How many GPM is enough for a fresh water pump?

[belfert]

After my experiences with the plumbing in my bus I am going to install a new freshwater pump.  I plan to get a Flojet Sensor since it does 12 volt or 24 volt.

They have a 3.7 or a 4.5 GPM model.  Is there a good reason to go with the 4.5 GPM model as it seems to me that 4.5 GPM will waste water when showering or running a faucet.  Isn't a standard RV water pump just 2.8 GPM?

If I get the 3.7 GPM model do I have to worry that the cut-out pressure is just 35 PSI instead of 40 PSI with the larger model?  The 3.5 GPM model I can get for about $40 less than the 4.5 GPM model.  Flojet says there is no need for a pressure tank with this pump.  Will I have issues if I keep my pressure tank?

[Jerry32]

I have the smaller VSR pump and it seems to have an accumulator action to it. I didn't see any need for a larger pump or higher pressure but will see as time goes on. Jerry

[skihor]

I think most of the faucets. shower heads, etc... are 2.5 GPM. I would go with the higher GPM. If your taking a shower and someone uses the sink or toilet. there isn't enough water to go around... I've had a Flo Jet for 1 1/2 years now withuot any issue other than what I just mentioned. The 45 PSI is nice as well.

Don & Sheila

[TomCat]

I've received great service from the ShurFlo 5.7gpm Extreme Series pump I installed. Quiet, smooth, and delivers 'house like' pressure to sinks or shower. Deals are available on the E place.

Jay
87 SaftLiner

[Kristinsgrandpa]

You shouldn't have any issues with your accumulator tank. If it's already installed keep it in case you change pumps.

When I started my coach I was told that 3 GPM and 35 PSI should be the minimum and more of each is better.

Using an extra cup of water is only a problem if you plan to boondock a lot.

Ed

[belfert]

Using an extra cup of water is only a problem if you plan to boondock a lot.

I never plan to use a campground, so I will be boondocking basically all the time.  I'm already kinda wishing I had bigger tanks, but no place for more capacity without sacrificing valuable bay space.

[luvrbus]

I changed from two 2.8 in series to 1 5.7 smart sensor pump like Jay and it was worth the extra cost as they are quite and it pump more water and has better pressure than the 2 in series also i by passed my tank because the pump seemed to work better with out it

[Kristinsgrandpa]

Belfert, some of the RTS converters use the space under the bed, a few smaller tanks with the capability to drain into the main might double your capacity.

 Only the holding tank needs to be lower than the commode.

Be inventive.

Ed

[belfert]

Belfert, some of the RTS converters use the space under the bed, a few smaller tanks with the capability to drain into the main might double your capacity.

 Only the holding tank needs to be lower than the commode.

Be inventive.

I don't have a large queen or king bed like traditional layouts.  I have eight bunks in the back with four bunks on each side.  There is very little space under the bunks.  My current design has almost zero interior space that is not utilized in some way.

My main issue is lack of holding tank capacity.  The fresh and holding tanks are the same size now and the toilet fills the holding tank faster than the fresh tank drains.  If I built my own tanks I could probably eek out a fair bit more capacity, but I'm not sure I want the expense of doing so.  I might make another trip to Elkhart to look at holding tanks and such.

[Nick Badame Refrig/ACC]

Hi Brian,

Glad you had a great trip..

I use the SureFlo smart sensor 5.7 gpm. It is well worth the extra money because of the preassure it gives us.

I also never hook up to a campground hose. They don't even come close to the presssure I have. I just use their water to refill my tanks

and it will go through my commercial Everpure Filtration system first.

Good Luck
Nick-

[Paladin]

I love this thread since I wanted to ask the very same question. What I was thinking seems to be pretty much what has been said. 
The average spec for residential plumbing pressure seems to be about 45 psi on the low side and about 60psi for a high but I may be totally wrong on that info, I tried to look it up.
I was looking at the Shurflow 5.7 which is spec'd at 65 max psi and 5.5 gpm. I was thinking that if you are running water and someone turns on another faucet or something it would help smooth out any drops. I also want to avoid low pressure flows.


So far the Surflow Extreme 5.7 looks good to me.

[tekebird]

Brian, Limit Beer consumption and your tank won't fill as fast.

[Jerry Liebler]

Belfert,
    Go with the larger pump.  You'll find that the pressure drops less as flow increases.  The rating is flow at no pressure, hardly useful.  I now have the 5.7GPM cousin and finally have reasonable pressure for a shower like at home.  Switching to the Sureflow 'Extreme' was, to me, well worth the $ and effort. 
Regards
Jerry 4107 1120

[belfert]

It looks like I am going to go with the Sensor 4.5.  Camping World has it on sale right now.  I just have to figure out how to get to Camping World some night this week before they close at 6 PM.

[Cary and Don]

On the issue of not enough tank space.  There are some soft bladder tanks out there. Not real cheap.  But we don't want to give up bay space for extra water either in the Neoplan we are working on.  We plan to add a connection to our fresh water supply, so we can add one or more of these in if we are going to be away from a water supply longer than our 100 gallon tank will last.  They fold up flat and can be stored anywhere empty. The sales pitch showed one mounted to the roof of a pickup so water could be gravity fed into a holding tank.

Cary
GMC4107