morco heater flame cutting out

[Fabdiddle]

Hello all!

 

I have a Morco F11E water heater. Every time I start it all the flames ignite but go out either immediately or after a few seconds. It then tries to relight but only one or two flames will light around the ignition. In the relighting stage I can manually light all the others with a handheld flame.

 

Seems to me there are two problems, the gas flow shutting down and the ignition failing to light fully after the first try. Any ideas?

 

I've cleaned out the water filter and pumped up the accumulator and the water flow sensor stays on while running so i don't think it's a water pressure issue, more likely gas pressure?

 

Thanks in advance!

[Tony Brooks]

I don't know these heaters but if it has a pilot light and flame failure cut out I would be looking at the size of the pilot flame. Too small or misshapen and it may not be getting the flame failure probe hot enough or not heating the air gap enough.

 

It may be time to de-spiderise the main and pilot burner air inlets etc.

 

 

Edited December 27, 2022 by Tony Brooks

[Fabdiddle]

It doesn't have a pilot light, just a spark over the main burners (picture attached). I've replaced the thermocouple and ignition (as well as fan and pcb...).

 

Could it be something to do with the air intake? Might explain why it lights well the first time but not after and maybe its choking the flames which is why they die off? Not my area of expertise at all!

[Tracy D'arth]

Fluff in the pilot burner air hole?  A general clean of the gas jets and the burner should sort this out.

If the flames are small when the burner is fully lit I would check the regulator on the bottle. There is gas in the bottle>  propane or butane?  Bear in mind the temperatures at present if on butane.

Any other gas appliance in the boat working properly?

 

 

So its an auto ignitor without a pilot. Same applies, clean the burner and main jet and the air venturis.

Edited December 27, 2022 by Tracy D'arth

[MtB]

3 minutes ago, Fabdiddle said:

I've replaced the thermocouple

 

I'm impressed you managed to do that, given it doesn't have one!

 

My own money is on the water flow rate being too low, but just a guess as I don't really know this appliance at all. 

Or, reviewing your first post, it looks like flame detection failure to me. The flame lights, the electronics looks for a flame but although alight, a fault prevents it detecting, so it shuts the gas off and tries again. Over and over an over. 

 

 

[Fabdiddle]

Youre

4 minutes ago, MtB said:

I'm impressed you managed to do that, given it doesn't have one!

You're right, it's an electrode! I don't really know the difference, it's new I know that much...

 

From what I can see the "micro switch" which senses water flow seems to be staying open when the water is flowing so would that rule out water flow rate? Or not?

Also would that explain some flames not lighting?

 

The gas hob runs fine but I'll check the regulator.

[MtB]

12 minutes ago, Fabdiddle said:

From what I can see the "micro switch" which senses water flow seems to be staying open when the water is flowing so would that rule out water flow rate? Or not?

Also would that explain some flames not lighting?

 

Ok, looks like the water flow is fine then. I don't think it would explain the flames failing to "cross-light" (the technical term).

 

I stand by my assertion this is a flame detection problem. Task is to find out why. It could be spider web/nests inside the burner bar(s). I had this in my own Morco the other day but on mine the flames lit but burned a horrible yellow on a couple of bars with the webs inside. 

 

I'm more inclined to suspect low gas pressure or an electronics fault. Have a look in the manual, there ought to be a fault-tracing chart

 

 

 

 

 

Actually, this could turn out to be the 'gloop in the pipes' problem older LPG systems suffer from.

[Fabdiddle]

Ok thanks all, I'll use your guidance and work the problem. Hopefully come back with good news!

[MtB]

3 minutes ago, Fabdiddle said:

Ok thanks all, I'll use your guidance and work the problem. Hopefully come back with good news!

 

Think about how you can rig up a water gauge or manometer to check the gas pressure at the burners. i suspect it will be either very low or jumping about all over the place.

 

Good luck! 

[Tony Brooks]

The photo shows three electrodes that are probably used for both ignition and flame detection. When an adequate flame is between the electrode and burner the flame ionizes the air and (I presume) creates a lower resistance path between electrode and burner. The igniter senses this and knows a decent flame is present. So if the air is not sufficiently ionized because of a poor flame the gas supply is likely to be cut off. I think the air gap must be critical so see if the manual gives any clues as to what it should be.