Problem with MAREY LP Tankless Model 23LP - $50 to whoever can diagnose!!

[Achtung]

OK this is a stumper and $50 to the first guy who can diagnose! Bought a Marey model 23LP about 2 years ago. Bought the accompanying vent kit with it. Sat in a box for all this time, which i was told was fine. had it professionally installed by the gas company, professionally vented by a plumber, and plumbed by said plumber. Unit display reads140 degrees - exactly what the book says it should - no error codes. water is running thru it cuz I can hear/feel it, plus when I close the shutoff water ceases. So what's the problem? IT WONT IGNITE!. i know it's getting gas, cuz tank has plenty and when dirt leg was unscrewed i smelled it, plus furnace runs. water is going in AND out, and it's vented. the exhaust blower won't even turn on, although it turns with no problem. i didn't install the pressure relief valve, but my dad's doesn't have one and his works (albeit his is a different brand.) So - KILLER water pressure, plenty o' gas, good venting, no error codes, troubleshooting was fruitless, all electrical connections are right/tight, tapped on ignitor and transformer or whatever it is (hey - it works on cars when you tap the coil!) I don't get it. Ideas? Again, it runs, you get a check in the mail for a cool $50 JIM, 218-566-1135 home, 218-256-1135 cell

[ballvalve]

try the ball pein hammer trick again... then no result,

Go to true value and get a $199 40 gallon electic tank model. Sell that junk on gee-bee-bay.

Prior to disposal, bleed out your gas line of air before starting up the rig.

I have a saw mill with a big hydraulic system with many new parts, but every now and then without a smack from the hammer on the box, it all shuts down.

[Achtung]

Tried the hammer, believe me. Even added a few choice words to "Coax" it to work. No luck. But you gave me an idea. This is new construction, brand new gas tank, new lines (that yellow, corregated stuff), and brand new blackpipe to the unit. Do you reckon maybe there is air in the line and thus the unit isn't sensing gas, thereby not even bothering to engage the ignitors since there's no/insufficient gas coming in? If so what's the remedy? I don't want an electric one - don't even want a tank one. Too spendy to use and I don't have the room to spare. These things are the cats A$$ when they're working properly. whataya think?

[ballvalve]

Gotta get all the air out of new gas line.....

[Jim Boerner]

LOL, yeah, I gotcha loud and clear. question is...HOW do I bleed the line so that GAS is coming into the unit and not just air??

[ballvalve]

The three stooges would hold a match to the pipe end.

If its a long line, you just have to estimate the amount of air held by the pipe to be bled off to a safe place. then try to ignite the rig.

[Dana]

I've never heard of (and couldn't find online documentation for) the Marey 23LP. Most of their NG & LP heaters have a battery-powered igniter- is that the case here? (If yes, are the batteries fresh, and installed correctly?)

[Charlot]

If you are still struggling (or you know someone who is struggling), here are my 2 cents:

How this WH works? When the water is flowing through the system, the differential mechanism is engaging the gas and the electric module. The diferential mechanism is very simple: a chamber divided in 2 by a membrane; one side is connected in front of a strangulation in the flow of the cold water intake (called Venturi tube), the other side is connected behind it. When there is no water flow, the two sides of the differential mechanism are at the same pressure, and the membrane is at the relaxed point. When the water is flowing, the pressure in front of the strangulation is higher than the one behind (Bernoulli's law), so the membrane moves towards the lower pressure side. A shaft connected to the membrane is pressing on a contact, thus signalling that the water is flowing. There is also a spring that resets the differential mechanism when the water stops flowing. If the membrane is pierced, the two sides of the differential mechanism are at the same pressure, so the membrane doesn't move.
The electric module opens the ignition gas valve and is starting the spark. The gas is suppose to ignite in 3-4 seconds, otherwise the security circuitry is shutting off the gas paths and you will have to reset the WH manually (and this is the way you purge the line: you try to start the WH and reset it repeatedly, until the gas is flowing. Once the gas is ignited, the flame electrode detects the presence of the flame (the fire is electrically conductive), shuts off the spark and the ignition gas valve and opens the modulation valve. The signal from the thermistor is compared with the preset value and the PID loop is controlling the gas flow and hence, the water temperature. I don't know the details of this particular model, but all the WH that I've serviced (and I have THOUSANDS under my belt; I'm from Europe where I was a serviceman for domestic water heaters for 12 years, before I came in America, and 95% of the European WH-s are tankless, because of the efficiency and tradition; the first instant WH was manufactured in 1879 and the Ruud company that introduced it on the market is still in business today), but all the instant water heaters are on the same principle. What is truly different is the technical solution and the efficiency of the burn; sometimes you have forced air pumped in the burner, sometimes you have forced exhaustion, sometimes you have sophisticated electronic controls and displays, but at the essence all of them are the same. The difference in controls, in the heat exchanger (copper vs stainless vs ceramic) and in the available service is what actually dictates the price.
There are a sum of safety interlocks that are meant to stop the thing to blow up your house when you try to shave. There is an interlock for the exhaust (usually is a resettable thermocouple switch - check to see if it's not tripped) that is placed on the chimney air flow (upper part of the WH, close to the chimney vent); it is a safety device for ensuring that the burned gases are vented outside. Get the user manual and locate it; if that one is tripped, the whole device is a brick.

Here are some possible causes that can cause your WH to stop working:

1. Your water heater is LP, that means is for propane, not natural gas. I don't know if you are trying to run it on NG, but if you do, it will not work very well (very small flame, since the bores for LP are smaller than the ones for NG. I hope you are aware of this. Even so, the WH is suppose to ignite at least, even though in certain conditions will not hold the flame for long, unless:
1. There is a problem with the batteries; either depleted or installed in reverse.
2. There is a problem with the differential flow sensor; the water flow does not press the contact for the electric ignition. Usually this means either a torn membrane; this can happen if the WH was left for extremely long times (years) without water; the rubber gets brittle and cracks when is connected. The membrane can be repaired with acrylic silicone (while you are waiting for the ordered one to arrive) if the damage is not too big. If you press on the contact while the water is flowing, you should be able to ignite the water. DO NOT start the fire without the water flowing, you will melt your WH!!! Better test he ignition without gas (just turn off the gas valve) and listen for the spark.
3. There is a problem with the ignition; usually the spark transformer gives up. You will need a new electric module - contact the manufacturer or its dealer.
4. The spark electrode is shorted or disconnected.
5. The sensing electrode is disconnected or shorted; the WH will work for few seconds and then will shut off.

I hope this is helpful. If you still have the device, I can help you fix it; I have some general foolproof methods that allows me to troubleshoot any WH, even the ones I haven't seen before in my life. Once you know the principle and you've seen hundreds of technical solutions, nothing is strange anymore.

I've googled your tankless WH and I can't find it; do you have some pictures and links that you can send?