The short loop dissipates a lot of heat when it is bypassing the thermostat that way.
While I can't disagree with your personal experience, I will point out that if I ran the hoses to the factory heater on the firewall (I've since deleted it), the circuit would have more than 5 feet of exposed heater hose. So I must politely disagree that the circuit is the problem. The circuit is BEFORE the thermostat, so I'm circulating coolant back to the water pump before it gets past the thermostat. Yet my temp sender (immediately after the T-stat) is reading 155*. At 155*, I don't think my T-stat has opened enough to allow more than a trickle of flow.
I'm still thinking it's an incorrect reading from my sending unit. I might find time to test it today.
