Munchkin Rumbling

Josh M.

Hey gents,

I have a munchkin 140 that rumbles on high fire. In fact I can put my hand over the intake and I can feel air coming out instead of in. A couple things that I have already done is to verify that the condensate is free and clear as well as exhaust, verified that the orifice is the right size. I also thought that it might be running to lean so I tried to adjust the gas adjustment screw until it stopped and the boiler still rumbles at every position possible. Appreciate your help guys

Josh

J.C.A._3

What are ,

You using for intake/exhaust? Chris

S Ebels

Rumbling..... usually not a good thing

What is the CO and CO2 reading at high and low fire? Check them and verify against HTP spec's

Did you double check the condensate drain?

Is the vent and intake free and clear of debris or restriction?

Have you inspected the HX to see if it's sooted or partially plugged?

What is the incoming gas pressure while the unit is running. Check at low all the way to high fire.

Bet you'll uncover the problem whilst investigating/verifying one of the above.

Josh M.

Thanks guys I have already tried all of your suggestions except the sooting thing because this is a start up. So if you have any obscure items that you might have run across I am willing to try anything!

jerry scharf_2

There was another thread about this a while back

I'm not sure this will be helpful, but wanted to pass this along just in case. Guy will know it for sure (I'm assuming Chuck is still on the hunt )

There was something that if the CO level on high fire was too low, there was a burner harmonic that would cause significant noise. So make sure that the CO level is really within spec, not just below the high spec.

good luck,
jerry

Weezbo

rumbling gas appliances is unacceptable.

Throw it back .... another idea is supply piping sufficent for the burn? another idea is what is the fuel pressure?

Marc Sherby_2

Josh;

Turn your throttle adjustment screw CCW in 1/8 to 1/4 turn increments to a max of 11/2 turns from factory spec. Also check your Gas pressure both static & dynamic. Should be NO lower than 9" WC LP gas or 5" WC natural on high fire. Check your CO on hi fire 105PPM is a good level. Anything higher than 175 will soot. Check to see your flame rectifier and ignitor are clean. Have had a few Munchkins that we sold with rumble incidents. The above usually fixes the condition.


Marc Sherby
Radiant Heat Supply 610-466-0500

Guy_5

Everyone seems to be on the right track here.
Is this a new installation or an existing job? If the boiler is equipped with the Honeywell control board, the boiler has a shorter post purge. In some situations I have, over time, seen latent heat break down the air intake venturi on the left side of the blower. This would significantly alter the air /fuel mixture.
One last possibility is the burner gasket itself: The borner has a flange at the base where it is secured to the face plate. If the flange has warped, or the gasket has disintegrated, you will get rumbling.
Give me a call at 800-323-9651 Ext. (9)57 and I will help you in every way that I can.



Guy Woollard
Heat Transfer Products

Alan(CaliforniaRadiant)Forbes

Josh

The first time we installed a Munchkin, we didn't pipe it primary/seconday. It rumbled all the time because it wasn't getting enough flow through the heat exchanger to pick up all the heat.

What's the flow like through your boiler?

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J.C.A._3

First \"rumbler\" I saw,

Had some of the same symptoms described. Positive pressure at the intake was the dead give-away. The exhaust on a concentric vent kit, had come loose. boilers run real good on air, when they're trying to recycle exhaust gasses, they rumble like no tomorrow. Just my experience So far. Chris

Josh M.

Thanks guys for all of your help on this one. I now have a few more things that I can try. However I think that possibly the primary regulator orifice isn't large enough to deliver the CFH required.

Rodney Summers

Can anyone tell me if the attached sketch is a true primary/secondary piping scheme?

THanks!

Alan(CaliforniaRadiant)Forbes

No

closely spaced tees so it's not primary-secondary. The boiler loop (primary) is not uncoupled from the secondary loop. There are a few other things wrong as well.

http://www.pmengineer.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2732,2755,00.html

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RoosterBoy

no .

it needs some pieces of pipe to make it parallel primary /secondary .
you have series for the most part...