Sunday, September 25, 2016

Hot Water Heater Intro


First, thanks to all who helped put this together - John, Erik, Judy and Andy.  They picked up a number of errors and omissions that helped me make it better.  

This is targeted at water heaters from Atwood, used in Lazy Daze motor homes.  It is NOT applicable to other makes of heaters.  It is not intended to be a detailed or comprehensive guide to troubleshooting your heater.  Rather, the intent is to allow you to become familiar enough with the electronics in the system to understand what is going on, and possibly to identify a failed component if professional help is not available.  Other articles address flushing the heater, and I do not plan to address issues with propane delivery here.

Now the disclaimers - Combining propane and electricity is dangerous.  Do not mess with the system if you do not feel able to do so safely.  Read your Atwood manual for more detail.  If you do not have one, you can download one from http://atwoodmobile.com/manuals/waterheaters/MPD%2093756%20SP%2011.19.07.pdf Their manual has step by step instructions for troubleshooting, and it is recommended that that be your primary resource.

Stay within your skill set.  If you are not comfortable with any of these steps, let a pro do the work.

Do not work on the water heater when the water is hot.

You may want to take pics of everything before you start, but if you only deal with one component at a time, getting things back together is pretty simple.

These water heaters run on 12 volts for the controls and propane for the heat.  There are some 120v heaters out there, but this does not address them.  They have a confusing array of wires running here and there.  When the heater isn’t working right and you are well away from help, it can be a challenge to figure it out.  This article is intended to give you a basic understanding of the parts, what they do, and perhaps how to check them if you are having problems.



Looking at the heater, in the top right corner is the circuit board.  It is the brains of the operation.  It senses what is happening elsewhere in the system and does things like allow propane to flow or not, send a spark to light the propane, monitor the water temperature, and monitor the flame.

To the left of the Board is the brass pressure relief valve.  It has two functions.  If there is too much pressure in the heater, such as from water that is overheated and boiling, it releases pressure rather than allowing the pressure to build and cause a steam explosion.  It is also used to restore or maintain a pocket of air at the top of the heater chamber which cushions the chamber and your plumbing from overpressure as water heats and expands.

Left of the pressure relief valve is the exhaust vent.

Below the pressure relief valve are two thermostats and a device (thermal cutoff) in a clear plastic tube.  The left thermostat, covered by black foam tape, is labeled ECO (Emergency Cutoff).  It shuts down the system if heater temperatures are too high.  It is normally in the closed position, conducting electricity through it, but if it senses temperatures that are too high it will open, cutting off flow of propane.

The right thermostat is the one the system uses to control the water temperature.  When the water is cold, this thermostat is closed, conducting 12 volts through it, and current can flow to the system.  When the water reaches the designated temperature the thermostat opens, cutting off the electricity, and the system cuts off the flow of propane.

Floating about in front of the thermostats is a little electrical part encased in a clear plastic tube.  This is a thermal cutoff.  If there is too much heat in the area behind the thermostats, perhaps from a blocked flue or exhaust vent, a propane leak or some such, this part melts, cutting off power to the system.  

Andy Baird’s “Eureka” talks about the thermal cutoff.  He said, ”Like a fuse, the thermal cut-off is a one-shot device... so if it blows, it must be replaced. This is where it gets interesting. A Google product search on 'atwood thermal cut-off' turned up prices ranging from $16.00 to nearly $23.00. I knew that a simple part like this couldn’t possibly cost that much—somebody, probably Atwood, was tacking on huge markups. But I was able to locate the part in the Newark Electronics catalog for just $2.16—a far cry from the RV dealers’ pricing! Here’s a link to the item.

http://www.newark.com/nte-electronics/nte8096/fuse-thermal-98-c-15a-277v/dp/55R1324?ost=nte8096&selectedCategoryId=&categoryNameResp=All%2BCategories&searchView=table&iscrfnonsku=false

For the record, it's an NTE Electronics #NTE8096 thermal fuse, designed to carry 15A and cut off at 98 degrees Celsius. It's not something you can find in a local Radio Shack store, so I carry a few spares with me just in case. You might want to do likewise.

