Efficiency test

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Old 03-25-13, 04:22 AM
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Efficiency test

Hi all, it an efficiency test the same as a combustion analysis ? For a propane fired boiler.

Thanks
 
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Old 03-25-13, 04:56 AM
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Yes, they are one in the same and should be done for any fossil fuel fire boiler
 
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Old 03-25-13, 04:56 AM
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Sort of depends on the context. It would be difficult for one to do anything other than combustion efficiency in the field. The answer is probably yes, it's the same, if this is something a tech is going to do with your boiler.
 
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Old 03-25-13, 05:03 AM
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As I talk to hundreds of contractors every week I hear that a lot since they are using a combustion analyzer.
 
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Old 03-25-13, 02:03 PM
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OK Thanks,my next question would be that my Buderus G124SP25 had an efficiency test this AM and all the reading were spot on,only notation was a code violation for the flue size being reduced 5"to 4" ,the boiler has been in service 9 years,recently the spill switch on the draft hood has tripped on occasion ,why then now should I increase the flue size?

Thoughts
 
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Old 03-25-13, 03:02 PM
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a code violation for the flue size being reduced 5"to 4"
Who was the person doing the testing? Not a code official, correct?

Did it pass muster when it was installed?

Did the guy give you his brother-in-laws card who just happens to be a chimney guy, and suggest you call him for some rework? ( me? cynical? naaaahhhhh )

I believe that NFPA allows 1 flue size up or down.

Is that a G A 124 ?

recently the spill switch on the draft hood has tripped on occasion
It's probably a bi-metal 'snap-disc' safety switch? The do have a tendency to go 'soft' over time, so before you get all freaked out, make sure that's not the reason for it tripping.
 
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Old 03-25-13, 03:08 PM
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Maybe this isn't your boiler... GA124, but this is in that manual:

USER NOTE
You must follow all directions for
installation of the flue venting in all parts
of the flue system, particularly the
assembly instructions of the flue system
manufacturer. Use only pipes with a
diameter of 3" for the flue pipes and
accessories from the manufacturer
named in Tab. 6.

Use rigid or flexible metallic pipes with a
diameter of 3" for the combustion line.
 
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Old 03-25-13, 03:15 PM
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The G124 X model (is this what you have?) says only this about flue pipe size:

The flue pipe must not be reduced in size and venting
must not be prevented by the installation of additional
components.
Never actually mentioning the size... (I didn't look ALL through the manual...)

What size is the flue outlet of the boiler itself?

Where is the reduction in size made?
 
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Old 03-25-13, 04:07 PM
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Flue size

Right it is the G124XSP25 it is a 5" reduced to 4" about 2' above the boiler,my problem is it has worked fine for 9+ years what will I gain by increasing the size now? I will be changing the spill switch shortly.
Cheers!
 
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Old 03-25-13, 04:33 PM
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Flue size

The boiler is a G124XSP25 flue size on boiler is 5" reduction is to 4" about 2' from the top of the boiler, no inspections in this part of NH unless it is oil fired, and NO the tech did not recommend any relative to replace the flue.Sure would like to find that NFPA article on flue size,but I believe that the code would say that the mfg. recommendations must be followed at least in the electrical trade it is that way.
I will look into replacing the spill switch in any case.
 
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Old 03-26-13, 12:16 AM
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Looking at this from a different way...
What has changed just before you started having spill switch issues ?
Did you tighted up the house any ?
Did you maybe enclosed a previously unenclosed boiler room ?
Did you install a new range hood that is higher cfm. ?
Typically these spill switches trip when the appliance back drafts for some reason.
Did the tech that came test the chimney draft under all conditions ?
If there are no changes that you can think of, try to crack a window in the mech room slightly for a while and see if the problem returns, if it does I might replace the spill switch. If it does not return then I suspect you have some depressurization issues in your home.
 
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Old 03-26-13, 01:59 PM
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What has changed is.
1.installed a pellet stove in the basement (with it's own makeup air supply).
2. We are leaving the door at the top of the stairs so the heat from the pellet stove will rise up
3. Installed a fresh air makeup duct for the boiler.
The tech did the testing under existing conditions. The spill switch has tripped a couple of times since.
 
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Old 03-26-13, 03:00 PM
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Sure would like to find that NFPA article on flue size
The applicable document is the "National Fuel Gas Code," NFPA 54. Maybe you can get a copy through your local library? Standards organization such as NFPA support themselves by selling their code documents and you won't find it for free on the internet. NFPA 54 will set you back $82.50. The NFPA 54 Handbook, which includes the code, costs $132.50.
 
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Old 03-28-13, 06:17 PM
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The code states that a vent pipe may be reduced one size up to 12" and two sizes above12". This is providing all other parts of the code are met and it meets the liner manufacture spec's. it also states tat any reductions are t the chimney base. Wonder if that is what the manual is referring to, full use to the chimney base.
Boiler chimney venting (category 1) is controlled by NFPA 54 and NFGC. Category 3 & 4 is controlled by the manufacturer. Manufacturers most of the time override the code.
 
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Old 03-30-13, 11:23 AM
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When doing an efficiency test, should the tech try tweaking the system for better results, or is it accepted to just do the test and record results on the hang tag?
 
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Old 03-30-13, 03:39 PM
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There isn't much to tweak except to adjust the air. If the combustion analysis shows too much or too little excess air, then I would expect him to adjust the air shutters. You'd have to ask him what he did. But probably fine tuning the air wouldn't change the efficiency drastically.

For an oil-fired boiler, I would expect him to clean it and possibly replace the nozzle? But it sort of depends upon what you hired him to do and what he said he was going to do. My primary experience is with non-condensing, gas-fired units, which usually require no routine professional maintenance.

Was this somebody you've used before or who came recommended by people you contacted? If you call somebody out of the yellow pages, caveat emptor.
 
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Old 03-30-13, 05:33 PM
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Although I'm grateful for the service availability, a part of me distrusts the routine annual service that comes from the oil company as part of their policy. On one hand they want to service it for efficiency, and on the other sell us oil.

They change the nozzle, electrodes, filters and vac the boiler. Sometimes they change the sight glass, clean out the chimney, flush some water and paint the face of the boiler. They've been back to replace things like the transformer, CAD cell and clear crud from the fuel line. They used to clean muck from the LWCO float chamber, but that went off their list.

I don't know if they really set it up as efficiently as it could be. They take the readings when done, write it all on the service card and take off.

Apologize if I've hijacked the thread, wasn't my intent. I've always wondered if the tests are just to verify safe operation, or to tweak the settings. No attention has ever been paid to things like the four main steam valves, the steam trap, condensation tank, the murky water etc in this light commercial system. An energy audit had suggestions for improving the draft and downsizing the nozzle. Would it be preferable to have it serviced by someone other than the oil provider?
 
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Old 03-30-13, 06:10 PM
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Would it be preferable to have it serviced by someone other than the oil provider?
Yes, if you don't trust them or are dissatisfied. What do your neighbors say? You have your choice of oil suppliers, too, right?
I've always wondered if the tests are just to verify safe operation, or to tweak the settings.
It's difficult or impossible for us here to answer that. You should ask your oil supplier and go from there.
 
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