Munchkin 140m; Broken blower shroud; Help- no heat

Steve M_2

A lot of Munchkin blower faiures I've seen have been caused by sucking in it's exhaust gases. If the gas pipe that connects to the gas valve inside the Munchkin cabinet is a brown color, that could be the problem. Check the vent termination and if it's a concentric vent, make sure the 3" termination is glued. After replacing blower, make sure you test the combustion with an analyzer.

coreys

Munchkin 140m- Broken blower shroud

What's going on here?

The fan seems totally fine, but this "shroud" piece has broken up.

The book says the Blower is part #7250P-086, but I wonder if that even includes this shroud piece?

Then I worry about the little shroud fragments, and where they went. Could they be clogging up the heat exchanger?

Anyone seen this one before? Kind of a silly point of failure. Thanks, -Corey

Perry_5

A similar failure was posted...

A similar failure was posted a year or two back. In that case more damage was done to the impeller, and pieces did get into the HX.

I wonder how many of these failures occur out there that never get reported here?

Perry

coreys

Update-That ain't no \"shroud\"

Argghh!

On further examination, it turns out the piece I thought was some sort of fixed "shroud" is really the broken off front face of the impeller itself. Now that's a really ridiculous point of failure. Not even a wearing sort of part. Looks like this cheap plastic bit is going to lead to a $500+ blower assembly. Anyone seen this before?

Perhaps I should send the broken part down to HTP.

Going to try to "McGyver" it for now.

tim smith

This happened to quite a bit on the Munchkins, was quite common

on earlier models of Munchkin, say pre 2007 models. I had at least one if not 2 fail just like that. Depending on age of Munchkin, they will very likely warranty it. Check with installer or whoever was supplier. They may have extended blower warranty to 3 or 5 yrs on those models when problem was happening.

coreys

Thanks Steve,

I'll check the glue joint on the concentric. If it's exhaust gases causing the plastic to break down, maybe I should dump the concentric for distinct pipes, and give them some separation.

I was able to McGyver the thing back together, and it runs, but loudly. Trying to get part now..

coreys

Thanks Tim,

For a 2002 model, I may be out of luck. My installer left the business, so I would have to work through it myself.

Jim Pompetti

Coret Snow

where do you live+

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coreys

Jim,

I live in MA

Wayco Wayne_2

In the past

I have extended the flu pipe on the concentric vents just to get separation to avoid recirculation. I recommend at least 18 inches of seperation. Seen lots of these failures. It helps to have long tee handle allan wrenches for the change out of the blower motor. Good Luck WW

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Big Will

Running temp?

I don't know if it could be related but I seem to be replacing more parts on condensing boilers that run at high temps. I have a munchie now that is a 2001 model that runs at 180. No controls for outdoor reset or domestic hot water production. I want to talk to them about upgrading the control's to the vision system so we cna let the boiler run cooler most of the time. Currently the outdoor reset is controlled by a mix valve with a outdoor reset sensor and controller. It seems like this could weaken plastics over time.

S Ebels_2

I'll ditto that

I have to say that exhaust gas recirc is a problem I run into often on all types of heating appliances. Some makes of equipment seem to have a little more trouble than others trying to "digest" it but regardless of that, it's something you want to avoid. The material used on about all the early production Munchkins seems to become brittle and break or just plain wear away as if an abrasive substance was present in the air stream....in the case of exhaust gas getting back into the burner, I guess that last statement would be absolutely true. The recirc'd gases are very corrosive in nature

troy_8

Munchkin

has a 100 second post purge that can be programmed into the board. This helps to ensure total exhaust gas evacuation after each cycle. With longer vent runs it seems to help. Lingering gases in the heat exchanger can break down the plastic as well as gases pulled in from outside.

coreys

Thanks Wayne,

I like your idea. I could extend the exhaust out from the concentric easily, assuming the outer diameter is something I can work with.

You are right about the wrenches. Access is not great, and there is not enough clearance for a ratchet bit. Had to remove the entire board, and make hundreds of little swings with a hex key. A tough-to-service design seems sort of silly given the vast amount of dead space otherwise in the case.

