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Jim Davis

Jim Davis

Joined on August 25, 2004

Last Post on May 5, 2014

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@ November 17, 2013 7:23 AM in combustion test

As Timmie said, sometimes you have to travel to learn the things you need to know.  You can't be that far from classes, where do you live.
In the mean time post your questions here are we will do the best to help.


@ November 15, 2013 8:27 AM in combustion test

Overfiring is caused by too big of orifices or to much gas pressure.  Too much gass pressure does not mean the gas pressure is higher than 3.5"  Too much gas pressure means you are putting more fuel into the heat exchanger tha there is air to burn it.  Gas pressure could be 5"w.c. and not be too high.  Orifice sizing is the biggest problem because you just can't be sure if they are drilled correctly.
The other condition of overfired that holds true with induced draft equipment is when you are producing more flue gasses than the inducer can remove.  Sometimes inducers are sized small from the factory.  In the field the blades get dirty and can't move as much flue gas. 
Each problem has unique readings that identify them.
On this job I am lowering the gas pressure until the CO is below 100ppm

carbon monoxide leak?

@ November 14, 2013 11:09 AM in Another

I love the term "carbon monoxide leak"!.   Do they make a sealer for that?  Some kind of paste or patch? 
How about another school, this time in Oklahoma!   I bet parents like sending their kids to school not knowing if they will be coming home each night.
Did they mention everything was installed according to Code and manufacturers recommendations.  Yes it was!   But we have to do it that way or we will get in trouble.  It is up to others to protect themselves not us!


@ November 14, 2013 9:35 AM in Short cycle

How do you know the burner is actually firing?  Does it lock out or does it relight right after it goes out?  Beckett does kill their spark after it is lit.  Possibly could be some air bubbles as other have said, from leaky fittings.  Does this happen all winter or just after it is serviced?


@ November 14, 2013 9:24 AM in First House.... Oversized, Short Cycling System.

The circulator pump should come on no later than when the burner comes on.  I used to recommend starting the pump just before the burners come on. 
Short cycling does not eat flues.  Underfiing the equipment and combustion air problems do.  Controls can be set for longer on/off differentials to make the cycles longer. 
Flue temperatures should be in excess of 400 degrees in oil, even in just two minutes.  If not there is something wrong.

gas pressure

@ November 14, 2013 9:11 AM in combustion test

Gas pressure is one of the most mis-leading indicators of how an appliance is firing.  We have found many appliances in the field with wrong size orifices.  Sometimes they are too big, most of the time too small.
The flue temperature is on the high side of the induced draft furnace range.  It is not over the range but with an O2 of 4.7% I would have to say it is overfired,
Higher flue temperatures can also be caused by poor airflow but they don't make the O2 reading that low.  6% O2 is the normal low side reading in the field on most furnaces but on occasion it can get to 5%.
Just knowing most induced draft furnaces, I would say yours is overfired.

High CO

@ November 13, 2013 2:30 PM in combustion test

Well maybe at least you learned that looking at flame color doesn't mean a thing. 
Analyzers measure 3 things - O2, Flue T and CO. The flue temperature is missing.  Of course without knowing what type of equipment the flue temperature doesn't always have meaning either.
Under 5% O2 on most residential furnaces is rare.  Sounds like the furnace is slightly overfired.  Usually on induced draft furnaces when this happens the CO keeps climbing the whole time it is running, but not always.
If that RSES webinar on cracked heat exchangers was free they still overcharged1   

combustion readings

@ November 6, 2013 8:17 AM in Combustion Analysis Results

Your flue temperature is too low. It should be close to 400 degrees.  I did not see any CO readings. 
Putting less fuel into equipment doesn't take advantage of all the surface of the heat exchanger.  It takes temperature difference to get heat transfer.  Your steam temperature is around 215 degrees and the flue temperature is 300 degrees. Not much transfer is going to occur in the top of the boiler.
O2 below 3% are unusual on residential equipment without making CO.  If opening up the air shutter quiets the boiler down then maybe opening the shutter and giving more fuel will bring everything closer in line,
Actual boiler efficiency is not 84%.  With it being underfire it is most likely is the 60% range.   Maximun efficiency without condensing would be around 73%.
Analyzer calculations for efficiency are rarely representative of actual efficiency.

testing location-CO

@ October 29, 2013 10:54 AM in co testing

As above, the round drafthoods have to be tested on the left, center and right.
Rectangular hoods allow for each burner to be tested independantly.


