Marine 12v air conditioning

[poiu]

Originally Posted by FlyingScot

I posted this: "From my research the 12VDC Mabru is the most efficient."

You posted: "The Mabru is actually equally efficient as the Velair and Frigoboat."

Then I went on and posted facts about the two units.

You responded that your system only uses 240w.

If you are getting 3K btu/hr from 240w and the Mabru does 3.5K btu/hr from 212w, then you are using 13% more power to achieve 17% less cooling.

Yours would likely need 280w to achieve 3.5K btu/hr. So apples to apples yours would use approximately 32% more power.

I think we can all agree that using almost 1/3 more power is not "equal" or even "about equal".

Even your 240w is suspect as the Velair specifications I read shows that it uses 240w in eco mode not including pump and inverter losses. So maybe you got an amazing one, or more likely it is putting out less cooling than 3K btu/hr.

On top of that, a few posts ago you let us all know: "Zero factory tech help and ignored emails" when you spoke about Velair.

Yes the Mabru costs more. But you will get support. It will be easy to install and run. No sourcing your own pump and constantly adjusting the pump for your cooling needs. Plus it will save 1/3 the power.

What does adding 1/3 more batteries and charging sources cost?

I stand by my assertion that the Mabru is the most efficient.

The Mabru needs to add pump consumption, so your figures are wrong and efficiency might be better, but very little where it counts and I haven’t disputed it might win that prize, it’s not enough. Also, it’s not just a little more expensive, it’s nearly double.. Plus, it’s only 12v. Most yachts with aircon need 24v. Also don’t underestimate fully modulated, inverter control. It’s what ensures unobtrusive running. All that is why I’m sure I’m right not to buy Mabru.

[FlyingScot]

Originally Posted by poiu

The Mabru needs to add pump consumption, so your figures are wrong and efficiency might be better, but very little where it counts and I haven’t disputed it might win that prize, it’s not enough. Also, it’s not just a little more expensive, it’s nearly double.. Plus, it’s only 12v. Most yachts with aircon need 24v. Also don’t underestimate fully modulated, inverter control. It’s what ensures unobtrusive running. All that is why I’m sure I’m right not to buy Mabru.

No, the Mabru includes the pump in the power consumption numbers. If it didn't I would have added it to compare apples to apples. The pump is included and controlled/powered from the main unit. You don't have to source the pump, tune the flow rates of the pump, etc.

I just confirmed that data with Andre@theyachtrigger.com.

The Mabru is the most efficient. Nothing on the market is it's equal.

Yes, it is more expensive. But what is efficiency worth? What is support worth?

[Rumrace]

Well this thread helped large. Turns out I have a crapped out last summer blowing no cold air. You made me crawl in the back to write down numbers and such. Turns out my Jeanneau has a Mabru. I needed 600$ in parts. It did run with the generator or at the dock. We use it maybe 8 days a year on Lake Ontario but probably cause it’s worked poorly. I’m working out the details to turn it and open vents remote. I have a stepper motor in one hatch.

[fivecapes]

The 'efficiency' of a 12V unit vs an ac inverter BLDC unit will likely depend on how you use it.

All else being equal.

If you plan on setting it at 64F (18C) on a hot day where compressors of both types will be on most of the time, the 12V unit is likely to be more efficient.

I suspect if you set it higher at 73F (23C) eg for less cooling at night, the inverter unit will perform better (especially in dehumidify mode) as the 12V unit cycles more often.

It's been previously noted the 12V unit's tight cooling range spec vs that of ac inverter unit. While a less cool setting is possible in the 12V unit, why isn't a current draw reported for that lower setting, because you won't be setting it there or because it remains high?

YMMV

[FlyingScot]

Originally Posted by fivecapes

The 'efficiency' of a 12V unit vs an ac inverter BLDC unit will likely depend on how you use it.

If you plan on setting it at 64F (18C) on a hot day where compressors of both types will be on most of the time, the 12V unit is likely to be more efficient.

I suspect if you set it higher at 73F (23C) eg for less cooling at night, the inverter unit will perform better (especially in dehumidify mode) as the 12V unit cycles more often.

It's been previously noted the 12V unit's tight cooling range spec vs that of ac inverter unit. While a less cool setting is possible in the 12V unit, why isn't a current draw reported for that lower setting, because you won't be setting it there or because it remains high?

YMMV

Mabru reports the amps for both the high and low setting.
https://theyachtrigger.com/wp-conten...04/SC12-GN.pdf
33 amps at 8200 btu/hr and 44 amps @ 12500 btu/hr. Remember this includes the pump. Those are 12v numbers and it has been demonstrated that the amps are lower when using Lithium batteries due to higher voltage.

You guys must like it cold! Who sets their air on 64F? We are happy with 77F. The reduction in humidity is almost enough. Just a couple degrees cooler makes an incredible difference in comfort for us.

Regardless, I see no scenario when the AC driven units will be more efficient or as efficient. Remember there is no startup spike loads with either unit. So help me understand why cycling on and off wastes so much power? It would have to overcome a 30-50% disadvantage.

[s/v Jedi]

Originally Posted by FlyingScot

Mabru reports the amps for both the high and low setting.
https://theyachtrigger.com/wp-conten...04/SC12-GN.pdf
33 amps at 8200 btu/hr and 44 amps @ 12500 btu/hr. Remember this includes the pump. Those are 12v numbers and it has been demonstrated that the amps are lower when using Lithium batteries due to higher voltage.

You guys must like it cold! Who sets their air on 64F? We are happy with 77F. The reduction in humidity is almost enough. Just a couple degrees cooler makes an incredible difference in comfort for us.

Regardless, I see no scenario when the AC driven units will be more efficient or as efficient. Remember there is no startup spike loads with either unit. So help me understand why cycling on and off wastes so much power? It would have to overcome a 30-50% disadvantage.

The AC will only be more efficient when it is the VFD type, using variable RPM and 3-phase compressor. The reason is that 3-phase is much more efficient plus the compressor running at low rpm is much more efficient.

I do not believe any claims about a VFD based A/C using twice the power of a 12VDC powered A/C with low/high speed settings without seeing evidence like from Wh meters etc.

I will have the choice and I’m sure it will be VFD. There is no reason they can’t make a 24V DC VFD unit but apparently they don’t because most boats that want these kind of units will have plenty AC power available.

[poiu]

Originally Posted by FlyingScot

Mabru reports the amps for both the high and low setting.
https://theyachtrigger.com/wp-conten...04/SC12-GN.pdf
33 amps at 8200 btu/hr and 44 amps @ 12500 btu/hr. Remember this includes the pump. Those are 12v numbers and it has been demonstrated that the amps are lower when using Lithium batteries due to higher voltage.

You guys must like it cold! Who sets their air on 64F? We are happy with 77F. The reduction in humidity is almost enough. Just a couple degrees cooler makes an incredible difference in comfort for us.

Regardless, I see no scenario when the AC driven units will be more efficient or as efficient. Remember there is no startup spike loads with either unit. So help me understand why cycling on and off wastes so much power? It would have to overcome a 30-50% disadvantage.

Cycling does waste a little power as the system takes power to produce a vacuum before it can start to work. Especially an issue with fridges and and aircon with long pipe runs.

It’s more about comfort. An inverter aircon will modulate its speed and output to match load so that there is little temperature hysteresis. When working optimally, at night for example, with little environmental changes the temperature will be close to constant with output matched to load. With a thermostat based system you don’t get that. If it is over sized as my old one was, the result is a blast of super cold air intermittently when temperature rises to the set point. It was uncomfortable and could wake me up.

[FlyingScot]

Originally Posted by poiu

Cycling does waste a little power as the system takes power to produce a vacuum before it can start to work. Especially an issue with fridges and and aircon with long pipe runs.

It’s more about comfort. An inverter aircon will modulate its speed and output to match load so that there is little temperature hysteresis. When working optimally, at night for example, with little environmental changes the temperature will be close to constant with output matched to load. With a thermostat based system you don’t get that. If it is over sized as my old one was, the result is a blast of super cold air intermittently when temperature rises to the set point. It was uncomfortable and could wake me up.

I agree it wastes a little to stop and start. Since it is self contained, the pipe runs are very short. The Mabru has two speeds, like full and 2/3 so it's not on/off like traditional units. I wish it was more variable but I guess I'll eventually find out first hand once I get this refit done and resplash.

Constant temp sounds great but I can live with some change if the overall effect is to save power. The current Cruisair/Dometic 16k btu/hr is terrible at keeping temperature. The swings are wild!

[Opie91]

Originally Posted by Russian007

Clark and Emily have a new video up for their solar powered 12/24v 5000btu one off AC. Apparently they've partnered with a 3rd party for manufacture. The parts and materials look excellent. The footprint for the compressor/evap is only 10"x10"x14". <200 watts, >7 coefficient of power. Salt H2o cooled. Dunno what the price is. Disclaimer: C&E's vids are longish, have poor production value and his wife doesn't parade and tease in her thong bikini but content trends excellent. So you've been warned.

The unit is pretty pricey, $2000 for compressor, condenser and evaporator. Add in the cost of all the other parts you need and the fact that it is a DIY kit makes the commercial units look pretty attractive.

[FlyingScot]

Originally Posted by s/v Jedi

The AC will only be more efficient when it is the VFD type, using variable RPM and 3-phase compressor. The reason is that 3-phase is much more efficient plus the compressor running at low rpm is much more efficient.

I do not believe any claims about a VFD based A/C using twice the power of a 12VDC powered A/C with low/high speed settings without seeing evidence like from Wh meters etc.

I will have the choice and I’m sure it will be VFD. There is no reason they can’t make a 24V DC VFD unit but apparently they don’t because most boats that want these kind of units will have plenty AC power available.

