[brío]

Since @simple commented on this... I'll be the antagonist and suggest that there's more to it than this. We've got at least one person on the board who really went hard to try to fix an Espar issue. Some mega-guru employee person finally did something to get it resolved; but it was finicky beyond basic install issues. And Bazz' experience regularly reminds me that - for no apparently different reason - there are also factory fuel lines that work perfectly at 10K feet.

I'd love to just think we nailed it on our two installs... but it seems there is some finicky-ness in here somewhere. 🤔

Well, maybe. But two things:
1) There are such things as sample defects. One problematic unit doesn't tell us much, except perhaps about the manufacturer's QA.
2) Any complex analog system like this is going to have engineering tolerances that will produce a range of performances clustered around the "ideal" engineered behavior. Each unit will operate at some point on a spectrum, but if the engineering and manufacturing are good, then all of them will be "within spec" and operate properly if used as specified. BUT some units will operate BETTER than spec, and so may prove to be more robust than other units, even though the others are working as designed. For this reason, it is not surprising that some folks can get away with a sub-par installation. Luck of the draw.

 

[brío]

First thing to try is to service the heater. All those old failed starts probably built up a lot of soot.

 

[brío]

But then a few times early in the morning (5, or 6am) it has failed to start when trying to cycle back on. However, after it errors out (same P000126 errors) I start it again and it works fine. So 🤷‍♂️. I'm OK living with this behavior. As other than that it has been starting and running 100% of the time.

Just to be clear:
When you got the P000126 codes, did it attempt the normal 3 restart attempts before quitting and you then had to manually restart it?

 

[brío]

This recommendation would be for any gasoline heater.

Do they all use similar pulse-style dosing pump technology? I assume that the issue is tied to that technique.

 

[brío]

I don't know enough to say whether the pulse vs continuous flow type of fuel pump has an effect on this.

I don't either. But, intuitively, I suspect that peak delta velocity is part of the equation. I do know that cavitation is ultimately due to the pressure of the fluid dropping below its vapor pressure. It seems obvious that periodic sudden pulses of suction are more likely to produce this condition than the much smaller suction that a continuous pump would require to move the same total amount of fuel.

I assume that the reason for the pulse pumps is that they serve two functions at once: they pump and they meter in one action. Separating these functions would be more expensive, but I suspect a continuous pump would be less susceptible to this problem, even if it were "pulling" rather than "pushing". 🤷‍♂️