I know there are other threads on this but I wanted to give some details on my issue. Prochem Blazer with 18 HP Vanguard. Two heat exchangers, a copper pre-heater, heats to 145 before valve opens on water box to dump some water and protect the water pump. Second HE stainless steel behind the copper once closest to where the exhaust enters the box. Takes about 10 minutes to heat the water box to 145 if there is full load 13Hg on the vacuum pump. Measured the exhaust temp between the two HE and under full load it measures about 300 degrees. with no load the exhaust temp drops to about 200 - 195. replaced the valve on the water box so no leaks there, and the bypass valve on the front of the unit appears to be working fine....no leaking water into the waste tank. Can't seem to get my water above about 160 or so. Already cleaned the SS heat exchanger (descaled) and the copper is new. My thinking is the exhaust heat just isn't as high as it needs to be when under a slight or no load. It has a catalytic converter off the exhaust and that thing gets red hot when running at 3k RPMs. Just wanted some thoughts the exhaust temp. Does it sound correct? Am I losing heat somewhere after leaving the engine? Thanks.