Weird debris in Lochinvar HX

Kestrel

Hi guys,

Attached is a picture looking down in the window on the top of the HX of my new WHN-085.

Heat and hot water are working great - but seeing all those little pieces of black stuff lying around below the burner has me worried.

The picture was taking when it was on 100% heating the indirect.  When it's modulated down lower for heating, they don't glow so much, just amorphous pieces of crud.



What is this?  Should I be worried?

Aaron_in_Maine

Propane?

Is it running on propane? I've seen the coffee grounds on a lot of condensening boilers.

Kestrel

nope

Natural gas.

Ironman

Amorphous Pieces of Crud

I like your description.



The intake air connects directly to the combustion blower inlet on the WHN and therefore anything that is drawn into it (dirt, dust, bugs, pollen, etc.) gets burned.



I've noticed that all the boilers that use this direct connection seem to have more debris in the combustion chamber than those that don't.

Zman

Check the venturi

I had situation with a triangle tube prestige solo a few years ago. The boiler combustion was horrible. The exchanger had similar debris on it. It turned out the black plastic venturi in the gas valve assembly had disintegrated.  I replaced the assembly and it has worked perfectly ever since.The lochinar uses the same exchanger and likely the same valve.

Kestrel

thanks guys

I want to believe it's the outside organic material  -  webs, bugs and stuff.

To address the disintegrating venturi theory, would I need to do another combustion analysis?  When we first fired it up a few months ago the numbers were great - we could compare.  If that had happened, would there be any other evidence?  The boiler seems to be working great right now - how would I know?

Zman

I do recall

I do recall an error code that lead us to the problem. It was the combustion analysis and the flame that made us take the valve apart. Were is you intake located? Is there a screen? If the flame looks good, I would just keep an eye on it and make sure the intake is not in a shrub.

SpeyFitter

Not always debris

Unless the debris is fine enough to penetrate the mesh into the combustion process, a lot of stuff just sits in the burner can/cylinder until someone pulls it apart and cleans it at an annual service. I've opened up burner cans with some dead flies in them, perfectly intact - they could have been there for at least a year or so.

Boilers that pipe the direct vent direct into the venturi will see more debris as was mentioned. Those that pipe the air into the cabinet and then the venturi/fan pull their air from the cabinet will have less issues with debris as the interior of the boiler cabinet acts as sort of big settling point and everything falls to the bottom of the cabinet. Boilers like the Viessmann Vitodens or IBC SL20-115 are examples of this.



Last I checked Lochinvar does offer an air filter housing that you can install on your direct vent air intake piping that will significantly reduce debris getting into the combustion process.

Steve Whitbeck

Z man

Z - man -- If you are loosing the plastic parts of the boiler it is due to exhaust reversion. You need to seperate the intake and exhaust vertically by at least 18 inches.  Never use a concentric vent termination.

Zman

Thanks Steve

Steve,

I think you are correct. The install (not mine) was under an overhang with fairly close exhaust/intake. Can you explain why? I am guessing it is sucking exhaust and throwing off the combustion causing overheating.

I had not realized the lochinvar does not vent through the cabinet. This reduces cabinet heat loss but seems to increase contaminants.

Always learning,

Carl

Gerry Alder

disintegrated venturi on triangle

In reference to the venturi disintegration I too seen this before . It was on a Prestige that had been short cycling it had unbalanced side wall direct venting about 15 foot separation between intake and exhaust . So everytime the boiler goes in standby after a burn cycle there is warm humid acidic air rising up through combustion chamber through burner through fan and out gas venturi these plastic and aluminum components are susceptible to corrosion and eventually fails. This reverse air flow when boiler is in standby is pretty common occurance more or less when using side wall venting and when conditions are severe I see component failures. When venting is through the roof there is almost no problems .

There has been an evolution of improvements over the last several years on most manufacturers boilers dealing with this issue , to name some improvements I have seen are:

blowers underneath the combustion chamber

check valve in the exhaust

fans with stainless blades

long post purge fan cycle

intake air directly connected to venturi

gasket tight boiler cabinets

Typically one or two of these improvements can be applied to an existing boiler that has this back draft problem and component failures.

Pay attention and be aware of the possibilities.

The excuse of exhaust reciculating in to the intake is scripted from a manufacture. (They don't want to be responsible and will try to blame it on your vent terminations) Although it is a bad thing to have happen . Recirc causes poor combustion due to lack of O2 and in severe cases you would have loss of flame but I don't believe it would cause component failures like a venturi disintegrating . In a vent recirc condition the air is very diluted and should not cause any evidence of corrosion on boiler components.

I come to this conclusion based on my observations and experience as a Service Technician.

And to comment on the nice Lochinvar pic the debris in the combustion chamber looks normal to me. I been told its carbon (often described as coffee grounds)

but I can not explain this process very well.