Iowa Troubleshooting Hot Ground Loops

Hello, I will try to keep this short and to the point.

The Geo Install Is located in Eastern Iowa. There are 2 Geostar Geo units with QT flow centers installed in a restaurant (2000 sq-ft) built 2 years ago, One unit is 5 ton and the other is 6 ton. These units have never been capable of keeping the building a comfortable temp since day 1 so after a year, they added an additional 5 ton conventional to the kitchen. The kitchen and dining area are each 1000 sq-ft, the kitchen has the 5 ton geo and the 5 ton conventional, and the dining area has the 6 ton geo, the kitchen and dining area are semi separated. The original contractor is gone so I have no information on loop size or location, I believe the loops to be 80-100 percent covered by the huge concrete parking lot, I wonder if it is holding heat under the slab preventing the heat from dissipating.

Info for 5 ton Kitchen Geo unit

Geostar Magnolia Model YS060TL140CBDSSA

Closed loop Horizontal

EAT 75.8F
LAT 61.3F
EWT 121.3F
LWT 132.3F

Info for 6 ton Dining Geo Unit

Geostar Cypress Model QT072TR131CBDSSD

Closed loop Horizontal

EAT 72.0F
LAT 56.3F
EWT 110.3F
LWT 122.1F


I can't believe its not kicking out on high head. What do you guys think? Let me know if there is any other information I can get. Thanks in advance.

 

My guess is that it is just bad building load calculations. The contractor didn't know how to do occupancy loads, equipment loads, building schedules, etc for a restaurant. So you're undersized. Definitely undersized on the loopfield.

Are those numbers kicking around?

So, add more loop capacity or look at conventional support.

 

Dito Chris here. For sure your loop is not big enough, but likely your equipment also lacks capacity. By adding more loop, your efficiency will increase, but also your cooling capacity.

 

The numbers do not ever seem to change. If I shut the units down for 24 hours or so the loop temp only drops 20F. I don't think there is a way to add more loop capacity without busting up lots of concrete, especially since no-one has a clue where the loops are even located. I have thought about trying to cool the loop with some sort of radiator with a fan or maybe connect the 2 loops together and try to use it for the 6 ton then swap the other geo out for a conventional. Do you think these are viable options ? Do you think 16ton is enough for a building this size and use? I know there are alot of variables that come into play but based on similar sized restaurants open 6 days a week Thanks

 

For a system like this, your equipment run time is likely what is killing you. Your loops are not recovering because your equipment runs (let's make a number up) 16 hours a day vs. 8 hours a day.

So you could figure out a way to only let the equipment run 8 hours a day and put it back in play, but that gets hard to do without a duplicate conventional system that can meet full loads as well. You can figure out a way to cool the loops but most often, the "cooling" is best directed into the load (building) side vs dumping it in the loops.

If I inherited this, I would likely go with a conventional cooling system that was triggered off the loop EWT. Or an aquastat that cut out the geo at a certain temp. Some seasonal monitoring would allow one to adjust this all better by watching run times and water temps to determine how best to stage things.

 

Makes sense, Could I put a conventional A-Coil in the plenum of the geo? So I could use the same blower and ductwork? Then just trigger the conventional from the EWT like you suggested. Thanks for the help, I appreciate it.

 

I've never actually added an A-coil after the fact, so judge accordingly. But I believe it has to be downstream of the blower. Upstream will cause a significant amount of condensation/moisture issues on the heat pump.

 

How is your hot water made? We use a w-w heat pump to make all the potable hot water for the restaurants. That takes a significant amount of heat out of the loop, and actually allows us to size our loops much smaller.

One would have to examine the pressure drop etc, but it might provide an option for you.

http://welserver.com/WEL0714/

Here is an example. The building has 4 restaurants, all on geo water.

 

Yes. As above. Running the heat pumps in heating may be the most effective way to "cool" the loops.

But some monitoring of the system would help determine an effective course of action. If the loops react quickly vs seasonally and so forth.

