Community Forums

Gary RVRoamer · 04-02-2010, 02:40 PM

It's an interesting point and one I've never heard mentioned before with respect to back-pressure. I don't think the size of the pipe affects the "head" pressure, but could not readily explain why it does not. Maybe somebody with a hydraulic engineering background can help out. I do not that all the weight of that volume of water is not concentrated in one spot, i.e. the point where the 1" pump output joins the larger pipe. Basic physics says the pressure is equal area at the bottom of that theoretical 5" pipe the tech talked about. The pump dopes not have to move the entire mass of water out of the way - it just has to push a little in and force a similar amount out the other end.

In any case, you aren't adding much volume to the head. The rise is only 4-5 feet and the volume in the head is therefore only about 4.5 ft x the difference between the 1" and the 1 1/4, which we already know is a 50% difference in volume. I think we are talking 0.1 gal difference here. Still, I'd like to know the true answer.

Jimmyzw22 · 04-02-2010, 03:31 PM

We ended up doing this on our home we built because our plumber who we fired came out of the house too low to get the proper fall to the septic system. I just put in an effluent ejection system. Basically a sump pump with a float that pumps everything through a 2 inch pipe 85 feet to the septic tank. Works great. My shop has an RV dump behind it that has the proper angle to it to get to the septic tanks. Good Luck. The whole system costs about 500.00

exrench · 04-04-2010, 09:05 AM

The pressure to move a fluid in a pipe is completely dependent upon the "head" against which the pump is acting.The head is the vertical measurement from the pump outlet to the surface of the fluid at it's highest point.A slightly larger discharge hose will eliminate frictional losses.

cvrvr · 04-04-2010, 02:59 PM

My vote would be for a sewer ejector system. Hopefully you will have water available in your new garage for clean up.

I sure wish I had a garage for my MH.

George

CaptBill · 04-04-2010, 05:01 PM

Well, I'll have to wait a bit more to find out what kind of pump will do the job, but I did put 1.25" schedule 40 PVC pipe in the ground, and the trenches are covered.. Oh my aching body. Installed power, security, telephone, Cat5e (2), cable TV and 2 spares, plus a water supply and frost-proof hose bib, and of course, the waste discharge pipe. I hope that's more than I'll need, cause I don't want to do any more trench digging and filling.

Thanks for all the replies and suggestions. Great bunch here. Tomorrow, we are supposed to do the concrete prep for the floor, and if all goes well, we should be pouring concrete on Tuesday or Weds.

Still lots of work ahead after that, but we're getting closer. Thanks again

Oemtech · 04-04-2010, 05:46 PM

According to my septic designer and installer I could dump up to 200 gallons daily in my dual chamber system and not have problems. When I asked about dumping 40 to 50 gallons from the black tank he said not to worry....

I lived for 4 years in my RV inside my RV barn and dumped my gray water almost daily (showers, dishes, older 4:1 RO system, clothes washing etc), black water (40 gals of 55) at least every 5 days and I never had any problems with my septic system. I just swapped drain fields monthly.

Ernie n Tara · 04-05-2010, 10:14 AM

A simple answer is that 5' rise is about 2-1/2 PSI. The pipe diameter has no effect, only the rise. Note that pumps are rated in terms of rise (suction or pressure) for that reason. (~30' equals atmosphere pressure or 14.7 PSI at sea level.
Ernie