Tapping the cooling system for a heater

remwines · Mar 10, 2016

kulas44 said:
One problem you may run into is that the heater system may cool the engine system more than normal.

To avoid over-cooling from auxiliary heater systems, Cummins supplies a restricted hose fitting, PN 3916256. Here is a link to the Cummins B and C Series engine installation (2015) courtesy of Seaboard Marine. Go to page 35 for Auxiliary Heating Circuits.

http://www.sbmar.com/wp-content/uploads/2015/01/B-C-Installation-Directions.pdf

I'm preparing a 6B5.9M that will be going in my boat next month, and I am using that fitting. I thought about using a regular NPT/hose barb fitting and an inline valve to control the flow, but the Cummins part just makes it simple.

remwines · Mar 10, 2016

I forgot to mention, my local Cummins Parts Department had it in stock and it was under $12.

FF · Mar 11, 2016

and is it in the engine water circuit while the engine is running ? or valved off ?
and last question....does it push the water in the same direction as the engine pump (when the engine is running). thanks in advance for the info

OTS small Groco bronze centrifugal pump.

Not on while engine is operating , but I guess if it got cold enough underway it might help.

Pumps in same direction as engine coolant pump, From hot wet exhaust manifold back to block.

refugio · Mar 11, 2016

My engine cooling system has a short loop to a heat exchanger inline with my hydronic system. I originally thought I'd heat the engine in winter AND be able to scavenge heat from the engine for cabin heat (which also heats the domestic water heater) but without a booster pump in the engine circuit I couldn't heat the engine when it wasn't running. And I've never gotten around to installing a hydronic circulation pump switch for scavenging. And trying to figure out whether I'm putting heat into or extracting heat from the cooling system when both are running makes my head hurt, so I've left the exchanger closed off.

Brooksie · Mar 11, 2016

CaptTom said:
I'm not 100% up on the nomenclature, but when I bought a "tempering valve" years ago for my house, it just passed a set amount of cold water, regardless of the relative temperature of hot and cold:

I ended up ripping it out and replacing it with a "thermostatic mixing valve":

I think the latter is what FF is referring to.

The tempering valve can only statically adjust the amount of cold water by turning the dial on the top. And even that didn't offer enough range for the wide swings of both the incoming cold water (seasonal) and the domestic hot water (from the boiler.)

I suspect it's the same in a boat, so I put in a proper termostatic mixing valve.

In my case, it wasn't so much about scalding - most people are smart enough not to hold their hands under steaming hot water that long - but to get a more even temperature and extend the time between having to power the water heater.

Both of the valves you show should work fine, functionally the same. Maybe you had a bad one. Both are tempering /anti-scald valves. The upper one, made by Watts, needs it's guts removed b/4 any soldering is done or it is ruined.

Arcticspud · Mar 11, 2016

All you guys with a circulation pump installed. How long was the hose run? I am looking at about 10 feet. The heater will be in the same area as the water heater and I doesn't have a pump on it.

Tapping the cooling system for a heater

remwines

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remwines

Senior Member

FF

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refugio

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Brooksie

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Arcticspud

Veteran Member

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