Munchkin 80MLP Advice Needed

dabineri

I have a 2003 Munchkin 80MLP that is working great but I opened the cover to try to track down a noise and noticed that the blower has a pretty good vibration to it. This model has no swirl plate.

Is this something that I should have my HVAC repair man replace after being in use for about 12 years?

If it is the bearings that are going will they be able to do that rather than replace the whole unit?

Is this a common problem?

Thanks for advice on this problem. Dave

Ironman

You can replace it now and not have to worry about it, or let it go, and when it quits, you may be without heat for days waiting on the part or the tech to show up.

You have to do the entire fan assembly.

dabineri

Thanks for the reply Ironman. If it is vibrating enough to hear and certainly feel then it should be replaced? How long do blowers like this generally last? Thanks, again. Dave

jpcallan

A Munchkin draft blower is an expensive part, maybe $400 to$700 depending on the installer, plus labor. These are made by EBM-Pabst in Germany. Two causes will make the blower vibrate:

1) Ingestion of exhaust gases. Looking into the blower's inlet and outlet to see the aluminum impeller. If it is pitted or obviously corroded, you need to replace the blower and (if present) swirl ring. Move your system's fresh air inlet and exhaust outlet further apart to prevent exhaust gases from recirculating.

2) Accumulated dirt on the impeller. I have repaired vibration issues with a thorough cleaning to where it runs nearly vibration free, like new. As you are probably aware, the Munchkin family of boilers do not have an air cleaner upstream of the blower, so any airborne dirt present is drawn into the blower. Usually the blower gets coated with dirt buildup uniformly, but eventually dirt deposits will build up unevenly and off-balance the unit. If you have a DIY bent, good mechanical skills and patience, remove the blower, open the case and flush the dirt away with a cleaner like CRC Brakleen solvent (available from any auto parts store). Gently scrub the nooks and crevices with the solvent and an old tooth brush. The aluminum impeller is delicate, so handle it very carefully. Reassemble the blower housing, then remove the plastic motor cover and blow the motor assembly out with compressed air.

If you want the maximum life from the blower, you can overhaul the blower by also replacing the motor's ball bearings. An overhaul will consume a lot of time, so it's probably a job for the off-season.

dabineri

Many thanks, jp, this is useful advice. Where might one get the bearings for this unit?
Dave

Steve Ebels_3

Typically the draft inducer is replaced as a unit. That is the only way they are sold due to product liability.
Don't mess with trying to repair it. There are far too many things that can go wrong. There is serious danger if the inducer is not functioning 100% perfectly.

I have never heard of bearings being replaced. Ever.

At 12 years of age, the issue is very likely to be that it is just plain worn out. The bearings themselves may be perfect but 9 out of 10 times the cause of vibration is the blower wheel/impeller/fan blade or whatever you want to call it. Not available as a spare part anywhere that I have ever come across.

At some point the inducer will fail completely and I can just about guarantee it will not be in July.
Bite the bullet and replace it. Or better yet..........replace the boiler. Any boiler mechanic with even moderate knowledge of these units will tell you it is at the end of its useful life.

hot_rod

Some of the early versions of the inducers had issues with the impeller getting loose on the shaft and causing the vibration and eventual failure of the impeller and or motor.

It gets to be an expensive hobby quickly when components on a mod con boiler start to fail or wear out.

Has it had yearly service and tune up? Heat exchanger cleaned and checked every year or so?

dabineri

I have replaced the inducer and all is running well right now.

Is the life of a boiler like this really about a dozen years? Which replacement boiler o you guys recommend from both a performance and maintenance point of view? This is a Munchkin 80. Thanks, Dave

hot_rod

It is hard to predict the life expectancy of mechanical devices. It depends on how well it was set up and maintained, how often it cycles on/ off, and at some point pure luck

I believe that boiler has been around since 2001, so there are 15 year old versions out there. The R-1 revision was built between 02 and 06, that is probably what you have.

Scrolling back through old posts in the early 2000's here, many predicted 12- 15 year life expectancy.

The question, or gamble is when you stop repairing and consider a replacement.

Sounds like you are up and going for now.

There are a confusing amount of choices for a replacement, have a heat load calculation performed to see what size you actually require. Go with the brand suggestions of the local contractors, they usually know what brands work well and have good product and parts support in your area.

dabineri

Thanks, hot rod, very good advice I believe!

Leo_G

I have only 1 Munchkin left that I service now. It is on a baseboard system, and supplies the heat for the hot water holding tank. Very little condensation seems to be the trick for these pioneering boilers. Any that I installed or serviced that were used for floor heat were all gone by year eight. That has a lot to do with our gas situation here in metro Vancouver, a lot of iron particulate in our gas, so it attacks the cheaper stainless used in these boilers as it condenses out.

