Facility Maintenance Checklist: How to Bleed a Radiator, Check a Pool Heater, and Care for Your Bitzer Compressor

I'm the office administrator for a 210-person company. I manage all facility services ordering—roughly $160,000 annually across 9 vendors. I report to both operations and finance, which is a polite way of saying I take the blame when the pool heater dies and the radiators go cold in the same week.

This is the checklist I run through before calling a repair company. It's saved us from a lot of four-figure service calls, and it'll help you figure out whether you need a technician—or just a bleed key and an afternoon.

1. How to bleed a radiator (before you call a tech)

If a radiator is cold at the top but warm at the bottom, or it's making gurgling sounds, the problem is almost always trapped air. Air collects at the highest point of the radiator—that's why the bottom heats up but the top stays cold. Bleeding takes five minutes. Here's exactly how to do it:

1. Shut off the circulating pump and let the radiators cool for 20 minutes. Working on a hot system is the fastest way to get burned.
2. Find the bleed valve at the top corner of the radiator. It's usually a small square nub or a slotted screw fitting.
3. Hold a rag under the valve. Turn the key counterclockwise, slowly. You'll hear a hiss as air escapes—that's normal.
4. When the hiss stops and a steady trickle of water comes out, close the valve. Don't over-tighten it.
5. Repeat on the top floor first, then work your way down. Air rises, so the highest radiators collect the most.
6. Check the boiler pressure afterward and top up if it's low.

I once assumed a radiator was broken because it was cold in the middle. Didn't verify. Turned out it just needed bleeding, and the service visit cost us $180. Now I bleed first and ask questions later.

2. Check the fans—the condenser fan and the one in your closet

Cooling systems fail when they can't breathe. The condenser unit, whether it's part of an AC, a pool heat pump, or a Bitzer condensing unit, needs a working fan to pull air across the coil. If that fan isn't spinning, the compressor will overheat and trip on the high-pressure switch.

With the power off at the disconnect switch, eyeball the coil. If it's caked with dirt, wash it gently from the inside out—don't blast the fins with a pressure washer. Spin the fan by hand. It should move freely. If it drags, the bearing is wearing out. Then turn the power back on and watch the fan start. If it hums but doesn't turn, the run capacitor is the usual suspect—that's a cheap fix.

And if you work in a cramped mechanical room like I do, keep a portable fan in the closet. My Ryobi fan is the tool I didn't know I needed. It's battery powered and seriously moves a ton of air, which makes a 100-degree compressor room survivable while you're pulling off panels.

3. Diagnose the pool heater before you replace it

Our building has a seasonally used outdoor pool. The pool heater is actually a heat pump with a scroll compressor inside. When the water dropped from 84°F to 71°F over a weekend, my first instinct was "we need a new heater." That would have been a five-figure mistake.

Start with the cheap checks:

• Water flow. A dirty filter or a pump with a torn basket will make the heat exchanger shut down. Clean the filter, check the skimmer, and make sure the pump has a happy flow.
• Error codes. Modern pool heaters display a fault code on the controller. Ours said "low water flow"—that led us to a dirty filter, not a dead compressor.
• Electrical components. If the compressor hums but struggles to start, the start capacitor or contactor is usually the problem, not the compressor itself.

If the water flow is fine and the compressor is running but the water stays lukewarm, then check the refrigerant circuit. A low charge means a leak, and a leak means it's time to call a technician.

When our pool heater eventually did need a new compressor, it was a Bitzer scroll compressor—the OEM's approved replacement. It wasn't a huge order: one compressor, oil, and a filter drier. Some suppliers didn't want to be bothered with a sale that small. The supplier who took it seriously now gets the bulk of our refrigeration parts business. Small orders have a way of growing.

4. Use the right Bitzer compressor oil—often BSE 170

This step gets skipped a lot. I used to skip it myself until a ruined compressor taught me better.

