Munckin 140m F14 error: blower and/or circulators?

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  #1  
Old 12-16-12, 12:30 PM
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Munckin 140m F14 error: blower and/or circulators?

2200 sq ft residence, converted gravity with cast iron radiators plus second RFH zone, Munchkin 140M mod/con is about 7 years old with 925 control panel and Vision (outdoor reset) control.

Boiler has begun throwing intermittent F14 codes, like once every day or two. F14 is a fan speed error, "blower too fast, more than 130% of expected rate for more than 60 seconds." I read F14 usually the blower, sometimes the control board. Both are original on this unit.

I am trying to troubleshoot before I spring for a $400 part. I have checked the blower molex connections, and the blower kicks in as expected when the bottom connector is unplugged, so no apparent problems there. FYI the blower did suffer from exhaust gas intake for a couple years after the initial install, but I altered the exhaust piping and there is no evidence (new pitting etc) that exhaust gas is still a problem.

Today it threw F14 so I watched it, here is what I saw: Stat calls for boiler and it kicks in, blower purges at high speed, boiler ignites and temp ramps up (system temp is close to set point right now), blower throttles the fan speed back to about 1900 (minimum is supposedly set at 1400), 1900 isn't low enough and the boiler short cycles within a few minutes. After this happens a few times, the system throws an F14. If I reset the error, this series happens very reliably right now: a few short cycles, then an F14.

So I put the boiler in test mode, to see if I can get it to run at less than 1900. Minimum I can run in test mode is 1450. But while I am running at 1450 I notice the boiler temp inches way up; after 5 minutes i exit test mode as the system temp is now 180. This thing NEVER runs higher than 160, I think the max set point is like 170 for when it is -20 F outside. I was really surprised, all three circulators were humming, and with the volume of water in this system it takes a looooong time to drive up the temp.

SO here's the question(s): could this in fact be a circulator problem, and the blower speed code is incidental due to short cycling? The Grundfos 15-58 FC units *sound* like they are working; should I pull them and test or inspect them somehow? Should I look for a clogged HeatX (ugh)? Or is this more obviously a blower problem to a more experienced eye?

Pics of the boiler are here, post #8 from a couple years ago, but I can post up some more if it would help: [sorry, links to other forums aren't allowed... linking pics is OK... I fix...]





 

Last edited by NJT; 12-16-12 at 02:03 PM.
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Old 12-16-12, 01:10 PM
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It seems that this is a problem with the computer that controls and monitors the boiler. Perhaps somebody here is familiar with your system, but otherwise, it will be difficult for anyone to identify the problem over the Internet? Does your manual have a troubleshooting guide? Can you link us to the manual and installation guide?

When you say that the boiler "runs at 1900," 1900 what?
 
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Old 12-16-12, 01:24 PM
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Oops, the 1900 refers to the fan speed, I just edited my post to fix that.

There is a troubleshooting guide in the manual but OI have tried to indicate that I think I have exhausted what little they say about troubleshooting an F14. Here is a pdf link to the manual:

http://www.munchkinboiler.net/upload...stallation.pdf
 
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Old 12-16-12, 02:06 PM
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Perhaps 1900 IS the correct speed, but the computer is SENSING something different?

OR

From what you can tell, the computer is telling the fan to go to 1900, and it IS slowing down, but perhaps it is running faster than that?
 
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Old 12-16-12, 02:13 PM
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d6 ó Actual Fan speed multiplied by 10
(Example: If fan speed displayed is
|410| RPM x 10 = 4100 actual fan
speed)
This is where you are seeing the 1900?

Is there a way to know what the computer WANTS the fan speed to be?

I find it a little bizarre that they want technicians 'tinkering' by replacing the fan first, and then if that don't fix it, to replace the controller... there should be some way to actually TEST to determine which it is...
 
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Old 12-16-12, 04:37 PM
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Yes to NJ Trooper's last question: I see 194 or 195 (i.e. fan speed of 1950) on the display when the boiler cuts out and throws the F14.

And Trooper you also figured out why I am a bit frustrated with the manual, apparently the field test for a tech is to just replace parts until it works!