I still have my druthers about these mod-cons. I service many standard boilers that are way past 30 - 40 years of age, and it appears that they will go another 20 or more. Taking into the life cycle, ease of repair and cost of our gas, I still believe the best investment is with a standard boiler, but most times feel like I am howling into the wind!

jpcallan

dabineri said:

Many thanks, jp, this is useful advice. Where might one get the bearings for this unit?
Dave

They are common metric ball bearings. The model of the bearing and maker is usually tattooed on the side on both dust shields. Applied Industrial, McGuire Bearing, or Grainger will all have them available. This is an off-season task.

"Steve Ebels" follow-on comment has some truth to it about product liability, and a professional HVAC tech would never rebuild a customer's blower and take hours to do so when a new one can be sold with (as an example, a blower for a Munchkin 199M) a profit of $200 to $400 depending on the market and locale. On the other hand if you own the boiler and the money is coming out of your pocket for a replacement part rather than going into your pocket as margin on a part sale, well then the picture looks different.

If you open up a failed EBM-Pabst draft inducer motor, you will find most models (not all) are electronically commutated and have no brushes to wear out. With the exception of the bearings, there is little to wear out (acid exhaust vapor ingestion is an obvious exception). If the impeller gets off balance or the bearing wear out, resulting vibration will eventually shake the blower's control board to death. But if the part is rebuilt before it passes the point of no return, there is no reason a blower couldn't last 30 years.

I am kind of an old guy. Years ago I learned to rebuild failed parts when possible and when time permits. I enjoy making old parts last longer than intended. I own a 1985 Lennox 4 ton condensing unit next to my house. When the GE fan motor failed about 5 years ago, the shaft and bearing were badly rusted from water intrusion caused by a cracked rain shield. A new motor was about $150, but I spent $200 having my machine shop fabricate a new shaft from 304 stainless steel; installing new stainless steel bearings packed with hydrophobic grease; and an AO Smith Rain Shield the was ten times better than the original Lennox part; my favorite machine shop has a balancing lathe, so the rebuilt motor was also precision balanced. The motor had no brushes wear out, and in the cool marine climate we enjoy here, the rebuilt motor will be just short of immortal.

This is my idea of fun, but I understand it is not for everybody.

dabineri

Do others agree or disagree with Leo-G?

Dave

hot_rod

How much have you spent repairing or maintaining it over the years?

Back then it may have been a $1000.00 or more upgrade from a cast iron equivalent?

It's not unusual for a standing pilot or spark ignition cast boiler to last 20- 30 years with little, sometimes no maintenance.

The numbers may not be in your favor, depending on when you pull the plug.

Hopefully it is on a low temperature system, or in condensing mode much of the time?

jpcallan

dabineri said:

Do others agree or disagree with Leo-G?

Dave

I must disagree with part of what Leo-G says above.

First the Munchkin and most mod-con boiler are made from 316L stainless steel, high nickel content, high chromium content with low carbon content (Fe, <0.03% C, 16-18.5% Cr, 10-14% Ni, 2-3% Mo, <2% Mn, <1% Si), which is just about the most corrosion resistant stainless grade the there is short of the so-called super-alloy families like Stellite, Hastalloy, Incaloy, etc. 316L is the first choice of stainless used on yachts in salt water above and below the water line.

High condensate production equals maximum fuel economy, which everyone wants. My customers use the Munchkin's Vision I firmware to absolutely minimize the flue gas temperature and maximize condensate production. I have yet to see a water jacket failure since my first install in 2004.

Leo-G is correct that 300 series stainless steel does not like contact with elemental iron in a corrosive environment, but I have my doubts about the gas fuel supply as the source. I have a customer near a busy road whose Munchkin loads with what I can best describe as black grains of rice each year. After blaming the gas company for a few years, I noticed how dirty the unit was under the cover. I have come to believe the black rice is fused road dust from wear and test on the local street and nearby main road carried into the boiler with the combustion air, probably basalt and asphalt.

Leo-G is also correct about good old rock solid cast iron boiler lasting a long, long time. They have few moving parts, so there's little to go wrong. An old time hydronic siphon or convection system had only one moving part: either a gas valve or coal stoker. What these venerable old soldiers lack is fuel efficiency.

dabineri

You guys have a great deal of useful info and I thank you sharing it. Now, when my Munchkin goes, what are the components most likely to fail? It seems that the main parts are the gas valve, blower, heating element, pipe surrounding the burner, and the electronics. What should I be watching most carefully?