Elusive Water Tank Drain
Dear RV Doctor:
My wife and I recently retired and are new to the RV lifestyle. We love it so far, but for the life of me, I cannot find the outlet to drain the water out of the fresh water tank so I can sanitize it. I found two hoses, a red one and a blue one, coming down in the back of the coach near the spare tire. Could those be the hoses? The salespeople did a poor job of explaining things.
Paul Martinelli, Hampstead, North Carolina
The blue and red tubing you see (some are red and white as in the photo) are probably for the low-point drains. They are used to evacuate the water in the fresh water distribution system for winterizing purposes; all except the fresh water container, that is. The fresh water tank will be equipped with its own drain valve. It can appear as a separate fitting directly on the tank, or it may be installed anywhere between the tank outlet and the water pump. The drain will always be on the nonpressurized side of the system (before the pump). The low-point drains are on the pressurized side (after or downstream of the pump). If you have a fresh water distribution manifold located in a wet bay, the drain valve may be on or near it as well. In some cases, the drain valve is isolated inside the motorhome under a cabinet or on the tank itself, but typically at or below the floor level. In other cases, the drain tubing may exit through the sidewall of the RV with the valve affixed on the exterior. In yet other cases, the drain tubing may exit through the floor. I assure you, there is a drain valve somewhere.
You didn’t mention the brand of motorhome you have, but if you call the manufacturer and supply them with the VIN number or make and model, a representative should be able to tell you where the drain is located. Send me the specifics of your motorhome and I’ll see whether I can find the location of the drain. Until then, see whether you can gain access to the water tank itself. Using a flashlight, mirrors, and/or a trained mouse (that’s a joke), look for fittings and tubes exiting the tank along the bottom sides. One piece of hose or tubing will lead to the input of the water pump. Remember, the drain may “tee” off this line. There may be a second fitting, tube, and valve exiting the tank elsewhere. There’s a slight chance the drain exits the tank at the very bottom and continues through the floor to the underneath portion of the RV. While this is possible, I doubt you would find such a drain on a motorhome made recently. But, like I said earlier, there is a drain somewhere.
Motorhome Electrical
Dear RV Doctor:
I bought a preowned motorhome, and the generator powers the air conditioner, the microwave oven, and the refrigerator, but all the lights run off the batteries. What could cause this?
Brandon, Tomball, Texas
If you’re wondering why motorhomes have two apparent electrical systems — high voltage (120-volt alternating current) and low voltage (12-volt direct current) — that’s just the nature of RVs today. The higher voltage is required for larger loads. A typical motorhome likely will have all smaller loads, such as the lighting, the water pump, fans, controls for appliances, etc., powered by the 12-volt-DC battery system.
Now, if you are asking why the AC components are working and yet the lamps only operate off the battery, even when plugged into shore power, the problem could be in the converter. Most RVs are equipped with an automatic AC-to-DC converter, so when you’re plugged in, the converter provides the DC power for all the low-voltage equipment. Conversely, larger coaches may be equipped with a DC-to-AC inverter, which changes DC power from the batteries to AC current. Appliances that use large amounts of electricity, such as the air conditioner, convection oven, the refrigerator (when operating on AC power), all the wall receptacles, etc., will still require 120-volt-AC electricity in order to operate. The converter should automatically switch the current from the battery bank to the converter for all 12-volt-DC needs whenever you plug in. Some converters require a battery to be installed in order to work properly. I’m not sure which type or brand of converter is in your motorhome, but the switching relay inside the converter could be faulty, causing the 12-volt electricity to be drawn from the battery bank instead of the converter.
A simple way to check this is to measure the voltage at the battery bank before plugging in the shoreline cord. Note this measurement and then connect to the shoreline outlet. In most cases, the DC voltage at the battery bank should increase once you are connected to shore power. This indicates the converter is providing DC power to the low-voltage system. If the voltage stays the same, chances are the converter is not switching. Some converters can be repaired, but most will need to be replaced. Without the brand name and specs for your converter, it’s impossible to determine whether it can be fixed.
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