Community Forums

dgerstel · 05-02-2009, 08:48 AM

Bob,

To the best of my knowledge, the new pump was used for mainly 2 reasons.

1) The ability to use an other source in the coach while showering without causing fluctuations in the shower flow. Besides lower flow this can cause changes in the water temp.

2) The new pump has a variable speed, allowing it to continue pumping at low flows, without cycling. I think that this is where most people are having problems, although I know there have been some failures also. The failures may be due to low voltage, the wiring in the new coaches was never upgraded to handle the new pumps amp draw requirements.

I have had both systems and find the new one to be nicer, when working properly.

rmmpe · 05-02-2009, 09:34 AM

Hi Dale,

I believe you on the inability to use the shower and a faucet at the same time (or the shower and commode at the same time). The 2.8 GPM pump provides adequate flow from 1 outlet but when more than that is open, the delivery to them suffers. I know this to be true because we'd use the pump system for showers before I fixed the City water system (I could hear Peg scream from the shower when I flushed the commode).

Also, I was not aware the 5.7 was a variable flow rate pump (perhaps I missed that).

Regarding the wires: I suspect the ampacity of the wires originally used to the smaller pump could easily be a source of problems. However, on mine, the wires are 14 gage, which is certainly adequate for the 2.8 GPM pump's 4 Amp motor.

My offering was also to illustrate the piping limitations of our rigs relative to a 5.7 GPM flow rate. Only considering straight pipe, the calculations did not account for such things as Elbows, Tee's and other fittings, which will dramatically affect flow and pressure.

Bottom line:
There have been enough reported problems that I'll stick with the 2.8 GPM pump. This is easy for me/us because we only use the pump for short periods and mostly just to flush the commode. If we camped where there was no shore water, I might re-think that.

EngineerMike · 05-02-2009, 11:28 AM

Customary procedure for accounting for elbows, tees, and other fittings is to add up the straight pipe, then add 7 feet of "equivalent" fittings per 1000 feet of straight pipe, i.e. 0.7% loss that must be made up by pump capacity. In a coach, that figure might maybe triple or quadruple due to the lack of long straight runs, call it 3% additional loss from friction. So flow loss due to velocity will always tell the story.

Just a side note, I don't see this type of interest in the detailed workings of coach innards on other forums. What's wrong w/those people anyway?

dgerstel · 05-02-2009, 11:54 AM

Bob,

Just for information, if you look at the pump switch and wiring at your tank monitor, you will see the wire at that point is only about 18 gage. With your pump and length of wiring I wouldn't be concerned.

The later coaches have 2 problems with that wiring.

1) 5.7 pump is suppose to have a 15 amp circuit with 12 gage for runs up to 50 ft or 10 gage wiring for over 50 ft. (Or a relay.)

http://www.shurflo.com/pdf/rv/911_tr...-D_English.pdf

2) On most? Of these coaches the tank monitor/pump switch was moved to the front of the coach. The wiring to the pump is: from fuses to bathroom switch, all the way forward to the tank monitor, back to the fridg area and then down and over to the pump. (A long run plus the small wire and switch at the monitor.)

rmmpe · 05-02-2009, 11:56 AM

C'mon Mike, you made no mention of Laminar flow..........

I believe the reason this type of discussion doesn't appear on other forums is they have few, if any, Prefessional Engineers.

We can be such a pain in the Butt.

rmmpe · 05-02-2009, 12:18 PM

Dale,
A relay would be relatively simple install.
Buy a 30 Amp automotive relay.
Run a fused 12 or 14 gage wire from the Coach battery to the relay's #30 terminal.
Run a 12 or 14 gage wire from the relay's #87 terminal to the pump
Connect the pump's existing power wire to the relay's #85 terminal.
Run a ground wire to the relay's #86 terminal.

The existing switch will actuate the relay, providing power from the relay's #30 terminal to the relay's #87 terminal, energizing the pump.

Forgive me if you know this. It is not meant to be insulting.

dgerstel · 05-02-2009, 03:49 PM

Bob,

I try to never be insulted. If you had caught some of the posts on the 5.7 pump, you would have seen that is what I recommended and did on mine. You did give a much better description of how to do it than I did, I am a lazy typist.

rmmpe · 05-03-2009, 04:38 AM

Dale,
I have those little relays all over the place. The 99 models didn't have DRLs and I usually drive with my lights on. The biggest problem with that was I'd forget to turn them off when leaving the Coach. To fix that I made a flip-flop circuit to remind me to do both as soon as I turned the key.
There's another under the bed that I use to excercise the Pac-Brake when lubricating it. Another to bypass the Pac-Brake circuit so it can be used on the mild declines without the shift to a lower gear.

