Air Conditioner VFD technology?

[ksanders]

I am in search of air conditioners for my boat.

The question becomes what do I buy???

In houses here in Mexico the mini split is very popular, service is available locally, but these are impossible to install on my boat. It is interesting thaty almost all mini split units currently being sold are VFD inits which are far more energy efficient.

Standard, old fashioned marine air conditioners are available in a variety of sizes and brands, one being Marinair which offers direct to customer sales as well as technicial support.

There are two that I can find marine AC manufacturers offering VFD technology, one being Velair out of Italy and the other being Mabru.

Does anybody have any experience with these brands???

What is your opinion and experience???

 

[mvweebles]

Kevin - as it happens, I reached out to Marinaire with a tech support question late last night. They got back to me early this morning. It's an older unit that I just installed. Unlike Lewmar, who wouldn't say squat about a hatch leak until I provided warranty information, Marinaire answered the question. It's still not resolved, but a decent sign.

I tried search CruisersForum for Mabru as I seem to recall they've come up several times in last 2 years or so. I couldn't find a decent thread using my phone for search. I seem to recall positive reviews, but they are expensive. At least 2x a standard Marine AC unit.

I know it might be a bit klugey looking, but given the dry climate there, any thought of a portable swamp cooler?

Peter

 

[DavidM]

I have never used one, but as a retired engineer I understand their advantages.

Speaking of Velair, their 16k btu/hr unit draws 9 amps at 115v at full load or 1035 watts and costs about $3,000. A standard Dometic unit draws 10.5 amps at 120v or 1,260 watts or about 25% more but costs about $2,700. The Velair will also be quieter particularly at partial load.

The Mabru is less efficient than the Velair and more expensive than the Dometic or the Velair.

So given the benefits of the Velair- efficiency and noise, it looks to me to be the best choice.

David

 

[Jeff F]

Has your boat never had AC? I guess I'm east where it's pretty much standard equipment.

I've looked pretty carefully at mini splits as a solution for my boat. They make a lot of sense for me. Put the compressor up top, cover it when it's rough and replace it every X years. A single 110v compressor can be used for zoned cooling. Lots to like.

I guess you're looking for a water-cooled compressor that works the same way?

 

[Nick F]

A split AC with VFD (called "inverter" AC) has a bunch of electronics to operate the compressor motor at variable speed. These electronics are in the form of circuit card(s) located in the compressor (outdoor) part exactly where the greater heat and humidity and salt atmosphere are. A non-inverter type split AC has NO electronics in the outdoor part.

I personally would definitely avoid inverter type AC´s. The best energy savings are achieved by not oversizing your AC unit.

Good luck!
Nick

 

[ksanders]

Well...

i have been talking to Rich over at Cruise RO and he had a novel suggestion.

His suggestion is to use a single chiller unit that connects to air handlers. Exactly the same idea as a hydronic heating system except using cold water.

He told me this would dramatically simplify my installation, and allow me to have one larger unit serving my cabin spaces.

 

[rslifkin]

Well...

i have been talking to Rich over at Cruise RO and he had a novel suggestion.

His suggestion is to use a single chiller unit that connects to air handlers. Exactly the same idea as a hydronic heating system except using cold water.

He told me this would dramatically simplify my installation, and allow me to have one larger unit serving my cabin spaces.

I've thought about that approach for my own boat. The biggest issue I ran into is that even the smallest chiller systems I could find are 240v. That would be an installation challenge on my boat, as I only have 120v available.

 

[Jeff F]

110v is a big challenge.

There are lots of small commercial water-cooled VFD units. Mostly 240v though. Then you put an evaporator unit in each cabin and run refrigerant lines.

I haven't considered this before. But couldn't you run one of these on a short coolant loop through a heat exchanger on a seawater loop?

 

[ksanders]

I've thought about that approach for my own boat. The biggest issue I ran into is that even the smallest chiller systems I could find are 240v. That would be an installation challenge on my boat, as I only have 120v available.

Here are some better photos. As far as the 230V I am checking if thgey offer a 120V model, if not I can easily install a step up transformer.

 

[Jeff F]

How do you handle condensation on air handlers? Are they self contained surface mount?

 

[ksanders]

110v is a big challenge.

There are lots of small commercial water-cooled VFD units. Mostly 240v though. Then you put an evaporator unit in each cabin and run refrigerant lines.

