Glycol Won't Flow

System

This discussion was created from comments split from: Switching to New Rhomar Glycol.

R60us

*** Update ***
System flushed 

I ended up removing and inspecting the check valve next to the air bleeder it was installed properly and working correctly.

I ended up flushing it from that location.
During the draining process I discovered when using the drain plug under the camper tilting the nose up as high as I could get it and then bringing it as low as I could yielded a lot more glycol draining from the system.

Thank you all for the help. Everything seems to be working well.  I guess this will remain a mystery...

....
I am trying to do a flush and fill of my Alde 3010 (2018 Tab 320s)  but can't get the fluid to flow.  I have made the adapters for the expansion tank and am able to pump some distilled water in the input line however the pressure increases and it becomes impossible to pump.
As I pump NO water is coming out of the return line. 
I have tried to using a shopvac on the return line and it only sucked a small amount out then hydrolocks and will not pull anymore fluid out.  It is sucking so hard it is collapsing the shopvac tank and overheating the motor...

I have also tried to turn the system on circulate but it doesn't seem to change anything. I can hear the pump click however it doesn't seem to let the fluid flow.

The expansion tank was drained from the plug under the camper and the plug put back in. 

It seems as if there is a valve in the system that is shut stopping the fluid from circulating. 
What am I doing wrong? 

Thanks all, 
Rob

manyman297

This is just me spitballing but are you pulling from the right hose (the return line to the reservoir)? There may be a check valve preventing you from pulling in the wrong direction. Again, just spitballing. I did a fluid exchange on our 400 and everything pulled just fine but I made sure I was pulling from the hose pushing glycol TO the reservoir.

R60us

I was thinking the same thing so I switched hoses and nothing seemed to change.

manyman297

That is very odd as it should just flow freely. I can’t imagine buildup of glycol (crystallization) could cause that…or maybe it could.

BridgerSunset

Can you get fluid flowing out the drain line you initially drained from? 

Seems like the system is fluid filled but plugged somewhere.  If the plug isn't within your adapter apparatus, then it could be anywhere in the system.  So trying to get it moving somewhere is worth a try.  Can you tell if the 3010 has a screen in font of the circulating pump intake?

Mobean

Your description sounds like you had the intake and outflows reversed initially.  Did you try adding more distilled water to the expansion tank, run the circulator pump again adding water as needed to keep fluid the expansion tank? 

    "I have also tried to turn the system on circulate but it doesn't seem to change anything. I can hear the pump click however it doesn't seem to let the fluid flow."

Perhaps the system is only partially drained and there is an airlock in the circulator pump?

pthomas745

This is a long shot, but: I wonder if the check valve has somehow jammed shut?  When you are trying to draw out of the tank, the inlet to the tank should eventually lead back to the check valve.  When you are drawing from the tank, the valve should "open" and allow for liquid/air to move through the lines to the tank.  If the valve is 'stuck" and not opening, that would prevent movement.  You could also have a stuck Auto Air Bleed Valve.  Same thing would happen if that valve was stuck closed: the closed lines would prevent any movement in the hoses.

You could open the hoses there at the check valve and have a look.  If it is stuck, you can easily figure that out. You can push it with a pencil, etc, or just blow into the hose.  If it is not, work over to the Air Bleed Valve.

Picture below shows the location of the hoses where the check valve is installed.  Removing the circled clamp will enable you to pull the hoses apart with the check valve still securely in place in the hose. There may be some "spillage" of glycol in the lines, so be aware of that .  If the check valve is "stuck" glycol may be able to flow the "wrong way" and come out of the hose, so be careful.

I used this point to remove "most" of the Century glycol in my 2017. This way, along with the drain,  "might" have taken out 90 percent of the glycol.  Since I simply refilled with the Century, I felt this was acceptable.  If you are doing a full replacement to the "Alde/Truma" "new" glycol, and flushing with water, etc, this might also be a good way to go about the swap.

The clamp circled in red is the one to take off to reveal the check valve.  The valve itself is the connector of the two hoses, about 2 inches long.

manyman297

I’m starting to wonder if the use of the shop vac damaged the check valve. If it was overheating the vacuum then I assume a lot of pressure was applied. 

pthomas745

The check valve is pretty robust.  If the pressure got to the point of compressing the hoses in that area, then maybe it could be damaged.   The little "valve" inside is some heavy plastic type material, and I suppose if it was already cracked or worn, then the pressure could have pushed it out of shape.

ScottG

This is novel problem and seems to be getting some attention, so I've kicked it out to its own discussion. Carry on!  :-) 

Robermcm

If check valves are the issue, don’t forget that Alde Flow equipped trailers have a second check valve in the flow plumbing. Either one could have caused the condition he experienced.