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steve_roach 25-05-2014 21:32

Hot Water slow to get going
Hi Guys,

Just finished connecting a Kuuma water heater to a Yanmar 3jh5e. The engine came with the hot water option so it was a matter of connecting hoses from those valves to the heater. Filled the heater main chamber with cold water, started the engine and...

Well, it didn't really get going the way I thought it would. I have a bypass valve and, with that fully open, after a while (I'm guessing once the thermostatic engine valve opened) the hoses started to get nice and hot. I closed the valve and the hot-side hoses got a little warmer on the inlet side of the water heater but it took quite a while. The outlet started to get warm but not by much.

I expected the coolant loop to the heater to get hot quite quickly - say, about 5-10 min. It seems that there is just not much flow around the coolant loop. One question; does this need bleeding? Also, I have pulled off the hoses; the inlet side flows freely but the outlet side just trickles.

Anyone done this before - and am I missing something?




sailorchic34 25-05-2014 22:02

Re: Hot Water slow to get going
You need to remove the coolant cap on the fresh water tank and top up the coolant level. Removing the cap will bleed air that was in the piping out too.
At idle much of the flow is bypass anyway. Need to have the RPM up a bit to get the flow to the heater moving.

steve_roach 24-08-2014 18:54

Re: Hot Water slow to get going
Hi Guys,

Eventually, solved - but it took a fair bit of playing around. First up, I swapped out the hose for 15mm (5/8") for much reduced resistance and also added a couple of bleed valves at the heater-end (hose goes under sole and there is a loop in that area). That's it - works very well now.


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