The ones that are not adjustible also limit flow a great deal. After many years of suffering with low flow (sounds like a prostate commecial don't it?) I switched over to a Watts. What a difference! I keep it set at 50psi and enjoy showers as good as I can get at home.
At 40PSI the flow is still better than the old regulators with the Watts.
I suggest using a washer with a filter screen on the input side of the regulator.
Perhaps Winnebago specifies 40 psi so you won't buy one of the cheapo 'pressure regulators' that restrict flow more than they regulate. Could be a wise move on their part......Or a vast conspiracy to run Campco and other distributers of the junk regulators out of business. Yea, maybe this was suggested by Watts so they could grab the market!!
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI
My manual doesn't say that and Winnebago told me they test to 80 or 85 psi (I forget which) and they said I coud set my regulator to 65 psi and it wouldn't a problem.
My Watts whole house regulator is set to 65 psi and I have spent entire summers with supply pressures of over 100 psi and the output line pressure of 65 psi caused no problems.
Side note: The supply pressure at our summer home in Palisade CO is 130 psi and there is a Watts regulator on the supply line. It is set at 65 psi also. That is what the town and our plumbing tech recommends.
Clay WA5NMR - Ex Snowbird - 1 year, Ex Full timer for 11 years - 2004 Winnebago Sightseer 35N Workhorse chassis. Honda Accord toad.