Wallace makes a great heater.  If I could have afforded it that is what I’d have.   I just installed a Planar furnace (4D equivalant).  Happy so far,and much cheaper than espar.   Planar is a German knockoff of the Espar and they mostly market to trucks and vans in Russia (cold there). I could have saved even more and got a Chinese knockoff but was dubious of quality (Planar had good reviews even in marine forums).    My only complaint is the thermostat wires ar a bit short, and a bit confusing to set mode of operation ( temp or %output and temp source(heater,tstat,remote sensor))

les

Wallace makes a great heater.  If I could have afforded it that is what I’d have.   I just installed a Planar furnace (4D equivalant).  Happy so far,and much cheaper than espar.   Planar is a German knockoff of the Espar and they mostly market to trucks and vans in Russia (cold there). I could have saved even more and got a Chinese knockoff but was dubious of quality (Planar had good reviews even in marine forums).    My only complaint is the thermostat wires ar a bit short, and a bit confusing to set mode of operation ( temp or %output and temp source(heater,tstat,remote sensor))

les

I just replaced a 12 year old Wallas heater with a new Wallas Viking air in March. I love it!
I am based in the Pacific Northwest (Seattle).
The contol is a bit different but once you get the hang of it, its easy.
I love the fact that it has an Android app to control the heater also. If f you have access to wifi, you can turn it on before you get to the boat. It tracks hours used, starts, and any fault codes.
Phone app control is Via bluetooth. I am very happy so far. It heats the boat very well, and sips fuel.
The fan is quiet and you can only hear the heated air blowing out the ducts. It also has a fan boost, which really gets the air moving.
It is installed in the rear birth, port side access area, under and behind port cockpit lazzerette.

I got this one https://heaters4you.com/kits/225-planar-4kw-small-boat-kit.html It was fantastic on the extreme winter cruise where we swept 3-5” snow off the deck at least 5 times. I think there is a USA rep (one above is In Russia) who was at the Seattle show. He said there may be a quieter pump coming, but it goes into background quick enough. The thermostat is the big dislike. I mounted in by the aft sliding door in the aft double. Exhaust went up and out the side. Had to cut access hole in lazerette to run exhaust. Cutting 4.5” holes is challenging. And old boats the fridge is Draper so you have to cut into the fridge space to run the duct.

Yes, not sure mine is a Mr. Heater, but this type works well on a cold damp day. I put mine under the main table to slow the heat rising and it is out of the way. 10-15 minutes the boat is comfortably warm. 

Catalytic heaters ( any cabin vented heater ) put lots of moisture into the boat.

I also have something similar which I have used during our winter when varnishing the inside of the boat.  Worked ok in terms of hat source but gave off a smell.  I put it under an open hatch somewhat defeating the purpose but it was ok.  Would not recommend for pleasure use while sailing or anchored/docked.