Dirty propane ?

KCA_2

Hello all...

I have a 4million BTU propane pool boiler. It's a Pentair "Mega Therm"... Laars makes it....
It suites up in 48 hours of usage.... one issue is keeping the water at 110degrees or better but the flame is quite yellow.... it's an atmospheric boiler so I don't have much in the way of adjustments other than air shutters..... manifold pressures are within specs... what have I missed or what can I do to get this boiler to run more clean?
Jets are a 38 for 7,000' ASL..... and installed by the manufacturer...

Any help is appreciated..

:-)) KCA

Abracadabra

When was the last time the heat exchanger was cleaned? These heaters are notorious for not playing well when cold water is run thru them.

Firecontrol933

If the heat exchanger is clean and everything else with the boiler is to specs........... where is it located? Is there something in the combustion air that is contaminating it giving you the yellow flames and soot?

What shape are the burners in?

As for "dirty propane" I've seen it once. They had used the same tanker to haul anhydrous ammonia that they hauled propane in. Not sure what it could or would do, but in the situation in our town they pumped the entire bulk tank down at the suppliers and shipped it back and then proceeded to burn off everything left.

lchmb

Is the unit piped primary secondary? another issue with these is under rating them due to elevation. I would try down sizing the unit to see if this helps...How long has it been installed and is there sufficient combustion air to the unit?

KCA_2

The unit was cleaned 48 hours ago.... it's been in for four years.... apparently worked well until a year ago... plenty of clean combustion air.... aaarrrgghhh.

Mark Eatherton

What is the manifold pressure Ken? Obviously, something has changed. Is the non-thermostatic anti sweat device (bypass) operational ? If you are struggling to get to 110 F, maybe its under fired?

Have you talked to the LP supplier?

ME

hot_rod

Many of those pool heaters have a thermostatic valve built right into the headed, maybe it is not working properly.

Lp pressure set and maintaining?

GreenGene

It could be too much mercaptan in the tank.

GreenGene

I've also heard of pool heaters having too high a delta t and causing cooling of the flame which will cause sooting, if it was in for years and worked though something has changed, bypass? 3 way valve? are they letting the pool cool down and then firing it up to use it?

It may help to sit there and watch this thing run with the doors closed if it's inside.

KCA_2

Thanks for all the insight guys..... I very much appreciate it!
Ill keep you informed ... :-))

Tim McElwain

Have you done a combustion analysis? What is the inlet and outlet gas pressure? Have you checked to make sure the air for combustion and air quality have not changed. Airborne Chorline fumes has a way of screwing things up.

The quality of propane should not be an issue in most cases. Too much odorant will typically not cause yellow flames as long as the air adjustment is correct.

GreenGene

This should be the manual, they seem to reference soot a lot, sections 3-5.

http://www.pentairpool.com/pdfs/MegaTherm Heater 2000-5000OM.pdf

They have a contact list, just be sure you've gone through the start up process and checks in the manual and have numbers for them before calling, like all tech support they will want gas pressures, combustion tests, etc.

http://pentaircommercial.com/contact/index.html

GreenGene

Tim McElwain said:

Have you done a combustion analysis? What is the inlet and outlet gas pressure? Have you checked to make sure the air for combustion and air quality have not changed. Airborne Chorline fumes has a way of screwing things up.

The quality of propane should not be an issue in most cases. Too much odorant will typically not cause yellow flames as long as the air adjustment is correct.

Tim, I hear you, heard of chlorine fumes getting sucked in, seen chlorine eat things up at a YMCA, seen a few and read about a few jobs where the fuel is suspected, tank changed, problem went away, although the gas co isn't usually too pleased, when I was at Carrier we did have a few issues with rooftop units running great on NG and some not good on LP, I really think like electricity, all fuels have become a poor product. What do you think?

KCA_2

Well.... my first time there was last Thursday..... the inlet propane was at 8.5" and when the boiler fired it dropped to 6-7"..... I adjusted the inlet pressure to allow for 9" when the boiler fired... manifold pressure at high fire is 9"..... secondly, the vent is 33"..
30' rise and 8' horizontal.... the 350month water heater ties into this as well.... according to the GAMA tables the vent should be closer to 22"....total of 4350000 btu...... that can cause overheating.....
Minimum combustion air contamination.....
But it did work fine for 3 years or more.....
Aaaarrghhhh...

Firecontrol933

What does the rating plate on the unit specify as required inlet and manifold pressures on LP? A quick look and I found something on the general unit that said minimum of 11" inlet, but nothing on what the manifold pressure should be on LP.

GreenGene

Firecontrol933 said:

What does the rating plate on the unit specify as required inlet and manifold pressures on LP? A quick look and I found something on the general unit that said minimum of 11" inlet, but nothing on what the manifold pressure should be on LP.

I posted the factory manual above

Firecontrol933

GreenGene said:

Firecontrol933 said:

What does the rating plate on the unit specify as required inlet and manifold pressures on LP? A quick look and I found something on the general unit that said minimum of 11" inlet, but nothing on what the manifold pressure should be on LP.

I posted the factory manual above

Read the manual and that is why I asked the question. KCA said his inlet was 9" when the manual says it should be minimum of 11" and I was curious as to what the rating plate (where the manual says the required manifold pressure for the unit is listed) had to say about what the manifold pressure should be when firing.

KCA_2

Rating plate calls for 9 on high fire for LP....