Boiler exhaust problem?

DL

Static electricity buildup on the central vacuum pipe appears to be the cause. I called a central vacuum installer and he says extra dust buildup is very common.

However, this does not totally clear my issue since the buildup on the pipe was not dust but BLACK carbon-like soot. I believe this must have come from the boiler.

On the 'normal' side of things, the boiler room does not appear to be abnormally dirty. Only the central vac pipe was black (but very black).

On the 'abnormal' side of things, the soot on the pipe was thick enough to make me think the PVC pipe could have been black in parts. There is 4" or 5" fresh air pipe directly from the outside so there shouldn't be negative pressure.
My central vacuum is exhausted to the outside.

So, my guess is I should look into whether or not my boiler is burning clean enough.

There is one other possibility. Apparently the boiler was run early in the construction process to dry out the wood frame house. Recently the previous owner had the boiler serviced, which included using a brush on the burners.
Maybe a lot of carbon ash was dusted out of the boiler and then clung onto the static charged central vac pipe.

Maybe I should see after 2 or 3 months whether or not new black soot accumulates?

Comments and suggestions? Thanks in advance!

DL

Boiler exhaust mystery

Hoping that someone will have experience with this.

My mechanical room has a Vitogas 050 (power vent to outside) with indirect DHW tank. My central vacuum unit is also in the room.

Today I noticed the plastic pipe to my central vacuum unit was covered in black soot. The area around the pipe was dirty too. Otherwise the mechanical room appears 'normal', no soot appears to be anywhere else.

What could be causing this?

Could the vacuum pipe have built up static that is a magnet for boiler soot? Is this an indication of improper combustion or exhaust gases that are backing up?

The house is only 1.5 years old.

What could be wrong or is this normal?
Thanks

[Deleted User]

Central Vac

My central vac is in a separate location & there is definitely a dust build up on the near vac piping. I believe it is a static cling issue.

Jack, CVMS

In cold weather

indoor humidity is often quite low, and static electricity is high. A ten foot walk across a synthetic carpet can generate a 10,000 volt spark. Air and dust flowing through plastic lines and hoses will do the same thing, and "static cling" becomes very strong. Try spraying some water (with a little dishwashing detergent added) onto the plastic pipe from a little squeeze bottle, then wiping the soot off.

munchkin-man

Perhaps the vac is creating - press in the room and sucking

through the boiler enclosure and overcoming the blower motor on the boiler. If the deposits you are seeing are infact soot / carbon then check the PPM of Carbon Monoxide in the room and in the exhaust pipe. If the ratio of fuel to oxygen is off because of this then the flue gases will show it.
Also use a draft gauge in the room near a small opening like under the door to see if the room is in negative pressure.
If it is then you must alow free air in to the room from some were be it from out side or the next room. I have seen this when the room they are both in is very tight.

Mike T., Swampeast MO

If the central vac unit

isn't vented to the outside (common and no problem I believe) the only possible pressure it could be putting on the mechanical room would be positive as the discharge is going out--not the reverse. If vacuuming in the mechanical room the net change would be zero--just as with a regular vacuum cleaner.

I just checked the central vac lines here--not everything is finished and some are still exposed. They DEFINITELY have a dirt/dust buildup significantly greater than other things around them.

The static thing is likely the answer and would be considered "normal".

IF however, your central vac has its exhaust going to the great outdoors you might want to verify that you're not having a depressurization problem in the mechanical room.

Dale

Candles

Any candles or fireplace, nowadays soot issues are usually candles.

hr

You'd be wise

to stick a mirror into the boiler and flue.

A combustion analyzer would also help to see where you are at.

The boiler does have the correct orfices, for the fuel being burned??

hot rod

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DL

Hot Rod,

I'm not a heating contractor, just a home owner.

What would the mirror in the boiler do for me?
What am I supposed to look for?

I guess I'm wondering how an average homeowner can verify that their boiler setup is running correctly (efficiently and safely). I know, call the a qualified contractor right?