To be fair, Atwood’s $20.00 replacement part includes two thermal fuses (worth four bucks), some plastic sleeving, and a couple of 3/16" crimp-on lugs (worth a buck, maybe)—but I'm sure most of us can scrounge those items for a lot less than Atwood is charging!”

Below the thermostat and ECO is the propane solenoid valve.  To the right is the mix tube or burner, which mixes air with the propane and turns and directs the air and propane mixture into the burn chamber.  In front of the mix tube outlet, at the entrance to the burn chamber, is a pair of contacts from a white ceramic ignitor, which acts like a spark plug.

Finally, above and left of the solenoid valve is a plug which allows draining of the heater for maintenance such as flushing or storage.

OK, here we go.  When you switch the heater on and the water in the heater is cold, 12 volts should go first to the thermal cutoff, then to the thermostat, then to the circuit board.  That condition is signaled by a red and a green light by the switch over the stove.  If the thermal cutoff is melted, or if the thermostat is in the open position, you will see only a green light on the switch above the stove, not the usual red and green lights on startup. 

When the board receives a 12 volt signal, it accepts that as meaning that the thermal cutoff and the thermostat are closed.  Then the board thinks it is safe to begin lighting the burner to heat water.  It signals with a red and green light by the switch, and begins the startup procedure, sending voltage through the ECO to the solenoid.  If the ECO is closed, that voltage reaches the solenoid, and the solenoid allows the flow of propane.

The board now sends a high voltage pulse to the ignitor.  Between pulses it measures the resistance across the ignitor’s 1/8” gap.  That resistance tells the board whether there is a flame or not.  It should try three times to light the burner.  If no flame is sensed, it will shut down the propane and cease further attempts.  If a flame is sensed, the lights by the switch go to green and it continues the burn until the thermostat opens, at which time it cuts off the flame.

So - what can go wrong?  Let’s assume here that you do not have dead batteries, and that you have ample propane.  What next?

First, there are a lot of spade connectors in the system.  They are subject to corrosion.  If they become corroded, the board will not get good information and the heater will not work right.  So, start by making sure all the connections are clean and free of corrosion.  Connectors can be cleaned with contact cleaner, with a fine abrasive such as a coarse eraser or fine sandpaper, or by other similar means.  When cleaning the contacts on the board, be gentle.  That material is thin.  You do NOT want to abrade it away.

Next, if you have a multimeter, you can check the thermal cutoff, the thermostat and the ECO for an open circuit.  All should read closed or very low resistance.  If any read open, you found the problem.  Replace the part.  If you do not have a multimeter, and you have a helper, you can test them by bypassing each of these items, one at a time, by unplugging the spade connectors from the device and connecting the two wire ends together.  WARNING - DO NOT USE BYPASSING TO OPERATE THE HEATER, just to troubleshoot it.  The recommended way is to have a helper inside, with the switch off.  Make the bypass connection and have the helper turn the switch on.  If the heater lights, you found the problem.  Turn the switch off immediately (you disconnected a safety device) and reconnect the failed device until you can get a replacement.  Do the thermal cutoff first, then the thermostat, then the ECO.

The Atwood manual gives places where voltage can be checked with a multimeter.  You could have a working ECO, but corroded contacts, leading to low voltage at the solenoid.  If you have a multimeter, do those voltage tests.

OK, you checked and the thermal cutoff, thermostat and ECO and all are showing closed or good, but you have no flame.  The voltage at the solenoid is good.  Is the solenoid operating?  You may be able to hear gas flow if it is.  My hearing is not good enough for that, but yours might be.  Make sure the mix tube is clear of debris, spider webs, etc., then try again.  If the tube is removed to clean, it should be put back in same location and make sure the flame is adjusted to provide the most efficient air gas mixture.  The color of the flame is the indication of this by seeing a good blue flame with a tinge of yellow on the flame tip. Too much air will be noticeable by a louder burn and yellow flame. This adjustment is done by loosening the screw at the beginning of the tube and making the air gap there larger or smaller, then tightening the screw.  This setting should not be done at higher elevations. 