Also, the newer blower will not work with the old stainless support block underneath because it has a different shape. Had to move it aside. Hope it is ok without support there.

The new blower had a different molex connector block which had to be cut off for the old cable to fit- fortunately my supplier warned me about this one in advance!

It's running sweet now, but not starting consistently. I've been getting pressure switch faults on some startup attempts. Guess I just have to keep tweaking the adjustment until it is happy.

Ah, warmth is a special thing. Thanks again,

-Corey

coreys

Troy,

I think I would need the 925 controller to get that feature.
Nothing in the manual about it.

Thanks,

-Corey

coreys

Will,

The temp is set to 160. That's as low as I can go with the DHW and still have it keep up.

Like you say, "downstream" mixing devices do not do much good in terms of getting the return temps down into optimal condensing range.

I would like to upgrade the card and get a Tekmar controller to reset the boiler temp directly, then run the DHW at 180. Just can never quite get up the will to shell out the cash for the upgrade. Too many competing old house projects... and now I'm out $500 for this new blower...

Thanks,
-Corey

coreys

Thanks Steve,

If it's a known problem, perhaps HTP should change their directions. They even show an example with 3 concentrics through the wall right next to each other:

http://www.htproducts.com/literature/lp-166.pdf

...or redesign the concentric vent kit they sell if it's not good for horizontal situations.

As for abrasives, since my intake is low on the house, I was thinking about using some sort of filter on the intake for mower dust and such, but I cannot figure any way to do so with the concentric kit HTP sells. Say I were to dump the concentric completely, is there a good filter option that would not ruin the airflow? Do you think this is a good idea?

Thanks
-Corey

tim smith

Corey, I am a little concerned that you did not get the right

blower. Check with heat transfer and find out if it was correct. Now if what you had to do was in instructions then ok but that does not sound right. Tim

coreys

Tim,

Thanks for your concern. I am sure the part number is a match, and all of the mating surfaces line up perfectly.

The casting on the "bell" is slightly different, with a little nub sticking out to receive a threaded fastener from one side. This just happens to stick out exactly where the support block is.

The support block is a short bit of stainless square tube with 2 posts sticking up on either side, and it sits on top of the Hx enclosure. A stainless strap goes through the center of it, and wraps all of the way around the Hx enclosure, holding it down. The old blower rested on the block, providing a little extra support. I had to slide the block off to the side, or the flange going to the burner side would not align. Too late to take the picture that would immediately explain the whole thing.

Probably would have been better to grind off the nub, and keep the support.

Thanks again,
-Corey

Bill de Jong

MUNCHKIN BLOWER

How old is your boiler? HTP has a three year warranty on the blower. The other issue we have had to deal with here in Central Alberta in Canada with the Munchkin boilers is the disintegration of the swirl plates on the Dung's Gas Valves. If you thought you had trouble before.....

coreys

Bill,

It's a 2002 or 2003 model. I notice they sell the swirl plate as a distinct part. Not a lot of money. I wonder if it would make sense to replace it prophylactically if it can cause a major failure downstream. What happens when it goes?

Thanks,

-Corey

ScottMP

Corey

We are in MA. and if you need some more hepl with the boiler let me know if we can help.

Scott Milne

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coreys

Thanks Scott,

I might need some things- perhaps in the Spring. A little far to MBTS though.

Wish I had called you for the installation years back. Did not go well.

Alex Bell

Check the sticker on the blower

HTP had a batch of mislabeled blower boxes recently. They had EBMPapst RG128 blowers in 140M blower boxes. There should have RG148s in the boxes. Check the sticker on the blower to make sure you have the right one. RG128s are for the 80Ms and maybe others. If you put the RG128 on the 140M it will work but will derate the boiler some and combustion numbers would probably be off.

coreys

Alex,

Thanks for helping me cross-check that number.
Fortunately, it turns out I do have the right blower.

It would have been no fun sorting out a bad-box problem!

I would just mention that intel on these types of obscure problems is exactly the sort of thing that makes this forum really great. Had I had the wrong part, imagine how impossible it would have been to figure that out.

The trick is gathering a critical mass of experts like yourself, as Dan has done here.