Compressor oil is the lifeblood of a screw compressor. The wrong oil won't kill it overnight, but it will slowly destroy bearings and internal components. If you've got a Bitzer screw compressor, check the sight glass. The oil should be at the correct level, not black, and not foaming.

Foam in the sight glass usually means refrigerant is migrating into the oil, which is a different problem entirely. Dark oil means it's overheated. If the oil smells burnt, schedule an oil change before the compressor fails.

Now, the part that matters: use the exact oil the compressor calls for. According to Bitzer's published lubricant guidelines and the stamped data plate, many Bitzer screw compressors running R134a, R404A, R407C, and similar HFC refrigerants use BSE 170, a polyolester (POE) synthetic ester oil. It's not mineral oil. It's not a generic "compressor oil." It's the specific viscosity and chemistry that the compressor was designed around.

BSE 170 looks like oil. Mineral oil looks like oil. Inside a compressor, the difference matters more than any other maintenance decision you'll make.

I learned this the hard way. I said "compressor oil for a Bitzer screw compressor" to a supplier. They heard "get us some refrigeration oil." Result: a pail of mineral oil in our store room we still can't use. We were using the same words but meaning different things—and the compressor sat idle for three extra days waiting for the correct BSE 170.

The oil charge varies by model too, so check the data plate and the spare parts list. Don't just pour in a full pail and hope it looks right.

5. Order genuine Bitzer compressor parts

Bitzer compressor parts fall into two groups: parts you should keep on the shelf (oil filters, filter driers, O-rings, gaskets) and parts you should leave to a technician (oil pressure valves, control solenoids, motors). But both groups have one rule: buy genuine.

Read the model and serial number off the compressor data plate, and order the part number that matches. Genuine Bitzer parts come in packaging with the Bitzer logo and a traceable part number. If a listing says "compatible" or "will-fit," it's not the same part. That's not me being a brand snob—it's about warranty coverage, material quality, and the fact that a failed part costs you ten times more in downtime than the price difference.

I went back and forth between an established distributor and a new online seller for two weeks. The online seller was 25% cheaper on a filter drier set. The established distributor offered reliability; the new seller offered savings. I chose the established distributor because the compressor downtime was costing us around $700 a day in lost cooling—maybe $800, I'm mixing it up with the electricity bill. Either way, a cheap part would have been the expensive one.

6. Keep a parts log and a spare-parts kit

The most useful maintenance tool in our building is a spreadsheet. It lists every compressor's model, serial number, oil type, filter part numbers, and service dates. When something fails, I can order the right part before the technician even arrives.

• Take photos of every data plate and store them in a shared drive.
• Keep a small stock of the parts that fail most often: oil filter, filter drier, gaskets, and a sight glass.
• Verify your vendor can produce a proper invoice. I once bought a condenser fan motor from a supplier with a great price, but they could only do a handwritten receipt. Finance rejected it, and I ate the $260 out of my department budget. On paper, the price was right. In reality, it wasn't.

Include part numbers, quantities, dates ordered, and which compressor each part fits. It sounds obsessive until the day your warehouse hits 90°F and you need to know if the filter on the shelf is the right one.

Maintenance mistakes to avoid

• Don't mix oil types. Mineral oil and POE oil don't mix, and topping off with the wrong oil makes the whole charge unusable.
• Don't start a screw compressor immediately after an oil change. If it has a crankcase heater, give it the pre-heat time the manual specifies.
• Don't ignore foam in the sight glass. It's a warning, not a normal operating state.
• Don't buy emergency parts from marketplace listings that don't show the manufacturer's part number.
• Don't bleed radiators on a system running at full temperature. Let it cool first.
• Don't top up oil without knowing where it went. If the level keeps dropping, you've got a leak, not a maintenance task.

Bottom line: a few simple checks can save you a five-figure repair. Bleed the radiators, make sure the fans are turning, verify the oil, and order the genuine Bitzer part the compressor actually needs. And buy from someone who treats a small order like it matters—in my experience, those are the vendors you'll still be calling years later.