Replacing water heater... Bleeding antifreeze

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NYSail

NYSail

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Jan 6, 2006
3,184
Beneteau 423 Mt. Sinai, NY
Hello once again!

I am getting ready to replace my hot water heater (6 gallon Raritan).... I am looking for other peoples techniques to ensure no air gets locked in the engine antifreeze loop. Hate to overheat!!

Is it necessary to take off the thermostat when doing this? Or can the system be refilled by just adding to the hoses from the top after reconnecting to the new heater, then check and fill through the engine fill cap... run for a while to make sure the thermostat opens, then shut down, let cool and recheck. Add as needed.

I have a Yanmar 3HM35F. I flushed and replaced all the antifreeze 4 years ago with the new stuff (non green) and changed thermostat also.

Thanks as always!!

Greg
 
M

MaranaF

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Jun 26, 2011
22
Bruce Roberts R50 Ipswich
Hi, I have usually installed a three way valve in the hose that is at the top most point in the system so when I refill I can have this open and wait till the fluid is seen before closing. With this in place I have never had an air lock. Hope that helps.
 
NYSail

NYSail

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Jan 6, 2006
3,184
Beneteau 423 Mt. Sinai, NY
that is what I did in the past with the thermostat off...... Where did you get the 3 way valve?

Thanks for the tip.
 
M

MaranaF

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Jun 26, 2011
22
Bruce Roberts R50 Ipswich
NYSail said:
that is what I did in the past with the thermostat off...... Where did you get the 3 way valve?

Thanks for the tip.
Click to expand
Well I am in the UK and would start in the chandlery if I was in a hurry and feeling rich but more likely a plumbers supplies.

I have been meaning to check out the people who install air con as they are likely to have some nice fittings. I was commissioning for Oyster Marine here last year and they use a very nice fabricated job comprising a piece of SS tube about 75mm long that the hose snugly fits round with a smaller pipe welded at right angles in the centre like a "T" then put a small compression fit isolation valve on the side pipe. Works well and looks good.

Stephen
 
Stu Jackson

Stu Jackson

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Feb 26, 2004
23,364
Catalina 34 224 Maple Bay, BC, Canada
All you need to do is to assure there is no air in the line from the engine to the new hot water heater. Whether you use gravity or a hand pump, your choice, just make sure it is filled with no air bubbles. Do a search on "burp" or "burping" under my mane and you'll find links to the many times I've answered this question on this board. It's not hard to do.
 
RAD

RAD

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Jun 3, 2004
2,330
Catalina 30 Bay Shore, N.Y.
I have a Westerbeke and it has a pet cock at the top of the thermostat housing which is the highest point to help with the air and what I have done is pulled one hose off the heater and held it up higher than the engine while slowly adding antifreeze till it comes out the open port on the heater and then very quickly putting the hose on and tightening the clamp, then I fill the HX tank and run the engine with the petcock open till it reaches operating temp
 
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