be helpful.

I would contact the engineering department of the manufacturer of the heat pump myself and solicit help finding answers.

SR

As someone said you need to verify the flow rate of your ground loop. Your piping layout is not be ideal but if your flowrate is low than it will make the issue worse. You can post the model of pump(s) you have.

Steve,

parallel loops work ok if the resistance of each loop is about the same and, as you correctly observe, do work fine if installed without problems. The main problem is that if there is an air lock in one or more loops, it will not necessarily be obvious, particularly if the pump is designed to give constant flow rate. This may be the problem the original poster has. In a series-connected set of loops, if there was an air lock, it would be obvious and hence easier to diagnose.

Way back in the 1970s in the UK my parents had a hydronic heating system installed that had two sets of manifolds (one for each floor) and parallel sets of radiators connected to the manifolds with microbore copper tubing. Some of them were prone to filling with corrosion products, greatly reducing the flow with the end result that some of the radiators were barely warm. The boiler happily circulated water overall but the heating performance wasn't as expected. The geothermal loops are the exact mirror image of this system with the loops acting as collectors, not radiators. It really sounds like one or more loops may not be working efficiently (i.e. collecting heat) and hence the overall circulating fluid drops into the 20s. Doesn't matter what the ground or air temperature is - if the load demand exceeds the capacity of the working loops to supply the heat, the loop temperature will drop until the heat extracted falls to meet the supply (via a reduction in the COP of the heatpump as the circulating fluid gets colder). In fact, this information may help diagnose how many loops are not working correctly.

Paul

Here are some further pix of my system. Split system - airhandler remote from compressor.
How do you determine flowrate?

Tom

Here is a link that might be useful: geo system

"How do you determine flowrate?"

This should be determined and measured (and logged) by your professional installer.

If proper procedure is followed during purging and flushing all air will be removed from all loops; this is science. It is always advisable to have the installer complete a fully detailed log or journal (sometimes found in the back of the ownerÂs technical manual) of this and all other start-up procedures, that the owner retains. This will provide a road map of what was done and how it was done. It is also a baseline for future measurements and diagnostics. Anyone buying a geothermal system must insist on this!

TomÂs system obviously has a problem(s). ItÂs also possible that a blockage or air lock is contained within the liquid to refrigerant heat exchanger inside the heat pump. As a last desperate measure, the headers may have to be dug up and have the loops disconnected to be purged, flushed and pressure tested individually. This is rather a last resort.

When purging and flushing is done of the TOTAL ground loop system it is important to isolate the ground loops from the heat pump and purge/flush them as independent and separate systems (ground loops, heat pump) so as to NOT bring up debris (such as HDPE shavings) that may lodge in the water heat exchanger contained within the heat pump.

Tom  log and document every procedure, every measurement! TAKE DIGITAL PICTURES OF EVERYTHING! That includes clear pictures of ALL meter readings.

Tom, take heart, this can and will be resolved. You just need the right professional with the proper training, experience, motivation and curiosity.

SR

So, what is the official consenses, is parallel ok, if you don't have a way to verify the individual loops, or does the system need to be changed to series.

If you change to series then the flow will decrease, which will reduce capacity. If you don't have a way to check individual loops, then you don't know the efficiency of the system.

We saw 2 supplys and 2 returns. Is this typical installation, or did the contractor go cheap?

When using multiple wires to increase ampacity, it is not recommended because there is no guarantee one wire is not overloaded. In theory the electricity will flow equally thru both branches, but in practice not always so. I can see a potential issue, of not having a bleed control that you can observe for each line. There is no way to tell if a loop is bad. I would expect the manifold to be accessable. This looks to be a quick and dirty job, that needs to be repiped. Ok experts, give some opinions.

Re: bob brown

Hi Bob, IÂm glad to see youÂre paying attention.

"We saw 2 supplys and 2 returns. Is this typical installation, or did the contractor go cheap?"

Your answer is in the 1st sentence of this entire thread.

"I have two split systems each 3 tons. Running off 6 vertical loops of 175 feet each."

They in fact did what you suggested in another thread, 2 separate systems.

"RE: Geothermal Question: split system requires two sep. wells?

Posted by bob_brown (My Page) on Mon, Mar 19, 07 at 20:11

In my area, N. Texas, each hole is drilled for a ton of btu exchange. 250 ft per ton. If you have a 3-ton system, you would drill 3 holes. Different areas require more or less depth. Each system should be seperate in case of failure."

If you carefully examine the photos provided in the above link, you will see 2 separate
systems with 2 separate loop pumps.

Parallel is the preferred way to go, in my opinion. One of the 1st things that has to be done is get a qualified installer in there with the proper flush cart to flush and verify flow rate  with the cart! This should Âreset the ground loops should there still be trapped air or debris. If there is still a problem, additional measures will have to be taken as deemed appropriate by the professional on site.

As you correctly pointed out, reconfiguring to series would be inefficient and non-advisable at this point  even if additional boreholes were drilled! The solution lies in solving the problem(s) at hand. Tom may even have the additional advantage of having 2 separate systems on site where comparisons can be made.

Bottom line Parallel is the way to go; BIG FLUSH CART REQUIRED! Flow velocity of 2ft/sec required at flush cart. Professional has to determine just how many GPM are required to achieve this flow rate. I suggest starting here if all else checks out.

SR

Thanks for all the help. I'll be contacting Trane and see if it can't be straightened out. I'll let you all know the results.

Thanks again

Tom

The picture says the loops are fused into the manifolds in the wrong order.

Here is a link that might be useful: Geothermal Heating and Cooling Information

Tom,

I have to agree with many of the replies you have recieved. I am afraid that Trane most likely will be of no assistance, telling you to contact the installer of your system. While not being truly able to get a good idea of the installation of your system your freezing problem stems from your loopfield. I have seen this problem with undersized systems before. How big is your home? What type of soil do you have. if you have soil that is sandy that will affect the size of your loopfield. While your house may be 6 tons, depending on your soil type you may have required a larger loop field. You see freezing like you are describing with an undersized loopfield. Also, while reverse return headers are ideal, it is not unheard of to install them in parrallel. Reverse return is the preferred method of loopfield installation and used by most installers. I would recommend you get a copy of the design that your installation company did for your particular project because not every system is identical. Even small oddities in your particular project could have a huge impact on the system design. If a system design was done at all.

Tom,

I have included a link to my blog. It discusses propylene glycol antifreeze, among many other topics, and how it is included in the system design for loopfield pump calculations etc.

Dan Frawley
Eagle Mountain

Here is a link that might be useful: Eagle Mountain Journal

Hope this is not too little too late.
In limestone, you have to pay close attention to the thermal conductivity between the pipes and the hole edge. It sounds like they may have used a low efficiency grout/silica compound or, even worse, just put sand down to fill it up. Huge difference in thermal conductivity here.
The other thing to check is leakage at the U joint, which is at the very bottom of the coil where the two pipes join. Unfortunately, this joint is so tight a bend that standard butt or socket fusion equipment can't seal the joint and even electrofusion here is iffy. Many contractors just glue this piece on and it leaks.
Just a couple of likely possibilities here and both are horrendously expensive to fix.
Anyone having an installation done should be aware of this though.
Hope this was helpful to someone.