@ October 29, 2013 8:31 AM in co testing

Actually neither Bacharach or Testo show the proper way to test a boiler with a drafthood which is why most are tested incorrectly.

CO testing

@ October 28, 2013 9:37 AM in co testing

Something that didn't make sense with the question is that you had a CO reading of 600ppm.  This boiler would have more than one burner therefore there should be a reading for each burner.  If there is a round drafthood on top, it must be traversed from left to right for the highest reading.  The highest reading must be watched for a couple of minutes to make sure it doesn't change. 
If the drafthood is in the front or rear then CO readings from each and every burner must be taken and watched to make sure they don't change. 
I have a feeling the CO is not staying the same which could indicate a major safety issue.

Modifying Equipment

@ October 28, 2013 9:24 AM in Gas conversion burner of choice for a Burnham V-905?

As Bob knows, there are no manufacturers that approve any modifications to their equipment in the field.  I think that should already be known by those on here after reading the fiasco with the Rinnai water heater.
Once in a while a local code official will be open minded about some of the things we do, but then someone that has very little knowledge about the mechanical operation of equipment is hardly the person I look to for advice or approval.
As soon as a manufacturer says it is okay to do something they become liable.  This is not going to happen.  It is their job to cover their butts and it is our job to cover our butts.
Competent and qualified contractors should not be afraid to do their job.  There would be a whole lot of dead people out there if I had let others dictate what can and can't be done in the field.  The field is not a lab with fixed conditions.  Infinite variables rely on infinite adjustments and modifications.  Changing from an oil burner to a gas burner on a boiler that is approved for both shouldn't be considered any problem at all.  Timmy knows and Bob knows and I know.

gas burner

@ October 28, 2013 6:14 AM in Gas conversion burner of choice for a Burnham V-905?

The Power Flame burner would be an excellent choice.  I sold Power Flame and Burnham for many years and found they perform quite well together.
Hundreds of thousands of pieces of equipment have been modified over the years for many different reasons.  With proper care and proper combustion analysis there never were any problems.  The skill of the technician play the biggest part in whether something will work properly or not, not the suggestions of others that have never done the work. 

Burnham V-905

@ October 27, 2013 7:21 PM in Gas conversion burner of choice for a Burnham V-905?

How many coal boilers were converted to gas or oil without the manufacturers approval?  Why do burner manufacturers call them retrofit burners not replacement burners?
For person that are afraid to do their job should not be in this business.  Burnham's literature specifically states this boiler can be operated with Gas, Oil or Gas/Oil.  Doesn't mention with their permission.
Since when isn't a contractor liable for the work they do??  I don't see manufacturers ever taking the bloame for anything.
I guess if this boiler was steam and you wanted to convert it to hot water that would be a modification that wasn't approved either.
Since when is a Fire Chief an expert boiler/burner man.  I bet he never asks for our help when he is at a fire!!!
Stupid is what stupid does.  If you are stupid, don't do it.  If you are a competent contractor do your job.
I truly believe there should be a catagory on all these HVAC talk sites named:
Mechanical Morons-Submit Your Ignorance

carbon monoxide production

@ October 23, 2013 5:35 PM in is it true

Besides combustion, the human body produces carbon monoxide chemically.  Cleaning compounds such as methyline chloride convert to CO in the body and cause CO poisoning.  According to my good friend Albert Donnay, a medical guru on CO poisoning and treatment, womens bodies produce high levels of CO when they are pregnant, time of the month and menepause.  Men beware!   Also chemicals like hydrogen sulfide(battery chargers), cleaning compounds and nitrous oxide can cause all CO Alarms and Analyers to read CO.

flame recirculation

@ October 11, 2013 11:43 AM in wall furnace flame recirculation

That has got to be one of the poorest definitions of a problem I have heard?  Sounds like he really doesn't know.  Maybe its flame fibulation?  Or flame resonance?  Don't know what any of those mean either.  Obviously he didn't do a combusion test!

New Carbon Monoxide Studies

@ August 21, 2013 3:26 PM in New Carbon Monoxide Studies

A recent study has shown that drywall does not keep car fumes out of homes.  If you plan on running your car in the garage you need to find a different material.
(Okay, I added the last line but it seemed to be implied)
CPSC funded a year long study and found that running gasoline power generators in you house can be dangerous and deadly.
(I think it took a year to complete the study because the testers kept being overcome by some type of illness)
I am betting using barbecue grills indoors might be the next study released, but I hear they are having a problem finding volunteers.