Thanks again,

-Corey

TimS

blower

I guess you have no 925 control. but the older analog blinking light board. The blower is supposed to come with the molex plug that adapts to the older controls. No big deal sliding the support block out of the way, I often have to do that too. Its easier to remove the whole blower and burner assembly then replace blower at the bench lots of space thats a good time to clean the burner and heat exchanger (that ruotine annual service) . What is the blinky light error you have . Occasionally I have had pressure switch problems with older controls and newer blowers . I highly recommend upgrading the controller to the new 926control add the vision 1 kit for two temperature operation with outdoor reset change piping as per vision1 instruction . I understand this may be hard to justify on an ageing mod/con boiler that has around a 10 year life. So atleast get the control upgrade it offers some good features like eliminates the blower prove switch and flame rectification at spark rod & flame rod.
The fan pictures are good notice the blackened dirty pitting alum. fan housing tells me the problem is worse than exhaust recirc. I susspect you have sidewall vent terminations there may be a negative draft of air flowing thru the heat exchanger out the blower picking up acidic condensate onthe way when boiler is in standby mode results early blower failure . You dont have any swirlplate these are on the R1 and R2 munchkins . TIP Fix the problem by installing 1/4 thick gasket (weather strip) seal around cabinet and secure cabinet cover with grabber screws and fill in any other cracks or holes on cabinet to stop all air infiltration and this negative draft.

coreys

Thanks for the info Gerry,

I trying to understand the physics of the draft problem you describe.

It seems like with both the intake and exhaust on the same sidewall that any wind forced draft potential would be equalized.

Anything coming down the intake pipe while the boiler is off should be clean, so...

Do you mean that cold air is flowing down the exhaust pipe, through the exchanger, the blower, out the gas valve, and into the house through gaps in the case while the boiler is off? That is the only way I can see for acidic byproducts to get back into the blower when it is off. Sealing the case does not look too tough.

TimS

yes that is whats happening

you can feel the humid air coming out of the blower after the boiler shuts down.
This is common problem with sidewall vent almost never a problem with thru roof venting. New homes are tight construction slightly negative air pressure so outside air will infiltrate any where it can even thru your boiler its like an open window so seal the cabinet cover to stop this infiltration the room air cannot communicate with air inside boiler cabinet .

Perry_5

Some Boilers are sealed enough that

Some boilers are well sealed and this is not a problem. House air leakage to the combustion side is minimized.

I cannot notice any issue with my Vitodens. My guess is that some other boilers also are sealed well enough not to be a problem. I do admit though that they are not likely to be the cheapest ones on the market (you don't get what you don't pay for).

Perry

TimS

this particular is not sealed

the new r2 are sealed cabinets ,most all other manufacturers are sealed well .
This boiler was very cmpetively priced alot were installed in my area several years ago . All I do is service customers usually call me when they have problems so I rarely see the boilers that are installed well and working well but I have seen more of this particular boiler than all others combined .

coreys

I would not say these boilers were exactly cheap, but I guess everything is relative when you bring in German hardware.

I never would have thought that a unit using external combustion air would have a "backdraft" problem, slightly leaky cabinet or none. I would have guessed that the combination of the blower's post-cycle purge (too short I guess) and the latent convective forces (exhaust not super hot, but still hotter than intake) would clear out the combustion gases in the right direction. Obviously not happening though.
Thanks for the insight,
-Corey

Unknown

yes.

A few years ago I had an 80 do the same thing. Pre 925 boiler.

s.teermjen2574372

swirl plate deterioration

Yep, my mc-80 is "chugging" intermittently. After several calls to thier tech dept. I still didn't have the answer. My heat tech buddy had me pull the blower and check the swirl plate. It is gone! (3rd. season) I cannot buy that the factory dept. hasn't clued in on this. It is clearly an exaust gas recirculation issue. HTP needs to correct thier specifications on concenrtics and termination specs. By ther way, all of the other signs mantioned are there. Brown brass,and discolored materials under the shroud, etc. Another contributing factor was the fact the condensate tube had shrunk at least 1/2" in length, partially pulling off the top of the cup. This allowed exhaust gas to directly re-enter the system. (Another problem they never heard of)