Reverse cycle aircon problem

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Deleted User YDKXO

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I am on my boat for the first time since last October. I put the Condaria reverse cycle aircon on heat as soon as I got on board and it worked fine for a a few minutes before the 32A shore supply blew. I reset the trip and it blew again within a few minutes. I switched the generator on and again, the reverse cycle aircon worked fine for a few minutes and then the gennie stuttered badly as if it was asked for too many amps. Then the gennie and aircon worked fine for a few more minutes before the gennie stuttered again. I have checked the seawater supply and its fine; the pump is working and there is seawater coming from the outlet as normal. The aircon unit produces heat in the boat as normal and all the air exchangers appear to be functioning normally. I should say also that the unit has worked perfectly all last year producing cool and hot air when required. The air temp here is about 8-12 degC and the I guess the sea temp is about 12-15 degC which should be warm enough to produce heat
Anybody got any idea whats happening?
 

sarabande

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did you manage to look at the output meter(s) to see if it was overload ??

Were all the distribution fans on in all the cabins ? Any other usage of serious power e.g. oven/microwave/engine room heaters, etc?
 

jfm

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What current is being drawn (per the gauge) when it is about to trip or stuttering?

If there is excess current being drawn turn on/off each element (each chiller, each air handler) to identify the culprit. If you cannot make the problem go away by turning off the culprit, it must be an item that is common to the system, which means either the raw water circ pump motor or the chilled/heated water circ pump motor. Power these up independently (by hotwiring; the boat's switching will not allow you to do this) to find which is duff, and replace or get rewound, but these days it's easier to replace. Probably £400 job for either of those motors (1.25hp kinda thing).

Or come back with further info!
 
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Deleted User YDKXO

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Thanks to both of you for your advice. An electrician came this morning and diagnosed a compressor problem. Apparently, the compressor works in 2 phases, a start up phase and a running phase. The compressor on my unit is not kicking in to the running phase from the start up phase, causing a spike in the current draw as it tries to do so. This is supposed to be a common problem for aircon units left idle for long periods. According to the electrician the cure is going to be one of 3 things. Either the capacitor controlling the transition is faulty and needs to be changed, or the compressor can be pushed into making the transition to the running phase with an electrical kick up the arse (dont ask me how, it sounds a bit like defibrillating a heart attack victim) or a new compressor is required. Lets hope one of the first 2 works 'coz the last one is megabucks.
Btw I am constantly amazed by the reach of this forum. My Croatian sparky who speaks not much English follows this forum and reads my posts:eek: I better not be rude about him
 

John100156

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Most single phse compressors have two internal windings, a start and a run. They have a capacitor which creates a difference in the sinusoidal waveform creating a different magnetic field causing the compressor motor to rotate. When the compressor starts, a relay detects a change in current (there are several types) that disengages the start winding. Sometimes it's just the relay, sometimes the capacitor but sometimes the more expensive compressor! Let's hope it's one of the former.

You could disconnect the compressor and if you can get hold of a Megga, you can test the insulation resistance of each winding, usually three terminals, CSR, common, start and run. Run winding across C&R.

Sounds like it could be the run winding that may have gone down, but if so this would only run for a very short time until it blows the breaker.

The only other thing I can think of is that it's the solenoid on the reversing valve. Try starting it in either heating and the cooling (some manufactures energise or de-energise the solenoid valve on heating). You can check this by disconnecting it. It will either heat or cool only. Much cheaper to replace.

If it's the compressor winding burnt out, it can leave acids in the oil so make sure the it a burn-out drier or test the oil, otherwise in a year or two you may need another compressor.

Anyway hope you get it sorted.
 

John100156

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Most single phse compressors have two internal windings, a start and a run. They have a capacitor which creates a difference in the sinusoidal waveform creating a different magnetic field causing the compressor motor to rotate. When the compressor starts, a relay detects a change in current (there are several types) that disengages the start winding. Sometimes it's just the relay, sometimes the capacitor but sometimes the more expensive compressor! Let's hope it's one of the former.