I haven't considered this before. But couldn't you run one of these on a short coolant loop through a heat exchanger on a seawater loop?

With this one you use a cold fresh water loop just like a hydronic heating system.
This is different than a traditional split system in that the refrigerant is all in the main unit.

 

[Nick F]

Quote " the refrigerant is all in the main unit. "

I see this as a BIG advantage.

 

[Jeff F]

What do the air handlers look like?

 

[ksanders]

What do the air handlers look like?

Here is one of several examples

 

[twistedtree]

Well...

i have been talking to Rich over at Cruise RO and he had a novel suggestion.

His suggestion is to use a single chiller unit that connects to air handlers. Exactly the same idea as a hydronic heating system except using cold water.

He told me this would dramatically simplify my installation, and allow me to have one larger unit serving my cabin spaces.

Our boat uses variable speed chillers, which I presume this one is too.


I think the biggest challenge on a retrofit will be getting all the pipe runs fully insulated. Any exposed piping will sweat and drip water, potentially doing a lot of damage. Success or failure will be all about access on your boat for the various pipe runs, and quality and care of insulation.


You also need two pumps in addition to the chiller; one for sea water to carry away the heat, and another to circulate the tempered (chilled) water. On my system the tempered water pump operates continuously and draws a lot of power. The sea water pump cycles on and off as the chiller cycles.


I can't say whether on the whole it's more or less power efficient than a marine split system, or marine combined units. There are a lot of factors with no easy way to compare.

 

[twistedtree]

Here is one of several examples

They will all need condensate drains, but so will any other types of AC air handlers.

 

[ksanders]

They will all need condensate drains, but so will any other types of AC air handlers.

ahhh, ok.

Well, I'm waiting for the quote to come back on the chiller system, and will take it from there.

Access for the pipes is very good but we'll have to see where this all comes out.

 

[bowball]

And I believe the a/c would be more effective if the vents were at ceiling height not the floor level where the heat may be?

 

[Jeff F]

I have a heating hydronic system with similar air handlers placed for heating. When I was considering a/c I didn't really consider piggybacking on that system. Concerns were placement and condensation handling.

I was thinking earlier of a water cooled split unit. The air handlers up to 16k btu are compact and easy to place, and have built in thermostat, remote, etc. So a 36-40k VFD unit supporting three or four wall units.

But based on a few internet searches these are not commonly found. Too bad.

 

[twistedtree]

For a combined heat and cooling system using tempered water, I think it’s much easier to add heat to an existing cooling, vs adding cooling to an existing heating system. The existing cooling system will already have condensate drains, plus be sized for a smaller water to air temp difference, roughy 35 deg for 40F chilled water and 75F inside air temp.

In contrast a hydronic heating system doesn’t have condensate drains, and is typically designed for a much higher temp difference, say 170F water temp and 70F inside air temp, so 100F difference. This allows for much smaller air handler that would be too small for cooling. Chillers typically can be heated to more than 140F, so you would operate it at 130F or maybe 135. That’s much less temp difference so the air handlers will be much less effective

All this can be done, but there are a bunch of considerations.

 

[Scottwb96]

The Velair 21k btu unit is a little less than $3k and runs on 110v. Yes, they are a bit more expensive, but:
1. You can get a 21k BTU that runs on 110v
2. It comes with the wifi connection ($300-$500+ upgrade for most other units)
3. VFD
4. Can run off an inverter/batteries
5. Solid reviews...

Check out satpro.tv for their listing...

 

[ramkay]

I am in search of air conditioners for my boat.

The question becomes what do I buy???

In houses here in Mexico the mini split is very popular, service is available locally, but these are impossible to install on my boat. It is interesting thaty almost all mini split units currently being sold are VFD inits which are far more energy efficient.

Standard, old fashioned marine air conditioners are available in a variety of sizes and brands, one being Marinair which offers direct to customer sales as well as technicial support.

There are two that I can find marine AC manufacturers offering VFD technology, one being Velair out of Italy and the other being Mabru.

Does anybody have any experience with these brands???

What is your opinion and experience???

Frigomar out of Italy. Up to 16K BTU.

 

[Simi 60]

So why are bog standard off the shelf household split systems not a thing there?
It's what most work and serious cruising boats seem to have here.

