My Oasis is "making " fluid

[Texas Clodhopper]

Probably even worse if Oasis went to the engine coolant.

Well, gee, thanks!

 

[d23haynes57]

The weak link in the Oasis is the domestic water heat exchanger. The usual failure is due to freezing. Freezing it will not even try to put up a fight. The ease of this failure is the main reason the units call for non-poisonous boiler fluid. The failure will usually only be internal, you will not see external leakage unless you really swelled it up. To test, you can use a cooling system pressure tester on the boiler cap. If turning on the domestic water raises pressure in the boiler you confirmed the failure. The heat exchanger is a some what off the shelf item. You can source elsewhere and if you want to be creative you can also use a larger one.

 

[Texas Clodhopper]

The weak link in the Oasis is the domestic water heat exchanger. The usual failure is due to freezing. Freezing it will not even try to put up a fight. The ease of this failure is the main reason the units call for non-poisonous boiler fluid. The failure will usually only be internal, you will not see external leakage unless you really swelled it up. To test, you can use a cooling system pressure tester on the boiler cap. If turning on the domestic water raises pressure in the boiler you confirmed the failure. The heat exchanger is a some what off the shelf item. You can source elsewhere and if you want to be creative you can also use a larger one.

The HX may be the weak link but I assure you, mine didn't fail due to freezing. You're correct, the only external leakage was from the overflow tank. As far as replacing the HX, I would need to remove the DM just to be able to get to the HX, and regarding putting a larger HX in the DM, I would guess that would be impossible to do because of space limitations. I guess you could mount the HX external to the DM, but then you've created a plumbing nightmare.

 

[newmarokie]

Well, it looks like I got lucky. I replaced the radiator cap and the overflow problem seems to have gone away. I am slowly putting the fluid all back in. I have cycled the heat and domestic water a few times and every time it cools off I put a little more fluid in the overflow. I am sure there is a more efficient way to refill and purge out the air, but I have time and this is working.

 

[Texas Clodhopper]

How did replacing the radiator cap stop the water from getting into the thermal fluid?

 

[newmarokie]

I don't think water was getting into the thermal fluid. I think constant pressure on the thermal fluid was pushing the thermal fluid out through the overflow through a leaky radiator cap. When I took the radiator cap off the gasket was degraded noticeably. With the new radiator cap, after heating the system up it is pulling fluid back into the system as it cools off. I am keeping the overflow at the "max cold" fill line. After it cools off it is at or below the "min cold" line and I have almost all of the fluid back in the system.

 

[Texas Clodhopper]

Gotcha! My brain was thinking the water was getting into the thermal fluid because that's what was happening to me. Your's is a lot easier and cheaper to fix than mine was.

 

[newmarokie]

Hopper, I was afraid I was headed down the same road you had to travel. I put the new radiator cap on, turned the city water on, and left it for five days. The level didn't budge. I have been cycling the burner and taking the system to temperature and letting cool off. It is slowly pulling fluid back into the system. I lack about two quarts getting it all back from whence it came.