You could disconnect the compressor and if you can get hold of a Megga, you can test the insulation resistance of each winding, usually three terminals, CSR (common, start and run). Run winding across C&R.

Sounds like it could be the run winding that may have gone down, but if so the unit would only run for a very short time until it blows the breaker.

The only other thing I can think of is that it's the solenoid on the reversing valve. Try starting it in either heating or cooling mode (some manufactures energise or de-energise the solenoid valve on heating). You can check this by disconnecting the solenoid valve. If the compressor starts and runs (It will either heat or cool only) it could be that. Much cheaper to replace a solenoid.

If it's the compressor winding burnt out, it can leave acids in the oil, so make sure they fit a burn-out drier or test the oil, otherwise in a year or two you may need another compressor.

Anyway hope you get it sorted.
 
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Deleted User YDKXO

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Most single phse compressors have two internal windings, a start and a run. They have a capacitor which creates a difference in the sinusoidal waveform creating a different magnetic field causing the compressor motor to rotate. When the compressor starts, a relay detects a change in current (there are several types) that disengages the start winding. Sometimes it's just the relay, sometimes the capacitor but sometimes the more expensive compressor! Let's hope it's one of the former.

You could disconnect the compressor and if you can get hold of a Megga, you can test the insulation resistance of each winding, usually three terminals, CSR (common, start and run). Run winding across C&R.

Sounds like it could be the run winding that may have gone down, but if so the unit would only run for a very short time until it blows the breaker.

The only other thing I can think of is that it's the solenoid on the reversing valve. Try starting it in either heating or cooling mode (some manufactures energise or de-energise the solenoid valve on heating). You can check this by disconnecting the solenoid valve. If the compressor starts and runs (It will either heat or cool only) it could be that. Much cheaper to replace a solenoid.

If it's the compressor winding burnt out, it can leave acids in the oil, so make sure they fit a burn-out drier or test the oil, otherwise in a year or two you may need another compressor.

Anyway hope you get it sorted.

Many thanks, John. Thats really useful. The so called Condaria expert is inspecting the unit tomorrow and I hope to get a report this week. As you say, fingers crossed for a capacitor or relay problem rather than the compressor itself
 
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Deleted User YDKXO

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John, it turned out you were spot on. It was the relay, thank goodness:)
 

John100156

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John, it turned out you were spot on. It was the relay, thank goodness:)

Glad to hear it Mike, it could mean the winding is starting to break down but not always, I have known compressors to run for many years after a relay has been replaced; if the start and running currents are all OK, looks like your problem is resolved, roll on summer!

2du9oye_th.jpg
 

aquatom

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How many amps is the circuit breaker for the chiller as I would have expected the chiller breaker to trip before the 32A shore power breaker. It may be a good idea to check this when the relay has been replaced.
 
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How many amps is the circuit breaker for the chiller as I would have expected the chiller breaker to trip before the 32A shore power breaker. It may be a good idea to check this when the relay has been replaced.

Aquatom, I dont know how many amps the aircon circuit breaker is but the shorepower breaker certainly went first. I have my doubts as to whether the breakers in many Med marinas actually trip at their stated current. Also the voltage is often much lower than what its supposed to be
 

John100156

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How many amps is the circuit breaker for the chiller as I would have expected the chiller breaker to trip before the 32A shore power breaker. It may be a good idea to check this when the relay has been replaced.

In commercial electrical installations it is required that adequate discrimination exists between circuit protection devices, sadly with most electrical systems on boats and in marinas that I have seen, this is rarely the case. So its not just the current rating of a protective device that matters, it is its time/current characteristics. You often see breakers rated at 'X' amps type B, C, D, etc. So it can be a little confusing. For instance a 20A Type D breaker may not descriminate (or trip) before a 32A Type B. So you would need to know the full circuit characteristics before reaching that conclusion. Given that boats move from one electrical distribution to another, it is unlikely all marina electrical installations would be the same.
 

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