Using the Viair 40047 400P Compressor to Winterize

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Using the Viair 40047 400P Compressor to Winterize

November 14, 2020, 05:32:26 pm

This is the 3rd year I've been using my Viair compressor to winterize my 2017 MB. It's the only time I use it. I've had to replace the Viair regulator twice because it just doesn't seem to work. Even though the gauge on the inline gun says 100 PSI, the regulator doesn't go above 25 PSI. I've tried turning the dial and it doesn't do anything. The Viair technical service agent says it should work. The original one I purchased and the replacement doesn't. Does anyone else use the Viair setup?

Re: Using the Viair 40047 400P Compressor to Winterize

Reply #1 – November 14, 2020, 07:20:04 pm

Hi Glenn; Is the pump flowing air? If so, then the pump can't get the pressure up to 120 psi, because the flow rate is too high. The regulator won't be able to get the pressure higher until there is little or no flow. Why do you want the pressure so high? Blowing out lines on the motorhome, you don't want to exceed 45 psi. Air will blow out hoses and connections if you get the pressure much higher than 60 psi. Really, you do want low pressure and good flow on a dry day, to propel water vapor and droplets out of your faucets and water lines. RonB

Re: Using the Viair 40047 400P Compressor to Winterize

Reply #2 – November 14, 2020, 08:27:38 pm

RonB - The pressure coming out of the compressor is 100 PSI. The pressure at the regulator spikes to 50 PSI for about 1/2 second then drops to a steady 25 PSI. The adjuster knob on the regulator doesn't appear to do anything. I don't want it to be higher than 50 PSI. I just wish it would be more that 25 PSI. So, what it all means is that it takes me longer to blow out the water lines.

Re: Using the Viair 40047 400P Compressor to Winterize

Reply #3 – November 14, 2020, 11:00:21 pm

Glenn,
Please update if you find a solution. I am planning to get this regulator for winterizing Amazon.com: Performance Tool M688 Locking Air Pressure Regulator: Automotive and if you are using same regulator for two years without success then perhaps I should look for some other solution.
Thanks

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Re: Using the Viair 40047 400P Compressor to Winterize

Reply #4 – November 14, 2020, 11:39:01 pm

I purchased this VIAIR Winterization Kit (Compatible with 400 and 450 RVS models ONLY) - TechnoRV to go with my Viair 400rv compressor. There is pressure regulator in this kit that is put inline before attaching it to the blowout attachment. I haven't used it yet, but It may be needed to make it work.

Linda

Re: Using the Viair 40047 400P Compressor to Winterize

Reply #5 – November 15, 2020, 01:44:39 am

Hi Glenn; I'm not familiar with the Viair compressor, but in my experience with theses little ones is that the output is very variable, and usually the needle bounces back and forth so much its hard to really pin down the pressure output. The burst at 50 psi sounds like what the pump actually provides, and the drop to 25 is just internal restrictions of the regulator that is wide open. Borrow a bigger compressor (110V type) and see if the regulator and pressure start doing what you expect. While small ones can be used to blow out water, they are really designed to inflate large tires. Hi pressure, small flow. When using it for winterizing it's the opposite; high flow and you get small pressure as a result. That little 1" bore and 1" stroke just can't provide much air flow at a higher pressure.
I have a small compressor for the air horn tank, and tires, that travel with me, and a larger 110VAC compressorwith two gallon tank at home for power tools and tires. RonB

Re: Using the Viair 40047 400P Compressor to Winterize

Reply #6 – November 15, 2020, 10:28:24 am

I have used our Vlair for years airing motorhome, airing jeep after off-roading and blowing out lines. I have never had an issue with it.

Re: Using the Viair 40047 400P Compressor to Winterize

Reply #7 – November 15, 2020, 11:44:52 am

When using a small compressor to winterize, better results can be had by using the compressor to fill a 5-gallon tank and then using the tank's output to blow water out. The tank temporarily can provide the volume and pressure needed.
https://www.harborfreight.com/5-gallon-portable-air-tank-65594.html?cid=paid_google%7C%7CAll+Products%7C65594&utm_source=bing&utm_medium=cpc&utm_campaign=&utm_content=All+Products&msclkid=305c73ffd0ab14d3a7e12c4e897ed164

Larry

Re: Using the Viair 40047 400P Compressor to Winterize

Reply #8 – November 15, 2020, 12:13:45 pm

Hi Larry, the larger 7 gallon aluminum tank is what is mounted behind my 37 gallon gas tank. It provides air for the air horns and for the tires when needed. It does provide air real time, the air compressor I have, catches up. https://www.harborfreight.com/7-gallon-aluminum-air-tank-94801.html
And my air horns; almost never used because the cats ride in the cabover, Amazon.com: Hadley Horns H00977N Twin Rectangular Horn Kit: Automotive RonB

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Re: Using the Viair 40047 400P Compressor to Winterize

Reply #9 – November 15, 2020, 02:27:01 pm

When I bought the Viair Compressor back in 2017, I also purchased the Viair 90150 Regulator. It worked just fine when I winterized then. It maintained a 50 PSI. The Regulator stopped working correctly when I winterized in 2018 so I purchased the Viair 90145. On the first use, it worked according to the description in my original post. I muddled through the winterizing process and made a mental note to purchase a different brand for 2019. But then we went on an extending wandering before winter arrived in Michigan and so I didn't winterize that year. For this year, I remembered that I forgot to order a different regulator. So I will order a different brand regulator.

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