Large heat pump project

Jim McLimans

It's been awhile since I've been to the wall so first of all a big hello to all. I am reponsible for the HVAC systems for a school district in eastern PA. Our high school (150,000sf) is not air conditioned and the troops are getting testy. An engineering firm has done a facilities study of the building and is recommending going to geothermal heat pumps in every room in the building. Using a closed loop system to a cooling tower (no room for the required wells) for the water, Does anyone on the wall have any experience,knowledge of such installations and any thoughts good or bad. All comments appreciated.

tim smith_2

cooling tower w/ water source heat pumps

Yes, have many we worked on over the years, ps not geothermal unless using ground loop. Positives, units tend to last long time, quite efficient. If most are same size then parts can be standardized. Negatives, need to keep up with chemical treatment for tower. Cleaning tower and heat exchanger can be tedious. But overall I think they work great for multi room larger projects. ? you don't have room for vertical bores for ground loops?

Ranger

Well Jim...

...yes I have,and here is what I can tell you from my experience..the chassis style units (Commandaire/Trane,McQuey,Nesbitt etc.)seem alittle noisy to me especially in a classroom environment in my opinion)I have done alot of work in buildings in the past with packaged heatpumps in the ceiling/mechanical closet (EDPAC,Climate-master,Florida Heat Pump,Comfort-aire,McQuey/American Air Filter etc.)and as long as thay are installed w/service & swap-out access thay are o.k.I've had troubles such as constant iron & welding slag build-up in the co-axial heat exchangers (steel pipeing),I had the same building shake like a dog poopin'razor blades (the tower is on the roof,the building is located right on the ocean and the salt got to the tower fan shaft..Big chunks of the shaft flaked off makeing it very out of ballance ..got 2 see a 150 ton tower dance atop a 12 story bldg.),Had 8" pvc sag in another building after the tower pump lost it's prime due to an underground obstruction in the pipeing (the tower is 100' from the building,what's that high water temp.alarm for again?)Went once to 4 story building w/no means to temper the water in the winter.(normally use an electric boiler to temper the medium water to 65-70F in these parts of central N.J.)had a school in South Jersey that had a thermal ice bank system (brine tanks) which worked well al long as the chiller ran all nite
makeing slush (The chiller was n-o-t large enough though to meet the cooling load if it did not ...)Mostly I have found the building pipeing/pumps not sized correctly as a general observation (never enought flow for all the units to run at once.)And constant maintenance is a must.But other than that...I would suggest keeping some spare units if posible. (for swap-outs)thay are easier to service (change compressors etc.)in the shop than in the ceiling or in the chassis in the classroom.
Ranger

S Ebels

My experience has been

If you can't do some kind of a closed loop system, IE; ground loop or vertical, stay away from it. Constant, and I do mean CONSTANT maintenance issues and parts replacement. I wouldn't want your job if this system is installed. A little too much "job security" for me.

Caselli

an actual cooling tower ?

I'm thinking they don't mean an actual cooling tower where the water enters at

the top and flows downward against air flow and is cooled by (mostly) evaporation.

I think when you said "closed loop" that is what you meant. We have a system that is a closed loop water source heat pump. It has a "fluid cooler" that wastes the heat outside. No open water.

In our case, it cools only. Otherwise there would also be a heat source to temper the loop in the winter.

Great concept. particularly in the case where, as it sounds in one of the replies above , you combine it with storing chilled water at night time off-peak rates.

Some repairmen don't like heat pumps, but they are efficient and flexible.

Ranger

S.Ebels

Right on!!

Jeff Lawrence_24

WSHP

One of my first maintenance jobs was building engineer in an 8-story building that had 72 water source heat pumps in it.

At first, it was a little daunting, but I got the system figured out (The chief engineer handed me the keys and said 'There it is.') I had a cooling tower on the roof that had a HX coil in it. The real name of the style tower was a 'solution cooler.' There was also a boiler in the penthouse and the 2 worked together (sometimes) to maintain a water temp range that was suitable for the heat pumps in the building.

Once I started setting up a PM schedule and got the tower cleaned (with regular water treatment), the bad elements in the electric boiler replaced and the dead band in the closed loop set so the tower and the boiler wouldn't be on at the same time, life became good.

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Jim McLimans

Thanks for the opinions.As always the wally's come through again. I have a feeling I going to end up with this type system so I appreciate the info. I have all the normal commercial systems already, Rooftop air handlers with DX cooling, Fan coils with chilled water, conventional air handlers with outdoor condensing units. I'm never opposed to new technology but feel more comfortable when there are known systems that do operate efficiently and correctly.
I don't like being a ginny pig if you know what I mean.

Oh, and by the way. I was refering to a closed loop cooling tower. Not open to the atmosphere.

Jim