[RV8R]

I doubt the standpipe significantly contributes to your issue. From the symptoms (severe carbon build up) there appears to be something defective in your unit causing a gross excess of fuel being burned.

Based on first principles, a larger diameter standpipe shouldn't have any effect on the fuel supply. Hydrostatic head is independent of the pickup diameter. There may be other factors involved, but nothing that would grossly increase the supply. I would like to hear from Velit what, exactly, is the issue and problems with the built-in standpipe. Just saying "performance may be compromised " doesn't work for me.

Wrong pump? Wrong nozzle? Wrong calibration (e.g. set for diesel)? Clogged air intake? Bad altimeter in the thermostat? It's likely going to be hard to figure out the root cause, but if/when you do, let us know!

For reference: I use regular fuel line from the tap to my pump, then the nylon pressure line to my Webasto, which I 'leaned out' a bit. After four years and plenty of run time at altitude (6-8k'), it has a bit of soot in the exhaust and still runs fine. Sample of one, YMMV.

I like what you wrote here @larry barello as it makes logic sense.

Going back to the Air/Fuel ratio and specifically oxygen, we have to consider if the fuel supply is too much or if the oxygen supply is too little. We can think it is the same thing but for that amount of soot in so little time something is drastically out.

What I mean by that is if the dose pump is supplying fuel @ a sea level computer calibrated air/fuel ratio but @ 8000’ the air is supplying a low amount of oxygen then it could be quite rich. At 8000’ DA a normally aspirated “piston” engine can only develop a maximum of 75% if its sea level power rating ,,, we typically lean out aircraft engines significantly at these altitudes as otherwise they tend to run poorly.


I’m hoping Velit brings the unit back to their facility & tests it & sorts out all that is wrong & then explains it to @scribblersix & also here.

Is Will @ Velit still on the forum ?

 

[MaggieMarty]

From the manual:
"The performance may be compromised when using the auxiliary fuel port above 6000ft."
This may be an understatement.

Thought I would try it @8000ft w/ aux fuel port since its not terribly far off from the recommended max and is the highest I will need to run it. Figured I could always install the standpipe if needed. It fired up great the first few times. Did notice some darker exhaust smoke.

Then would not always fire up, or would flame-out after a few hours.
Then would not fire up at all, or flame out within a minute, even at lower elevations.

Decided to take apart as it was just a paperweight at this point.
Exhaust was nearly completely clogged. the inside of the heat exchanger was caked with 1/2" of soot as well.

Is this the effect of trying to run at altitude without the standpipe? Bricking the unit?
This doesn't feel salvageable but I am cleaning the thing out and reinstalling.
View attachment 112839

Following this with interest.

I’m curious how long your exhaust pipe is and how many bends it has. I read through the install instructions of a Webasto or Espar (with should be very similar) and I limits the exhaust pipe and air intake pipe length to max 6’, with few bends.

I’m planning on using the Velit mostly on low here in California, so I’m concerned about coking.

 

[Pierre O]

Following this with interest.

I’m curious how long your exhaust pipe is and how many bends it has. I read through the install instructions of a Webasto or Espar (with should be very similar) and I limits the exhaust pipe and air intake pipe length to max 6’, with few bends.

I’m planning on using the Velit mostly on low here in California, so I’m concerned about coking.

Your best bet will be to open windows to make sure you run it at max for at least 15 minutes. Running short cycles at low is a recipe for carbon formation regardless of brand or altitude.

Also you should get a cheap CO meter to check that the combustion is not rich.

And personally I would skip the muffler - it will be much more apparent if you have combustion issues, you will see carbon in the tailpipe or chunks of carbon on the ground.

 

[scribblersix]

@MaggieMarty I was using complete supplied exhaust tube (maybe 24"?) cut in half to accommodate the muffler in the middle. ~60º bend before the muffler. The idea was to get the exhaust tip just past the edge of my vehicle so that CO doesn't work its way up through any cracks/holes/voids in the floor.

This is an under-passenger-seat install btw, requires a lot of pipe to come down far enough.

@Pierre O - what if the combustion IS rich? Velit units have no programmable calibration besides whatever automatic adjustments are supposed to happen based on elevation.