At this point, some guesswork is involved.  If you see no spark at the ignitor electrode tip, then either the ignitor or the board is bad.  If you see a spark but no flame, you may not be getting adequate propane flow, indicating a problem with the solenoid, you may not be getting air mixed with propane, or the spark may be weak or in the wrong place.  If you see a flame that burns briefly before going out, either the ignitor or the board is probably bad, but a blocked mix tube or propane orifice could be to blame.  

Let’s look at the ignitor.  You should hear a tic - tic - tic sound as the ignitor shoots a spark across that 1/8” gap, and unless you are in bright sunlight you should be able to see the blue spark.  You might even see a jet of flame come on, burn briefly, then go out.  Remember, the ignitor does more than just throw a spark.  It also tells the board when a flame is present.  A dirty ignitor, corroded electrodes or a crack in the ceramic can result in improper resistance, shutting down the gas flow.  The ignitor can be removed fairly easily.  The Atwood manual says, “The gap between the sparking probe and the ground probe should be 1/8”. The probes should be clean and free of cracks, flaking and corrosion. Position the probes so that they are in the path of the gas flow. Cracks in the ceramic insulator can also be the source of an intermittent problem. To check for cracks insert a fiber washer or any other type of insulation material in the 1/8” gap between the rods. Remove the gas valve from the circuit and turn the unit on. If you see a spark jumping from the ceramic to the ground rod or bracket, replace the spark probe.”  

If you service the ignitor electrodes, after cleaning the igniter rods the gap adjustment should be made with two pairs of pliers, one to hold the straight rod right above the ceramic to not put undue stress on it while bending the curved rod with the other pair.  If you have gotten the ceramic wet, it is somewhat porous and may take a while to dry completely.  Rain won’t do it, but direct water spray, such as your hand slipping when flushing the heater can do it.  Guess how I know that…  Until it is dry, it may send a bad resistance reading to the board, preventing the heater from working.  A day of dry conditions should deal with a moisture problem. 

OK, the thermal cutoff is good, the thermostat and ECO are good, and you see nothing wrong with the ignitor, but you still have no hot water.  The remaining problems are gas flow and a bad board.  A board is not cheap, but can be replaced fairly easily.  It is NOT RECOMMENDED that you mess with the solenoid or the propane orifice.  There is simply too much risk if you mess something up. If you are confident that propane is flowing, but you have no flame, your problem is pretty much narrowed down to the ignitor or the board.  The ignitor is cheap.  Replace it.  Still no good?  Now, finally, it is time to try replacing the board. 

Hopefully, this will help you understand the heater’s steps and may give you a clue what to look for if you are having problems.  Again, stay within your skill set on this.  With some understanding and a sense of how the parts work together, you may be able to figure it out.  If not, get thee to a qualified service person.

Ken Fears - September 2016


As Editor I can not resist adding a few very minor points to this fine article.

Note the nylon drain plug in the picture. A suggested improvement. One way to easily remove the drain plug is with a socket wrench with an extender and a swivel. That allows you to get around the gas plumbing.

Also note the position of their air/fuel “mixer tube”. It's all the way to the left. That position may yield the bluest flame. You need to know this if you disassemble the tube for cleaning. That needs to be done every few months of use. A few minutes with a wire brush and WD40 will clean it up.

I have my spare thermal fuses in a ziplock bag taped to the inside of the heater cover, so I can find them if I ever need one.

The adjustable thermostat allows you to lower the temperature to the level you find most useful. Some set it so that no cold water needs to be mixed. We keep ours at 120. I think the factory setting is about 140. How do you know what the temp is? You add an aquarium thermometer to the tank.  I guess we need to add a How To for that Andy B improvement.





