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Originally Posted by twistor

I have 3 heat pumps that go off on high head pressure only in the hot summer months. Not sure why this happens. Has anyone had this happen on other systems. Here are the Model#s.
• GPU-1 Model No. -TTH026AGS40ELPS Serial No. - L13781181
• GPU-2 Model No. -TSHO18BGS40ELWS Serial No. - L13781140
• GPU-3 Model No. -TTH026AGS40ELPS Serial No. - L13781180
The system has pumps individual pumps for each unit on the loop. There is a well field for the system. The system works fine all year untill the outside air reaches 90degrees or higher.

we give all this advice and he doesn't come back to tell us anything. We don't even know what the EWT's are. those unit could be pipe in backwards. we need to know what the entering and leaving waters temps are for each unit. otherwise its a waste of time.

How many units are on the loop? Where are the 3 HPs located on the loop? Is it a single pipe loop?

Agreed,

High head pressure can be a direct result of the ewt. In the big install book, not the pamphlet there is a chart that reflects what the head pressure should be for any given ewt. If the gas charges are a little off, the units are more prone to lock outs at the extreme ends of their ranges in regard to ewt.
Eric

Hi head pressure is caused by too warm a water loop or water flowing too slowly. (assuming all equipment is A OK) You should see a 10-12 degree temperature rise between heat exchnager entering and leaving water temperatures. EWT higher than 110 degrees F. is NOT COOL.

Is loop temp high? I would start there then go to water flow. Water setter could be set to low or could have stopped up lines. I've had to back wash a few with the same problem.

Sounds like your loop isn't rejecting enough heat. It probably does the same thing in the winter, you just don't know it cause the backup heat hides it.

I found one 18 ton on 16 ton loop.

Water source heat pumps

I have 3 heat pumps that go off on high head pressure only in the hot summer months. Not sure why this happens. Has anyone had this happen on other systems. Here are the Model#s.
• GPU-1 Model No. -TTH026AGS40ELPS Serial No. - L13781181
• GPU-2 Model No. -TSHO18BGS40ELWS Serial No. - L13781140
• GPU-3 Model No. -TTH026AGS40ELPS Serial No. - L13781180
The system has pumps individual pumps for each unit on the loop. There is a well field for the system. The system works fine all year untill the outside air reaches 90degrees or higher.