I am pretty sure rich or inconsistent fuel delivery caused the soot buildup. Over a couple dozen hours, the exhaust and the interior of the unit got completely loaded with soot.

While the combustion chamber itself is not horribly sooted, I see some soot scarring on the fuel dispersion pad in the combustion chamber. I am thinking this prevents the gasoline from diffusing through the pad or reaching the glow plug.

Solvents like brake cleaner did not clean up the diffusion pad. I as considering trying to burn it out with a torch.

My main plan is this

• Order replacement combustion chamber and gaskets from Velit
• Order Chrysler tool for removing top of fuel tank
• Install Velit provided standpipe
• Install new combustion chamber in Velit heater unit
• Remove muffler from exhaust

 

[scribblersix]

@larry barello & @RV8R
Sorry Ididnt catch your response before my last reply.
Thanks for the thoughts on the standpipe and the rich fuel/air mixture.

The control unit at least acknowledges "8400ft ASL".

I should share one more thing thats a little embarrassing, but relevant.

I originally received one of the 1st gen units and all the aforementioned stuff happened. I told velit of my situation and the constant ERR01 codes and they sent a 2nd gen (bluetooth) heater unit free of charge. I was grateful for that, but they expressed no interest in diagnostics or taking a look at the unit.

Without much thought, I dropped the new unit in place and had the experience mentioned above. Basically same as the first.

Since I managed to bork 2 units I am feeling like this must be my fault. Followed instructions to best of my ability (30º fuel pump, line always running up from pump, no air bubbles etc)

But at the same time, if some of you are saying this looks symptomatic of rich-burning, well, wouldn't it be kinda hard to "improperly" install a unit causing it to burn rich?

 

[RV8R]

@larry barello & @RV8R
Sorry Ididnt catch your response before my last reply.
Thanks for the thoughts on the standpipe and the rich fuel/air mixture.

The control unit at least acknowledges "8400ft ASL".

I should share one more thing thats a little embarrassing, but relevant.

I originally received one of the 1st gen units and all the aforementioned stuff happened. I told velit of my situation and the constant ERR01 codes and they sent a 2nd gen (bluetooth) heater unit free of charge. I was grateful for that, but they expressed no interest in diagnostics or taking a look at the unit.

Without much thought, I dropped the new unit in place and had the experience mentioned above. Basically same as the first.

Since I managed to bork 2 units I am feeling like this must be my fault. Followed instructions to best of my ability (30º fuel pump, line always running up from pump, no air bubbles etc)

But at the same time, if some of you are saying this looks symptomatic of rich-burning, well, wouldn't it be kinda hard to "improperly" install a unit causing it to burn rich?

I am not knowledgeable with the inner workings of the Velit Gasoline heater, however I assume it has a little controller ( computer ) & that is setup for an air/fuel ratio for a particular “atmospheric condition” ,,, eg sea level / 15C / 29.92 inches of mercury / dry air / etc.

If it has “barometric altimeter” & that altimeter alters the air fuel ratio, I would like to know how ,,, assuming the intake flue has a blower, it could be performed by sucking in more “combustion air” when @ higher altitudes 🤷‍♂️ ? That would be performed by the controller I suppose.

I had a cheap diesel heater @ my cabin, the only “controls” I “the user” had was;

Off / On
Dose Pump Speed
(Fuel line purge)

Everything else was done by the computer controller.

As for something that you might have installed incorrectly, I can’t say. When I had an issue with my Propex “propane” furnace @ 8000’ ASL it was the propane “regulator”. I had to dial it way back to 9WC from the standard 12WC. I was pretty disappointed with the discovery of the Propex being fussy @ 8000’.

 

[scribblersix]

Here is the combustion chamber; the fundamental difference between Velit and other heaters.
In my former chinese diesel heater for example, the fuel was injected into an atomizer to aerosolize the fuel for combustion.

The Velit seems to use what i will call a steel "diffusion pad" built into the combustion chamber. It would seem the gas is meant to spread through this thing and vaporize/burn. The glow plug goes directly into a hole from the side.

It was my theory that soot buildup was interrupting the gas diffusion across the pad. I used a butane heater to try and clean out the soot. Here is a before/after of the combustion chamber "diffusion pad".