From my observations, the fan ratchets up and down in correlation with the displayed speed, and the boiler "seems" to be modulating the way it always has. Granted I have no way of knowing if fan speed is displaying accurately. One thought I had is that the computer is telling the fan to run at say 1400 but it is running at 1950 as per the display; that would be 30% over (1.3 x 1400 = 1820, so anything over that would be an F14). At 1950, the blower is more than 30% over for any speed under 1500.

Now that the system temp has cooled down it is not short cycling. It seems less likely there is a pump/circulation issue, more so a computer or blower problem.

But which ???
 
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Old 12-16-12, 04:54 PM
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But which ???
Good Q...

There's 4 wires on the blower right?

Two going to X-4 and two going to X-5 ?

I'm presuming that one (probably X-5, labeled HOT and NEUTRAL) are the power to the blower, and the two on X-4 are probably the 'tachometer'.

I have no idea what the tach sigs would look like, but if one had an oscilloscope with an ISOLATED DIFFERENTIAL PROBE, that tach signal could be visualized... but what would one be looking for? And how many of us own and know how to use oscilloscope anyway?

Can you see the motor end of the combustion blower? Any identifying labels/part numbers on it?
 
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Old 12-16-12, 04:57 PM
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Holy Guacamole ! I bet you thought the computer board would be more than the blower, diddincha?

Munchkin Combustion Blower with gasket.
 
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Old 12-16-12, 05:16 PM
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I know this isn't much help... but here anyway:

F13: The Fan is running too Slow. Check the wiring of the blower. Check the rpms of the blower. The series A 199Mís polarity could be the reason. Older blowers, series A, with a non molex connection should not be used with series B & C 925 controls. Usually, this means the blower needs to be replaced. However, check the termination for exhaust air recirculating back into the intake air. This will destroy the blower and the next blower if not fixed.



F14: Fan is running too fast. See F13, but not a recirculation or deteriorating blower problem.
That earlier price is undoubtedly retail... should be able to find for maybe half.
 
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Old 12-16-12, 09:54 PM
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Cheapest I can find the blower is $400. Out of Omaha, which is close to me. The control board costs right about the same!

Yes on the 4 wires, yes I don't own or know how to use an oscilloscope ...

It never occurred to me to try to see if the blower has some identifiers on it. I will check that out next, thank you. Hopefully can get to it tomorrow night.

Should be completely breaking down right about Dec 25, right on schedule ... At least it isn't very cold so far this year.
 
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Old 12-17-12, 03:00 PM
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Should be completely breaking down right about Dec 25, right on schedule
Well, chances this year not so good, Christmas is not on a Sunday; but if it were, there would be a 500 year blizzard and it would be 3 AM.

At this point, I'd probably pick up a can of "De-Oxit Gold" and give the connectors a squirt of cleaner... after that I would plug and unplug every molex connector I saw in order to 'wipe' clean the contacts. Take a bright light and shine into the end of connectors looking for any kind of corrosion or decrepitude. anything to avoid having to replace a $400 part!
 
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Old 12-17-12, 06:47 PM
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Most good digital multieters have a Hz setting on them. Both of my Flukes do. You should be able to connect your meter's leads to that sensor and read it on Hz. You would multiply that reading times 60 to get RPM's.
 
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Old 12-17-12, 07:04 PM
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I was thinking that too...

But we don't really know for sure how many 'pulses' per revolution that sensor is outputting.

It may not even be a pulse, it might be a sine wave even... but still measurable with a multimeter... IF we knew for sure how it related to the actual RPM... 1:1 ? possibly, but maybe not.

Still, would be interesting to try! Maybe we'll 'invent' a procedure? Maybe HT will pay us royalties? ha ha ha ha NOT!
 
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Old 12-17-12, 07:06 PM
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Steve, why don't you call HTP and see if you can talk to an engineer... pretend you are an engineer too! You know how engineers love to BS each other... (uhhhh... I'm not speaking from experience! )
 
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Old 12-17-12, 07:56 PM
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Uh oh.......road trip to Iowa
 
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Old 12-17-12, 09:56 PM
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Gee, looks like I missed the fun while I was at my daughter's winter band concert. Generous hospitality for anyone who makes the trip to Iowa. Beautiful time to visit

My decade-of-service meter is a cheap Sperry but just crapped out on me last month, haven't picked up a new one yet. Maybe I need one with a Hz setting.

Next step: clean everything with a connector on it. I've already inspected the connectors to the blower and they look good but might as well check them all.

