Calorifier on a raw water cooled engine

[seaangler23]

So my boat has a raw water cooled bukh, previously it had the calorifier running off the raw water circuit off the block and a mag drive pump but hot salt water eventually killed the pump and the calorifier. I fitted a new calorifier a few years ago but never got round to plumbing it back in but it would be good to get it running again. I’d rather not commit the new setup to the same fate and converting the engine to a heat exchanger isn’t really viable at its age.
I’m considering a separate system using a heat exchanger, mag pump and a header tank to circulate coolant through the calorifier and tap the exchanger in to the feed to the exhaust elbow to remove the need for a circulation pump on the raw water side.
I know it will take longer to heat and not get as hot which I’m fine with and will put a little more strain on the raw water pump but are there any other reasons not to give it a try anyone can think of ?

 

[vyv_cox]

The feed to the elbow is a mixture of heated and bypass water, with a likely temperature of less than 40C. Many have tried feeding this to their calorifier and found it does not work.
The original electric pump used by Sadler typically lasted 10 - 15 years. Today we can use magnetic drive pumps that do not rely on a seal, so they will last considerably longer.
A calorifier with a copper coil should resist seawater almost indefinitely.
There is a page on this subject on my website, with pump suggestions Calorifier installation

 

[Boater Sam]

Solar heating would be more productive.

 

[wingcommander]

Or a Bobil heat exchanger fitted to a diesel heater. Works great, 20 minutes or so for a 20 litre calorifier. Its a direct feed system, so allows the coil to be reserved for the engine ( on a single coil calorifier) I am now in the process of adding the raw water engine heating (Bukh 24 ) . All pipework is connected as per Vyv's instructions and now in search of a reasonably priced 12v pump.

 

[seaangler23]

Thanks, I did wonder if it would get to temp, I have all the stuff to go back to the old set up so il dig it out and have a go, the old calorifier was a home made one so I think it was the soldering that let go the surecal should hopefully hold up better