DSI Fault light (water heater)

Idafrog · 06-15-2015, 10:14 AM

My on demand water heater quit working this weekend. I get this light DSI Fault that is on but can't get it to shut off. I have reset the main switch on the heater itself as well as the switch on the wall, also checked breakers in the panel. Still nothing. I can't find a manual for it so no clue where to look now.

Any help would be much appreciated. Thanks.

**Herk7769** · 06-17-2015, 08:39 AM

I am not familiar with on demand systems.

However, just in case it works like a Suburban with DSI:

The DSI stands for direct spark ignition. The sparking is controlled by a control board and the light should come one when the unit's thermostat is calling for heat. That heat is provided by burning propane which heats the water in the internal piping (a tank in one that has a reservoir).

When the unit is "ON" and using propane as the heat source, when the water in the pipe is cold, the thermostat attached to the pipe will be closed completing a circuit that routes 12 volt DC power to the gas valve (opening it) and the spark control board. The spark control board starts the spark going and "looks for ignition." The DSI light will be ON all this time.

The Control board has a detection circuit that uses the ionized gas in the flame itself to complete a circuit that tells the board that the flame is lit and it is OK to keep the main gas valve open and everything is normal and the DSI light WILL GO OUT when the water in the pipe is HOT and the therostat opens.

If the flame does not light in a few seconds, the control board will stop sparking, purge the combustion chamber for about a minute, and try again.

After 3 light attempts, the control board will assume you have a major fault and stop trying. The DSI light will remain on and no further start attempts can be made until power is completely removed from the water heater by turning OFF the power switches.

The main cause of this condition is "no gas" - make sure you have plenty of propane.

Another thing to check is for bugs that build nests inside the combustion chamber and or flue pipe. These will obstruct the flow of air and cause a gas mixture too rich in propane to burn.

After those two, the sparker itself could be broken or the control board could be bad.

Good luck,
Herk

Idafrog · 06-18-2015, 09:14 AM

Thanks for the info.

Thinking it has to go back to the dealer for service. I disconnected all power to the trailer for 15 minutes.... still no reset.
Dealer told me to disconnect propane tank and reconnect it and opening the valve slooooooowly so a check valve won't "slam shut"..... still no reset.
Hooked to 120v power...... still no reset.

Nothing seems to be working. Can't even hear it clicking like it's trying to spark. The exhaust fan runs but that is it.

I will let everyone know what the dealer finds. Could be couple weeks but I will update this thread.

**Herk7769** · 06-18-2015, 10:49 AM

Quote:

Originally Posted by Idafrog

Thanks for the info.

Thinking it has to go back to the dealer for service. I disconnected all power to the trailer for 15 minutes.... still no reset.
Dealer told me to disconnect propane tank and reconnect it and opening the valve slooooooowly so a check valve won't "slam shut"..... still no reset.
Hooked to 120v power...... still no reset.

Nothing seems to be working. Can't even hear it clicking like it's trying to spark. The exhaust fan runs but that is it.

I will let everyone know what the dealer finds. Could be couple weeks but I will update this thread.

We are talking about the water heater right?
If you can run 3 stove burners on high, propane is not your problem.

Idafrog · 06-18-2015, 10:57 AM

Ya the water heater. Service dude told me that there is a check valve in the WH that will shut if the propane tank is turned on too fast. Dunno

**Herk7769** · 06-18-2015, 11:07 AM

Quote:

Originally Posted by Idafrog

Ya the water heater. Service dude told me that there is a check valve in the WH that will shut if the propane tank is turned on too fast. Dunno

You must have misunderstood him. It is the propane tank that can shut off if opened too fast. There is a safety valve in the pigtail that will prevent an uncontained leak if the hose is severed in an accident.

Dirty pigtail connectors have been known to stick shut if the tank is opened too fast.

If you can run the stove burners on high with blue flames, that is NOT your problem. I just wish I knew more about your model tankless water heater. Tanked water heaters do not have "blowers".

I found your manual (attached) and will try to read up on your unit.

Idafrog · 06-18-2015, 11:11 AM

Gotcha.

I will try the stove here in a bit. Its weird that last Friday it worked fine and Saturday it was not

so really thinking it wasn't propane issue either as the fridge stayed on all weekend fine.

Just checked and stove burners are fine and fridge is ice cold. Gotta be something with the ignition as it won't even try.

**Herk7769** · 06-18-2015, 11:13 AM

So it turns out your unit has a "sail switch" just like a furnace.

If the sail switch is stuck you will experience exactly what you are seeing.

There is an installer warning about this.

**wmtire** · 06-18-2015, 11:17 AM

You have turned on the stove burners to make sure you are getting propane thru the lines, correct?

The check valve you are referring to is most likely in the propane tank, which will shut off excess gas flow in the case of problems. Sometimes, when you open the cylinder valves too quickly, the check valve activates and shuts off or severely limits the flow of propane from the cylinder.

This is why you were advised to completely turn off the propane cylinder handle, then slowly reopen it.......to reset the check valve inside.

Make sure you have good propane flow from the stove....then move on to the water heater.

You may just have a propane problem....and thus the water heater is not getting the propane it needs for the Direct Spark Ignitor to light.

More info:

Propane 101-The basics

EDIT: Wow, I type slow. Herk added 3 more posts by the time I did my one little post. LOL

Idafrog · 06-18-2015, 11:45 AM

Quote:

Originally Posted by Herk7769

So it turns out your unit has a "sail switch" just like a furnace.

If the sail switch is stuck you will experience exactly what you are seeing.

There is an installer warning about this.

The sail switch is moving freely when the blower is on and swings back when blower shuts off.

**Herk7769** · 06-19-2015, 07:19 AM

I would sniff for propane when it is trying to light and then if you smell it; check for obstructions in the flue.

If you hear sparking and no smell, bang on the gas solenoid a bit to see if it is corroded and can be tapped free. (you can also check for voltage there).

I understand there might also be a troubleshooting "code" related to the control board. (LED on the board itself?)

Idafrog · 06-25-2015, 09:44 AM

Well after talking with the service dept at Camping World where we bought this trailer and getting less info than when I started I found a phone # for Girard tech help. Turns out there is a small limit switch installed that has a reset button on it. Push the itsy bitsy tiny button in and BAM.....hot water. The DSI Fault light is still lit up for some reason but maybe that will go out after some more use, time will tell.

Hope this info will help others having similar issues.

You may also like: