Community Forums

neoflyer · 12-18-2022, 06:58 PM

I am winterizing my motorhome by blowing out the lines with an air compressor. Using a Viair 450P-RV with a winterization kit. I’ve set the output pressure to about 45 psi. When I squeeze the trigger the pressure jumps to the 45 psi level then immediately drops to about 10 psi. Is the normal? I caould understand this if the lines were empty but I am just starting to winterize so I would assume they have water in them. If I hold the trigger at the now lower number is it still blowing water out of the lines? Am I doing anything wrong?

Jon_C · 12-18-2022, 11:55 PM

That small compressor does not provide enough volume of air to do what you want.

If you get a portable air tank and let it fill the tank to 30psi then use the tank to blow the lines that should work

neoflyer · 12-19-2022, 01:50 PM

Quote:

Originally Posted by Jon_C

That small compressor does not provide enough volume of air to do what you want.

If you get a portable air tank and let it fill the tank to 30psi then use the tank to blow the lines that should work

Using this compressor is recommended by The RV Geeks on their website. They use the same compressor to winterize their 43’ motorhome. I may use my motorhome’s onboard compressor.

Marine359 · 12-19-2022, 01:57 PM

If the low point drains are open, or if the water heater is not bypassed, the pressurized air will simply go out through them. After draining it, bypass the HWH.
When I use pressure air, I first open low point drains to get much of the water to gravity drain out. Then I close them, and blow pressure air, opening one faucet at a time. You’ll only lose as much pressure as what comes out of the open faucet. After all faucets blown, reopen low point drains and blow that water out. Don’t forget to blow the toilet valve, outside shower, and inside shower.

Gary RVRoamer · 12-19-2022, 04:16 PM

Psi isn't important, but air volume (cfm) is critical for pushing the water out. A small compressor simply cannot deliver enough cfm to push the water very well. 10 psi will move water, but the reason for that dramatic pressure drop is that your compressor couldn't supply the air volume needed to fill the pipes and push out the water.
Bottom line: you need a compressor with a high cfm rating (doesn't have to be high pressure - 30 psi is plenty.

Argosy · 12-19-2022, 04:50 PM

Quote:

Originally Posted by neoflyer

Using this compressor is recommended by The RV Geeks on their website. They use the same compressor to winterize their 43’ motorhome. I may use my motorhome’s onboard compressor.

Don't use the onboard compressor, it's oil lubed and oil does end up in the air system, you don't want it in your plumbing. They don't really make a lot of air either. It's easy for inexperienced drivers to over tax the compressor just with the brakes.

The 400P Viair outputs 1.64 cfm at 50 psi. You need to maintain 50 psi and at least 5-6 cfm to blow the plumbing out.

If the RV Geeks are using that compressor they're not blowing the lines, they're taking advantage of the fact moving air will evaporate water faster than still air. it will eventually work, but it could take hours, especially in a big motor home with a bath and a half, washer, ice maker, etc.

Ray,IN · 12-19-2022, 07:36 PM

Quote:

Originally Posted by neoflyer

Using this compressor is recommended by The RV Geeks on their website. They use the same compressor to winterize their 43’ motorhome. I may use my motorhome’s onboard compressor.

The MH compressed air system is not a high volume capacity system.
There is a new post on the Spartan forum about a safety recall, which involves the air brake system and inadequate storage tank size(volume) now.

Mighty_J · 12-19-2022, 08:41 PM

I wrote that post on the recall. Glad someone read it!! When there’s no responses you never know if it was helpful or not.

To the O/P here, I’ve used the 450p to blow out my lines. Same observations as you and some of the other posters. It moves even less air than the 400 - the 450’s strength is duty cycle not cfm. I added RV plumbing antifreeze after blowing it all out just to be safe. Best of luck!

Donskiman · 12-19-2022, 09:21 PM

I don't use the Viair, but here is the video in question. I do only use air to winterize and it worked fine last year in -20 temps. I cycle through all lines 3 times to make sure I get all the water out. Antifreeze only goes in P-traps, toilets and the washing machine pump. I don't have an icemaker.
https://rvlife.com/how-to-winterize-...ut-antifreeze/