Re: [PUP] CENTRAL AIR CHILLED WATER SYSTEM VERSUS STAND-ALONE UNITS
We have a "Chiller System" that works great and has had very few repairs over it's 38yrs of service.
I definitely agree with what Hal's said here and, now that I know how I would like to redesign our system, wanted to contribute some thoughts.
--Our system, like Hal's and I think most, is based on one humongous compressor/chill barrel. I agree that this is NOT the way to go. It is a 240V, high draw unit that requires a 50AMP min dock service, or our 30KW gen set as our 6.5KW won't run the compressor/circulating pump/condenser pump.
--If I, like you, were designing from scratch today I would still consider a chiller system but it would definitely be a multi zone system with 2 or more independent systems, depending on boat size/layout etc. I.e. our boat has two staterooms in the bow, engine room in ctr, and master berth in Stern. Then the salon/galley/dining area, and the pilothouse. If I were designing a boat today, I would also attempt to make, as much as possible, a DC boat in a 12/24VDC system. That is to say utilize direct DC power as much as possible and then utilize inverter generated AC as much as possible.
That said,
FIRST: I would focus on only a system for the master berth that was as low-draw energy efficient and insulated as possible that was independent of the other system/s and NOT generator dependant. Would probably be an inverter dependant system but a 12/24VDC system might be better.
SECOND: I would find/put together/design/build as low-draw a chiller system as possible that could handle a "zone". If this could be a DC or inverter powered system all the better. Not that it would necessarily need to be run via inverter but because "it" could be run while underway without a gen-set running as the DC charging system would provide power for it while underway, with gen set running, or on shore power. This probably wouldn't be possible for our boat due to it's size and other limitations of design. I would complete the heating side with a diesel fuel fired boiler and also a combination hot water tank with 120VAC/12VDC elements coupled to a smart KISS wind generator that could also be valved into the heating/chiller system when desired, such as when on shore power.
Because our boat is very well ventilated and because we live in the Eastern Caribbean on the hook, we never use the A/C. During the 5yrs we've lived on the boat the only times we have has been when on shore power in a marina, mostly in FL but a few times in the islands, to just exercise the system, and a very few times when a stationary system has resulted in no air movement and we just wanted to cool the boat before bedtime.
CONTRARY to some speculations made in this thread, the Chiller system works absolutely great and is nearly instantaneous in cooling. As a matter of fact, if the circulating pump does not work, it will freeze the chill-barrel and kick out in about 20 seconds. We can cool the entire boat, 62' three decks, with the doors open if we like. I know this sounds like a strange thing to do but we've actually do it sometimes when we're running the 30KW and just need to exercise the system for a while. Usually on Sunday, as that's the only day we run the 30, to make water, do laundry, make sure all the batts are charged and the holding plates are as solid as possible. Of course the room units also provide heat, via the 38yr old diesel fuel fired Penn boiler, and it provides potable hot water also. So, the system is very practical and an efficient use of components.
Hope these thoughts are of some help,
Jon
-----Original Message-----
Message: 1
Date: Fri, 8 Jun 2007 19:44:36 -0800
From: "Hal Wyman" twl2@halwyman.com
Subject: Re: [PUP] CENTRAL AIR CHILLED WATER SYSTEM VERSUS STAND-ALONE UNITS
After having individual direct expansion units in my previous boats, I opted for a central chilled water system in Que Linda. I made a mistake.
The main difficulty is that the compressor with the capability to cool the whole boat draws a huge amount of power, frequently more power than the shore power can afford. To be specific, the chiller requires about 35 amps 240 volts when running. When cooling one stateroom it is on a very low duty cycle, (iow, it runs full power but only about 10% of the time) but the shore power needs to be able to handle the peak load.
Individual units for each stateroom or each area on the boat would allow a smaller shore power connection to cool just the master stateroom, for example.
Hal
-----Original Message-----
On Behalf Of Mike and Ann Michelin
Sent: Tuesday, June 05, 2007 9:24 PM
To: passagemaking-under-power@lists.samurai.com
Subject: Re: [PUP] CENTRAL AIR CHILLED WATER SYSTEM VERSUS
STAND-ALONE UNITS
Hi All,
I am currently deciding on an air conditioning system for my boat.
The debate is between having the usual stand-alone air conditioning units in each room, versus using the central system that uses chilled water, and basically a small radiator and fan in the room.
I understand that the chiller system is the same as that used in big buildings, and that they now make it in systems that are marine-adapted for boats.
Note, I am in the tropics, so "winter freeze" sitting at dockside is not an issue.
Thanks for the pros and cons to help me decide.
Mike
John & Susan
MV "MARIAH"
living aboard (Simpson Bay Lagoon, SXM)
Gwynn's Island Trawler,62
http://makeashorterlink.com/?A26A5224C
On Sat, 9 Jun 2007, Jon Boy aka:TrawlerGuy wrote:
--If I, like you, were designing from scratch today I would still
consider a chiller system but it would definitely be a multi zone
system with 2 or more independent systems, depending on boat
size/layout etc. I.e. our boat has two staterooms in the bow, engine
room in ctr, and master berth in Stern. Then the salon/galley/dining
area, and the pilothouse. If I were designing a boat today, I would
also attempt to make, as much as possible, a DC boat in a 12/24VDC
system. That is to say utilize direct DC power as much as possible and
then utilize inverter generated AC as much as possible.
An alternative is to have a system with multiple, smaller compressor
systems. I had such a system on Gentle Wind. With an appropriate
control board, it was able to run just one chiller when possible, but
turned on the 2nd one if there was a substantial temp difference in
chilled water vs return water. The single compressor was more than
adequate to run heat exchangers in the staterooms, but of course as
soon as we started to cool the salon and pilot house, we would need
the 2nd unit.