420DB – Bridge A/C and Heat Installation

Alex F

Alex F

Well-Known Member
Nov 14, 2006
9,166
Miami / Ft Lauderdale
Boat Info
2005 420DB with AB 11 DLX Tender, Raymarine Electronics (2x12" MFDs) with Vesper AIS
Engines
Cummins 450Cs, 9KW Onan Generator, 40HP Yamaha for tender.
By now we have good number of people upgraded to 420/44DB, so I was wondering if I can get some tips on addressing the project.

I have seen couple of threads on the subject, but I still have number of questions and was hoping that if we can reconcile the complete installation with pix in a single thread it would be much better for anyone who would like to attempt this installation in the future.

So far these were the treads I’ve found that share some details of the project:
http://clubsearay.com/showthread.php/37660-Adding-bridge-heat-ac
http://clubsearay.com/archive/index.php/t-47343.html

I think first thing on the list is the unit purchase. There are few brands on the market and it would be great to hear some recommendations on choosing the best unit for the job. I’m looking at the following as a primary candidate:
[h=1]Vector Turbo Series: VTM10KZ-410A 16,000BTU[/h]https://www.yachtaidmarine.com/inde...e=flypage.tpl&product_id=1351&category_id=155

Does anyone have any feedback on the unit? Are you happy with it or would you recommend something else?

Any suggestions are greatly appreciated.
 
Is my understanding correct that Dometic is the leading brand on the market, in regards to AC/Heating systems?
 
Alex

I read the other thread and Festivus installed a 18,000 btu unit and wrote the following. Why are you thinking 16,000 BYU's?
festivus44 said:
The hardtop is the key. Air conditioning a bridge with a dark fabric soft top is a tough proposition for a number of reasons. I have installed an 18,000 BTU unit and agree that it has a tough time keeping up on sunny days.
Click to expand...
 
Vince_nj1 said:
Alex

I read the other thread and Festivus installed a 18,000 btu unit and wrote the following. Why are you thinking 16,000 BYU's?
Click to expand...

Vince, the key in the unit I'm looking at is the TURBO. These units use new technology and 16K BTU is equivalent to the older technology 18K BTU units. These are smaller, quieter and more efficient units.
 
Good luck with everything. It should be a fun thread to watch.
 
BTU's are BTU's, no matter what the advertising words say. Besides, that, I replaced a 16K unit with a new 16K turbo compressor unit, and there is no substantive difference, other than the quiet, and perhaps slightly less cycling that isn't even measurable.

I know this area has hotter temps than you do, but a 16 or 18K unit isn't going to cool your bridge, other than just knock the top off the heat. If that is all you want, great. But, if you expect to cool the bridge area, you need to be thinking about more like 30K to 36K BTU capacity.
 
Gary said 24K BTU keeps the ice from melting in his drinks. I would ask Gary how he installed his unit.
 
Turbo is a just B.S. marketing ploy. A 2 ton unit is 24,000 btu's, high efficiency or low efficiency makes NO difference in the output of a unit. It's just a reflection on operating costs, nothing more.

An enclosed bridge with clear glass is no different than a greenhouse. Unless low E glass is used the solar gains will be substantial and greatly increase the total tonnage needed for a given square footage.

I think part of Gary's success with his unit is due in large part to his light colored hardtop which helps reflect heat as opposed to Alex's dark colored canvas which will absorb that same heat greatly increasing the total BTU capacity needed to provide comfort cooling assuming the same square footage for both boats.
 
fwebster said:
BTU's are BTU's, no matter what the advertising words say. Besides, that, I replaced a 16K unit with a new 16K turbo compressor unit, and there is no substantive difference, other than the quiet, and perhaps slightly less cycling that isn't even measurable.

I know this area has hotter temps than you do, but a 16 or 18K unit isn't going to cool your bridge, other than just knock the top off the heat. If that is all you want, great. But, if you expect to cool the bridge area, you need to be thinking about more like 30K to 36K BTU capacity.
Click to expand...

