I have a custom-made heat exchanger fitted onto the exhaust of the air-cooled Lister HR2 on Bream, used to produce domestic hot water. The heat exchanger has 11 pipes of 1/2" or 1" diameter and the rest of the exhaust is the standard 2" diameter so the total cross-section area is actually greater in the heat exchanger but clearly there is resistance caused by the baffle where the pipes start (if this description isn't clear think of a steam train, it's quite a similar concept.)
It has been suggested that problems we are seeing with the engine are caused by back pressure due to reduced effective diameter. There is loss of oil from pretty much every orifice of the engine, typically a pint a day. Its not labouring or losing power, though the engine room is very hot as the cooling air is not ducted out. Oil pressure is steady at 20psi, which is normal. The question is, is it the heat exchanger causing the problem, or the lack of ducting, or is more likely to be something else altogether? Thoughts anyone? Steve NB Bream