Friday, June 3, 2016

Getting AC from an inverter to the rear of a MB

Most of our stuff is powered from 12volt, so we don’t have much need for 120.
Things like computers and MiFi are the exception. We use these almost exclusively in the rear of our MB. So that’s where we wanted 120volt. We asked for an outlet there when the rig was built and were turned down.

What follows is a how to specific for MB’s. I have no idea how or if it could be implemented on any other floor plan.

So for both of the people that 1) Have an MB, 2) Want a 120 volts in the rear and 3) Are willing to take on a fairly simple DIY project 4) You do not make the beds into a King - read on.

I mounted the inverter on the wall behind the drivers seat. That was unused space and it is close to the batteries. I used a cheap 1000w inverter from Harbor Freight. It has the same case as the one used by a well known brand and may have the same internals. A hole was drilled through the wall panel behind the drivers seat and another into the battery compartment to run #2 wire to the batteries. I sealed the latter one. The former can not be seen.

I cut an extension cord using the male end to plug into the inverter and ran the cable through the same hole in the panel used for the cables to the batteries. Remove the interior panels in the cabinet under the refer. [Mark each panel so you will know how to put them back. They are not cut square] Make a connection from the extension cord to #14 standard house wire. You want to use this as the stiffness will make it easy to snake the wire to the back of the rig. Do observe correct polarity.

Snake the #14 back over the fresh water tank. There is a small opening in the “wall” to the bath. Use a small child for this. Remove the panel behind the toilet that covers the plumbing and snake the wire through there and through the panel wall behind the shower. Attach the female end of the extension cord you cut and secure it with P clamps to the forward end of bed platform and terminate it adjacent to the factory 120volt outlet in the “hall”.

Step Two.

Mount a power strip in the middle of the rear wall near the top of the carpet. [No holes to show] Run the cable from the power strip under the driver’s side bed to where the wire from the inverter terminates.

When boon docking you plug the cable from the power strip into the wire from the inverter. When on shore power you plug the wire from the power strip into the factory outlet.

Pretty simple actually. 




Saturday, April 30, 2016

CPAP Amp Usage

This post is about conserving DC when using a CPAP while boon-docking.

Any device can be powered from an inverter. But, inverting/converting is not without some loss. Call it a toll fee. Now consider a CPAP that runs on DC voltage, requires a “brick”, that rectangular object on a power cord, to convert AC to DC. In the  RV environment this means inverting the batteries DC power to AC and then the brick converting back to DC. Two toll fees. Both unnecessary, since my CPAP requires DC and the coach batteries have want it needs.

My CPAP unit, a Dreamstation by Respironics, is native 12 volt, that’s why I selected it. It comes with a 120 volt power cord and a brick that converts to 12 volt DC. Normally I would have made up a 12 volt cord for it, but I had to buy a power cord from Respironics, since I could not find a source for the odd size 9mm plug it uses. I now own an $18 length of wire with a cigarette lighter plug on one end and the 9mm plug for the CPAP on the other end.

I did not want to install a female “cigarette plug” over my bed as the Mothership does and have the wire hanging down. So I tapped into the 12 volt house system in the raceway above my bed. [MB] I drilled a hole in the bin floor behind the cornice and dropped the power cord down and then across the bed platform so that it’s totally concealed. The machine lives on a table between the beds.

I went to this trouble to minimize amp usage. Powering it from inverter used 3 amps. Now, usage is 1.7 amps. [That’s without the humidifier which I am yet to use]  That’s about 13.5 amps used during 8 hours. I can live with that. 24 amps was a concern for me.

I suggest that anyone concerned about battery use when boon-docking and that has a CPAP that is 12 volt powered to make or buy a cord to power it direct from the house batteries and save those toll fees.

Monday, April 4, 2016

Replacing The Toilet Wash Out Hose

This is for the die hard DIY group.

