I was only asking about the coolant heat exchanger in particular. The 2500psi is probably the max PSI for exhaust heat exhanger.
I have an SS 870, the preheating of the water box and the coolant heat exchanger are both prior to the pressure pump. The pressure pump has a heat limitation because of the seals. To protect them the thermal relief valve is always opening and dumping water. The coolant heat exhanger that is on their now can not handle the PSI needed to plumb it after the pump. I was wanting to know the PSI of the coolant exchanger to see if it could be plumbed in after the pressure pump but before the primary exhaust exchanger.