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The House Plumbing System
Flxy’s “house” plumbing system incorporates a number of elements:
- Water Tanks – for “boondocking” or just a supply on the road. Each gallon of water you decide to carry along will weigh 8 pounds. Thus,for example, your 4 X 20 = 80 gal of fresh water storage, when full, adds 640 Lb. to the vehicle gross weight. And don’t forget the hot water tank – another 3 to 5 gallons, or 25 to 40 pounds. Remember also that your waste water tanks will be the ultimate recipients of much of this wate.
- The fixtures – the sinks and RV toilet – which require a supply of hot and/or cold water under pressure – provided by the tanks/pump system, or by “shore water” under pressure.
- The “hose bib” – provision for hooking up to pressurized outside water, when available, for use when parked, and to fill tanks if required.
- The 12V water pump – to move the water from the tanks to the taps.
- Hot Water Tank – this is propane-fired tank holding 5 gal of water. We’ve always found that the pilot light by itself maintains the temperature just fine for everyday use – washing hands, dishes, etc. If you find you use more hot water than this supplies, you can light the hot water tank as outlined below.
- Valves – to “dump” water from the tanks, and to reconfigure the system depending on whether you’re dealing with external supply pressure, or pressure provided by the pump.
- Accumulator tank – this air-over-water addition will maintain a “springy bubble” of air over the water it contains, so as to store pressure between pump cycles.
- The 12V pump. This is controlled by by the switch at the front of the kitchen sink so that you can manually add pressure to the system when required. Some systems have an automatic pressure switch, but we elected to use this system instead – less problems.If you decide to change to a pressure switch, you’ll want to be sure to protect the system against burn-out. This can happen if your battery runs down too low to run the pump to bring the pressure back up to shut the switch off. Instead, the motor just tries to run at a low-volt stall until it burns out. Don’t ask! Using the lowest-rated fuse or circuit breaker which will maintain the pump when voltage and water supply are good is one way to protect. The other is a “low-pressure cutoff switch,” which will automatically drop out below a certain pressure – usually 20psi – and will require manual re-setting. It needs a minimum pressure to stay closed, also dropping out at the adjustable high setting, and cutting in at the also-adjustable low, or “cut-in” setting – generally 30 psi. High setting is usually about 50psi. A manual switch as described above may be used to bring the pressure up enough (20psi +) to re-set the pressure switch.
- The Propane Tanks. Flxy has two main RV propane tanks, located under the left side between the wheels. These have filler fittings, shutoff valves, and level gauges. Law requires that they be shut off when traveling.
System Schematic
Here’s the schematic of Flxy’s system, which allows use of “shore pressure,” both for using the system and also for filling the tanks before leaving, as well as drainage of the tanks and lines through the shore pressure bib – located under the bus. Tank Level Sight Glass is just a piece of 3/4″ clear plastic open to atmosphere at top. The tanks may also be filled with a regular hose through the 1 1/4″ ABS pipe fitting located on the forward baggage room bulkhead just below the inter-compartment door. When filling, be sure to monitor the level by reference to the level gauge – the clear plastic tube mounted vertically to the bulkhead behind and below the bedroom sink. The baggage compartment filler tube is also the tank vent – air must be admitted through this tube to replace water as it’s drained from the tanks.
Valve Positions:
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Real Life
Here’s what the schematic looks like in real life:
Pump is mounted atop water heater – under bedroom sink counter. Note location of pump bypass valve.
Water tanks, shown mounted under the bed platform. Note manifolded 1/2″ copper lines which run alongside and forward, through the tank shutoff valve to the works as shown in the schematic.
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