I really REALLY should refrain from trying to start this thing at 8000ft and hope that this cleaning leaves me with something that will at least work at lower altitudes.

 

[MsNomer]

What setting were you using at 8,000? My personal rule of thumb is PL3 or above at 8,000.

How early in production was your first unit?

I think your plan forward looks good, but I’d also try to discuss with VeLit.

I’m curious as to when they added the muffler. The one other person I know with a similar experience had used his existing Webasto AT2000 muffler and exhaust (smaller diameter).

 

[scribblersix]

I believe I was using temperature mode which alternates PL1 and PL5 (mostly PL1 in my case).

I think I set the replacement unit on a path of self-destruction by installing it into a coked up exhaust without knowing it. The exhaust obstruction reduced airflow causing a rich air/fuel mixture, in turn leading to even more soot & exhaust obstruction.

So the failure of my replacement unit was likely my fault for not replacing everything like i should have.

Anyhow, I reinstalled the unit after torch-cleaning the diffusion pad and it fired right up! Ran it at PL5, for about 2 hours @ 8400ft w/ aux fuel port. Exhaust looks clean, couldn't get exhaust CO to register on a household CO detector.

Note that cleaning the carbon out of the diffusion pad was essential as it did not fire up after cleaning the rest of the unit.

I think my takeaways are:

• Ensure your exhaust is unobstructed and not accumulating soot
  • If it is obstructed, clear it out and figure out why
  • Be wary of added backpressure from mufflers
• If you are having ignition problems and are noticing extra soot, you can disassemble the device and burn the soot out of the diffusion pad with a torch
• The Velit 4000P can run at 8000ft w/ the aux fuel port.
  • This one is still under investigation for reliability
  • Maybe keep your PL @ 3+ for higher altitudes

I will update if I get any info from Velit RE: standpipe

 

[Pierre O]

Here is the combustion chamber; the fundamental difference between Velit and other heaters.
In my former chinese diesel heater for example, the fuel was injected into an atomizer to aerosolize the fuel for combustion.

The Velit seems to use what i will call a steel "diffusion pad" built into the combustion chamber. It would seem the gas is meant to spread through this thing and vaporize/burn. The glow plug goes directly into a hole from the side.

It was my theory that soot buildup was interrupting the gas diffusion across the pad. I used a butane heater to try and clean out the soot. Here is a before/after of the combustion chamber "diffusion pad".
View attachment 112851 View attachment 112850

I really REALLY should refrain from trying to start this thing at 8000ft and hope that this cleaning leaves me with something that will at least work at lower altitudes.

It looks quite similar to a webasto burner.

I assume the unit was emitting very thick white smoke? Usually that's a symptom of a unit that's packed with soot.

 

[scribblersix]

Yeah it was thick with sour-smelling white smoke.

Update: 10 days later and some single-digit (F) temps, I can run PL4 and PL5 at 8400 ft. I had a flame-out ERR02 at PL3 after a few hours so will be avoiding that moving forward.
Flame-outs may have a side effect of soot buildup and should be cleaned up by running at max power for awhile. Allowing multiple consecutive flame-outs could compromise your unit, requiring a deep cleaning and possibly new gaskets.

I do question their design decision of using a high volume fuel pump running at a low duty cycle. At lower power levels (@ high altitude) I hear breaks/surges in combustion in between clicks of the fuel pump. I wonder if a smaller volume pump would have provided a smoother combustion.

In regards to cleaning the fuel diffusion pad with a torch, I read that 380ºC is sufficient to burn up all soot (not specifically in relation to parking heaters). I measured about that temp using a butane torch. Using a MAP torch (2020ºC lol) as I originally intended probably would have burned away the diffusion pad entirely.

Also, Velit never responded to me regarding inquiry relating to symptoms of a need for a standpipe. I get the feeling they are short on technical staff/knowledge.

 

[jflochner]

We used a discount code MOTM for 50 dollars off. Not sure if that still works but if you ask for a code they will likely accomodate you.

View attachment 112115

14 Jan 2025 - update -
MOTM no longer valid. Velit provided new code- '1425' giving the same $50 discount. However, current retail is now $699, a net $649 with 1425 code. Also currently on backorder (gasoline), expecting mid February shipping.