Manufacturers and inspectors

@ August 9, 2013 8:34 PM in Gas Conversion Burners

When you are talking about inspectors you are talking about egotesticle(I didn;t spell this wrong, its a new word) authoritative, mechanical morons.  Theyare that way in many parts of the country.  Once in a while you may find an intelligent one but I doubt it.  I am in Minnesota right now and the  constractors have been telling me about the idiots that inspect their jobs and their opinionated, non-practical requirements.  I put up with it in Cincy.  It is impossible to expect any of them to have common sense or anything else.  My inspectors told me they didn;t accept AGA as an authority many years ago?
Manufacturers commit to nothing.  Back in the 80's they tried to void their warranties when we added spark ignition and flue dampers.  They will dismiss their warranty if you use a wrong screw. 
I keep hearing if something goes wrong what will happen.  What is going to go wrong.  I sold gas conversion burner in the 70's,80's & 90's for oil boilers by the bushel.  Nothing has gone wrong yet. 
Wasn't there a post on here about a water heater that was exploding.  One of you came out and modified a design flaw and it worked perfectly.  When the manufacturer came out he made you change it back and it exploded again.  They turned their backs and walked away.  The home owner had to buy another make. 
Whose approval is on the burner?  Maybe they need to be called and told your local authority doesn't accept their certification.  Maybe the burner manufacturer needs to be questioned about false advertising.  Could this be a restraint of trade?  I hate when stupid people rule!!!
Once a boiler leaves the plant the manufacturer doesn't own it and has nothing to say about it other than warranty.  The only thing in warranty is the boiler sections and there is no way a gas burner is going to hurt them if an oil burner didn't. They fire with a lower flame temperature.  Anyone afraid of what might happen needs to figure out what they are doing wrong because only a mistake by them could cause a problem.
Does doing something on a job that is code approved guarantee nothing will happen?  Are we afraid?  Most the jobs I see that cause problems are code and manufacturer approved which would be about 99%. 
An Inspector wouldn't know safe if it hit him in the face. 
The manufacturer says he not reponsible for alterations and modifications, nor should he be, that is our job.  Doesn't that statement in their instuctions tell us we can do it as long as we are responsible?  Aren't we anyway?
At least three of us know the drill.  Don't be afraid to do your job!!

burner shutting down

@ July 15, 2013 10:11 AM in Beckett AFG Stalls

If you have a 2-line system the problem is simple, you are losing prime.  If that is a newer burner with the interrupted spark I would expect this to happen.  I don't recommend either one.  Need to go to single line or constant(intermiitent)  spark.

Medical Examiner in Utah amazed!

@ July 12, 2013 12:12 PM in Medical Examiner in Utah amazed!

Aguy dies from CO poisoning boating on Lake Powell and the Medical Examiner was quoted to say "That is really unusual because he was boating on an OUTDOOR lake!"  Do some places have indoor lakes?

Portable CO Detector

@ July 12, 2013 12:04 PM in Travel Carbon Monoxide Detector

The sensorcon is good and durable.  Low level CO monitors that are battery powered are good also. 

smoke problem

@ July 12, 2013 12:00 PM in White Smoke after shutdown

Even if there is after drip the smoke shouldn't be coming out the front of the burner, it should be going up the flue.  So you either have some combustion air issues or possibly a wet chimney.
An oil burner will suck all the combustion air it needs when running, however if there are negative pressure problems that will cease when the burner shuts down.  The key is the draft reading, above the baromtric, when the burner shuts down.  If the draft disappears within seconds after the burner shuts down the above is your problem. 
This is where monitoring CO not CO2 during the Light-off(spike) Run and Shutdown(spike) can be very helpful. The smoke may just be what was in the flue when it shut down and it came back in.  The smoke is white because it is mostly clean and contains water. 
Combustion air problems are sometimes as easy as adding a supply register to the plenum.  A wet flue problem usually means there is no flue cap or the furnace is underfiring and condensing. 
If there was a hole in the heat exchanger the smoke would be coming out the whole time not just at the end..  CO readings, Flue T and draft readings can easily solve this problem versus just guessing which has already been done.
If I was guessing I would say the furnace is sending out smoke signals for help!!
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