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Mr Heater (Big Maxx 50) vibration problems

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b uddy555

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Mr Heater (Big Maxx 50) vibration problems - Update

Just finished installing my big maxx 50. It is mounted directly to 2x4's (screwed to the roof joists) using the supplied brackets. i.e. it is hard mounted and not suspended.

The heater works great but the vibration inside the house is pretty bad. The vibration doesn't come from the induced draft blower and is definitely coming from the main fan.

The cage that protects the fan (and the motor itself) can be felt vibrating but only when the fan is under power. Once the fan turns off but the unit is still spinning, the vibration stops immediately.

If it was a fan balance issue I thought the vibration should decrease as the fan free-wheels to a stop, but as soon as the power to the fan stops - the vibration stops.

Does anyone know if it is possible that the motor is bad? It doesn't make any other noise - it just vibrates. Any possible fixes other than buying a new motor?

I read some threads about people using vibration isolators when they had suspended their heaters using readi-rod, does anyone have advice for vibration isolation in a hard-mount scenario like mine?

Thx

Update: Replaced fan and it still vibrates. More in new post below.
 
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tarbellb

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My Mr.Heater 45k came shipped with a very unbalanced fan. To the tune that no matter how much I tried to balance it myself, it wobbled and produced a high pitched rattle.
Called the warranty center, no questions asked other then S# and they shipped me a fan + motor within a week.

From what I gather, these fans are prone to being out of balance.

Also, check the forum for people using vibration dampers for hanging their heater units. A little pricey at $15-20 per hanger but also a solution.

OH! one last thing to check. Mine also came with a stripped bolt for the fan mount. Check to make sure the threaded sheet metal hasnt stripped leaving the bolt loose.
 
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b uddy555

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tarbellb said:
My Mr.Heater 45k came shipped with a very unbalanced fan. To the tune that no matter how much I tried to balance it myself, it wobbled and produced a high pitched rattle.
Called the warranty center, no questions asked other then S# and they shipped me a fan + motor within a week.

From what I gather, these fans are prone to being out of balance.

Also, check the forum for people using vibration dampers for hanging their heater units. A little pricey at $15-20 per hanger but also a solution.

OH! one last thing to check. Mine also came with a stripped bolt for the fan mount. Check to make sure the threaded sheet metal hasnt stripped leaving the bolt loose.
Click to expand...

I checked the bolts and they are all tight. I will call Mr Heater tomorrow and see if they will ship me a new motor. We'll see what happens.
 
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b uddy555

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Called Mr Heater today and they were great! They are going to send me a new fan and motor.

As an experiment I took the motor off and ran it detached from the heater and the vibration didn't seem as bad when I was holding it. Based on how the machine vibrated with it attached I thought it would shake or vibrate right out of my hand. The vibrations bust resonate when the fan is on the heater and amplify themselves.

I will post an update when the parts come - I just thought I would let everyone know that Mr Heater's warranty dept is top notch.
 
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b uddy555

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I replaced the fan and it still vibrates. I am going to try and replace the motor now.

it seems like the heater box acts as a big resonsnce box. The little vibration from the motor spinning makes the box resonate, which vibrates the roof joists, which transmit the vibration and humm all the way to the other side of my house!
 
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b uddy555

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I just finished replacing the motor. It still vibrates and hums throughout the house along that outside wall where the heater is mounted. I have no idea if a different brand of heater would behave differently but I am not impressed.

The new motor and fan ran very smoothly in my hand - but as soon as I attached it to the heater the metal box of the heater resonates and the unit hums/vibrates.

I am going to look for more of those rubber washers to install with the fan mount/cage. I will see if that helps. My only other option is to find a way to isolate the hum/vibration from the structure of my house and garage. I cant use those isolation hangers because mine is direct mounted to the roof using the supplied angle bracket.

Another option would be to install some kind of rubber pad or sheet between the heater mounts (angle iron) and the roof. This would lower the heater which is already piped up and vented so I would want something relatively thin.
 
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tarbellb

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Thats really unfortunate you are still getting the vibration. As I stated earlier, mine had a very bad blower fan and it was replaced.
After replacing it ive noticed that my Induced Draft Motor (part #16) also makes some racket. Its in my shop that I usually have a vacuum, grinder, or other tools going so im not totally annoyed, but not happy with it.
Also my shop is disconnected from the house, I would be totally unsatisfied if it resonated through the house.

Im not looking forward to replacing my IDM if needed.

