Fixing DSI Water Heater

DriVer · 01-04-2005, 02:41 PM

Just a few words about doing some thing yourself.

I had 2 issues that were troubling me as of recently since we got back on the road with the MH. The first was that the water heater did not fire when the DSI Mode was selected.

The second problem was that the knob fell off the shower valve. This was easily fixed because I found that the screw that holds the big plastic knob on, backed off and was found behind the cap cover on the knob. Once I put the screw back and tightened it, all was well again.

About the DSI heater, I had to figure that one out step by step since I'm not a tech.

My quest to repair the WH immediately began on the phone in a vain attempt to call Camper Sales & Service here at the campground however the phone was busy. Darn! So equipped with some wire, a test lamp, some stake on connectors, a small amount of 12 volt knowledge gave me enough courage to take this task on.

I began by testing the wires coming into the WH enclosure and found no 12 volt anywhere. I specifically keyed on the schematic on the wall of the Atwood DSI and the brown wire. I moved all the spade connectors and the edge connector on the module several times and it wasn't a connectivity issue I figured.

I knew one principal about water heaters and that something has to trigger the heater to fire. This is brought about by the limit switches closing and allowing power to flow to the gas solenoid.

Initially I couldn't figure out why there wasn't any power in the enclosure so I decided to introduce some alternate sourced 12V power to rule out problems with the basic functionality of the heater. I made a jumper and opened the water pump circuit to see if I could rob some power from next door to fire the heater. I also inserted a temporary SPST in the circuit just in case.

I fed the power to the input of the high limit switch on the diode side and I didn't get anything to fire. I tested the wire and I had power and then I tested the other side of the diode where it connected to the switch and I saw no power.

I turned off the 110V circuit to the HW so it wouldn't make any heat, opened the kitchen faucet, flowed water and allowed the temp to fall in the tank.

Once the hi limit switch closed I was able to get power into the enclosure from the brown wire. I hooked up the brown back on the diode and yet the WH did not fire. I tested the opposite side of the diode, still no power and I then determined that the diode was bad.

Captain Bud and I went to the parts store at a local RV dealership Kamper Country on 544 and picked up a package of new diodes. Returning I put the new diode in the circuit and the WH immediately fired up.

Ta-Da!

All in all a very good day in learning how to deal with the water heater and I probably saved a hundred bucks by fixing this thing myself. The diodes cost 18 bucks for 2 and I have a spare diode in case it happens again.

DriVer · 01-04-2005, 02:41 PM

Just a few words about doing some thing yourself.

I had 2 issues that were troubling me as of recently since we got back on the road with the MH. The first was that the water heater did not fire when the DSI Mode was selected.

The second problem was that the knob fell off the shower valve. This was easily fixed because I found that the screw that holds the big plastic knob on, backed off and was found behind the cap cover on the knob. Once I put the screw back and tightened it, all was well again.

About the DSI heater, I had to figure that one out step by step since I'm not a tech.

My quest to repair the WH immediately began on the phone in a vain attempt to call Camper Sales & Service here at the campground however the phone was busy. Darn! So equipped with some wire, a test lamp, some stake on connectors, a small amount of 12 volt knowledge gave me enough courage to take this task on.

I began by testing the wires coming into the WH enclosure and found no 12 volt anywhere. I specifically keyed on the schematic on the wall of the Atwood DSI and the brown wire. I moved all the spade connectors and the edge connector on the module several times and it wasn't a connectivity issue I figured.

I knew one principal about water heaters and that something has to trigger the heater to fire. This is brought about by the limit switches closing and allowing power to flow to the gas solenoid.

Initially I couldn't figure out why there wasn't any power in the enclosure so I decided to introduce some alternate sourced 12V power to rule out problems with the basic functionality of the heater. I made a jumper and opened the water pump circuit to see if I could rob some power from next door to fire the heater. I also inserted a temporary SPST in the circuit just in case.

I fed the power to the input of the high limit switch on the diode side and I didn't get anything to fire. I tested the wire and I had power and then I tested the other side of the diode where it connected to the switch and I saw no power.

I turned off the 110V circuit to the HW so it wouldn't make any heat, opened the kitchen faucet, flowed water and allowed the temp to fall in the tank.

Once the hi limit switch closed I was able to get power into the enclosure from the brown wire. I hooked up the brown back on the diode and yet the WH did not fire. I tested the opposite side of the diode, still no power and I then determined that the diode was bad.

Captain Bud and I went to the parts store at a local RV dealership Kamper Country on 544 and picked up a package of new diodes. Returning I put the new diode in the circuit and the WH immediately fired up.

Ta-Da!

All in all a very good day in learning how to deal with the water heater and I probably saved a hundred bucks by fixing this thing myself. The diodes cost 18 bucks for 2 and I have a spare diode in case it happens again.

Our Cow · 01-04-2005, 05:02 PM

DriVer

This happened to me last summer and I found a wasp nest in the venturi tube. Please be sure yours is not plugged and causing the heat from the gas flame to back up. That diodes a safety feature just in case that does happen. I used compressed air and blew the tube clean and no more problems to date. Enjoy your winter in Florida as we are having a winter storm here in Tucson. Rain in the valley and snow about 6500 feet. Colder than normal temperatures....

troth · 01-05-2005, 01:20 AM

Cool, er hot, Driver!

