[77newell]

Richard: I think my memory is faulty regarding the core inlet and outlet temps. Based on comparible core sizes my heater core should be rated at 35,000 btu/hr. The big question is how they calculate that. As a Chem E, you know the variables. I did a rough calculation that suggested that with whatever the water temp drop was, at reasonable pump flow rates according to the manufacturer's chart the core was in good shape and that boosting the water temp by 20 degrees would probably get me to the rated heat capacity. Yeah, I know, I'm a recovering engineer and think way too much.

I am getting a 40 degree rise in air temp, but since I don't know the air flow rate I can’t use that to confirm the 35,000 on the output side.

Based on the above commentary, all the coolant flow circuit is operating just fine. A year or so ago I checked the fan and they are operating ok.

It’s not that I'm without heat, it's that, as Forest experienced, a bit weak.

I do need to research the standard method manufacturers of heater cores use to rate their heater. I will share what I discover. And I will do a before and after report. Y'all be good now hear.