My 33' REO has a few also, which protects the new and modified circuits on it (4-way signals, horn, lights, etc.).

That's my story and I'm stickin' to it.

Safe roads and happy travels.

Bob

They are wonderful little things and perhaps one of the cheapest mods that can be made to add/improve features.

EngineerMike · 05-17-2009, 05:07 PM

My 5.7 failed to the run-full-time-&-overheat mode. I never did have it working without cycling except for a brief time after adjusting the middle set screw per S.F.'s tech line instructions, but went back to cycling w/in a few days.
Soooo, I'm running off the spare pump I mounted next to the 5.7 a year or so ago, and getting ready to do the relay project.

I opened the pump switch panel @ the front above entry steps; switch has:
Top --------O--------- (18ga yellow (~4"), crimp, 14ga black)
Middle------O--------- (18ga red (~4"), crimp, 14ga blk w/red tape)
Bottom-----O--------- (18ga orange (~4"), crimp, 14ga black)
So three 14ga black wires out, middle one w/red tape. Only ~4" of 18ga.

Pulled drawer in bedrm to check wires to toilet room switch:
Top ------------------ (14ga black)
Middle======== (14ga double black, i.e. 2 wires to spade)
Bottom--------------- (14ga black)
i.e. 4 wires total, all black, disappear thru floor to basement between frame rails.

@ the pump: 5.7's black wire crimped to two 14ga white, 5.7's red wire crimped to one black. The 2-wht + 1-blk disappear into the mess-o-wire above the inverter & I can't trace from there. On the 08 there is a fuse block just ahead of the RR tire in the waste tank compartment; on it there is a 15A fuse w/black wire to "pump." That'd make 2 15A fuses, including the in-line fuse on the red 5.7pump wire a few inches from the pump (I think mfgr includes this in-line fuse holder w/pump wiring). Conceivably WRV may have taken to wiring a relay inline, and maybe that's why there are white wires for ground instead of black. However, that doesn;t explain two white wires. I can't figure that one out.

dgerstel · 05-17-2009, 05:46 PM

Mike,

The 2 whites are 1) 2 grounds (WRV just trying to be extra careful) 2) One wire to ground and the other to something else that needs a ground.

I connected a 10g wire to one of the unused positions in the 12v fuses panel in the pass side service bay and ran it over to the pump area. I used it for power to the pump thru a relay. Used the old pump 12v supply to activate the relay and installed my own ground at the pump area. I used a 20 amp fuse on this circuit.

What I have found with WRV's color coding system: The 115 volt AC system is normal, color hot, white neutral and green for ground. The Chassis 12 volt wiring is mostly white for + power, some colored that WRV added after the fact and black for ground, like the batteries. The house 12 volt system seems to be sort of like 115 volt AC wiring with colored for + (hot) and white for neutral, which is ground in a 12 volt system. So in other words, make sure what you are connecting to, don't trust the color. Some of the chassis wires are labeled with just numbers and others (few) say what they are.

One of my future projects is to find out what each fuse actually does and remark them.

takepride · 05-18-2009, 09:30 PM

Dale:

After much wiring, testing, re-wiring, testing, etc., it seems the chassis was wired with white as power if it passes along the loom. If connected to a third-party chassis part, the power is colored though not usually black. If it has to do with the house 12 volt, the power is white, but again third party is colored, sometimes black. On the 120 side, the usual colored-is-hot is followed. I too, have learned to check each and every wire.

I seem to have become the slowest electrician on Earth with this coach, but I want to make it right. However, I sure am learning a lot about Alpines, kinda enjoy it, too.

I'll work on the pump situation soon and use the Intellitec controller with new power source and relay switching. I really want a pump switch in the utility bay. Thanks to all the folks who PMed and emailed me their opinions. There seems to be a general concurrance. With all the wiring to date, I am no longer afraid to try it out. BUT, if someone would like to draw the installation all out on a piece of paper and post it here, I'll certainly follow it and gratefully.