Repairing Leaky Joints
Dear RV Doctor:
Our 2009 Newmar Dutch Aire has developed several leaks in the joints of the PVC gray and black waste systems. The black one is especially bad. Is there a product designed specifically for such a repair on PVC joints?
Earl Bean, F420436
Oklahoma City, Oklahoma
I’m assuming you are referring to the black drain pipes common to RVs, boats, and even residential and commercial waste plumbing applications. Those are made of ABS plastic. PVC, although also a thermoplastic, is not typically used for drain plumbing applications in motorhomes. ABS is less prone to damage due to cold temperatures and has a higher impact resistance, among other benefits.
If the leaks are actually at the joint itself, and found at multiple joints, it sounds as though those connections either were not prepped properly, or the wrong cement was used to form the bond, or perhaps not enough cement was used. There is such a thing as an aftermarket ABS patch kit that often is sold to correct cracks in ABS holding tanks. I normally do not recommend patch kits for holding tanks; I consider them, more often than not, a temporary repair at best. In my opinion, the only true way to permanently repair a crack in a thermoplastic holding tank is by plastic welding. But in your case, if the leaks are at the actual joints where the pipe enters a fitting, then those ABS patch kits just might do the trick. I’d certainly try that first.
Another option is to have a technician back-weld around those joints using a plastic welding machine. The third, least acceptable option, is to cut out all the leaky joints and start over with fresh fittings and piping. But as long as you have access all the way around each joint that leaks, I’d give the patch kit a try first.
No Ho-Hum Matter
Dear RV Doctor:
I installed a new transfer switch, and it hums when the coach is connected to a 120-volt landline. What is the problem? Also, I have two new 6-volt batteries, and they are not holding a charge after charging at two amps for several days. I have installed a shutoff switch, which deactivates the batteries. Do I assume these batteries should be disconnected totally in order to charge? Does one assume that I have a continuous drain?
Ed Beaumier
Via E-Mail
You didn’t state the brand of transfer switch you installed or the type of motorhome you have, but if it’s an IOTA transfer switch, know that recalls have been issued related to failure of some of their units.
Inside all transfer switches, you’ll find moving parts and contactors, coils, relays, etc. If you’re not familiar with how the device is constructed, I’d leave further internal troubleshooting to a certified technician. However, many transfer switches “hum” because of loose wiring connections or dirty contactors. If you can gain access to the contact pads, they often can be cleaned. And certainly all connection points can be tightened. Obviously, disengage any and all sources of 120-volt-AC electricity — shore cord, generator, and inverter outputs — before taking the cover off the transfer switch.
Clean compressed air can be used to blow out any dirt or dust from the contacts. Any transfer switch employing aluminum contact points with copper wiring has a tendency to work loose as the coach travels over the road. It’s a good idea to check and tighten most all electrical connections once a year anyway. This includes the panelboard distribution box (breaker box), DC converter fuse blocks, etc. In all my electrical-related seminars, I speak about “clean, tight, and dry” concerning all electrical components, connections, and terminations. Ninety percent of all anomalies can be eliminated or minimized by remembering those three key words.
Dirty contacts and loose wires/connections are but two of the possible causes. Another is an overloaded system. Some transfer switches are controlled by 12 volts DC. It all depends on your brand and model number. Those with DC coils rarely hum. By the way, it’s totally feasible that some hum is normal. At 60 hertz, it’s not uncommon for AC wiring to emit an audible hum from time to time.
Another possibility is simply a faulty transfer switch. Some armatures in some transfer switches contain laminations that can work loose. I’ve actually seen this issue in brand-new switches. This can be prominent if the coil is activated by AC electricity instead of the aforementioned DC coils. As the electromagnet holds an AC armature in contact, loose laminations actually can vibrate enough to create a humming noise. If the hum ever changes in intensity or volume, it usually can be attributed to loose plates in the armature.
Many of today’s products are so cheaply manufactured that some people have come to acknowledge the audible hum as “normal.” Minimal hum is perhaps acceptable, but in most cases, clean contacts and tight connections and quality materials should not produce an annoying hum in the switch. And rather than replace individual components in an attempt to eliminate hum in a less-than-stellar transfer switch, I’d recommend an upgrade to a higher-quality switch altogether. All this, of course, after proper diagnostics.
Regarding your battery bank, at only two amps per hour, charging can take upwards of five days for a 225- to 250-amp-hour capacity such as yours. And that’s with no use of the amp-hours already in the battery bank. I’m a fan of “smart” battery chargers to ensure proper charging algorithms. A smart charger takes into consideration the status of the battery, and then coordinates the charging voltage and amperage based on the temperature of the batteries. A full battery charge with the least amount of heat rise, without fear of overcharging, can be accomplished only by a smart charger. And the batteries must remain in the system in order to charge and to discharge. If you open that switch to disconnect them from the system, they will not charge at all.
I would not assume you have a drain on the battery system until you eliminate the batteries as the cause. I’m thinking your new batteries have not had the benefit of a full charge yet. If the batteries simply will not hold a charge and they are in good shape (no fouled cells or electrolyte issues), then you can start looking for a drain on the system. To know when the batteries are fully charged, monitor the specific gravity of the electrolyte during the charging process. As the battery bank accepts a charge — any charge — the specific gravity will continue to rise, perhaps slowly. At some point, the specific gravity will plateau and remain at one reading for two to three consecutive hours. Then you know that the battery system cannot accept any more amp-hours from the charging source.