If you've ever had a brand-new McQuay chiller trip on 'Low Evap Temp' before it even got a real load, you know that sinking feeling in your gut. That's not a McQuay problem. That's an 'assumed the factory settings were perfect' problem—and I've been on both sides of that phone call.
Over the past 4 years in quality compliance for commercial HVAC, I've reviewed roughly 200+ chiller and air handler installations per year. I've rejected a lot of first-attempt startups. Here are the 7 questions I always wish contractors had asked before the crane left.
Note: My experience is based on mid-to-large commercial installs (200-800 ton range). If you're working strictly with residential or small package units, some of these points won't apply.
1. Is this McQuay thermostat actually compatible?
Honestly, the most frustrating part of my job: seeing a brand-new McQuay fan coil unit paired with an off-the-shelf thermostat that doesn't speak the same language. People assume that because it's a 24V thermostat, it'll work. That cost one contractor a $4,200 callback after the control board fried.
McQuay units often require specific zone controllers or a communicating thermostat—especially their newer Vision or MicroTech II equipped models. Check the controller part number against the McQuay submittal. If the wiring diagram calls for a 4-wire thermostat and you bring a 2-wire, you're going to have a bad day.
Per McQuay (now Daikin Applied) documentation, many of their fan coil units require a dedicated controller for proper staging of the electric heat or valve actuators.
2. Did you verify the chiller start-up sequence?
I ran a test once with our start-up team: same McQuay centrifugal chiller model, one with factory-default settings, one with field-tuned parameters. The default one tripped on 'surge protection' 3 times before lunch. The tuned one ran smooth for the entire 8-hour test.
What's my point? Just because the McQuay chiller leaves the factory with a certain setpoint doesn't mean it's right for your building load. You need to check the refrigerant charge, the entering condensing water temperature, and the leaving chilled water setpoint before you hit 'Auto.'
In our Q1 2024 quality audit, we found that 13% of first-time chiller startups had a control sequence error—most commonly a misconfigured soft-load parameter. That's an easy fix if you catch it during the pre-start checklist. If you catch it after the chiller has been running for 3 hours, you're looking at potential compressor wear.
3. What's your plan for the heat exchanger maintenance?
This one is kind of a pet peeve of mine. People buy a heat pump or water source heat pump, install it, and then assume the heat exchanger will self-clean. That's not how it works.
On a recent project, a facility manager called me complaining about 'low refrigerant pressure' on a 6-month-old McQuay water source heat pump. The water-side heat exchanger was fouled with sediment and scale. Water flow was down to 60% of design. The solution? A $400 clean-and-flush. The cost of ignoring it? That could have been a $6,000 heat exchanger replacement and a 4-day shutdown.
The rule of thumb: budget for a heat exchanger flush every 12-18 months in commercial applications. If your water treatment isn't great, make it every 6 months. The maintenance cost is a fraction of the replacement. Take it from someone who's rejected a batch of 8,000 units in storage due to improper cleaning procedures.
4. Are you accounting for 'unknown unknowns' in the controls?
I assumed once that a MicroTech III controller would integrate seamlessly into a legacy BAS protocol. Didn't verify the BACnet object mapping. Turned out the points map was configured for MSTP when the building was running BACnet IP. That mismatch delayed commissioning by 2 days.
Now every contract I review includes a clause about controls integration testing before the unit is declared operational. McQuay units offer multiple control options (BACnet, LonWorks, N2). Verify which one your building needs. Don't assume.
To be fair, the Daikin Applied documentation for McQuay controls is actually pretty good. But you have to actually read the integration guide—not just the installation manual.
5. Did you size the tower fan for the chiller?
I get why people rush this one—the chiller arrived late, the roofer is done, and you just want to get the tower fan on the pad. But a mismatched cooling tower fan can kill chiller efficiency faster than anything else.
On a 2019 project, a contractor installed a standard fan kit on a McQuay chiller that was designed for a high-static tower. The fan couldn't pull enough air across the condenser. The chiller started cycling on high head pressure within 30 minutes. That $200 savings on the fan turned into a $2,500 problem when we had to swap the fan assembly and re-commission the unit.
My view: the lowest bid on the tower fan is rarely the right answer. Check the McQuay chiller's required condenser air flow (CFM) and static pressure. Then match the fan. It's that simple.
6. Is your budget including a service contract?
This is the question that makes facility managers uncomfortable. 'We don't have the budget for a service contract right now.' I hear that a lot. But a McQuay chiller without a service contract is like a milwaukee leaf blower without a battery—it might start, but you won't know until it doesn't.
I've rejected proposals that included a chiller purchase with zero aftermarket support. That facility manager ended up calling us 3 times in 6 months for what would have been covered under a standard service contract. They paid more in call-out fees than a contract would have cost.
McQuay's service provider network is actually pretty robust (their parts availability is a big reason people search for 'mcquay hvac parts'). But you need to enroll in that network before you need it, not after the chiller is down on a July Monday.
7. Do you have the ASHRAE specs for the air handling unit?
Let's address the elephant in the room: the heat exchanger in your McQuay air handling unit (AHU) isn't like the one in your car. It's a chilled water or hot water coil. And its performance depends entirely on the water temperature and flow.
I've seen well-meaning contractors install a McQuay AHU with a cooling coil that was sized for 42°F entering water when the building loop provides 48°F. The coil couldn't meet the dehumidification load. The building got mold complaints within 3 months.
Check the submittal for the entering water temperature, the temperature drop (Delta-T), and the air pressure drop. These specs are not optional. If you don't have them, call McQuay or Daikin Applied. The data is there—you just have to ask. Per standard ASHRAE methods, coil performance should be tested at rated conditions. Don't guess.
Bottom line: McQuay makes solid equipment. I've rejected very few pieces for manufacturing defects. But installation errors? Those are common and expensive. Trust me on this one: check the compatibility, verify the controls, budget for maintenance, and read the specs before you start.
My experience is based on about 200 installs, mostly mid-range commercial. If you're working on residential or oversized custom jobs, your mileage may vary. But for everyone else—start with these 7 questions.
