I received this question on the comments page of my website… Ken, Re: your latest what’s new post.
After all of the talk about Nordhavn and their fantastic boats, support etc, I am surprised to hear “you” trying to solve your AC/chiller problem. Since this has been a problem for you from day one, shouldn’t Nordhavn step up and solve the issue? I am a huge Nordhavn fan and hope to own one someday. However, if I interpret correctly, this situation surprises me. Just looking for some insight into this ownership issue.
Ken, Re: your latest what’s new post.
Nordhavn is a great company, and does have awesome support, AND, my boat is still under warranty. The air conditioning problems have existed from the beginning, and Nordhavn would have already fixed them, but the boat hasn’t stood still long enough. The same exact chillers I have are on at least one other Nordhavn, which initially had problems, but now is working, and similar chillers are on several other Nordhavns, and working fine. Everyone agrees that mine aren’t working, and Nordhavn’s perception is that they can fix all problems in an afternoon, and will do so, when the boat is somewhere that they can work on it.
Despite this, I’m less convinced than they are that these particular chillers are ever going to work. They were a new model from Cruisair, and seem to have longer start times and higher current draw than the other models. It is encouraging that the other Nordhavn with identical chillers is now doing fine, but it is a new Nordhavn that has not really cruised anywhere warm yet. My fear is that the Nordhavn technicians will fly to Seattle, on a day when it is 50 degrees, they’ll work some magic, we’ll all pat each other on the back for a job well done, and then I’ll depart for Indonesia, only to find out that real-world conditions, and the weather in Seattle, vary. This may be a case where I pay my own money to swap the chillers, for an alternate version with soft start. (Note: Soft start is a technique for limiting the electrical demand of a motor during start-up, to reduce the initial current need).
We’re starting a circumnavigation, and I want to be proactive in dealing with anything that I am concerned about. My concern, which Nordhavn would say is irrational, is that I’ve lived with these chillers for a year, and watched the current draw, read the specs, and just flat don’t trust them. Perhaps if Nordhavn fixes them, and I were to cruise, and they work, then I would build confidence, but I’m not planning any cruising between here and departure for a circumnavigation. We get one shot at it, and that’s it. Over the next month (currently, I can’t do anything with the boat in Costa Rica), I need to decide whether I’d like to spend money on a solution that I have faith in, or allow Nordhavn to tweak my chillers and see if the problem goes away. The Nordhavn guys are smart, and have gone through this on other boats, plus I hate spending money — so, it isn’t an easy decision.
I don’t want to get overly technical, and put people to sleep, but here’s the problem in a nutshell:
The air conditioning system consists of four chillers. These chill the water which circulates through the boat to provide cooling. Depending on how warm it is, one chiller may be adequate, or all four might be needed. All electric motors have higher current draw during startup, than after they are running. The startup current can be MUCH larger than what is needed after the motor is running. For instance, the spec sheet for my chiller shows a requirement for 100 amps to get the chiller running (only a few seconds) and then the current need drops to “only” 12 amps. To give a sense of how much power this is, a 16kw generator only puts out 88 amps of electricity. Squeezing 100 amps out of an 88 amp generator is not easy, and it gets tougher when there is more than just the air conditioning to be run (as there always is). This is a common issue, and generators are made to be able to supply high amounts of current for very brief periods. If all is going well, the lights dim for an instant, as voltage drops, the generator lugs for a bit, and then the chiller starts. Unfortunately, on my particular chiller, the startup is slow, and the lights dim too much, oft-times blowing fuses, or the generator gives up and quits. With proper tweaking of the electrical system, it can work. My feeling though is that I’d prefer to simplify the whole process by swapping to a chiller which has a lower startup current draw. This means swapping to a chiller which has “soft start” capability, wherein the chiller doesn’t draw an enormous amount of current at startup. Soft start chillers cost more and take up more space. My leaning as I type this is to pay the price, and have something which won’t put stress on my boat’s electrical system.