Late to the party, but I'll jump in here! My first thought when I bought my used HarChinaAmazNorth parts washer was that it needed a heater. Mine didnt come with one, but I figured there was some way. My thought was a fishtank heater. I've since seen a number of posts on various sites, and YouTube videos on putting on filters and using various heaters.
I'm using Purple Power, which is water-based, and not a true "solvent" like Berryman's or gasoline/diesel fuel. I then thought of using just a magnetic engine block heater, slapping it underneath, and trying that. I also saw people utilizing water tank heaters.
The magnetic slap-on heaters seem to cause the paint to separate. I'm looking for cheap and easy...
Why wouldn't an aquarium heater work? I've seen comments about solvent possibly damaging the heater. Well, this is water based. Most aquarium heaters are encased in glass. My washer is 20 gallon, and most of these heaters are rated for 50-150 gallon aquariums. Plus, you can regulate the temperature and let it keep it "warm" until you come outside, then crank it up for heat. Maybe use in conjunction with a block heater to get up to temp (110 or 120deg F)?
I've also seen where people weld brackets on the underside and modify pancake griddles and attach them underneath. Same principal as a block heater.
So, has anyone actually used an aquarium tank heater, and thoughts on it? I had a 50 gallon tank years ago, and my piranha accidentally hit it and kicked it on overnight, and cooked himself...so I know that they will get the water up to 140 degrees.
Oh, quick side note: for the cost, the aquarium heater seems to be as cheap as pancake griddle, unintrusive (no drilling/welding)