Let us know what you find!
 
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b uddy555

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curiousB

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Hangers can go above the surface in the joist bay and then threaded rod through ceiling skin to heater mounting flange.

See picture:
 

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aveguy

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Hi buddy555,
I suspect the solution curiousB proposed is going to produce the best results for issolation. Any attempting to construct rubber issoation using rubber washer wont likly produce the issolation you are looking for. Simply because the vibration will still be transmitted through the the lag/screws/bolts being used to sucure the heater bracket to framing member, regardless of any rubber interface washers. The vibration hanger that curiousB showed gets around much of those concerns.

With regard to your pipe slope. If I recall the install manual called for the pipe to be sloped slighly back towards the heater to prevent the condensate from draining out the end of the pipe to the exterior. Such a slope would also create a slight up draft which helps the blower do it's venting job. But I never like that concept because I didnt want the condensate draining back into the heater for rust reasons. I also dont have any local code that says I can't discharge condensate to the outside. I also did not want to deal with installing moisture traps in the vent pipe to deal with condensate. So I sloped my straight-shot short horz pipe slightly down towards the outside of the building. The point is... depending how much slope change you are talking about it might not really matter. Because if your horz run is as short as you say it is, than I really question how much condensate would actually build up in the pipe, wouldnt most of it just be discharged out in gas form?
 
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b uddy555

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I will try the hangers. But first I am going to try some sorbothane washers I bought off amazon.

I am going to use these as isolation between the fan 'cage' and the heater body. I think these may be better than the stock rubber washers. If that doesnt work then I will investigate the hanger isoloators further.

I will let you guys know how the sorbothane works.
 
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nwav8tor

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b uddy555 said:
Great solution but i don't think i can use it. This would lower my heater (which is horizontally vented) and would make my vent go from sloping downhill to sloping uphill). The wall that I vent through is very close to the heater and I dont think I could make up the drop over that short of a distance without reversing the slope.
Click to expand...

I thought Big Maxx heaters were supposed to have UPWARDS sloping horizontal vents... That's what my manual said...
 
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b uddy555

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I used multiple combinations of sorbothane washers on the connection between the fan cage and the heater body. Ultimately what worked best was just replacing the stock rubber washers with sorbothane. However the improvement wasnt so good that I would recommend them. The reduction was very slight and not really worth it.

I also tried doubling the washers for a 2x thickness. The problem was that the nuts couldnt really be tightened properly because of the soft spongy sorbothane. I also tried a sorbothane washer between the cage and the body, as well as the cage and the nut. This didnt really work either - too much soft sorbothane to properly tighten the nuts.

I have some extra washers I might try and use where my lag bolts connect to the roof - but I am not too optimistic. I think I will have to modify how it is attached to the roof and use some of those vibration isolation hangers.

I will keep you guys posted.
 
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curiousB

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Well it was worth the effort to give it a go. The key aspect is you need mechanical isolation for the vibration between the source and the radiating surface (or plane). The problem with washers is they just compress and the lag bolt combined with the compressed washer become transmission points for the vibrations to the ceiling rafters. The plywood on the top side of the rafters becomes a wonderful speaker cone to radiate the sound upstairs.

The isolation from the spring hangers is dramatic because they break the linkage between these planes. If you can find a way to make them work in your installation you will be rewarded with great improvement. It sounds like you have challenges with the ceiling height though.
 
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b uddy555

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curiousB said:
Well it was worth the effort to give it a go. The key aspect is you need mechanical isolation for the vibration between the source and the radiating surface (or plane). The problem with washers is they just compress and the lag bolt combined with the compressed washer become transmission points for the vibrations to the ceiling rafters. The plywood on the top side of the rafters becomes a wonderful speaker cone to radiate the sound upstairs.

The isolation from the spring hangers is dramatic because they break the linkage between these planes. If you can find a way to make them work in your installation you will be rewarded with great improvement. It sounds like you have challenges with the ceiling height though.
Click to expand...

What brand (and strength/stiffness rating) of hangers did you use? I want to make sure I get it right if I am going to have to rework things.
 
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dandan111

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Justin whacked his with a broom stick. Makes me think sheet metal flex may be causing the vibration? Push up on it while its running and see if it settles down any.
 
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justintiime

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not having any eye hooks or string right now, i was super fed up wjth my heater. i took a 2x4 to the rear of the motor and pushed up on it a good .25". i saw the heater body flex a little and the vibration is GONE. i will run it all day and report back.
 
