Water Heater Issues...

[aanderud]

OK, someone here might have just the answer I'm looking for....

My water heater is not lighting very well. Here's the background on what I have. It's a power-vent water heater vented out the side of my house. It has a hot-surface igniter toward the bottom which lights the gas burner, and a honeywell control unit controlling the gas/ignition system.

The problem is this. When the hot water heater needs to heat water, the fan comes on at the top (the power vent), then the control unit it clicks once and the hot surface igniter glows bright red. About 5 seconds after the first click, when the igniter is good and red, the control unit clicks one more time to let gas in, and it successfully lights a nice fire (blue flame, not sure if this is normal or if it should be more orange). It burns for like 4 seconds, then the control unit clicks gain and stops the gas and it quits burning. It then waits like 30 seconds and tries again. It'll do this 4 times, then wait some number of minutes (10 or 15?), then repeat. It'll do that whole cycle (4 attempts, then a break, then repeat) like 10 times and then give up until it is power cycled.

Well, the thing is, usually it will 'take' on one of those 40 or so ignition attempts, sometimes as soon as the third or forth one...but once in a while it doesn't 'take off' at all, it goes through the 4 second burn cycle and stops and repeats until it has exhausted it's 40 cycles and quits. This forces me to power cycle the whole thing to get it to forget it tried 40 times already. It starts over and works eventually...

It seems like there's plenty of gas getting there, there's a good flame. I have tried unhooking the vent line from the top and letting it vent straight into the basement (just ONE time, not permanently!!) while it's 'having trouble', thinking there was possibly an obstruction in the PVC pipe (hornet nest or something) causing a back-flow. That did not help.

One other thing that I tried, which seems to get it to keep itself lit on the FIRST try, is if I lightly blow air in the bottom with my air compressor, sorta turbo charge it. Seems like that might point to some type of blockage preventing it from getting enough O2, but I can't tell where said blockage would be. I've blown it all out with high pressure air to try and remove any dust bunnies, etc...

What does anyone here think the problem is? I am really no home improvement guru, that's for sure. I would like to figure this out because I am almost certain that my hot surface igniter is going to wear out about 20 times faster than normal, because it has to try a bunch of times before it actually lights!

Thanks for any help you can give.

[sparcebag]

Blue flame is perfect.

I dont know lots about your heater,My first attempt would be the thermostat on the heater not the wall,sounds like it may be faulty,cutting gas off. May not be called thermostat but a unit that controls gas flow on demand after glow plug makes a ignition flame.

[fastkaw]

What kind of water heater is it?

How old is it?

It could be a couple of things. Believe it or not it bight be the igniter. Cheap fix.

It could be the hoes/tube from the venter motor to the pressure switch is slightly

plugged. With the unit (off) remove the hose from the venter motor take a paper clip bent straight and probe the nipple at the venter motor. They get corrosion

in them some times.

After that it almost has to be the ignition control module. Not cheap....

Also make sure there is nothing plugging the vent pipe at the out let.

Bees, Birds, Bugs. I had one with a peanut butter jar in it once.

[backlash 1]

This has got to be an A O Smith heater I bet

Its more than likely one of two problems. The older power vents had problems with blower motors. The way to test the blower is to remove the short clear plastic tube from where it connects to the blower housing. While the heater is trying to light, suck on the plastic hose, you should hear a click, and then the heater should fire. If you keep suction on the hose and heater continues to fire, the blower is the problem. Take the blower apart and clean the squirrel cage fins very well. Also use a paper clip to clean the fitting you pulled the hose off of. Then reassemble.

Newer heaters within a few years old are having ignitor assembly problems. If your heater passes the blower test, them remove the ignitor assembly in the burner compartment. Best to just replace the assembly, but you might get a quick fix by very carefully cleaning the "flame sensor" rod with steel wool.

These are the two most common problems with power vent heaters, good luck with your fix.

[aanderud]

Thanks for the ideas, fellas. Will let you know what I find out.

[Surface Tension]

"It could be the hoes/tube from the venter motor to the pressure switch is slightly

plugged. With the unit (off) remove the hose from the venter motor take a paper clip bent straight and probe the nipple at the venter motor. They get corrosion

in them some times."

Look to see if that hose is rotted.

[Eric Wettschreck]

If it's an AO Smith, or a few other varities, there's a good chance there is a flame rod somewhere down there. Take a look for a ceramic rod a couple inches long. On some burner models this flame rod is the same as a boiler flame scanner. If it does not detect the heat of the flame, it will tell the controller it didn't light. Your flame will be put out, go through purge, then try again.

You can sometimes clean a flame rod with alcohol and a soft cloth. DO NOT SCRATCH IT!!! if this does not work, replacements are not very expensive.

If it does not have a flame rod pay no attention to what I just typed.

Blue flame is just what you want. Yellow or orange fingertips on the end are OK, also. Orange flame is fuel rich, and not what you want.

[hunterlaker]

Its the flame sensor, I had the same problem, clean it with

0000 steel wool. Takes about 10 minutes