step up transformer to run air con

[captianjuan]

Any recommendations for a transformer to run the AC onboard. I just purchased a boat and the air con is set up for 230. Dock only has 120 available (U.S.). I intend on keeping the AC or buying another with equal capacity (seems to be all 240 after 16k BTU) so not looking for musings on sailing without AC and the joys of the wind blowing through the cabin. Ive been there plenty. I see Victron makes a transformer. Im also converting to Lithium and contemplating buying two Victron inverters, one for 240 dedicated to my high usage systems and another for 120. any thoughts on that?
thanks in advance,
fair seas

[Jammer]

My advice (aside from various suggestions you have already discarded) would be to install two air conditioners that are both 120v.


Transformers are big, heavy, and expensive but you can get them e.g. https://www.grainger.com/product/ACM...mer-120V-4WUD8 - that's a listing for a 3 kva one. You might be able to get away with 2 kva but they're not much cheaper or smaller.


Looking around, Automation Direct has better deals: https://www.automationdirect.com/adc...ted)/c1f003wes


One or two other members have boats with combined 120v/240v systems with lithium batteries and inverters but they are complex to operate and maintain. I wouldn't recommend that.


The Victron isolation transformer would work OK too I would think.

[smac999]

even with a transformer the AC system might only want 50hz

and if you only have 30a 120 you won't be running much on it anyways.

[stormalong]

Be sure that your electrical system can handle the current to supply the air conditioner. Remember that when you double the voltage the current output of the transformer is half the input current minus 5 to 10% efficiency losses.

[wingssail]

If you supply 120VAC to a transformer to get 230VAC output for the air conditioner, you will HALVE the current. The wiring should be OK.

But at the dock you will be limited by the dock supply, either 30 amp (meaning 3600 watts) or 50 amp, meaning 6000 watts. A 23,000BTU unit will use over 2300watts, probably more on start-up. Considering the efficiency loss of the transformer you will probably be stressing your electrical system, and it will be expensive. Two units might not be possible.

THEN, try running it on the batteries, Lithium or not. You will need a lot of battery capacity, a huge inverter, and extensive recharge ability.

Maybe a 5000KVA genset could handle it.

But, if you must be cold at anchor or sailing, go for it, and let us know how it turns out.

[captstu]

Assuming the existing aircon is 240V/60 Hz, you might be fine.

In the potential a/c is a replacement, getting a 120 a/c will draw about the same current as the transformer feeding the 240 a/c.

If you plan to run two a/cs, consider replacing both with a mini-split. Mini-splits are roughly 3 times as electrical efficient as most existing continental air conditioners.

You might also look at the newer inverter marine air conditioners - hard to find, but lower current draw and no start up load.

My mini-split draws 500 Watts.

[sinnerman]

[QUOTE=smac999;3654717]even with a transformer the AC system might only want 50hz


VERY GOOD POINT!!

[redneckrob]

Not the most efficient setup, but you can buy a 230 volt/50 hz inverter and either a big charger or another 120 volt/60 hz inverter/charger that's the same size. You turn the 120v/60hz to 12/24/48 volts DC then the inverter turns it back to 230v/50 hz.

[ebs001]

While the receptacles on the marina pedestals indicate that they are 120 volt, the 50 amp receptacles are 120/250 volt. If the pedestal has a 50 amp receptacle you already have available a 230 volt supply. That supply is at 60 hertz so the there thing that needs to be checked is what the hertz the ACs require. A 50 hertz motor will operate on 60 hertz but the life expectancy is reduced.

[Adelie]

Originally Posted by captianjuan

Any recommendations for a transformer to run the AC onboard. I just purchased a boat and the air con is set up for 230. Dock only has 120 available (U.S.). I intend on keeping the AC or buying another with equal capacity (seems to be all 240 after 16k BTU) so not looking for musings on sailing without AC and the joys of the wind blowing through the cabin. Ive been there plenty. I see Victron makes a transformer. Im also converting to Lithium and contemplating buying two Victron inverters, one for 240 dedicated to my high usage systems and another for 120. any thoughts on that?

thanks in advance,

fair seas

Over 16k BTU needs 230v in order to keep the amps reasonable on the service side. If you use a step up transformer to get the voltage you want it doubles the amperage demand on the 120v side and you will pop breakers.