Frank,

My understanding was that if 24K BTU unit keeps 480DB's bridge at very comfortable temps, the 16K turbo should be able to handle mine.

So far I've had feedback from only two people, John Hampton and Tim (from his thread). Tim statement is along your line claiming that his unit knocks about 20 degrees. John was pretty satisfied with his installation.

You're right that I can't expect this little thing create a miracle, but logically thinking we have only handful of days when temps reach 100 or so degrees. If on those days my bridge can stay at 80deg. then I'll ok with it. This means that on 90-95deg days I can expect to see my bridge at mid 70s deg. Is this realistic expectation?

I've noticed the same issue Tim points out in his post that power management is an issue, not so much when genny is running, but at the dock where I'm plugged in to 2x30amp. This is why I thought that having 2 x 12,000BTU units is more likely to create more power management issue and chances are I'll end up using only one most of the time. That's why I thought that a single 16K Turbo would be the best solution.

If you have better solution, please share it. I'm here to listen and learn. This is my firs A/C installation, so my ears are wide open.
 
Turtlesboat said:
Gary said 24K BTU keeps the ice from melting in his drinks. I would ask Gary how he installed his unit.
Click to expand...

You're funny guy, Mike....LOL...
 
You're forgetting about the greenhouse effect. It may be 100 out side but the bridge would be hitting about 120-130. Cheaper way to cool the bridge by 20-30 degrees would be to remove all the plastic windows. Run with the wind in your face.
 
jg300da said:
Turbo is a just B.S. marketing ploy. A 2 ton unit is 24,000 btu's, high efficiency or low efficiency makes NO difference in the output of a unit. It's just a reflection on operating costs, nothing more.

An enclosed bridge with clear glass is no different than a greenhouse. Unless low E glass is used the solar gains will be substantial and greatly increase the total tonnage needed for a given square footage.

I think part of Gary's success with his unit is due in large part to his light colored hardtop which helps reflect heat as opposed to Alex's dark colored canvas which will absorb that same heat greatly increasing the total BTU capacity needed to provide comfort cooling assuming the same square footage for both boats.
Click to expand...

Do you think that my theory is wrong and I should look in to 2x12,000BTU units?
 
Turtlesboat said:
You're forgetting about the greenhouse effect. It may be 100 out side but the bridge would be hitting about 120-130. Cheaper way to cool the bridge by 20-30 degrees would be to remove all the plastic windows. Run with the wind in your face.
Click to expand...

I don't think the admiral would be very happy when we're in 5-6'ers with spray getting on the bridge, then all over inside the bridge. I always run with side panels open but there were just too many times when I said I wish we had A/C on the bridge.

You're right, if the general figure is about 20deg extra for the greenhouse affect, then I may have to rethink the installation approach.

The problem I came across was that 18K BTU was the max they make for 115vac. I was unable to find 24K BTU unit that runs on 115v. So, to make the installation 100% adequate to handle most of the heat I'll need something like 2 x 12K 115v units.
 
Alex, this is what my boat temp is with the top up on a typical day in June/July/Aug.

P1050018.jpg
 
I think that your cooling load will be greater than Gary's even though your area is smaller. Festivus' 44DB unit struggles to keep up. The part that makes it difficult is not knowing the various "R" factors involved in the materials that make up the bridge enclosure. Given the correct "R" factors and square footage, there are programs that can calculate tonnage required. At that point it's just math.

It would sure suck to go through all that expense and work and not be happy with the result.
Is bridge A/C an option with your model? What size unit does Searay supply? Know anyone with your model boat and bridge A/C?

Bonus question; Can your current generator support the additional electrical load a 2 ton or larger unit would place on it?
 
Last edited:
You may need more like 2 16K BTU units. Then the questions becomes, can your generator handle the load of 4 16K units, along with the fridge, freezer, etc.... But that's an easy fix, just buy a bigger gen.

Don't forget all the plumbing, ducts and electrical runs. This is getting pretty expensive.
 
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