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Tim McElwain

Tim McElwain

Joined on August 17, 2009

Last Post on April 24, 2014

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Let metry this again

@ March 15, 2014 11:06 AM in Natural Gas to LP gas conversion .. orifices

·                                 Natural Gas to LP gas conversion .. orifices
Hello,
My 95% efficient furnace was installed by a licensed contractor in November 2012.  This furnace is a 90,000 BTU with 6 in-line burners.  Upon the furnace installation ..the installer converted this furnace from NG to LP.  But, he installed size 54 orifices even though the owners manual specified size 1.15 orifices. 

 
A 90,000 BTU furnace with 6 burners is 15,000 BTU per burner. The correct orifice size for LP at 10” W.C. is a # 57 drill. A lot of poorly trained folks have been told that you can always be safe with LP using a 54 drill and for natural gas a 42. Well that is not always the case you have to calculate each installation. Your furnace with a #54 drill size was firing at 25,000 per burner which is 150,000 BTU’s way over gassed. If he had ordered a conversion kit from the furnace manufacturer he would have received the correct orifices.
 


The furnace failed in December 2013 due to the secondary HX completely plugged with soot. The furnace has had a new HX put in.  When the new HX was put in and the furnace turned back on, it started short-cycling immediately ..approximately 6 minutes burners on then approximately 2 minutes burners off ..all the while the blower motor was on.  Note: It had been short-cycling like this since I can remember.  I originally assumed it was the new 2-stage blower kicking in.  (I am not an expert in furnace operation!)
 

Because it was overfired it was cycling off on high limit. This also can damage the heat exchanger due to thermal stress.



Eventually I asked for the improper gas orifices to be replaced with the correct size orifices, and the furnace seems to be working properly.
The original installer told me that the old HX might not be covered by warranty, and that he would not accept responsibility for the cost.  He said that improper size gas orifices will never cause soot. 
 
The oversized orifices will definitely cause soot (Carbon Monoxide), you are fortunate no one was killed.



It seems to me after a bit of internet research that he may be wrong.  It seems an improper (oversized) gas orifice will cause incomplete combustion, and that the 2 products of incomplete combustion are soot and CO.
(Also, as a side note, ..during the time this furnace had operated on the oversize gas orifices, my propane usage increased by nearly 30% even though last winter was relatively milder than most in my area.)
 
You will definitely use a lot more fuel when you oversize as drastically as this was done.



I would like to ask the furnace installer to assume the cost for fixing the furnace, but again, he says his improper size gas orifices would never cause soot. 
 
Again he is definitely wrong as too much fuel into a combustion chamber will always cause soot.
 


He says it might have been my outside regulators at the tank and at the house are probably faulty. 
 


If that were the case why didn’t he have the LP provider look into that?
 

 If I could get the manufacturer to honor the warranty on the HX, then I would only have the costs for labor to fix the furnace.  Unfortunately, hHe also says it is not his responsibility to pay for labor to fix the furnace even if it were possible that the wrong gas orifices were part of the problem (which he insists was not the cause).
Is my furnace installer correct that the oversize gas orifices will not cause any soot and that he has no responsibility at all?  Also, is there any possibility that the oversize gas orifices might have resulted in increased propane usage.
 


I think it is time for the lawyers to get involved as you have definitely been wronged if all that you are posting here is a fact. I would also contact the manufacturer of the equipment.

I do not know what keeps happening

@ March 14, 2014 10:16 PM in Natural Gas to LP gas conversion .. orifices

I had a nice long posting to answer your questions but the site kept dumping me off. You can e-mail me at gastc@cox.net or call me at 401-437-0557 and I will answer all your questions.

No it is not the

@ March 14, 2014 9:49 PM in Please help aquastat

L8148A is a 120 volt burner circuit. The L8148J is a universal replacement relay for 24 volts of millivolts(Powerpile Self Generating). You have to replace an "A" with an "A".

Yuo are correct if the bottom of the boiler is

@ March 14, 2014 9:44 PM in excessive draft and stack temps

open and gets its air for combustion from the room (atmospheric boiler) then a full pad must be placed under the boiler extending 2 1/2" out on all sides. Putting such a boiler up on blocks will drastically increase excess air and can cause high levels of Carbon Monoxide along with a high stack temperature and excessive draft due to the larger package of air and products of combustion that needs to be removed.

