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Jeanneau SO 40
March 11, 2011
1:18 pm
quantum
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Hello

 

I am considering a similar AC install in an Island Packet 370. I am wondering if dlane has finished this project and how it turned out. I am very interested if he is able to start and run his AC with the Honda 2000 generator

November 27, 2010
3:16 pm
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Steve Pooler
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dlane said:

Steve,

 

Thanks for your prompt reply.  It has made me reconsider a single Dometic 16K unit to air condition both cabins and would be a lot simpler to install on several counts.  If I do this, I assume there will only be a thermostat control in the main cabin.

1) What is your take on controlling the temperature in the forward cabin at night?…

That would depend on a few things Don…First is do you want to cycle the fan with the compressor, or do you think you can live with an automatic slow fan speed setting when the compressor cycles off…All the Dometic controls offer the option of either but..If you want to cycle the fan with the compressor then the temp sensor should be out in the cabin since that is where you are…

If you can live with the fan running continuously…Then you can go with a remote sensor placed in the return air path that with the fan running is getting a continuous "Average" sample of cabin air temp…Most folks are happier with this approach/result over the in cabin choice, as a boat is different than a house in that it faces differing directions, and it's tough to locate a sensor in a boat cabin where it will never see cold or heat from another source such as an engine room bulkhead, a port light, sun heated bulkhead, hull/overhead, or opening companionway etc… 

2) How would you accomplish return air flow from the forward cabin?  I mentioned that I could put a return air grill in the bulkhead between the storage area the AC unit would go in and the forward cabin, but just to let you know, this vent would wind up in the bottom of a cloths locker in the forward cabin.  I was planning to use this arrangement for the 5K unit.  Since the space in the bottom of the closet is used to store some shoes, I was going to also put a return vent in the bottom of this cabinet which would facilitate the flow of air from the forward cabin into the locker and then through the bulkhead into the storage space where the AC unit would be located.  Of course I would install a larger return vent in the AC storage space in the main cabin.

I like this idea and it would lend itself well to Average cabin temp sensing…

3) Would a single 16K unit leave sufficient 110v power for the rest of the boat?...With 30 amp shore power it should leave you with around 18-20 amps…

 I have a Heart 2500 Inverter with a battery charger that I think can pump out as much as 120 dc amps.  I assume I couldn't charge the batteries if they were low while also running the AC,..You probably could while on shore power...If you didn't run the water heater at the same time...Those three items, A/C, Charger, and Water Heater use the most amperage aboard...Charger should taper back usage as the batteries come up and it's output starts dropping...Managing your power usage by watching/checking a AC amp meter (do you have one in your main panel ?) and turning on & off things as warranted, or needed would be the key to not overloading your shore cord...

Inverters either Invert DC power to AC power, or Replace that DC power as a battery charger…They can't do both at the same time…Boy it would be nice if they could…I would have a big one here at home and wouldn't be paying these crazy electric bills… Cool

But really…When I said I have started & run a 16 on a 2000 watt inverter…Which I have…But I should have quantified that you would need a huge bank of batteries to do it for, say a nights sleep…Even if your inverter is 90% efficient, the 11-12 amp AC current draw (compressor, fan, and pump) would likely be drawing 120-150 DC amps from those batteries doing so…Your better off planning on that Honda for A/C usage…I would also caution that you do need a good Carbon Monoxide detector in the cabin, and test it each time you start the generator…Those fumes do have a way of making it into the cabin…

4) With a smart start on a Dometic 16K unit, what size generator do you think I could get away with if I don't run the charger or microwave at the same time?

I would think the 2000 watt Honda should handle it with a SmartStart…With not much left over, but you can use your inverter for the short periods of Microwave & TV watching etc….Then use the main engine alternator to re-charge the batteries & to heat water while at anchor or underway during the day (if you have a water heater that has a heat exchanger connected to the engine's cooling system)

Either that or yes…Disconnect the A/C and use the Honda to power the charger part of the inverter to recharge the batteries. 

5) Is it possible to have two thermostats controlling one AC unit?…

Not with factory made parts, but we could rig up a switch/box…Or something I have done that is cheaper, is use 2 remote sensors with a switch to select day or night time (main or fwd) but I still say the Average method is best…Also simplest.

Thanks for your help.

Don

 

Steve~


November 27, 2010
1:26 pm
dlane
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Steve,

 

Thanks for your prompt reply.  It has made me reconsider a single Dometic 16K unit to air condition both cabins and would be a lot simpler to install on several counts.  If I do this, I assume there will only be a thermostat control in the main cabin.

1) What is your take on controlling the temperature in the forward cabin at night?

2) How would you accomplish return air flow from the forward cabin?  I mentioned that I could put a return air grill in the bulkhead between the storage area the AC unit would go in and the forward cabin, but just to let you know, this vent would wind up in the bottom of a cloths locker in the forward cabin.  I was planning to use this arrangement for the 5K unit.  Since the space in the bottom of the closet is used to store some shoes, I was going to also put a return vent in the bottom of this cabinet which would facilitate the flow of air from the forward cabin into the locker and then through the bulkhead into the storage space where the AC unit would be located.  Of course I would install a larger return vent in the AC storage space in the main cabin.

3) Would a single 16K unit leave sufficient 110v power for the rest of the boat?  I have a Heart 2500 Inverter with a battery charger that I think can pump out as much as 120 dc amps.  I assume I couldn't charge the batteries if they were low while also running the AC,

4) With a smart start on a Dometic 16K unit, what size generator do you think I could get away with if I don't run the charger or microwave at the same time?

5) Is it possible to have two thermostats controlling one AC unit?

Thanks for your help.

Don

November 27, 2010
12:06 pm
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Steve Pooler
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Just went back & studied the Webasto specs from this page…** you don't have permission to see this link **

If you notice the 16K unit requires only 24 sq in of discharge duct/grill area…That's a bunch less than the Dometic spec of 80 sq in for a Cruisair or Marine Air unit…

That fact suggests that they may be rating their units on a different scale than the Standard of the HVAC industry, and what Dometic uses.

That standard dictates that a 16K unit should move 535-560 CFM of air…It's very hard to move that much air thru that small an area without making a lot of air noise…Believe me, I know this to be true from experience…Volume is what you want…Not velocity…

Velocity only makes Hurricane noises  Surprised Wink

Yet they do claim the 16K moves 505 CFM  ???…Thru the same 5" duct ring that they recommend/comes with a 12K unit ???…Hmmmm…A Cruisair/Marine Air 12K unit requires 6" duct (as did the older Cruisair 10K unit)

Comparing Apples to Apples…I wouldn't expect the same size Webasto to perform as a Same rated Cruisair/Marine Air unit…As the whole line specs are much smaller for air delivery than the known standards.

My guess is the Dometic 8K (or maybe one of their older 9 or 10K units) would likely match the performance of the Webasto 16K with less air noise…Again…From experience I have a hard time believing they are forcing that much air thru that size duct…

If you care to compare specs to the above link…Here is Cruisair's PDF specs ** you don't have permission to see this link **

 

** you don't have permission to see this link **Steve~ 

November 27, 2010
9:57 am
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Steve Pooler
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This is a copy of a e-mail sent to Service @ Marine AC by member dlane…I have moved it here so as to allow others to see & to give him credit for a well thought out plan…So Hi Donald…Thanks for asking & I'll try to answer each question…If I miss one let me know here please…

 

Hi Steve,

I want to

install air conditioning in my 40' Jeanneau sailboat. Because my wife and I are

out on our boat for weeks at a time during the summer and prefer to stay on

moorings and at anchor, my initial thought was to air condition just the forward

cabin which is around 270-300 cubic feet so I could sleep in comfort when needed

by running the AC using a portable Honda or similar generator.

In

general, the best location for an AC unit is under the dinette settee just

behind the bulkhead that separates the main cabin and the forward cabin.

Unfortunately, this is a large space that I would hate to loose in it's

entirety, but if I install a 5k unit here and duct through the bulkhead into the

forward cabin, I may be able to retain use of about half of this storage space.

I would also be able to install a return air vent in this bulkhead.

After careful consideration of the space under this settee, I think a

Webasto 5k unit would fit the best considering both ducting, sea water lines and

condensate lines. Since I need to locate the unit close to the hull with the

blower output facing the point in the bulkhead where the ducting has to go, I

like having the blower located on the outboard side of the unit and drawing air

in from the inboard side. This allows the blower to extend past the sub-floor in

this storage space.

I also like the Webasto because it comes with a

digital control as well as a remote control and has a dehumidifier mode. The

only thing that would discourage me from using this unit would be if it is

unreliable. My experience with the Webasto diesel heater in our boat has been

very good, but I would appreciate your thoughts and experience with Webasto AC

units…

The Webasto line is fairly new to our shores, and not marketed thru our standard network of Dometic Cruisair/Marine Air distributors or dealers…So To be Honest…I have No experience with the product either in installation or service…

I can say that I recently attended a 3 day service school with other servicing dealers from all up the east coast of the US…Of course during breaks & lunch we chat…During one of those lunches the Webasto subject came up, and not one of the guys that had had a chance to work on one had much good to say…I don't know it for fact, but my guess is you might have trouble getting service if needed.

Just for your info…All Dometic digital controls have a dehumidify mode, and the Cruisair SMXir has an optional remote control available.