 

It is all about load. Add up all your heat emitters and add 650 btuh per person sitting still. Get them drunk and dancing add more. Do not forget the service staff, if they stand around 650 each and plan on closing soon.

Mark

 

Use the loop through a heat exchanger to heat the building water. Good Idea, I think they currently have an tankless water heater tied into a heat exchanger tank which is used for in floor heat in the winter. I will be curious to see what the loop temps do as the season changes, what are some typical loop temps and how do they change as the season changes? The restaurant has 20-30 people in it for 10 hours a day 6 days a week, no Alcohol or dancing.How do I go about calculating the emitters just go from the wattage? For some reason they installed the walk in cooler and freezer completely inside, I was planning on relocating the compressor and core outside. That will remove a good amount of heat from the building.

 

Watts will convert to BTUH or you can convert BTUH to watts/amps.

 

I was more referring to adding an additional heat pump for potable hot water.....to take heat out of the loop. Yes, compressors to the outside in a shed.
Also check how the make up air for the kitchen is brought in.

 

1 watt = 3.412 BTUs per hour. Once I find the total Btuh then how does it relate to the btuh of cooling that is needed?

Can you recommend a HP to do this with and how does it tie into the potable hot water? The makeup air is brought in, in front of the vent hood with a vent at each hood section. Any other things to look at? Anything I can do with the dishwasher and the steam it puts out when it is opened?

 

You probably want to use a high temp Waterfurnace (optiheat or dual compressor) or Geostar (which is a different brand made by Waterfurnace) to get your water to 130-135F degrees for the restaurant.
What you need even more is a skilled designer who knows how to play well with the cards he has with your current setup. Combining the loops for more flow, central variable speed pumping and indirect passive hot water tanks come to mind.

In terms of heat and steam, the best way to deal with it is to suck it out to the outside!

 

A 2000 sq ft building that is never kept at the right temperature with 11 Tons of Geothermal and an additional 5 Tons of AC in the Summer.

Since the owner didn't say the building is fine on days that they are closed, then the cooking and people load aren't the problem in the Summer. These two loads would help heat in the Winter, but the building is not at the correct temperature in the Winter either.

Based on the Water Temperatures, it appears that the 2 Units are in series using the same water loop, with the 6 Ton LWT at 122 feeding into the 5 Ton EWT of 121.

Since the Units aren't tripping due to low flow, I would say adding a New correctly sized Loop for the 6 Ton, and using the unknown loop size for the 5 Ton Unit would be a good start.

Did anyone else notice that these units appear to be in series on the loop side? The heat appears to be more than the parking lot loop can handle.

 

They each have a separate loop, I thought that they may have been improperly purged so I hooked a flush cart up and there is 2 loops for sure one for each unit. It doesn't change on the days they aren't open. the water temps are always within 20 degrees of the number I posted. I haven't had the opportunity to monitor the loops in the winter so I am interested to see what the numbers are.

 

The dining room has a Cypress unit, which is like a Synergy 3D from WF. So it does radiant water heating. Add an indirect type tank and make hot water...

Is it possible the ground loops are not being fully utilized? Partially air bound?

I had to submit an "as built" diagram of my ground loops to my building dept.

Edit: posted before I saw the last entry.

 

The Cyprus radiant water heating aux pump is hooked to an indirect tank already for the heated floor in the winter. It isn't being used in the summer though and that could attribute to why the Cyprus loop is 10 degrees less because it's heating the indirect tank.

 

As Arkie said, you can hook up an indirect hot water tank, but keep in mind that it can make either hot water or hot/cold air. 2 reversing valves will have to move inside the unit every time you switch back or forth. It might not help your cause if the unit makes hot water for 30 min each hour, and during that time you don't have A/C in the restaurant. Better would be a water-water heat pump dedicated to make hot water during the same time when the A/C is running. Best would be one for each loop. It might be well worth it, giving you current gas use for the amount of hot water you need for the restaurant.