Heating thoughts.....

[oscarvan]

Just some musings I want to throw at the mind boggling brain power here....... Not saying I would do any or all of this, just kicking things around.

The reverse cycle machines work very well, as long as the water is not cold and there's heat to extract. This means Fall season is covered as, in my case the Bay is still above 60ºF.

Spring and, of course, winter are a different story.

One could add electric heat sources from space heaters plugged into outlets to built in electric floor heat to base boards.....

One could install diesel forced hot air heaters, of the Eberschprächer/Webasto variety...Fuel supply, ducting, air supply/exhaust. Number and location TBD

One could install and Aquahot style hydronic system with a boiler, water supply and return lines, heat exchangers with fans or, again, floor heat.

But I had the following idea..... All the distribution is already there in the reverse cycle machines, the only reason they peter out is because the water gets cold. So how about I give it warmer water? Redirect the cooling pump flow from/to either a tank or on demand heater. Fill it all with glycol and it would be frost proof. When the water warms up again flip the valves and go back to overboard....... Could be electric, which would be somewhat limited, or diesel fired which could be quite effective.....

This guy puts out 15KW of energy which, in theory, would heat 2000 square foot...

https://www.heatso.com/webasto-12-volts-water-heaters/

Thoughts?

[SKYCHENEY]

Aquahot is way overpriced for what it is. You can build one for less with a Webasto and some pumps and relays.

[Looking Glass]

I had the same thought a couple of years ago but decided on an easy solution. I tapped into the 220v air conditioner/heat pump power lines and installed 220 outlets. One in the hallway, below deck and one in the salon. I purchased (2) 220v 4000 watt electric heaters, which only use about 15 amps each.

When the water gets too cold for the heat pumps, I just turn them off and plug the electric heaters in. Occasionally, i put a regular space heater in the bow. Between the 3 heaters my 58MY is nice and cozy and uses less than 50 amps. It eats a bit of electricity, but it is only for a few months so I do not care. When Spring comes I unplug them and throw them in the closet.

Altogether, it puts off about 10kw and cost about $350.

https://www.amazon.com/-/es/gp/produ...ge=en_US&psc=1

[davidwigler]

A PO installed a separate electric panel with five 240v wall heaters 1500 watts each. I added in-line digital programmable thermostats. I also added block heaters to the engines and plug them into a digital wall thermostat.

The heat pumps work down to a water temperature of about 40°. The last couple of years we didn’t reach that. Hey, a benefit from global warming.

[davidwigler]

Just some musings I want to throw at the mind boggling brain power here....... Not saying I would do any or all of this, just kicking things around.

The reverse cycle machines work very well, as long as the water is not cold and there's heat to extract. This means Fall season is covered as, in my case the Bay is still above 60ºF.

Spring and, of course, winter are a different story.

One could add electric heat sources from space heaters plugged into outlets to built in electric floor heat to base boards.....

One could install diesel forced hot air heaters, of the Eberschprächer/Webasto variety...Fuel supply, ducting, air supply/exhaust. Number and location TBD

One could install and Aquahot style hydronic system with a boiler, water supply and return lines, heat exchangers with fans or, again, floor heat.

But I had the following idea..... All the distribution is already there in the reverse cycle machines, the only reason they peter out is because the water gets cold. So how about I give it warmer water? Redirect the cooling pump flow from/to either a tank or on demand heater. Fill it all with glycol and it would be frost proof. When the water warms up again flip the valves and go back to overboard....... Could be electric, which would be somewhat limited, or diesel fired which could be quite effective.....

This guy puts out 15KW of energy which, in theory, would heat 2000 square foot...

https://www.heatso.com/webasto-12-volts-water-heaters/

Thoughts?

You could make a circuit with the Webasto to a 10 gallon water heater to the AC units with the AC pump circulating the coolant. I wonder if the Webasto could be set to heat up to about 70°. You don’t need/want 140° water.