I have just completed a chore I have been putting off for over a year - replacing the toilet wash out. The squirter mechanism was on it’s last leg, sometimes hanging up and not turning off the water. The cheap plastic OEM squirter was one piece with the hose, so both had the replaced.

If your bowl seal shows signs of wear, you may as well order the grossly over-priced bowl seal and replace both at the same time.

First, turn off the water.

To remove the hose from the supply line, you first have to remove the bowl. That’s fun. On our 2007 Sealand, there is a skirt that has to be removed and also a plastic cover over the foot flush pedal. Then you will see a metal clamp below the bowl that goes all the way around the bowl. The nut to loosen the clamp is in the back - so inconvenient. Loosen the clamp until the plastic parts it is seated on can be removed. Note well the orientation of these parts. They have to go back on the same way.

Raise the bowl straight up so as not to move the bowl seal. Set the bowl aside and note well, the orientation of the bowl seal. Especially the hole in the seal.

Loosen the clamp on the wash hose supply line and remove it. Assemble the new parts and put a little Vaseline on the new supply hose, push it on and secure it.

Now the fun part comes - getting the bowl secured. If you have never done it, I just can not tell you how much fun it will be in the confined quarters. Ensure the seal is in the correct position and put the bowl back down without disturbing the position of the seal. Tighten the clamp around the bowl with a nut driver hand tight. Do not use a wrench, as you may crack the plastic parts under the clamp. Know also that it needs to be tight enough so that it does not come apart when you sit on it. This is real important.

Run the water for a few minutes and check for leaks. If none found, replace the skirt and have an adult beverage.

Tuesday, February 23, 2016

Water Purification With Chlorine Dioxide

Step 1

We use bleach to disinfectant the system after the rig has been sitting for awhile. Add one cup of bleach, fill the tank all the way, let it sit for awhile, drain, fill and drain. 

If you want to disinfect the lines OK by running the bleach water through the lines, but be sure to run fresh water through all the lines and dump the water in the hot water heater. Bleach is no friend of rubber gaskets. And does not taste good either.

Step 2 

Now add chlorine dioxide and fill the tank. Add another table spoon every time you refill.

It's safe, you are already ingesting it as it's the most commonly used chemical to disinfectant, for instance, food prep counters and it's used in city water systems.

We always run out of the tank. We never hook up to city water. That keeps the tanks filled with clean water.

Here is a source for the brand name Purogene which is nothing more than 2% Chlorine Dioxide.

Thursday, February 18, 2016

Drop Table

Who says something as simple as the drop-down table cannot become a problem? Got some rambunctious grand-kids that travel with you? Among the havoc they might be able to cause are bent brackets for the table hinges.


Well, fear not - here is where you can find replacements:

http://www.dyersonline.com/ap-products-table-hinge-bracket-table-plate.html

The price is $5.99 for two (2) plus shipping.

Contributed by: Ed of Dallas

Posted: 18 Feb 201

Thursday, February 11, 2016

Fuel Pump Problem....or Not? (AKA Quits when Hot)



When an engine quits running, it is common for folks to suspect a fuel pump problem. After all, enough LD'ers have had that experience.

But....while a noisy pump often indicates a problem it doesn't necessarily mean you have found the problem. There are other parts that would can cause the engine to stop running that are also heat sensitive, failing only when hot and working again, once cooled. The two most likely items of a ignition system of older LD's are the ignition coil and ignition module.
Heat related failures are very hard to troubleshoot, you need to be able to quickly check for spark, fuel pressure and pulsed power to the injectors, at the time of failure. Without actually checking it when it will not start, it's an educated guess.
Back in the good old days where a lot of parts needed frequent replacement.I carried a spare coil, ignition module and a full tune up kit.

