Carboned up combustion chamber...

Reply

  #1  
Old 11-06-06, 01:59 PM
Member
Thread Starter
Join Date: Aug 2006
Location: usa
Posts: 902
Carboned up combustion chamber...

My multifuel boiler has separate combustion chamber for the oil burner. I relined the chamber a few years back. I recall the chamber always burned "clean", maybe a light gray color or off white. Lately the chamber is black. I suspect a combustion problem. I mentioned it to my oil tech (from my oil provider) who only did a smoke test on the stack and proclaimed it was buring clean. Burner is about 25 years old (Becket) with correct nozzle for chamber .85H80. Been a long time since I did smoke tests, but calling it a #2 would be generous... No oil pressure test, no analyzer to see what the startup looked like (uses a wet kit).. No CO test. Should I call the company back or shop for a new service technician? This is a backup boiler to my Biasi/Riello, but I'd still like it right. Should I have it checked by someone else? The boilers are in a large cellar, adequate air, etc.
 
Sponsored Links
  #2  
Old 11-06-06, 03:51 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,928
Carbon

All he did was a smoke? No draft, no CO2, no temperature, just smoke?
Even if all he did was a smoke, #2 is NOT acceptable. Nothing more than a trace (<1). Preferably 0 with at least 15 pumps (10 is standard).
I think it's time to find a new tech or at least call your fuel supplier & complain bitterly.

The carbon could be from a poor pump shut down (small after drip). How does the inside of the vent pipe look?
 

Last edited by Grady; 11-06-06 at 04:41 PM.
  #3  
Old 11-06-06, 04:18 PM
Member
Thread Starter
Join Date: Aug 2006
Location: usa
Posts: 902
Vent pipe..

The flue pipe had loose granular carbon buildup, but the pipe wasn't cleaned for a few years... I cleaned a LOT of combustion detritus out of the cleanout too. It's hard to tell which fuel left the stuff in the pipe. The pipe is new this year. I did have an a problem with the burner dripping oil on shutdown previously, and mentioned it to the tech from the previous oil company who serviced it last year.

Since this is a backup burner, and basically used for emergencies or to get the wood going, should I just buy a new pump and coupler and then have the thing retuned? The oil guy was here primarily to set up the Riello and Biasi and did a quick check on the old unit. I would complain, but they didn't charge any where what I would have expected to pay for a good tuneup.
 

Last edited by radioconnection; 11-06-06 at 04:55 PM.
  #4  
Old 11-06-06, 05:00 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,928
Carbon

If it is a pump problem, an electric solenoid will cure it.
http://www.suntecpumps.com/model_r_and_c_shut_off_valves.htm

There is always going to be a very slight puff upon ignition but even that can be all but eliminated by use of a delayed opening solenoid. Without very expensive (lab grade) test equipment, this initial puff can't even be detected usually. Ordinary combustion analyzers are not fast enough but you might be able to pick up a spike in CO. It would not be of long enough duration to get a meaningful number but you might see a spike.
 
  #5  
Old 11-06-06, 05:29 PM
Member
Thread Starter
Join Date: Aug 2006
Location: usa
Posts: 902
Talking pre purge

So, that valve will give a prepurge delay, and (I assume) a positive shutoff when the burner shuts down? Where is that valve installed on the burner--right at the pump inlet? I couldn't find any directions online for it. I've heard good things about using pre and post purges... But, am I just bandaiding a problem that shouldn't, and probably didn't, exist in the beginning? The valve does look like something worth having on any system, and I will put one in if it is something I can do on my own.

If I was a lot younger, I'd seriously consider taking some courses and investing in a combustion analyzer, but at my age there'd be no payback... Otherwise this is an interesting field.