If boats that want these type of units have plenty of AC available, why would they pay more for efficient units? I'm not sure I agree with your logic. There is definitely growing demand for A/C from batteries and solar. The holy grail of sailboat life.

Mabru has a bunch of videos of installs. Many of them show meters that display voltage and amps and fully describe the systems.
https://www.youtube.com/c/MabruPowerSystemsINC

For some reason I can't find a single Velair VSD or Frigomar VSD that shows the amps/volts or watts through an inverter while running.

Good luck with whatever you choose.

[s/v Jedi]

Originally Posted by FlyingScot

If boats that want these type of units have plenty of AC available, why would they pay more for efficient units? I'm not sure I agree with your logic. There is definitely growing demand for A/C from batteries and solar. The holy grail of sailboat life.

Mabru has a bunch of videos of installs. Many of them show meters that display voltage and amps and fully describe the systems.
https://www.youtube.com/c/MabruPowerSystemsINC

For some reason I can't find a single Velair VSD or Frigomar VSD that shows the amps/volts or watts through an inverter while running.

Good luck with whatever you choose.

I’m not sure why you say that…. But here’s the reason why they want efficient units: so that they can run longer from their battery banks. We have 6kVA inverter power and a 10.5kWh lithium bank + 10kWh AGM bank. Power efficient units allow us to run A/C all night until the solar kicks in again.

Compare that with the 12V DC units: I can’t run them unless I install enough DC-DC converters to create the 12V power source. Boats thathave these large solar arrays and lithium banks have 24V or even 48V battery banks, with only enough 12V for starting an engine, using the radio etc.

This is why they go for the AC powered VFD units. Compared to the old style, they save 40% energy.

[flee27]

Originally Posted by Opie91

The unit is pretty pricey, $2000 for compressor, condenser and evaporator. Add in the cost of all the other parts you need and the fact that it is a DIY kit makes the commercial units look pretty attractive.

Is it pricey? Compared to the other options this actually seems like a good value. The only other unit that is a little comparable is the Mabru unit for almost 2.5 times the money. The next in line would be a VSD unit at almost 3K.

Now I can't speak for the finer technical details of Clark's design so not sure how comparable it really is. I am sure a lot of his efficiency it gained through the air handler unit. Appears to move a lot less air and is not really designed to be used as a central air type of unit. Mounting and air distribution from the type of handler could be a negative or a positive depending on the specifics of the install.

I personally am interested in Clark's unit and look forward to hopefully hearing some more real world experiences.

Foster

[Pelagic]

Originally Posted by fivecapes

The 'efficiency' of a 12V unit vs an ac inverter BLDC unit will likely depend on how you use it.

All else being equal.

If you plan on setting it at 64F (18C) on a hot day where compressors of both types will be on most of the time, the 12V unit is likely to be more efficient.

I suspect if you set it higher at 73F (23C) eg for less cooling at night, the inverter unit will perform better (especially in dehumidify mode) as the 12V unit cycles more often.

It's been previously noted the 12V unit's tight cooling range spec vs that of ac inverter unit. While a less cool setting is possible in the 12V unit, why isn't a current draw reported for that lower setting, because you won't be setting it there or because it remains high?

YMMV

That is an interesting observation about what users set the Temperature at.
My guess is that those who live in temperate climates tend to overcool when it gets hot, while those of us who live in the Tropics have adjusted to higher set temperatures so as not to get shocked by heat & humidity when going outside.

Here in the Philippines I set the aircon at 26C/79F as we average 33C/91F during the day

It is more about dropping the humidity inside and pacing yourself outside

[Opie91]

Originally Posted by flee27

Is it pricey? Compared to the other options this actually seems like a good value. The only other unit that is a little comparable is the Mabru unit for almost 2.5 times the money. The next in line would be a VSD unit at almost 3K.

Now I can't speak for the finer technical details of Clark's design so not sure how comparable it really is. I am sure a lot of his efficiency it gained through the air handler unit. Appears to move a lot less air and is not really designed to be used as a central air type of unit. Mounting and air distribution from the type of handler could be a negative or a positive depending on the specifics of the install.

I personally am interested in Clark's unit and look forward to hopefully hearing some more real world experiences.

Foster

It is certainly interesting and sips power, but it also does not put out a ton of cooling.


Also that $2000 leaves quite a few parts missing, it is going to take at least another $500 to complete the installation which pretty much equals what it cost for a Velair 4-10k unit.

[poiu]

Originally Posted by Pelagic

That is an interesting observation about what users set the Temperature at.
My guess is that those who live in temperate climates tend to overcool when it gets hot, while those of us who live in the Tropics have adjusted to higher set temperatures so as not to get shocked by heat & humidity when going outside.

Here in the Philippines I set the aircon at 26C/79F as we average 33C/91F during the day

It is more about dropping the humidity inside and pacing yourself outside

Agreed. I set at 77F to 78F at night and that would be far too warm in a northern latitude for most people.

Also, it is true that the dehumidification the aircon does is a big part of the way it keeps you cool and comfortable.