Now to help troubleshoot problem with the LD, I carry a fuel pressure gauge, a wireless spark detector and fuel injector noid lights (used to check the fuel injector circuits).
Many times a faulty part will set a Check Engine light (CEL).  An inexpensive code reader, one capable of erasing codes, is very helpful to have. You need to have a list of what the codes mean or an internet connection to check online. I have found a lot of ScanGauges and UltraGauges that will not erase Check Engine codes, where a code reader will.
Add to the box a 12-volt test light and a decent multimeter, the type with a clamp-on amp meter is useful for a whole range of troubleshooting.
With these basic tools and proper knowledge you have a good chance of finding what part of the equation is missing.
Working with engines, gasoline and electrical can be dangerous so if you do not have the proper training or experience, let a pro do it or find a good teacher. It's cheaper than going to the hospital.

Think your fuel pump isn't working or it suddenly stops, the fuel pressure gauge can let you know if it is providing adequate pressure, which need to be within a few PSI of the set point.
The pump does not require that the engine is running to be tested, only the ignition needs to be turned on.
When attaching the gauge, have the ignition switched off. Hold a rag around the connection point to capture any gas that may still be under pressure and spray out. Safety glasses are a must.
Please stay safe or find an experienced mechanic. Try this at home so you know how it's done before needing to use it on the road. Also find the specified fuel pressure for your engine's fuel pump.
Besides helping to find a defective pump, the fuel pressure gauge can also help find leaking injectors and check valves.
http://www.harborfreight.com/fuel-injection-pump-tester-92699.html http://www.harborfreight.com/fuel-injection-pump-tester-92699.html

Many newer engine have the coils mounted right on top of the spark plugs, also known as COP, coil on plug. This arrangement makes it impossible to use a conventional inline spark tester.
The LD's V-10 has COPs that cover most of the access to the spark plug. They do have slots where the thin tip of a wireless spark detector can be fitted.
I use one of these. It's sensitivity is adjustable, a handy feature as every engine seems to have a different physical layout requiring more or less sensitivity.
With someone cranking the engine, check for spark at one or more plugs.
Practice at home so you have a good idea where the best spots are to test for spark and how to adjust the sensitivity. Actually, the V-10 is hard to access when checking for a heat related failures, because of the difficulty of removing the doghouse quickly, needed to access the rear eight plugs. It you look and tie things back, you can access the front two plugs and injectors from under the hood.  Coils do fail, so carrying a spare is't a bad idea. A bad coil will usually set a specified code for the cylinder.

If spark and fuel pressure are present, then test the fuel injector circuits for pulsed signals. Use the proper size "noid" light for your injector's plug. Noids are are small lights, that plug into fuel injector plugs, once uncoupled from the injector.  They test the fuel injector circuits for pulsed signals, when the engine is cranked or running. They are useful for finding a dead ignition system, a failed injector or a failed injector circuit.
My fleet contains four different sized fuel injectors plugs so it was cheaper to buy the big set and keep the extras for the future.

If the engine is running but is either making noises or missing, an inexpensive mechanic's stethoscope can be invaluable. You can listen to individual fuel injectors, Comparing them each other. A dead or stuck injector usually makes a much different noise. You can isolate noisy bearings and eliminate changing the wrong part. Be extremely careful to stay far away from the moving belt and pulleys, they remove fingers quickly.
Even good parts can make strange noises, it's good to know what "normal" sounds like.
http://www.amazon.com/Powerbuilt-640582-Mechanics-Stethoscope/dp/B004KEHGZY/ref=sr_1_1?s=automotive&ie=UTF8&qid=1455164440&sr=1-1&keywords=mechanic+stethoscope http://www.amazon.com/Powerbuilt-640582-Mechanics-Stethoscope/dp/B004KEHGZY/ref=sr_1_1?s=automotive&ie=UTF8&qid=1455164440&sr=1-1&keywords=mechanic+stethoscope

For all the test tools above, the internet has hundreds of sites and videos that explain how the various tools and systems being inspected work. Above all, work safely.

Contributor: Larry Wade

Published: 11 Feb 2016