I looked at those but 2 things popped into my head. A. My engine has a heater core control valve so with the truck off no coolant can flow through it. And B. With the thermostat closed and no flow through the heater core wouldn't it basically just be warming a tiny portion of the coolant in the heater core line? Correct me if Im on wrong on this, its just how I'm picturing it in my head...
The block style heater wont circulate but will warm all the coolant surrounding the block which sounds to me a better method? Although more complex to install.
The heater hose valve is only used in MAX AC setting, and its vacuum operated so can only work with engine running in any case.
It cuts off flow thru heater core when driver wants "MAX AC" cooling in the cab, lol
That setting also closes Outside Air vent, just FYI
COLD-HOT temp setting on the dash controls the Blend Door, it directs air thru or around the heater core.
Car makers have found that heater cores that always have coolant flowing thru them last longer than they did in the "old days" when there was a cable operated valve in engine bay that controlled the flow thru the core, it was the temp control, if left in COLD setting the coolant may sit in the core for months and months and lose its corrosion inhibitors so core was more likely to rust thru or clog up from debris settling at the bottom.
Thermostat is not involved with heater, it just controls radiator flow.
Block heater is a better choice IMO, if it can be install fairly easy at this time.
Circulating heaters and Ether injection systems are for long term cold climates
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