$466 USD for 2.5 kw of lovely cold goodness.
As an example

https://wholesaleaircon.com.au/prod...ColDr-BQqgQZrwv0oLw5kgtAkG3EfPHBoCRx0QAvD_BwE

 

[Bmarler]

So why are bog standard off the shelf household split systems not a thing there?
It's what most work and serious cruising boats seem to have here.

$466 USD for 2.5 kw of lovely cold goodness.
As an example

https://wholesaleaircon.com.au/prod...ColDr-BQqgQZrwv0oLw5kgtAkG3EfPHBoCRx0QAvD_BwE

Coming up with the space to mount the indoors portion can be difficult. A ducted unit is much more appealing, especially if you have ducting already.

 

[rslifkin]

So why are bog standard off the shelf household split systems not a thing there?
It's what most work and serious cruising boats seem to have here.

$466 USD for 2.5 kw of lovely cold goodness.
As an example

https://wholesaleaircon.com.au/prod...ColDr-BQqgQZrwv0oLw5kgtAkG3EfPHBoCRx0QAvD_BwE

I do see them occasionally on boats (especially work boats). But on many non-work boats, space is an issue, especially to mount the outdoor compressor / condenser unit. A water cooled system is more compact and doesn't take up deck space, so it's an attractive option. Smaller boats will also expose them to salt spray more often, and I'm not sure how well those units hold up to it.

 

[FlyingScot]

I have never used one, but as a retired engineer I understand their advantages.

Speaking of Velair, their 16k btu/hr unit draws 9 amps at 115v at full load or 1035 watts and costs about $3,000. A standard Dometic unit draws 10.5 amps at 120v or 1,260 watts or about 25% more but costs about $2,700. The Velair will also be quieter particularly at partial load.

The Mabru is less efficient than the Velair and more expensive than the Dometic or the Velair.

So given the benefits of the Velair- efficiency and noise, it looks to me to be the best choice.

David

I found different information when I researched Velair, Frigomar and Mabru.

Where did you find that the Mabru was less efficient?

Mabru includes the water pump in their specifications.

A friend who was a dealer of all 3 brands told me that the Mabru is the most efficient.

Chris
SV Cosmos

 

[ksanders]

So why are bog standard off the shelf household split systems not a thing there?
It's what most work and serious cruising boats seem to have here.

$466 USD for 2.5 kw of lovely cold goodness.
As an example

https://wholesaleaircon.com.au/prod...ColDr-BQqgQZrwv0oLw5kgtAkG3EfPHBoCRx0QAvD_BwE

I am very familiar with what we call a "mini split" AC system here in Mexico.
Believe me I would LOVE to use them on my boat.

Why??? because they work great, they are reasonably inexpensive, and there are a zillion tech's locally to service them.

Here is the problem...

The outdoor unit is approx 30" L X 12" W X 24" H. Where to bolt it down out of the way??? Theoretically I could remove my deep freeze and use that space.

Then you have to route a insulated copper pipe and electrical cables to the indoor unit which bolts to a wall and is approx 30" W X 10" H X 10". That kind of real estate is just not available on a boat.

 

[Graeme Walker]

The Velair 21k btu unit is a little less than $3k and runs on 110v. Yes, they are a bit more expensive, but:
1. You can get a 21k BTU that runs on 110v
2. It comes with the wifi connection ($300-$500+ upgrade for most other units)
3. VFD
4. Can run off an inverter/batteries
5. Solid reviews...

Check out satpro.tv for their listing...

The issue I'd have is that I'm using my Inverter to create 120v AC and then using the inverter contained in this unit to convert back to 12v, seems like fairly significant overhead, 20%?. I like the idea if it ran directly off 12v like the Mabru, just bought new A/C but couldn't justify the price, will run small 6k unit directly off 3K Inverter.

 

[rslifkin]

The issue I'd have is that I'm using my Inverter to create 120v AC and then using the inverter contained in this unit to convert back to 12v, seems like fairly significant overhead, 20%?. I like the idea if it ran directly off 12v like the Mabru, just bought new A/C but couldn't justify the price, will run small 6k unit directly off 3K Inverter.

The drive in these is converting power regardless of the input. They're not 12v DC internally, they're variable frequency AC. Possibly 3 phase.

 

[hmason]

We have an AquaAire chiller system on our boat. I’m very happy with it. We’ve never had an uncomfortable day even in the summer inferno in Florida. It also works in reverse cycle for heating. Big advantage is a thermostat in every stateroom, galley, and saloon.