How to Choose a Pump for your
Boat or Rv Water Filter System
Finding the right 12v pump for your UV water filter system in your
boat, rv or off grid cabin.
A common question that I am asked
is "what 12v pump do you suggest for my boat or Rv?" When looking
for a good pump for your new UV water filter systems there are a
few questions to consider.
1. What gpm of water will your UV system
treat?
2. Are you using the standard carbon block filters or a high
flow filter set?
3. What is the power draw up the rv/marine pump you
are looking at.
Here are some steps to determine what pump you
will need.
Step 1. Determine the flow rate your UV system
can treat. WaterFixer Model 1000 UV Systems treat up to 4gpm.
SafH2o UV filter systems treat up to 3gpm.
Step 2. Know the limits of your filters. Both UV Systems use a .5micron
carbon block filter as the pre-filter before the UV purification
chamber. This .5m carbon block filter will slow the flow rate of
your treated water down.
Step 3. The truth about 12v rv and
marine pump gpm ratings. 12v Rv and Marine pumps are rated for
their gpm in a testing facility that has no resemblance to real
life. They gpm rating does not account for any variables such as
line loss, fitting size, suction/lift height, head/rise or filter
backpressure. All of these will cut the gallons per minute of your 12v rv pump
down. Let me explain those terms.
Line Loss - When water flows
through pipe the walls of the pipe create friction against the
water molecules. This friction causes the water flow to slow down
or loose speed. The smaller the line means that the line loss will
be greater.
Fitting Size - This is pretty straight forward. If
you have small fittings in your water system the flow rate will be
reduced sometimes significantly.
Suction/Draw/Lift Height
- How high your pump is above your water source. Rv and Marine pumps
cannot suction lift water very high.
Head/Rise - How high your
12v pump can pump water. Rv and marine pumps can pump water quite
high, but loose pressure and flow as they do.
Filter Backpressure - How much pressure it takes to push water through a
water filter.
Step 4. Oversize your 12v Pump. After looking
at the variables above you will see the need to oversize your 12v
pump above the gpm treatment rating of your UV filter system,
especially if you are using a .5m carbon block filter. If your
unit treats 4gpm you will want to have a 5gpm 50 psi pump to get
all that water through. 3gpm unit should have a 3.5 gpm 50 psi
pump. If you are not concerned about reaching maximum flow rate
you can have a lesser pump. If you are us-ing a 1m high flow
filter you can use a lesser pump in many situations.
Step 5. On Demand vs Variable Speed 12v Pumps. This is very important.
YOU CANNOT USE A VARIABLE SPEED PUMP WITH A UV FILTER SYSTEM!!!
The backpressure of the filters will destroy the pump, in days or
even hours. YOU MUST USE A STANDARD ON-DEMAND RV OR MARINE 12v
PUMP.
Step 6. Locating the 12v pump in your water system.
12v marine pumps are designed to push water, not pull it. They do
a great job of it. They are very bad at pulling/drawing water. The
rv or marine pump should always be before your UV water filter
system. It is best to put the 12v pump near your water source.
Step 7. Soft Pipes. When installing your water system it is
best to attach the pump to the UV water filter system with
non-rigid pipes. If you use rigid straight pipes from your pump to
your UV water filter system and the distance is less than 6 feet
the vibration of the pump might cause fittings on the filter
system to come free and leak.
Step 8. Choose your Wire Size. Check the amp draw on your chosen pump and make sure that
your 12v power source and wiring on your boat or RV can supply the
correct amps for your pump. If your 12v pump and 12v UV water
filter system are connected to the same wiring be sure that both
can be powered when the pump is at maximum amps. If your pump
overdraws and 'steals' power then 12v ballast on your water filter
system will be the first to burn out.
Step 9. Check for leaks. I suggest doing this a few times the day of the
installation and every few days soon after the system is first
installed. If you hit some rough road in your Rv or rough seas in
your boat it is always a good idea to check your pump and water
system again.
Step 10. Do a bucket test. What's a bucket
test? It is a way to measure how much water is flowing through
your filter system. Take a bucket and measure how long it takes to
fill it up. If your system treats 4gpm a 1 gallon bucket should
take 15 seconds or less to fill up. 3gpm treatment should fill a 1
gallon bucket in 20 seconds or less. IF it fills up faster you
will need to limit the water flow through your UV system by
installing a shutoff valve and turning it down until you reach the
desired water flow.
TO ORDER UV STERILIZERS