While considering my options, several people have advised me that

I should put a 16K unit in to air condition both the main cabin and forward

cabin. While I would like to air condition the entire boat, doing this would

make air conditioning the forward cabin when on anchor or mooring impractical

since I don't want an generator larger than 2000 watts. Nonetheless, this

thought has made me think about installing a second unit to air condition the

main cabin which is around 1200 square feet. I may be able to install a 12K

Webasto AC unit in a separate storage space under a different section of the

same dinning settee….

I have started/run an older King Air (less efficient than todays units) on a 2000 watt Heart Inverter…2000 watts equates to about 17 amps…Your Webasto 16 quotes 11 amps draw "Average" load according to their site specs…A Dometic 16K unit is 9.4 amps in cooling mode & 12.4 amps in heat…

Yes…Starting amps is the main issue, but you can add a start relay & capacitor, or a Dometic SmartStart to any unit…The SmartStart though not cheap, is really the way to go as it can drop starting amps by as much as 65% and can mean the difference in which way you go with your Honda 2000 watt…One 5-6K unit for the V-Berth or Cool the whole boat with a 16K…

I have installed several of the SmartStarts and they really do live up to the claims…

 ** you don't have permission to see this link **  

With two units, I would still like to install a new

dedicated 3/4" through hull with a single sea water pump and

strainer.

To install 2 units aboard would likely require you add an additional 30 amp shore line with associated panel, and also a Pump Relay box.

Though the pump relay would not be a problem...Two systems would be close to the limit of one shore cord, and would not leave you much power to run anything else such as a microwave, battery charger or water heater...

With this as background, I have several questions.

1) I

assumed I would use a T or Y splitter on the output side of the water pump to go

to the two units. I also assumed this would essentially split the water flow

evenly between the two units. Using a 500 gph pump would deliver 250 gph to each

unit which should be sufficient as I understand it. Am I correct on this

count?…

Yes…As long as you don't have to pump long distances which increase pump head and reduce the rated flow…But you should be Ok in your instance since 500 GPH is enough for 2 tons & you would only have 1.4 tons.

2) With respect to the Cruisair/Marine Air model PML500 pump, it

is my understanding that the intake is in the center of the impeller housing and

the output is perpendicular to the intake. In most cases, it seems the output of

the pump is pointing upward/vertical. For me, this would require the output hose

to the AC units to be higher than necessary. Can the impeller housing be rotated

so that the pump output is horizontal? This would better facilitate keeping the

hose routed on an upward slope from the pump to the AC unit(s)….

No, the PML500 pump head cannot be rotated due to the liquid cooling tubes that go in & wrap around the motor inside…you can however mount the pump on a bulkhead in the sideways position (as long as the outlet is the highest and not lowest part) or you can go with the PMA500 pump that is air cooled, has no liquid cooling tubes, and the head can be rotated…Of course that pump is not submersible with it's open ventilation. 

3) Due to

limited space for running ducting behind cabinets etc., I was planning to

install a single vent in the outboard shelf behind the settee seating closest to

the galley which is near the middle of the cabin. This would result in supply

air blowing upward in inward with some ability to direct air forward and aft at

the same time. I would prefer to use a long narrow grille rather than a shorter,

wider grille. In this case I am considering a 20x4 grille rather than something

like a 12x6 grille. Do you feel using a single source of supply air like this is

adequate and is there an advantage to either grille size?…

Either grill size would be sufficient for 16K…It's the Duct size & length that is most important…For a single outlet 16K you would need space to run 7" duct or be faced with ice up in cooling, or cycling on high head pressure in heat….For dual outlets, a duct splitter could be used, and 6" to the Salon with 4" to the V-berth should be sufficient.

As far as grill orientation, just remember that the last set of vanes the air hits are the ones that do the most work (provide the most effect)

4) Some

installation guidelines say to completely seal the compartment in which the AC

unit is located from the bilge and the rest of the boat other than for the

return air grille. In addition, they say not to run the condensate drain into

the bilge. How critical is this and how do you accomplish it? It would appear to

be difficult to completely seal a storage compartment from the rest of the boat.

In addition, my bilge area is very shallow and won't easily accommodate a

separate sump. Because my mast steps on the cabin, and I have a fairly dripless

stuffing box, I get very little water in the small bilge sump other than from

condensation from the 2 refrigeration units on board…

A/C will suck air (and odors) from wherever it can (especially if the return filter is too small or clogged) this can add heat load to the unit also, so a tight space is preferred…Expandable spray foam is one quick easy way to seal up…It can also be trimmed for appearance once dry.

6) If I install two

AC units, can I combine the condensate drain lines into one that goes into the

bilge sump, which by the way, has a float switch and an associated external

bilge pump…Yes...

Thank you and please advise what components for this

installation I can purchase from you…

Thanks again for asking Donald…I can supply everything you might need from pumps to grills, but it's the Webasto unit/s I can't help with…

Steve~