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b uddy555

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The sorbothane washers are toast. I think they were too compressed and they eventually just split/tore apart.

Can anyone recommend a type of hanger? There is a spring type (supposedly better for low frequency vibrations) and a rubber/neoprene type which is better for high frequency vibrations.

The vibration in the house is actually very interesting. If I am walking along that one side of the house in some locations it is very annoying. If I move two feet over I cannot hear it at all. The intensity is very much dependent on the specific location in the house. Of course my bed is in a bad zone...
 
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dandan111

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I would call the factory and complain. I'm sure they would send you some washers. I would then try what Justin did...
 
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curiousB

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KCarGuy

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The only vibration that i got from mine, was from the directional Fins in front.
The right side had the pivot pins, Metal to Metal. (where the vibration was)
The left side had the Springs on the pivots to keep the right side in the pivot holes.

I could hold the fins and it would quite it down, so I cut a small piece of rubber tubing and added it to each Fins Pivot. Worked Great.

I have mine Hanging from threaded rods (on the Right side) and Bolted directly to my I-Beam on the Left side. (it doesnt vibrate or cause excess sound as you would Expect)

I hope you can find the problem...
 
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kenfath

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Don't know IF we ever had a vibration problem with our 45K Mr. Heater. It is mounted on a diagonal and lag screwed into three ceiling joists. I think the lags used were 5/16" x 3.5" going thru 5/8" drywall into 2x12" joists. Neoprene washers (from Home Depot) were placed along with fender bolts on the lags. Heater has no vibration or excessive noise. In fact I'd classify it as quiet. We did have to grind a flat on the fender washers so they would clear the mounting bars and fit properly.

I had the good fortune many years ago to attend a seminar on shock and vibration (S&V). The outfit that put it on manufactured laboratory quality vibration test machinery that could produce the shocks and vibrations found most everywhere, and had considerable expertise with the topic. The equipment's purpose was to produce a range of S&V that would allow designers and engineers to see firsthand, in a lab setting where failures might occur, and to design and build a product that would function well in the known environment. It was amazing some of the fixes: a larger screw or washer here, a stiffener or dampener there, sometimes thinner or thicker materials. Another technique is to 'listen around.'* This is where a stick, broom handle, etc is placed on a working machine and you listen with your ear how the inner workings are performing. This technique is great for locating and diagnosing problems. My point is twofold: you want to determine positively where the vibration(s) is/are coming from; then review how the heater is secured and fastened, etc. A 2x4" ceiling joist will resonate differently than a 2x10" joist. This might be a source of amplification of the normal vibrations. *SAFETY WARNING -- Don't get the stick caught in the machinery, don't stick the stick in your ear, etc. (Actually saw someone get the stick caught between belts and flywheel.)

Someone suggested whacking the heater and that it produced an improvement. The real question should be "what did the whack do?" Obviously something! Could the cabinet or the fan motor or mounting be tweaked somehow? Perhaps loosen and re-tighten some of the critical fasteners. Another suggestion would be to put some blocking in-between the 2x4's. This might change the way they amplify and transmit vibrations. Good luck!
 
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rodm1

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See if its the tin by moving your hand around the side of heater. I ended up putting 2 layers of plastic material at each screw and the noise stopped. I made plastic shims out of that plastic packaging you get from products.:thumbup::thumbup:
 
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ewang

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Just got my 75000btu beacon Morris started up today and the vibration is driving me nuts! Seems if I hold on to one of the fan guards bolts, it's dampens down.
 
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franksinatra

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This is obviously an issue with these types of heaters. What I had did with my 75,000 Hot Dawg heater was to take as much of the sheet metal off of the unit as I could. I siliconed each edge that was to come into contact with another piece of metal and allowed it to dry over night. I then used dynamat (for car stereos) on all of the sheet metal. I also installed rubber wahers on the top of the 2X4's that held the threaded rods from which the heater hung. Unless someone is willing to balance there fan blade, It is what it is. Most Electric motors should run very smooth out of the box so I would guess the fan blades have been bent or dirt/dust collected on them. Hmmm... I better go check my blades too. lol Been sitting up ther for 10yrs without any cleaning. HA!
 
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mexeng

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I installed a Big maxx 80 heater last week the fan vibrated terribly. After emailing Mr Heater several times I gave up and ordered a similar dayton fan from Grainger and you can barely tell it's running now. I know this is an old post but maybe it will help in the future.
 
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