How Do Heat Pump Compressors Fail?

November 26, 2018

Recognised as a heat pump’s beating heart, a system’s heat transferring action isn’t going to work if its compressor fails. And, since it’s an active device, a part that’s full of smaller moving parts, this key component is susceptible to damage. The core mechanism incorporates an electrical motor. And, as any electrician knows full well, motors burn out from time to time.

Compressor Motor Failures

A pungent odour is wafting out of a heat pump. It’s coming from the vents, from the housing and all around the water tank. It sort of smells like burning varnish. That’s the motor windings. The electrical stator coils are insulated in resin. If there’s a short-circuit, the resin burns and discharges that odiferous stench. Other compressor motor failures are caused as a direct result of deteriorating mechanical parts. Bearing failures, perhaps due to a lack of lubrication, squeak and squeal, then the entire system comes to a crashing halt as those friction-mitigating parts seize.

Checking the Vibrational Reasons

Heat pump compressors use piston-action mechanics to kinetically squeeze large volumes of refrigerant down, to compress the fluid so that it efficiently transfers thermal energy between its heat exchanging coils. To make sure the dynamic assembly keeps its vibrational forces in check, there are rubber inserts and dampeners installed between its housing and the heat pump interior. If the dampening mechanism isn’t performing as designed, expect big problems. Electrical wires break, mechanical components, including fasteners, loosen and disengage. As a worst case scenario, a hose or pipe could loosen. Compromising the fluid network, the loosened hose spills system refrigerant. Even if a spill doesn’t occur, the vapour charge could evaporate, so severely that the equipment no longer delivers adequate water heating power.

Faulty Supplementary Elements

Squealing bearings make themselves known. Faulty motors, too, they discharge noise, radiate odours, and cause drastic drops in thermal transferrence efficiency. There are still a few other flaws to troubleshoot, though. What if the compressor is starting, but it comes to a halt less than a minute later? A seasoned technician will go straight to the reversing valve, where he’ll hope to discover seating damage. Solenoids clicking, motor start relays burning out, refrigerant levels dropping precariously low, these indirect-failure causative factors can easily impact compressor performance, so much so that the accumulated damage becomes permanent.

In theory, some of the above problems are correctable. A low refrigerant level will require the attention of a repair engineer, someone who knows how to charge the compressor. Solenoids and stuck valves are also repairable/replaceable. For damaged bearings or faulty compressor motors, however, a full replacement is, more often than not, the cost-effective solution.


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