HVAC trouble in a 2 story commercial building

[richard.bessey]

again did you check pump gpm? the problem may be a fouled heat exchanger

No, we have not been able to check the flow rate from any of the pumps. There is not fittings on each side of the pump to plug into. To install fittings, we would have to drain the tower and the main loop. Something I hope to do when it cools down.

I agree we may have a fouled heat exchanger, but at the current moment the only thing I can measure is amps going to the pumps.

On the main loop side, I did notice we have a pressure guage on the supply and return. They are showing 33 PSI supply to the building and 22 PSI return from the building, so roughly 11 PSI drop through the building loop.

[Chris_Worthington]

All,
I was hope full to get some feedback how to best proceed.

Building info
The building is a commercial building that has a cooling tower out back (open loop with plate heat exchanger) and has a closed loop of glycol that runs through the entire building through plastic pipe.

Your running on borrowed time "if" this truly is the case. I have seen several times where the water stops flowing, the WSHP's keep running, The PVC has a melt down and the next thing you know your stairwells resemble the Niagara Falls

I would get a handle on preventing such an occurrence

[richard.bessey]

The PVC has a melt down and the next thing you know your stairwells resemble the Niagara Falls

Thank you for the advice, I really appreciate it.
We already had this happen
We had a pipe burst in a large conference room, all 100+ gallons of glycol drained in our conference room, it was quite a mess.
The suggestion has been brought up to replace all of the plastic pipe with copper, problem is the price. I imagine it would cost us $100,000 or so to replace all of the pipe with copper.

[Chris_Worthington]

Thank you for the advice, I really appreciate it.
We already had this happen
We had a pipe burst in a large conference room, all 100+ gallons of glycol drained in our conference room, it was quite a mess.
The suggestion has been brought up to replace all of the plastic pipe with copper, problem is the price. I imagine it would cost us $100,000 or so to replace all of the pipe with copper.

100+gallons you lucky bastard !! I have seen thousands of gallons land on, well nothing water proof and it all cost a ton to replace, not to mention the man hours billed.

100K sounds like an investment to me, but lets say things are tight....

Have flow switches installed at each and every last WSHP, Interlock your EMS (should you have one) with flow, temps, etc..

Best way to go though, as I am certain you already know, go with something that does not melt when bad things happen

[richard.bessey]

What is:
WSHP?
EMS?

[Chris_Worthington]

What is:
WSHP?
EMS?

My Bad....

WSHP = Water Source Heat Pump/Could be AC only in your case? (same result though)

EMS= Energy Management System

[richard.bessey]

Ah, I think I now understand.
Basically your advise is to have sensors and controls in place, should a leak/malfunction happen, shut down systems and waterflow to reduce the amount of damage, correct?

We really have no central monitoring of the heat pumps. We have one honeywell controller that controls wether to run the cooling tower or boilers based on the loop temperature.
A then small controls on the boilers and cooling tower to control the pumps/fans/burners on those units.
The heat pumps are stand alone units with thermostats and simply put heat or cold into the water, depending on demand. Its a very simple, yet complex system.

Again, I really appreciate the info you provided.

[Chris_Worthington]

Ah, I think I now understand.
Basically your advise is to have sensors and controls in place, should a leak/malfunction happen, shut down systems and waterflow to reduce the amount of damage, correct?

We really have no central monitoring of the heat pumps. We have one honeywell controller that controls wether to run the cooling tower or boilers based on the loop temperature.
A then small controls on the boilers and cooling tower to control the pumps/fans/burners on those units.
The heat pumps are stand alone units with thermostats and simply put heat or cold into the water, depending on demand. Its a very simple, yet complex system.

Again, I really appreciate the info you provided.

Generally what causes the PVC to melt is when the flow stops in the loop and units keep on running and adding heat. PVC is good for 140ish? and water temps can hit 180-200 in no time flat without flow.

There are items such as "Flow" switches that can be installed at each unit to shut down the unit, should the flow cease.

"If" you had an EMS you could have this done via software commands to the WSHP's....

Still though these are bandaids on a stab wound and copper would be the way to go

[richard.bessey]

Question - What would be a good healthy water temperature to see coming from the heat pump while in cooling mode? I think the heat pumps start locking out when the loop gets near the 93 degree mark, but I don't know what the exiting water temperature is of the individual heat pumps when they trip due to high head.

[Chris_Worthington]

Question - What would be a good healthy water temperature to see coming from the heat pump while in cooling mode? I think the heat pumps start locking out when the loop gets near the 93 degree mark, but I don't know what the exiting water temperature is of the individual heat pumps when they trip due to high head.

The cooler it is the better the heat transfer and the higher the seer rating on the WSHP's. With that said there are limits and they are different manufacture to manufacture....

Sounds like your limited to whatever the outdoor ambient temperature happens to be with a cooling tower only. No Geo loop as well here?

What happened to your pipe that burst? Did heat play a role in that failure?

[richard.bessey]

Geo loop? I assume you are referring to a geothermal loop? If so, no we do not have a geo loop. Just the cooling tower.

The pipe that burst was a plastic 2" pipe at a fitting. We ended up replacing the pipe with another plastic pipe, and filled the system again. Everything is back up and running again.

We don't know if heat played a part in that leak or not. It happened sometime overnight. When we came in at 7:00 AM in the morning we found it with water leaking out of the pipe. By then, all of the glycol had already been lost.
It was a 95 degree day that day, at night I think it got down to 81 or so.

[chillerout1]

most water source heat pumps are good to about 100-110 degree incoming water should be about a 10 degree rise in water temp. run the main lines in steel and branches to wshp's to in copper , with proper water treatment they will last thirty years

[Shophound]

My only concern wish acid clean is the cost of cost and labor of flushing the heat pumps vs. the cost of replacing the heat pumps.

The other recent theory I have thought of is - Air in the main loop. We have air bleeders in the attic, but I don't know if they are working.

You should verify if the bleeders are working or not. Not hard to do, especially if they have isolation valves on them. If they do, and those isolation valves hold, you can remove the bleeder and then shake it to hear if the check ball inside it rattles. If it doesn't, you need to clean or replace the bleeder.

Even if the ball does rattle, take the bleeder to a faucet and fill it up with water while holding the ends closed with your fingers. Shake the bleeder. Pour water out. Repeat until you see no more particles of crud flow out when you drain the bleeder.