Well the motor has identifiers, "EBM RG148," but using that number I can only find it for even more expensive than $400. So the HTP part is the one I am trying to avoid buying.

The behavior is very predictable now that I have been watching it for a few days. When the system temp heats up and the blower needs to be most tightly modulated, i.e. at its lowest steady speed, speed creeps up and throws the F14. So in other words, it works pretty well except when it should be condensing the most! OK, still either the panel or the blower but on some other boards, at least one Munchkin expert tells me this is a bad blower.
 
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Old 12-18-12, 07:36 AM
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Schematic on page 4... looks like PWM (Pulse Width Modulation) speed control.

I don't fully understand the schematic though, it shows lots more connections than what it seems your boiler uses.

I believe that there is the AC power going in...

And the other two wires, one is probably the PWM speed COMMAND from the control board, and the other is the TACH OUTPUT (2 pulses per rev) FEEDBACK. These are probably referenced to system ground.

img.ebmpapst.com/.../EC-centrifugal-fan-RG14812003633-ENG.pdf

Probably getting way too techno-geek here, but this PDF also has info:

http://www.ebmpapst.us/techdocs/Prem...%20Blowers.pdf

Some real scienterrific stuff in that one...
 

Last edited by NJT; 12-18-12 at 08:03 AM.
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Old 12-18-12, 01:35 PM
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Gee, looks like I missed the fun while I was at my daughter's winter band concert. Generous hospitality for anyone who makes the trip to Iowa. Beautiful time to visit
You were lucky to get out of (Fort?) Dodge when you did: NOAA National Weather Service
 
  #19  
Old 12-23-12, 09:12 AM
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I was given instructions how to test the blower motor (fan) with a voltmeter and I used them, so I post them up here:

(1) Make sure there is 120v going to the fan. This is easily tested by unplugging the 3-pin connector and testing the black wire. Then plug it back in.

(2) From the 5-pin connector, while it is still connected to the fan, measure the DC voltage from the red fan wire to the ground. It should be between 24-40 volts. If it is lower than 24 volts, check for excessive external loads connected to the boiler sensor terminals.

NOTE: I found it to slip an external wire in where that red wire connects to the controller board, and hooking the DMM to that external wire. Be careful to not accidentally ground the external wire. I hooked the other DMM lead to the little terminal block with green wires (the ground block).

(3) Leaving the DMM in place for checking the voltage on the red wire, now disconnect the 5 pin plug from the fan. The fan will turn on. Observe voltage on the red wire again. If it is still between 24-40 volts, replace the fan. If it is below 24 volts, replace the control board.

I was told "95% of the time it is the combustion motor and not the board."

When I did test (3), I saw 37.2 - 37.5 DCV on the red wire, plugged in or not. So I replaced the fan. Installed it yesterday afternoon, so far, so good. I'll post up if I have any problems, otherwise consider this one solved.
 
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Old 12-23-12, 01:54 PM
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Thanks! I'm putting that in my 'notebook'...

Hopefully it will help others with same problem.

With the price of that assembly, I myself would be looking to see if it could be opened and repaired.
 
  #21  
Old 10-19-13, 01:55 PM
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Same F14 error message on our Munchkin

I am getting the F14 error on my Munchkin now. The guy is telling me the part is $900. I am not convinced he knew much about this boiler want to make sure I need the part before paying for it.

sbar11 - what did you ultimately need to do to solve the problem?
 
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Old 10-19-13, 05:58 PM
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Sadly, today's techs are for the most part what I call "Tinkerticians". They will 'tinker' with your system, changing parts one at a time until they say: "There, I fixed it" and will send you an exorbitant bill for all the parts they changed that were NOT the problem.

I'm sure he is marking up the parts substantially.
 
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Old 09-17-14, 09:12 PM
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I know the last post on this was a year ago but just to clarify: the solution is in post #19.

Those tests showed very clearly that I needed to replace the blower motor (i.e. the fan, the combustion motor). Zero problems since. The cost was about $400 from a supply house called KSC Direct, out of Omaha. I have bought several repair parts for the Munchkin there, over the years. If they don't have it they will get it, and their prices are reasonable. Probably spent over $800 by now, in 8 years ...
 
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Old 09-18-14, 04:23 AM
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Old thread... Closed..

Please start new..

Thanks..
 
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