It is amazing how many of these I see in the field.

You are correct Plumdog

@ March 14, 2014 10:39 AM in Propane and condensate

it had been a long day I will correct the posting.

I answered you

@ March 13, 2014 8:03 PM in Raypak Boiler Low Temperature Reading

in the gas section.

The cold air being more dense it

@ March 13, 2014 8:00 PM in Propane and condensate

could be argued will give a better mix for combustion. MY testing and experience however show that as long as the intake air is above 10° F it does not seem to have much of an effect. I will however concede to lower temps (less than 10° F) causing some difficulty with the air gas mix and getting a good combustion condition in the fire box. This seems to be different with Mod/Con air gas mix and is less of a problem. This is a good argument for Concentric vents as the intake air would pick up some temp as it passed over the exiting flue gas products in the other pipe.

Now as to whether it would change the amount of condensate that I would believe would be a very small difference. The air (O2 and N) mixing with the gas (carbon and hydrogen (CH4 for natural) (C3 H8 for propane) producing a certain volume of water vapor, CO2, CO (trace) and Nox. The fact that you need less air for natural gas than you do for LP could make a difference but very little. The Mod/Con boilers only allow the exact amount of air to be drawn in to match the ODR demand so at lower outdoor temperatures we would be running at higher input, more air, more condensate. The reverse as we lower combustion air blower speed and BTU demand with higher outdoor temps.

Jim Davis and I had a discussion here on the Wall about this several years back if memory serves me.

What is it being used for?

@ March 13, 2014 4:38 PM in Mercury control replacement

Is it SPST or SPDT? The L6006A is a SPDT but can be used to replace SPST by wiring to R - B (Normally closed opens on a temperature rise) used as High limit, Low Limit or Domestic aquastat, or R - W (Normally open closes on a temperature rise) used as a circulator control.

The L428 is a series 40 - 120 volt control so the 6006A can be used to replace it.

How old is your boiler?

@ March 13, 2014 3:19 PM in converting oil burner to gas

Why do you want to convert? Is the oil system working to your satisfaction as far as providing adequate heat? Has the boiler been serviced every year? Is your chimney lined? There are a lot more questions I would ask as an installer.

Now to your question, Burnham does not authorize any of their boilers being converted from oil to gas. It will void the warranty if there still is one in effect. As long as the installer is a trained gas power conversion burner installer and follows the instructions from the gas conversion burner manufacturer and ANSI Z21.8 version 2002  there is no danger. I have converted over 3,500 systems from coal, oil to natural gas and propane. To this date I have had no issues with any of them other than routine maintenance.

The choice is between you and your contractor.

Mike a theoretical

@ March 13, 2014 3:05 PM in Propane and condensate

number is about a gallon per 100,000 BTU's, which is actually the amount relative to the vapors created by complete combustion which if those vapors cooled completely would come to that number. That being said the mod/con condensate must also calculate as to return water temperature and the stack temperature in the vent. So I would say it would be difficult to calculate without more sophisticated measuring devices. The stack temp and return water temp vary based on the demand placed on the system. The theoretical dew point of the flue gases is 140 ° F for gas, oil and propane. That added to the point of condensing on most boilers being around 135° F return water temperature adding the two gives 275° F which by most is considered the lowest stack we would allow on a conventional boiler systems. Mod/Cons operate at much lower temperatures which is why they condense, the lower the return water temperature and the lower the stack temperature the higher the amount of condensate based on firing rate. That presents another problem which is the modulating side of the picture which is controlled by some kind of outdoor reset or a combination of sensing both indoor and outdoor to control the firing rate of the system. Most residential systems have a 5 to 1 turn-down ratio. Taking the number 5 and dividing it into the input will give you the lowest firing rate an example 100,000 BTU's divided by 5 would give you approximately 20,000 the lowest firing rate.

As to propane being different than natural gas as to condensate the answer is in a given situation all things being equal they would produce the same amount of condensate

The system you have

@ March 12, 2014 8:39 PM in Bryant Plus 90 Code 33 to 13 but doesn't seem to be the limit switch.

is 24 volts so I would set the meter on AC volts to start with.

