Heat exchanger quality and sizing

Stokehold

I guess all brazed plate heat exchangers are not created equal.
I'll be using two, one zone is a glycol mix.
I know the size and specs., but need to know if there are quality issues between the cheaper units and the more expensive ones (i.e. Brazetek vs.Kelvion). Is it a case of getting what your paying for?
Also, is it OK to use a larger exchanger than necessary? Meaning, if my load is 50,000 BTU and a particular heat exchanger flows 5.0 GPM @ 3.8 PSI pressure drop (10 plate) can I use a 125,000 BTU exchanger (20 plate) rated at 12.6 GPM @ 4.8 PSI drop?
It would be nice to keep overall head losses to a minimum considering I already own some new circulators and am trying to stay within their parameters. If I am understanding correctly, a 3.8 PSI drop in pressure translates to a 8.75 ft. head loss?

hot_rod

I would agree that you get what you pay for. I've seen some unbelievably cheap plate HX on e bay and some of the wood boiler dealers sites.

I'd guess metal quality and assembly procedures are where the difference shows up. For glycol I would want to be sure of the metals used.

Sounds like you have already found Flat Plate and their free sizer

http://flatplateselect.com/site/pub/login.aspx?ReturnUrl=/site/hx/chooseapp.aspx

Oversizing adds cost and at some point I've heard that channel velocities can drop and effect HX.