180 degree thermostat?

I learned several years ago to heat water to the advertized temp and test thermostats before installing them.
I got another one that wouldnt open at the prescribed temp, so I took it back to "the zone" for exchange and was told that it "ISN"T DEFECTIVE UNLESS IT DOESN"T OPEN AFTER 20 MINUTES AT 180".
The guy said somebody tried to sue for a burned down engine, but the stat mfg defends itself with the above lame claim (The mfg is in Israel, so might be hard to sue)
I took the replacement 180 stat home and it doesnt open below 195.

Am I wrong to believe that 20 minutes after the engine reaches 180, it would be MUCH hotter with the thermostat just starting to open?

I guess I'll exchange for a 160 thermostat and hope it opens at 180!

Or buy a high quality thermostat like a Milidon or similar. They not only open at close to the rating but also flow better. Places like Summit carry a wide variety and although they cost about $ 20 compared to $ 7 at the Zone, they are a better value long term.

Don

160 is fully open at 180 , 180 is fully open at 195, 195's will run to 210 before there open.. Common and won't hurt a thing

I just replaced my stat in the '33, and I put in a Stant 180F which is a step above the "bargain" priced units at the zone or shamrock stores. but still a standard construction allowing me to drill a 1/8" bleed hole in the flange to let air out on fill. With my gauge sender in the top of the water neck it reads 180-182F with almost no variation cruising. My ECU, sender in the intake runner just off of the head reads 192F cruising, and hits 203F under heavier loads. My fan is set to come on at ~195 ECU temp, with high speed at ~210 to 215F so it does not run at the control point. I did not check it in hot water first, but I'd say that Matt is pretty close in his analysis. You're buying a modulating control point, not a snap open/snap closed at the action point. I will say that on initial startup it ranged up a little more, maybe to 190/195, but once it went through a couple of thermal cycles it's been steady as a rock.