Good info. Any chance we could get a pic showing the diode location?

DriVer · 01-05-2005, 02:55 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by troth:
Cool, er hot, Driver!

Good info. Any chance we could get a pic showing the diode location? <HR></BLOCKQUOTE>Sure you know me.

I'll see if I have enough time in my busy retirement schedule to accommodate this request.

DriVer · 01-10-2005, 02:40 PM

Because "YOU" asked for it. Here's the picture of the water heater diode.

12 Volt Diode location

The diode is contained in a clear plastic sleeve and is plugged into the high limit switch. The diode is located just about in the center of the photo.

It's great using a Broadband connection again! They happen to have one here in the recreation room at Southern Aire RV Resort in Thonotasota, FL.

One person at a time though, they should have installed a hub and or a wireless router.

01-10-2005, 03:05 PM

DriVer,
If you get a chance to stop by the Supper Show in Tampa, Attwood will give a couple of those diodes free. I don't think anyone has brought this problem up on the forum, but the water manf. knows about it and they have plenty of spares to pass out.

Tomcat F15

troth · 01-11-2005, 01:48 AM

Excellent pic DriVer. Now I'm gonna get a spare diode, just in case the same thing happens on mine...
Could you see any broken wire or burnt spot within the clear plastic sleeve on your old diode?
I suspect you could also have tested it with a continuity tester, right?

El Jeffe · 01-11-2005, 12:32 PM

Driver - Our's was blown during the PDI and the tech refered to them as "blow back protectors". I was at a total loss until I saw your photo.

Thanks, at least I know what they are really called - we carry I spare also.

DriVer · 01-11-2005, 02:15 PM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by Tomcat F15:
If you get a chance to stop by the Supper Show in Tampa, Attwood or Subruban will give a couple of those diodes free. <HR></BLOCKQUOTE>No kiddin' I just paid $18.00 for 2 and I was glad to have paid the $18 BUT FREE is also good.

I did not see Atwood or Suburban vendors today but then again I wasn't looking specifically for these 2 manufacturers either.

Thanks for the heads up!

DriVer · 01-11-2005, 02:20 PM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by troth:
Could you see any broken wire or burnt spot within the clear plastic sleeve on your old diode? <HR></BLOCKQUOTE>No I couldn't. I thought that it would be burnt out or have shown some sign indicating the thing was NG but it looked pretty normal in appearance.<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>I suspect you could also have tested it with a continuity tester, right? <HR></BLOCKQUOTE>OH yes! Before diode no 12 volt on the other side of the diode. After the new diode, plenty of 12 volts on the diode. Knew right away it was going to work when the red LED pilot light out indicator lit up when I turned the heater switch on.

DriVer · 01-11-2005, 02:21 PM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by El Jeffe:
Thanks, at least I know what they are really called - we carry I spare also. <HR></BLOCKQUOTE>You're welcome!

3huskies · 01-12-2005, 03:02 AM

They are called thermal cutoffs and you can find them here for $8.49 ea along with anything else you need.

http://www.marksrv.com/atwoodelectronic.htm

01-13-2005, 02:30 PM

3huskies,

If your water heater is with in warranty, Attwood has been giving the diodes to owners at no charge. They know about the problem and have taken a positive position to help owners with their product. Maybe a call to Attwood is in store! 574-264-2131.

Tomct F15

3huskies · 01-13-2005, 02:40 PM

Thanks Tomcat. Sounds like they are doing the right thing.

Okie · 01-13-2005, 03:35 PM

Had this same problem with the diode going out....when the tech replaced it in Lousiana,,,he bent it so that it was as far as possible from the two tubes that ignite and heat the water...said he had found the heat from these were causing the diodes to go bad....anyway,,,havent had the problem since and that was bout 2 years ago...

cyko · 01-13-2005, 05:59 PM

We've blown out many of these diodes in our '03 Journey. The Atwood guy blamed it on the coach design in which the solid door comes down too tight outside the heater door. He put a little spacer to keep the door open but I still blew out a diode. In a pinch you can just bypass the diode by plugging the input wire into the board, but you had better keep an eye on things if you do that, and get some new diodes as soon as possible. Atwood makes some "tougher" diodes (green-colored) that seem to last longer.

troth · 01-14-2005, 06:36 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR> If your water heater is with in warranty, Attwood has been giving the diodes to owners at no charge. They know about the problem and have taken a positive position to help owners with their product. Maybe a call to Attwood is in store! 574-264-2131.
<HR></BLOCKQUOTE>

When I spoke with Atwood Service this morning, I was told that these diodes (thermal cutoffs) were not a warrantable item and he directed me to my local RV dealer to get a replacement (at whatever their price may be). He said that the only way they go bad is from seeing excessive heat. I explained that mine appeared fine, nothing melted or burnt, but there was no electrical continuity thru the diode. No dice; still not warranty.

rvten · 01-14-2005, 07:46 AM

Thanks driver. I saved a picture you had here. So I know what to look for.

Roadking · 01-17-2005, 05:33 PM

I had the diode fail in my Attwood about 18 months ago. I replaced the diode with a 1 amp, 250 PIV (Peak Inverse Volts) diode I purchased from Radio SHack for around $3.00.

The diode is basically a surge protector and I don't believe the diode has anything to do with temperature, but the diode indeed fails due to the high temp around the water heater.