Is this the two

@ March 12, 2014 8:38 PM in Raypak H3-0135B Low Heat

stage version? You state that the pilot is on so I assume you are saying that the main burner is not on. Does the gas valve have a "red" handle (Robertshaw) if so make sure the handle is not on pilot it should be in the full on position.

This boiler also has a boiler outlet sensor which could be holding the boiler off. There is a high limit, vent temperature switch, and flame roll out switch any one of those could be holding the system from running.

Do you have a vent damper on this version?

There is also a fast response temperature sensor which could also be holding the system off it shuts off the 24 volts to the ignition control.

When an appliance states

@ March 12, 2014 8:03 PM in convert Nat gas to prop

for a certain gas only then it is not to be converted and if you choose to do so you are in danger of excessive carbon monoxide issues. DO NOT CONVERT IT!

It has to do with burner design, chamber size and internal venting issues. It also as Ice stated can be very costly as you literally would almost have to completely redesign it with all new parts.

Is your furnace getting its

@ March 12, 2014 11:53 AM in Gas ignitor only lasts one heating system

air for combustion from outside or from the room in which it is located? Igniters tend to last longer when air comes from outdoors, the indoor airborne VOC's (Volatile Organic Compounds) tend to drastically shorten the life of the igniter. That along with high voltages, short cycling etc.

Igniters both silicon carbide and silicon nitride have a somewhat short life as compared to other ignition systems.

Is it a furnace or

@ March 11, 2014 8:26 PM in Gas ignitor only lasts one heating system

a boiler there is a difference. What is the make and model as that will help in case there is a particular history. By the way some contractors change the igniter every year because some trainers tell them that is what to do as it will prevent a service call during the heating season.

Find out from your oil

@ March 11, 2014 1:40 PM in Carlin Gas Conversion or new oil tank?

man what size nozzle (GPH) you have on the burner and what the pump pressure is. That can be calculated to give you input.

We have a police

@ March 10, 2014 8:54 PM in Legionnaire's found in heating system

station in Mass that had to close due to Legionaire's: in the domestic water system in the station.

In Section "B" of the troubleshooting

@ March 8, 2014 1:20 PM in Help needed on flame rollout switch keeping tripping

manual Weil McLain part # 550-141-565/0691DCP page 6 and 7 "Checking Air Pressure Switch" under things to check one is DIRT ACCUMULATION ON FLAPPER IN TRANSITION.

There is realy nothing that

@ March 8, 2014 1:05 PM in Adjusting a Gas Control

you can do as you would need a Combustion Analyzer to a test and then of course you have to understand what the readings on the tester mean.

Are you having any problems with the installation that we might otherwise be able to help you with?

It is my

@ March 8, 2014 1:01 PM in Carlin Gas Conversion or new oil tank?

procedure to do a heat loss, then measure square feet of radiation and then look at what the oil guy was firing the unit at as far as nozzle size and pump pressure. That will bring us to a starting point as to input, then an accurate combustion test will allow you to fire the boiler at its maximum designed firing rate. This can then be adjusted by using the pressure regulator on the gas valve.

As for the lining on the chimney ANSI Z21.8 Procedures for the Installation of Gas Conversion Burners requires a liner with all conversions since 2002.

I've also been told that if the new conversion burner is within 95% of the BTUs of current oil burner than I can safely avoid lining the chimney. Does this sound correct? THAT RULE IS OUTDATED AND ANSI Z21.8 APPLIES.

Yes the action of that flap

@ March 7, 2014 1:24 PM in Help needed on flame rollout switch keeping tripping

affects the flue gas travel which in turn affects the chamber pressure and the extinction of the gas flame in time. The pressure switch works on differential pressure red hose to white hose with the flapper in between, the gas valve is directly controlled by the SPDT pressure switch making and breaking at the correct time other wise you have residual gas in the chamber with no air entrainment hence flame roll-out. The flue collector needs to be opened up and a professional who is familiar with the Weil McLain HE series to take a look at the flap.

I am sure if he or she was familar with gas

@ March 7, 2014 1:18 PM in Adjusting a Gas Control

conversion burners you got an excellent service call and a good combustion analysis.
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