Changing the Alde fluid in a Cirrus 620

db_cooper

Did the exchange this past weekend and lots of lessons learned.  The big lesson is that unlike the 320s that I successfully replaced by filling from the reservoir,  the 620 has too many up and down runs of pipe to do that without getting a big airlock.

First off if you're just replacing the Rhomar with Rhomar, there is no need to remove the bottom panel, and use the low point drain.  All you need to do is build the hand pump that @ScottG did on page 12 of this thread.  Pump the fluid counterclockwise from the expansion tank with the old fluid going into a bucket. For the 620, it takes exactly a gallon, and since you're doing this every 2 years, it's probably fine if you don't get 100% of the old fluid out.   The piping in the 620 is much smaller diameter than the rubber/epdm tubing in the 320s we had.  I'm not going to go over the entire procedure as it's documented multiple times in this same thread:

https://tab-rv.vanillacommunity.com/discussion/2665/changing-out-the-alde-fluid/p12

Pump links:
Tubing for riser
https://a.co/d/cxVX9hN

Pump:
https://a.co/d/cFWNl5X

#2 drilled stopper: easy to find at homebrew store
https://www.northernbrewer.com/products/no-2-stopper-drilled


Since I was replacing with the european spec fluid,  and needed to flush thoroughly, I removed the bottom panel of the camper. In hindsight, I should have built the pump and flushed from the reservoir and saved myself the trouble.

If you do decide to drain,  remove the bottom screws starting at the front of the camper and only remove back to where the water drains are.  No need to drop the entire panel, as the drain is located on the drivers side about in the middle of the bottom.

I did this, and flushed multiple times,  until the water ran clear on the last 3 flushes.  But when I tried refilling from the reservoir,  I found I had an airlock between the Alde unit and the reservoir, and hot fluid would only make it part way to the reservoir.  So I stopped what I was doing and made the pump.  So in hindsight I will probably never bother taking the bottom panel off again.  I'll just use the pump.  Hopefully my 3 separate days of floundering blindly will save you some time!

Cherokee

Everything we do is part of a learning curve. I changed the Fluid in my320 and the #2 stoppers I bought from amazon didn't seal around the copper pipe so I provided a little encouragement:

BarrettWinsmere

db_cooper said:

Did the exchange this past weekend and lots of lessons learned.  The big lesson is that unlike the 320s that I successfully replaced by filling from the reservoir,  the 620 has too many up and down runs of pipe to do that without getting a big airlock.

First off if you're just replacing the Rhomar with Rhomar, there is no need to remove the bottom panel, and use the low point drain.  All you need to do is build the hand pump that @ScottG did on page 12 of this thread.  Pump the fluid counterclockwise from the expansion tank with the old fluid going into a bucket. For the 620, it takes exactly a gallon, and since you're doing this every 2 years, it's probably fine if you don't get 100% of the old fluid out.   The piping in the 620 is much smaller diameter than the rubber/epdm tubing in the 320s we had.  I'm not going to go over the entire procedure as it's documented multiple times in this same thread:

https://tab-rv.vanillacommunity.com/discussion/2665/changing-out-the-alde-fluid/p12

Pump links:
Tubing for riser
https://a.co/d/cxVX9hN

Pump:
https://a.co/d/cFWNl5X

#2 drilled stopper: easy to find at homebrew store
https://www.northernbrewer.com/products/no-2-stopper-drilled


Since I was replacing with the european spec fluid,  and needed to flush thoroughly, I removed the bottom panel of the camper. In hindsight, I should have built the pump and flushed from the reservoir and saved myself the trouble.

If you do decide to drain,  remove the bottom screws starting at the front of the camper and only remove back to where the water drains are.  No need to drop the entire panel, as the drain is located on the drivers side about in the middle of the bottom.

I did this, and flushed multiple times,  until the water ran clear on the last 3 flushes.  But when I tried refilling from the reservoir,  I found I had an airlock between the Alde unit and the reservoir, and hot fluid would only make it part way to the reservoir.  So I stopped what I was doing and made the pump.  So in hindsight I will probably never bother taking the bottom panel off again.  I'll just use the pump.  Hopefully my 3 separate days of floundering blindly will save you some time!

Thanks for sharing your experience! It’s great to know about the airlock issue with the 620 and how the pump really helps. I’ll definitely skip removing the bottom panel next time and just go straight to the pump method. Appreciate the detailed advice and links!