Pete
 

Last edited by radioconnection; 11-06-06 at 06:04 PM.
  #6  
Old 11-06-06, 06:28 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,928
Pre-Purge

It technically isn't pre-purge because of the length of the delay (only 3-5 seconds) but it still allows the air to get moving & the spark happening before introduction of the fuel.
The valve gets installed downstream of the pump. Honeywell also makes one with about a 15 second delay which works well if you have a 30-45 second safety time on the primary control. Another option is to use a valve with no delay & a primary with a valve on/off delay. I converted mine to delay about 15 seconds on start up and to keep the burner motor on for 2 minutes (with the valve closed) for post purge.
This is as near to an installation instruction sheet as I could find online:
http://www.suntecpumps.com/PDFs/Form%202040%20-%20Solonoid%20Safety%20Valves.pdf
 
  #7  
Old 11-06-06, 06:33 PM
Member
Thread Starter
Join Date: Aug 2006
Location: usa
Posts: 902
Honeywell

My friend has a Honeywell V4046A1074 I can have. I take it I have to provide the 3/16" flare fittings and lines to interface the device between the pump and nozzle?

Pete
 
  #8  
Old 11-06-06, 06:51 PM
Grady's Avatar
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 13,928
Valve

That valve will give you (per Honeywell) a 5-9 second delay.
Yes you will have to supply the 1/8" MPT x 3/16" flare fittings and the line to go from the valve to the nozzle. You could hard pipe from the pump to the valve, which is how I usually do it. You need two 1/8" MPT x 90 street ells & a 1/8" nipple. I usually use brass but steel is fine.

You know, I too wish you were younger. We can use all the TECHNICIANS we can get. In this trade, even decent parts changers are getting hard to find. Nobody wants to get their hands dirty nor have to roll out of bed at 2:00 in the morning to go work on someones heater.
 
  #9  
Old 11-06-06, 09:59 PM
Ed Imeduc's Avatar
Member
Join Date: Aug 2002
Location: Mountain Williams Missouri
Posts: 18,389
Wink

That old could use the delay valve on it. Also when was the last time you checked the blower wheels blades and see if they are clean and the cup in them not filled up with dirt so it dont blow like it should?

ED
 
  #10  
Old 11-07-06, 03:30 PM
Member
Thread Starter
Join Date: Aug 2006
Location: usa
Posts: 902
Originally Posted by Ed Imeduc
That old could use the delay valve on it. Also when was the last time you checked the blower wheels blades and see if they are clean and the cup in them not filled up with dirt so it dont blow like it should?

ED
Good points Ed! Yes, the impeller had dirt problems in the past, and it may well need cleaning again. I'll check into it more when I have a chance to tear into the blower section. I'll probably add the delay, but this boiler and burner aren't worth putting a lot of money into--just there for backup and wood heat if the power goes out or if there's a 1 AM failure on the main unit.

Pete
 
  #11  
Old 11-11-06, 02:15 PM
Member
Thread Starter
Join Date: Aug 2006
Location: usa
Posts: 902
Valve

Picked up the valve today and have it installed. The burner kicks off smoothly after the five second (+/-) second delay. Ed, the impeller was spotless! No dirt built up on the blades. Everything else looked clean..

Pete
 
  #12  
Old 11-11-06, 10:25 PM
Banned. Rule And/Or Policy Violation
Join Date: Feb 2006
Location: In the corner.
Posts: 42
Carboned Combustion Chamber

Pete:

Ed is right about checking for adequate air flow.

I completed an insulation project for the boiler room the first part of last year's heating season; all of a sudden I started having boiler carbonization problems in the 2nd part of the season; I tried everything, but couldn't find the cause.

I recently completed another project where I added a 4" floor drain leading outside to a drywell & a 4" vent.

To my amazement, when the boiler came on, I could feel a rush of cold air coming up out of the 4" floor vent (located near the burner motor).

I had made the cellar so airtight with the insulation job that the boiler & the flue was starved for air; there has been no soot buildup ever since the drain/vent was put in.

The flame is bright & hot & clean as a whistle.

I would also recommend you remove the flue piping & vacuum or brush thoroughly to get all the soot deposits out; soot acts as an insulator inside the pipe; the flue pipe has to get hot in order to create a draft for the chimney to operate properly; a dust mask is a MUST when removing soot from the system.

Also check the draft by holding a smoking piece of rope or cigarette near the open inspection hole while the burner is firing; the smoke should be quickly pulled into the combustion chamber if you have adequate draft.

A stack thermometer, if you have one, should read 500 to 600 degrees when inserted into a drilled hole 6" below the draft regulator; cover the drilled hole with a metal screw when done.
 

Last edited by jack horner; 11-11-06 at 10:42 PM.
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes