Hydronics on P39 Catamaran

[nick83]

Starting a thread to document the hydronics system I'm installing on our Privilege 39 catamaran.

For the burner I'm using the "HLN Aquano 10K Coolant Heater 12V - Truck Original Equipment; Installation Kits, WiFi Controller Included"

Planning to have 3 thermostat zones within the cat: main salon and each hull.

The salon to receive the Kalori Silencio 2 radiator.

The hulls to receive a Kalori Evo 1 in each below the floorboard. These each have 4 outlets (55mm each, or ~2"). Planning to run the 4 little air ducts to fwd cabin, hallway, head, and aft cabin, respectively.

Additionally, down the road I may add heat to the engine compartments or fwd compartments.

As components are installed I'll update progress!

[nick83]

I received the Kalori Evo 1 radiator fan today and tested it out. Was surprised at how loud it was. Even when I put it under the floorboards it was still noticeably noisy, which I was disappointed about.



Pretty much sounded like a fan blower in a car. Which I was expecting, but in a car usually the low speed is very quiet. With this fan, there are 3 speeds, but even the lowest was noisy.

On the plus side, it doesn't draw as much power as the spec says. The Kalori catalog says it uses 70 watts.

Measured:
Low Speed (Red wire) 2.46amps * 13.59volts = 33 watts
Medium Speed (Yellow wire) 3.14amps * 13.59volts = 43 watts
High Speed (Orange wire) 3.69amps * 13.59volts = 51 watts





Another thing is the Evo 1 comes in several different output configurations. I have the one with Qty (4) 2" outputs. One thing I noticed is that the air doesn't blow equally out of all 4. The two side ones barely have air coming out, while the middle two blow quite forcefully.



My thought was to have an Evo 1 in both hulls and run 4 little air ducts to the 4 spaces in each hull (fwd cabin, hallway, head, and aft cabin). However, with the noise issue I'm re-thinking.

I was trying to get away from having so many plumbing fixtures which would result from putting Kalori Silencio's all over the boat. They only draw 7 watts each (per Kalori catalog), and have 2 speeds. The lower speed probably draws even less.



Decisions, decisions.

[nick83]

Originally Posted by GordMay

A Buffer Tank adds volume, to a heating, or cooling system, and helps prevent boiler short cycling.
A buffer tank’s primary role, is to keep a minimum volume of water “in circuit”, when the heating load is very low. This prevents the heating pump from short cycling, and provides a bypass route, to maintain the minimum flow rate, through the heat pump, if most of the heating zones have shut down. The minimum flow rate, and the minimum volume of water, in the circuit, are necessary, to keep the heat pump operating efficiently.

The formula for sizing a hot water buffer tank is:
Buffer Tank Size, in Gallons = [Min. Cycle Time x (Min Output Min Load)] ÷ [Temperature Differential ▵T x 500]
Where:
Minimum boiler turndown output in BTU/hr
Smallest load in BTU/hr
Temperature differential in degrees F
Boiler cycle time (minimum) in minutes

Taking a stab at the formula for my boat, assuming the heater mainly operates at full bore for 20 minutes and raises the temp from 40F to 180F.

Buffer Tank Size (gallons) = (20 minutes * 34,000 BTUS) / (140 * 500)
= (680,000) / (70,000)
= ~10 gallons


I'm envisioning the system only coming on every few hours for a ~20 minute blast to heat up all the coolant.

[pnw2022]

Aren't you already getting 6.6 gallons of heat storage from the water tank?
Also - on your first post here, maybe put in a link over to the original thread for reference.

[nick83]

Yes, the water heater is a buffer too, but it can't accept the heat as fast as the burner can put out so additional water is needed. However, the amount in the hoses and such may be enough without a separate tank. A 10 gallon buffer tank may be way overkill.

One concern I do have is that the water in my hot water tank will get to 180F, which is much too hot for the taps. Have you guys added a mixing valve at the outlet of the hot water tank? If so, any recommendations on a good product?

I did receive the buffer tank today as well as 300' of 1/2" PEX-AL. I also bought 100' of 3/4" PEX-AL.



This is turning into a project.

[pnw2022]

Yes on the mixing valve - especially with children around.
The IsoTemp water heaters (I think all models?) come with one already so something to factor into costs if you are buying a new one.

[nick83]

Update from 1/20/24.

This project is moving slowly and not going to be complete this winter. However, in the meantime we're getting by with two space heaters that run at 800 watts each.

They can generally get the boat about 25 degrees F above outside temperature. Or they can keep 2 cabins even warner. We've had nights in the 20s, but generally day time temps are 30s or 40s. With some layers on, it's not bad on the boat.

We fought condensation under the mattresses for awhile, but resolved that problem with HYPERVENT AIRE-FLOW™ MOISTURE BARRIER from mattressinsider.com underneath the mattress (and up the walls a few inches higher than the matress).

All in all, I'm realizing the boat doesn't need a ton of heat as the P39 is pretty well insulated. Most surfaces have a foam backed headliner material. And the hull itself has a core.

Having heat in the heads would be very nice, they can get extremely cold. Also, having a small amount of heat in the engine rooms and fwd storage lockers (that have our water tanks) would be nice knowing our engine blocks and water tanks wouldn't freeze. Currently I have our diesel engines winterized, but I'd like to go use the boat and I don't really want to de-winterize them.

The EVO 1 did come in and I measured the sound level. It's quite loud:

** High **
(orange wire)
3.42a * 13.2v = 45 watts
Noise: 80db

** Medium **
Red wire
2.98a * 13.2v = 39 watts
Noise: 77 db (lower pitch, but about same noise as high)

** Low **
Yellow wire
2.1a * 13.2v = 28 watts
Noise: 75 db

I've decided to use the silencio 1 as much as possible because it is so much quieter. Basically just a computer fan in there.