We've decided to go with Wallas air heaters in our 4788 Bayliner. Here's why...
Having had several Espar hydronic systems we really liked them except:
They're noisey. They sound like a jet turbine going off. You can also hear the fans in the heat exchangers, especially on a quite night.
They provide great heat, but no ventilation. Our cruising area in Alaska is wet. Think Seattle in the winter, that kind of wet, and thats our summer!
Our understanding is that the Webasto units are the same, as far as the noiseyness goes.
Because of the ventilation issue, we wanted to go with air heaters. That way we could bring in a mix of outside air, and inside air. This will ventilate the boat by removing stagnant air.
Our thoughts were to use mulptiple smaller air heaters, to provide zone control, since our new boat has three levels being cabin, salon, pilothouse.
We contacted Sure Marine, and a major Webasto dealer in the PACNW and got the same answer from both of them. The Webasto air heaters would not hold up in our application because they would run too much, exceeding the "duty cycle" of the heaters. Both recommended a hydronic system.
The Espar marine distributor in the PAC NW was unresponsive, and didn't seem interested.
We'd had a Wallas stove/heater combo unit in out old boat and were pretty impressed not only with it, we were impressed with the service we got from the Wallas distributor, Scan Marine. So we decided t see what Wallas had to offer.
What we found is that Wallas makes a range of forced air diesel furnaces, designed specifically for boats. We worked with the distributor and ended up with a 30DT 3Kw output heater for the salon, and an identical model for the stateroom level. Even though*the distributor offered a way to heat the pilothouse (which would have seved some $$$) we went with a 2Kw unit for the pilothouse.
Here's some of the cool features these units have that the others don't.
The heat output is infintely adjustable. As the cabin gets warmer the heat output decreases. As the room gets colder the heat output increases. This eliminates the on/off temperature swings you get with any thermostat only system. It also elminates the startup/shutdown process which is what seems to drain the batteries. (for example our hydronic system would turn on and off every 15 minutes or so all night long as the thermostat called for heat.)
The units have a ventilation mode so that if its warm and you don't need heat, but the boat is stuffy, you can ventilate only.
Ther heaters are QUIET. They will not keep you or your neighbors up. The noise (in the engine room) is approx the same as a low conversation in a peaceful boat. I can attest to this quietness having had one of their stoves. I'm betting we don't notice the heaters at all.
This is not a system that will keep this boat toasty warm all through a bitter cold Alaskan winter. Its a system designed*for 30 degrees ambient air and warmer. If we were going to try to live aboard in the winters, we'd have to run the electric heaters which the boat has plenty of, or we'd have to get a larger system.
-- Edited by ksanders on Friday 23rd of September 2011 09:41:02 PM