Vegetable Oil SVO WVO waste cooking oil as biofuel

[gary]

Sun, what do you think about putting the fphe on its on coolant loop so it gets full coolant flow and is not restricted from the small pipes in the rest of the system?

[240Volvo]

That is how it is supposed to be done. It should also be the first tap off the engine.

[SunWizard]

Sun, what do you think about putting the fphe on its on coolant loop so it gets full coolant flow and is not restricted from the small pipes in the rest of the system?

Its not needed on the cummins since it has good flow, on mine it works great down to -10F (the coldest its gotten here in >3 years.) Having a separate loop will give the FPHE less total heat, since part of the hottest flow then goes to the 2nd loop instead of the FPHE. The heat transfer is not limited by flow rate (slower is fine since the FPHE has huge heat transfer capacity), the order of flow is what matters.

[John Galt]

Having a separate loop will give the FPHE less total heat,

Not true, but it's not worth arguing over. My observation on these forums is that people will believe who they like, not based on facts. 240Volvo is totally correct.
BTW I'm a MechEng with over 30 years experience with heating systems, FPHEs, etc. FWIW. Believe whatever makes you feel good.

[BMW Fan]

IMHO John Galt and 240 Volvo are correct.

BMW Fan

[SunWizard]

it's not worth arguing over.

Agreed. You wouldn't know until you tested it both ways since it depends on too many factors. I know it works good as mine is even in extreme cold. The extra money on the added fittings, hoses and insulation aren't worth it since I am always within a few degrees of coolant temps. You could spend the extra and find that not enough flow is going to the heated tank pickup. Then you would have to either re-plumb or put a valve on the FPHE loop to restrict it.

One thing many don't do is put a valve on the heater core loop to adjust and restrict its flow. This I have found makes a large improvement in heat the the VO side.