If you do use the step up transformer you’ll a 230c inverters that can synchronize with shore power and provide the amperage boost needed to avoid popping breakers.

Alternative would be to get 2 120v AC units and make sure they are plugged into different circuits on the shore side.

[redneckrob]

Originally Posted by Adelie

If you do use the step up transformer you’ll a 230c inverters that can synchronize with shore power and provide the amperage boost needed to avoid popping breakers.

The step-up transformer is still going to provide 60hz. Unless you find some crazy Korean 60hz 230v inverter, the inverter is going to be 50hz. You can't feed 60hz AC into that and expect it to provide a boost. I'm not sure what would happen if you wired one inline with 60hz but I'm guessing it wouldn't be anything good.

[s/v Jedi]

Originally Posted by captianjuan

Any recommendations for a transformer to run the AC onboard. I just purchased a boat and the air con is set up for 230. Dock only has 120 available (U.S.). I intend on keeping the AC or buying another with equal capacity (seems to be all 240 after 16k BTU) so not looking for musings on sailing without AC and the joys of the wind blowing through the cabin. Ive been there plenty. I see Victron makes a transformer. Im also converting to Lithium and contemplating buying two Victron inverters, one for 240 dedicated to my high usage systems and another for 120. any thoughts on that?
thanks in advance,
fair seas

The reference diagram that gives both 120V and 240V aboard is attached. You can leave things out or add more, like the Multiplus units (even one can be used for having both 120 and 240V) which you just add for more capacity or the output distribution groups when you want more flexibility (you can use just one). Most of this is 240V; any 120V shore power is transformed to 240V by the isolation transformer and the familiar split phase plus neutral 120-0-120 is created by one or more auto transformers in the distribution groups.

[Adelie]

Originally Posted by redneckrob

The step-up transformer is still going to provide 60hz. Unless you find some crazy Korean 60hz 230v inverter, the inverter is going to be 50hz. You can't feed 60hz AC into that and expect it to provide a boost. I'm not sure what would happen if you wired one inline with 60hz but I'm guessing it wouldn't be anything good.

The OP did not mention Hertz in any post here and they are in Hawai’i which runs US standard so I don’t understand how there started being a discussion of a frequency mismatch.



Is there a post in another thread where the OP indicates European boat using 50Hz?

[s/v Jedi]

Originally Posted by redneckrob

The step-up transformer is still going to provide 60hz. Unless you find some crazy Korean 60hz 230v inverter, the inverter is going to be 50hz. You can't feed 60hz AC into that and expect it to provide a boost. I'm not sure what would happen if you wired one inline with 60hz but I'm guessing it wouldn't be anything good.

We don’t know the frequency required by the A/C nor what the boat is wired for.

My diagram posted above can do the frequency conversion if two Multiplus units are installed, with one doing the inverting and the other feeding DC to it from shore power.

[wingssail]

Originally Posted by redneckrob

The step-up transformer is still going to provide 60hz. Unless you find some crazy Korean 60hz 230v inverter, the inverter is going to be 50hz. You can't feed 60hz AC into that and expect it to provide a boost. I'm not sure what would happen if you wired one inline with 60hz but I'm guessing it wouldn't be anything good.

I would just mention that we made a similar conversion, if lf lesser capacity.

We had an 230VAC 50hz air-conditioner when in Asia. Our boat was wired for 110VAC. We tapped into the 230v shorepower for the AC before running it through a transformer to step it down to 120 for the rest of the vessel. We ignored the 50hz/60hz issue as almost all of our electrical equipment ran off of 12v. We used the Inverter to supply 60hz when we needed it. The battery charger/inverter was indifferent.

When returning to 120VAC land we ran shore power directly into the boat and used the transformer to step it up for the AC, which worked fine despite the Hz difference.

Now we have new AC which is 110VAC and it is even better. (but we only need 8000BTU.

Depending on your capacity to supply the needed wattage, a transformer setup should work.
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