|
|
RV Doctor ColumnRV Doctor #339 Dear RV Doctor, I have an older Hydro-Flame 19,000 BTU furnace, the serial number is 0066957. The thermostat is a Robertshaw CM60. My problem; I can't get ignition. I have had the DSI board checked and the technician said that it was okay. What I need to know is how I can eliminate each component one at a time, such as the thermostat. How can I wire across it to call for heat to see if it is okay. How can I eliminate the DSI board, the sail switch, the fan limit and the solenoids on the gas valve? The instructions that came with the furnace are very vague. I have a full bottle of propane and it's hooked up with a very short hose so I have fuel. Any help will be greatly appreciated. Charlie Hopkins, (Wheeling, WV)
Charlie, there are actually two versions of your furnace, though the difference involves only the flame sense circuit and does not apply directly to your question. Here's how to test the components you mentioned. The thermostat can be tested by eliminating it from the circuit. Remove the two wires and connect them together. If the furnace fires up, the thermostat is faulty. The circuit board can only be tested by using an approved electronic board tester, or by swapping the board with a known, good one. Most RV service facilities will have the correct board tester. The sail switch is a "normally open" switch. With the voltage disconnected, attach a VOM to the two terminals on the sail switch. There should be continuity measured only when the paddle of the switch is manipulated. When released, the meter should show infinity. The limit switch is just the opposite; it's "normally closed." Being a thermal switch, the limit switch will open at a pre-set temperature. Attach the VOM to both contacts and carefully heat the thermal disc portion of the switch with a match. The switch should open when the disc is heated. The board itself performs basically three different functions. It sends voltage to the gas valves, it creates the spark for ignition and monitors the micro-amp remote sense circuit, and it will perform a lockout if ignition did not take place. The voltage to the board first passes through a breaker, the relay, the sail switch and the limit switch. If the motor turns too slowly, the sail switch will not close and voltage will never reach the board. This is common when the squirrel cage becomes heavily laden with dust and lint. The extra weight slows the revolutions to the point the sail switch won't even close. If you have voltage present at the gas valve while the fan is turning, then the relay, the sail switch and the limit switch are all okay. On some early Hydro-Flame units, there is an additional on/off switch located between the board and the gas valve. If this switch is turned off, the gas valve will never open. If the fan does not operate at all, it could be the relay or the fan motor. If the fan runs, the board activated and no spark occurs, but there is voltage at the gas valve, chances are the board is faulty. Be sure to check the ground connection carefully and be sure you have a fully charged battery in place. Low voltage can cause a plethora of additional problems as well.
Dear RV Doc, I am thinking about installing a 600-watt inverter to power my 27-inch TV and dish system. My question to you is, are the two, 100-amp batteries that I have in my motorhome enough battery to watch TV for four or five hours at night and then recharge my batteries in the morning with my generator? If not, any ideas on what to do or where one would install more batteries. Tom Sadecki, (Seattle, WA)
Tom, first it will be necessary to determine exactly how much wattage the television and the dish requires. If they are rated in amps simply multiply the amperage times the voltage; the result is power measured in watts. Then multiply the wattage requirement by the number of hours you will watch the TV. This result is the daily wattage requirement, not including any other 12-volt devices being activated, such as fans, water pump or lamps. The bottom line is: multiply all the 12-volt devices you will be using times the amount of time to obtain a final amperage requirement figure. Then add a 30% safety factor. Assuming the batteries are in fairly good condition and you can fully charge the two of them, divide your final amperage requirement calculated above into 200. The mathematical result will determine if you have enough storage capability. Next, look at your charging method. Typically the RV power converter is used to charge the batteries. The generator will simply provide the 120-volts AC to power the converter/charger. The power converter with a well designed charging feature is a very good method of keeping the RV portion of the 12-volt DC system charged up, especially if your unit is equipped with a sophisticated, three or four step converter/charger, which is what I recommend. The typical charging converter is not capable of charging the batteries quickly. Extra batteries should be installed as close to the others as possible, but basically anywhere they can fit, though not inside the living areas. The AGM battery is what I recommend. Highly touted, the AGM battery has many intriguing features. Their recombinant gases are effective to about 99%. The hydrogen and oxygen are recombined inside the battery within each separator, unlike the gel type where the recombining occurs between the plates and the battery top. This keeps dangerous hydrogen gas levels to a minimum. Most AGM batteries vent hydrogen vapors at less than 2%, where 4.1% is needed to support flammability in air. The inherently low internal resistance is a welcomed benefit to RVers who store the motorhome part of the year. AGM batteries can be charged ten times faster than a same rated gel battery and five times as fast as a like-sized flooded lead acid battery. You indeed have many things to consider, so do the math first to determine your exact plan of attack.
Dear Gary, I have trouble with a Winegard crank up TV antenna. It seems to continue to work loose where it travels through the roof of my motorhome. I have had it tightened three times, and the main section replaced once. I still have the problem. Any suggestions? Gerry Sudman, (Henderson, TN)
Gerry, You didn't mention the model number of your Winegard or the brand of your motorhome, but many such problems are usually caused by insufficient blocking support inside the roof cavity of the RV. There is usually no problem associated with solid roof RVs. With a soft roof, the antenna must be installed next to a rafter for support. In those instances when it is impossible or impractical to do so, insert a piece of 5/8" plywood, 18" x 18" square, between the mounting plate of the antenna and the roof. Have the plywood straddle two adjacent rafters. Secure the plywood to the roof first and be sure to carefully seal against water intrusion. Then, install the antenna to the plywood support piece. This will then distribute the stress of raising and lowering of the antenna to both rafters equally. Also be sure the gears on the antenna are lubed periodically.
Dear Gary, any insight into this would be very welcome. When we park our motorhome outside all closed up, my wife and daughter both complain about a smell that burns their eyes and stuffs them up. It has a rubber roof and a small slideout I have washed the roof a couple of times to see if that helps. It seems to be worse on hot days. Thank you for your help. Alan Augustine, (Ann Arbor, MI)
Alan, it is quite possible your wife and daughter are experiencing a case of formaldehyde irritation. This happens often with newer RVs, especially if they have been sealed and stored for any length of time. Formaldehyde is often found in some common products used during the manufacture of certain recreation vehicles. Because of its broad adhesive ability and high bonding qualities, formaldehyde is used in the production of pressed wood products, wallboard paneling, and possibly in some furniture and cabinet components. It can surely be a perplexing problem and a definite hindrance while trying to enjoy the RV lifestyle. Simply masking the odor with air fresheners or letting the coach "air out" will not eliminate the problem. The following steps will neutralize the effects of the formaldehyde contamination you are experiencing. Be sure to take the necessary precautions while performing the following procedures. It may be advisable to take your motorhome to a reputable RV service facility and have them perform these steps if your eyes and throat are easily irritated. The procedures outlined here involve the use of aqueous ammonia, more commonly known as ammonium hydroxide. This ammonia, while it will eliminate the formaldehyde problem, contains strong irritants that also affect your eyes, nose, and throat during the fumigation process. If you choose to do it yourself, be sure to wear a protective mask, eye protection and gloves while handling the ammonia. Also be sure to read the first aid instructions that come printed on the ammonia container. You will need approximately one gallon of ammonia.
|
|
|
[ Home ] [ Ask the RV Doctor ] [ RV Doctor Column ] [ Memorandums ] [ Interesting Articles ] [ Product Spotlight ] [RV Service Technician Training ] [ Seminars ] [ Links ] [ Gary's Bio ]
Send your questions and comments to:
gbunzer@cox.net |
|