What do the pump strainers look like?
PHM
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Originally Posted by
tridiumtech
Doing an efficiency check out on a 106Ton Carrier 30RBA110 - 10 years old.
Put in data loggers on the electrical feed and pressure sensors on the main supply & return ports (measure the evap. pressure drop to determin flow). The single B&G constant volume CHWP (2.5BB) is 5HP with a capacity of 254gpm (about 60ft head).
Took spot readings on the CH supply/return temps and the pump pressures and amp draw.
1) getting an average 14.7F difference between the leaving and entering temps - readings from the operator display (verified with a water draw temp test). Issue: the chiller is 10F design.
2) getting average 9.9 amps on the CV CHWP draw - very constant. Calculating about 4.5HP. Flows should be close to design capacity (254gpm). However getting approx. 12 feet of head (?). Could be impeller issue. No idea what the flow is out of the pump.
3) getting an average 1.2 psi drop across the evaporator (validated with calibrated Dwyer digital pressure gauges). Using the Carrier Performance Head-GPM data, that yields about 140gpm. Getting lots of flow from opened pressure ports - shower time - so no restrictions. That low dP seems to be real.
I'm thinking we've got a crummy impeller that's resulting in low flow. Never seen a delta T over the design spec. That sounds like a symptom of low flow.
Need to get an accurate GPM # to determine the actual Tons (then kW/Ton).
Any insights would be appreciated.
PHM
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When faced with the choice between changing one's mind, and proving that there is no need to do so, most tend to get busy on the proof.