- A chiller contractor is distinguished from a general HVAC one by whether they record performance readings rather than attendance.
- The readings that matter are condenser and evaporator approach temperatures, delta-T, current draw, pressures and water chemistry.
- Record the ambient conditions alongside every reading, or February and August figures cannot be compared.
- Condenser water chemistry is where fouling starts, and it is frequently owned by a separate provider with no interface named.
- Clean the condenser in spring; doing it in August is recovery, not maintenance.
A Dubai mixed-use tower changed chiller contractor and asked for the previous year's log sheets. What arrived was twelve monthly PDFs, each with a photograph of the plant room and the words "chillers running normally". No approach temperatures, no delta-T, no water quality results, no vibration readings. A year of attendance and not one number to plot.
Twelve visits. Nothing to trend.
In short: a chiller contractor is distinguished from a general HVAC one by whether they record performance readings. Approach temperatures, delta-T, current draw, pressures and water chemistry, logged with the ambient conditions at the time, are what let you see fouling and charge loss building months before a breakdown. A report saying the plant ran normally cannot predict anything.
Choosing a chiller AMC company in Dubai is mostly about that gap. Chiller plant fails slowly and announces itself in numbers long before it announces itself in a breakdown, and a contractor who does not record numbers cannot see any of it coming.
What separates a chiller contractor
Chiller work is more specialised than general HVAC, and the differences are worth testing before appointing.
- Do they log performance, or attendance? Approach temperatures, delta-T across the evaporator and condenser, current draw, pressures, and the ambient at the time of reading.
- Can they work on your machine? Centrifugal, screw and scroll differ, and manufacturer controls often need proprietary access.
- Do they hold refrigerant handling capability for the gas in your plant, including recovery?
- Is water treatment inside or outside their scope? Condenser water chemistry drives fouling, and fouling drives everything else.
- Who does vibration and thermographic work? Frequently subcontracted, which is fine if disclosed.
- What happens at 2am in July? Cover hours, escalation, and whether a chiller technician rather than a general engineer attends.
QSERV reviews your existing chiller records and shows you what has never been measured on plant you depend on.
The numbers a competent contractor records
| Reading | What a drift in it indicates |
|---|---|
| Condenser approach temperature | Fouling on the condenser side, or reduced water flow |
| Evaporator approach temperature | Fouling, low refrigerant charge, or flow problems |
| Delta-T across each vessel | Flow rate issues and heat transfer degradation |
| Compressor current draw | Load, mechanical condition and efficiency loss |
| Suction and discharge pressures | Charge condition, fouling, and control behaviour |
| Condenser water chemistry | Scaling and corrosion risk before it becomes fouling |
| Vibration on rotating equipment | Bearing and alignment condition |
| Ambient at time of reading | Makes every other figure comparable between visits |
The last row is quietly essential. Chiller readings taken in February and August are not comparable unless conditions are recorded alongside them, which is why a log without ambient data cannot be trended even if it contains numbers.
The stance
Here is the stance, from plant we take over. A chiller AMC that produces no trend data is a breakdown contract with a schedule attached. It will fix things after they fail, competently perhaps, but it cannot tell you anything is coming.
That matters because chiller failures in Dubai land in the worst possible window. Plant is at maximum duty through July and August, which is exactly when fouling, charge loss and bearing wear turn from readings into shutdowns, and exactly when replacement lead times and site conditions are least forgiving.
Chiller maintenance is bought as insurance and delivered as bookkeeping. The value is entirely in whether anyone reads the books.
Who actually attends, and when
The engineer who turns up matters more on chiller plant than on almost any other discipline, because diagnosis depends on interpreting readings rather than finding a broken part.
Three questions that reveal the answer:
- Is the same engineer assigned to your site? Trending is a human activity. An engineer who has read your plant four times will notice a drift that a rota of different people will not.
- What happens outside working hours? A chiller failure at 2am in July needs somebody who can work on that machine, not a general technician who attends, confirms it is off and books a return visit.
- Who holds the controls access? Modern chillers log faults and performance internally. A contractor without access to the manufacturer's interface is diagnosing from gauges while the machine already knows the answer.
Ask for the escalation path in writing, including who is called second when the first engineer is unavailable. Most contracts do not say, and the gap only surfaces during the one failure that matters.
Water treatment is where fouling starts
The most common preventable cause of chiller performance loss on the sites we survey is condenser water chemistry that nobody owns.
Scaling and biological fouling build on the condenser side, approach temperature rises, the compressor works harder, and efficiency falls before anything reads as a fault. If water treatment sits with a separate provider, the interface needs naming, because chemistry results and chiller performance data only mean something when somebody looks at them together.
What to do before summer
Chiller plant is judged in July and prepared for in March, and the gap between those two months is where most avoidable failures are made.
A pre-season routine worth running every year:
- Clean the condenser before the load arrives. Cleaning a fouled condenser in August is recovery; doing it in spring is maintenance, and the difference in the machine's summer margin is substantial.
- Compare this spring's readings against last spring's. Same season, comparable ambient, genuinely like for like. That single comparison is more informative than a year of unmatched monthly figures.
- Verify the water treatment regime and its results, rather than assuming the separate provider has it in hand.
- Test the alarms and the escalation path. Not just that the BMS registers a fault, but that somebody is reached at 2am and knows what they are authorised to do.
- Confirm critical spares. Which parts stop the machine outright, and whether any are held in the country.
None of that is sophisticated and all of it gets skipped, because spring is when the plant is behaving and nobody is thinking about it. That is exactly why it is the right time.
The honest trade-off
A contractor logging full performance data, with water treatment integrated and vibration analysis included, costs more than one running scheduled visits. On a small single-chiller installation with modest duty, that instrumentation is more analysis than the plant justifies, and a competent scheduled contract is the sensible purchase.
On multi-chiller plant serving a tower or a mall, the trend data is the product. Without it you are buying attendance in the months when the plant is easy and hoping in the months when it is not.
Related: what an HVAC and chiller AMC guide covers technically, and how refrigeration differs from comfort cooling.
Explore the Chiller Contractor Selection Cluster
Each page below covers one part of choosing and running chiller maintenance.
Next step, and it takes ten minutes: open your last three chiller service reports and look for approach temperature. If the figure is absent from all three, nobody is watching the one reading that tells you fouling is building, and you will find out in July.