[oscarvan]

You could make a circuit with the Webasto to a 10 gallon water heater to the AC units with the AC pump circulating the coolant. I wonder if the Webasto could be set to heat up to about 70°. You don’t need/want 140° water.

I was wondering the same thing......

[gondolaguy]

... But I had the following idea..... All the distribution is already there in the reverse cycle machines, the only reason they peter out is because the water gets cold. So how about I give it warmer water? Redirect the cooling pump flow from/to either a tank or on demand heater. Fill it all with glycol and it would be frost proof. When the water warms up again flip the valves and go back to overboard....... Could be electric, which would be somewhat limited, or diesel fired which could be quite effective.....

This guy puts out 15KW of energy which, in theory, would heat 2000 square foot...

https://www.heatso.com/webasto-12-volts-water-heaters/

Thoughts?

I like that idea. I was also thinking about something similar. You could use the water tank that is in the guest cabin. I think the tank would need to be pretty substantial to meet the heat transfer needs of the reverse cycle machines. Also, there are a few things to take into account. The Watt rating of these units is the nominal heat content of the fuel they burn when running wide open. Some of that heat goes out the exhaust and some is given off into the space where the unit is (they don't tell you how much). Then you'll have some thermal loss from the tank. What goes into the cabin isn't really a loss, but if it is in contact with the hull, there will be much more heat transfer through that surface because of the higher temperature differential. Finally, you'll have efficiency losses through the reverse cycle units too. These all add up and reduce the amount of heat that will come out of the vents. You'd be spending several thousand dollars even if you did the work yourself. It may take a while to be worth the effort.
What I am doing to start off with is to put a 5KW diesel heater in the port engine room with a supply duct that goes into the hallway next to the guest bath. I can control where the heat goes by opening and closing doors. I have the return ducted to the outboard side of the stairs to encourage the heat to move forward on its way back to the heater. I'm using 4" insulated flex duct on both supply and return.
Next, I'm going to start to remove the head liners and add two layers of 1/2" foil faced polyisocyanurate foam board with a sealed air gap between them. I'll start with the galley, then do the master, then the salon. For every BTU you can keep from going out, that's one less BTU you need to provide.
If I'm still needing to use the electric space heaters in the salon, I'll add another diesel heater just for that space.
Another thought I had about the reverse cycle units is that the water temperature on the surface is significantly colder than it is several meters beneath (in the winter). I was thinking of installing that valve, like you said, but instead of it going to a tank of heated water, it would go to a hose that has a perforated metal intake on the end that I hang over the side. This would be much less costly, and might extend the use of the reverse cycle units a few months of the year. I have 25' of water at my slip and I'm curious to find out how much warmer the water is a few feet off the bottom in the winter.
My background is in boatbuilding and residential energy auditing, so I think about these things a lot. Keep us updated on what you decide.
Thom

[Glory]

I lived aboard a 43' trawler for 10 years in the Northeast, used Espar, diesel forced hot air. And it worked well.

On many boats getting 3 or 4" vent somewhere is a challenge. Plan in advance.

Multiple units may offer some redundancy, that is some thing I might consider should I add heat.

Good luck.

[Finalee]

I lived 10 years on my 43 Hatt. Ran the boat all year long. When the engine room was still warm after a run, even in 35 degree water, the heat pumps made heat.

[rsmith]

Buy lots of towels. Every thing inside the boat that shares the outside cold will sweat. It’s physics. Showers cooking just breathing puts a ton of moisture in the air. It then condensed on the plate glass windows bulkheads overhead hatches almost everywhere. We lived on the boat for a winter. We constantly fought mold. I lifted the mattress in the owners stateroom one day to get to storage underneath and the edge where it meets the inside wall of the hull was covered in black mold. And then there’s the radiant cold coming from the glass it may be warm inside but the windows are like having blocks of ice cascading cold air across the floor. It’s ok for a weekend or even a week but long term it just sucks