Changing 50 cycle fan motor to 60 cycle

[ohbie1]

In '08 Bioheat (Tarm) shipped their Innova models with 50 cycle fan motors, and promised to replace the motor when the 60s became available. Well it's been a year! Now they are sending me a capacitor that they say will convert the motor from 50 to 60. I don't trust them because when my unit came, they tried to pass off the 50 cycle as being a 60, but I read the nameplate which said 50. I doubt that a capacitor will make the conversion. Can anyone give me a definite answer on this? Thanks.

 

[Singed Eyebrows]

Hi Frank; I wondered about this too & checked with the experts at Smart Fan Stratos. They are one of the few companies making small single phase drives. They said the capacitor will not change the cycles it may however change the speed as intended. As long as Tarm is willing to warrantee this "fix" you might be ok. I would be a little leary of this lasting as long as a purpose built 60 hz motor though, Randy

 

[ohbie1]

Thanks Singed. You confirm my suspicions. I'll accept their "fix" under protest, and document my protest, so maybe I'll have a leg to stand on if the motor fails prematurely.

 

[Gooserider]

The other thing to keep in mind is that from what I've heard, while the motors involved are 50hz by design, most 50hz motors will run just fine on 60hz, although they will run faster than expected (however 60hz motors won't run well on 50hz)

Not sure just why this is, but I've heard it from multiple sources that I thought were reliable... In the boiler application, the only real issue is that because the blower motors are running faster, they move a bit more air, which requires stopping the vent controls down a bit...

The bigger issue for most people is that EU motors are designed to run on 220vac rather than 110 - this can be a pain when it comes to wiring as it needs a 220 circuit or the use of a stepup transformer...

Gooserider

 

[jebatty]

Goose, I agree. The speed of most AC motors is synchronized with the cps, so increasing the cps will increase the speed. I suspect changing the capacitor has nothing to do with this, but has to do either with starting the motor and/or balancing the motor's power factor to get it close to a little less than 1.0. By increasing the speed the PF could have been adversely affected.

 

[hayrack]

Don't get hung up on the 50 vs 60 hz. According to a couple of electrician's I talked with about the fan on my eko 40 it does not matter. My fan works fine.

 

[Dune]

These posters are absolutely correct. Running a 50 cycle motor on 60 cycle current will cause the motor to spin faster with no other deleterious effects. It is very common these days to use variable frequency drives (VFD) as speed controllers for industrial machinery.

One thing to bear in mind is that this aplies only to motors and NOT solid state circiutry.

 

[pybyr]

Totally agreed- 50 Hz motors will run happily, though a little faster, on 60 Hz-- though it does not work the other way around-- 60 Hz motors that are not dual-spec'd for 50 will overheat at 50.

Same is true of transformers- and most, but not all electronic circuitry- things that run OK at 50 will [usually but not always] run OK at 60 (and not the other way 'round) except when the circuit relies on the frequency of the power line for some reference function.

 

[raybonz]

Motor speed is determined by the frequency and the number of poles which are always in pairs (windings) in the motor.. Motors do some amount of "slip" caused by loading them and this will slightly reduce that speed.. The motor will run faster on 60 hz vs 50 hz but it should be OK.. The only real concern in my mind is whether the bearings can handle the mechanical stress and I am sure they will do that just fine..
Ray

 

[ohbie1]

I see the consensus is not to worry about running the 50 on 60. OK, so then the question is: Why is Tarm sending out a capacitor as a conversion kit (50 to 60)?

 

[pybyr]

I see the consensus is not to worry about running the 50 on 60. OK, so then the question is: Why is Tarm sending out a capacitor as a conversion kit (50 to 60)?

Because it is probably more efficient at 60 when paired with a capacitor that is intended for 60.

 

[Dune]

I see the consensus is not to worry about running the 50 on 60. OK, so then the question is: Why is Tarm sending out a capacitor as a conversion kit (50 to 60)?

So the fan will rotate at design speed.

 

[Singed Eyebrows]

That's my guess also Dune. So that the heat isn't going right past the exchanger. My Atmos has the same deal. I bought a speed controller from Zenon because he said you need to watch flue gas temps on this boiler. Eventually I'm probably going to buy the Smart Fan Stratos. This is programmable & will take a number of thermometer inputs. Theoretically I should be able to set it for 350 degrees flue gas temp & it should vary the fan to meet this, Randy

 

[ohbie1]

Do you think it's worth buying a VFD to control this 50 HZ fan? I see one online for $159 that covers the volage and HP of my fan motor. Maybe it would extend the life of the fan and I would be able to control the speed. No?...........or just run the fan and get a new one when it goes?

 

[flyingcow]

I was supposed to send my fan down earlier this season. Would have made a lot more sense than to do now. But this is an interesting thread.

 

[raybonz]

Do you think it's worth buying a VFD to control this 50 HZ fan? I see one online for $159 that covers the volage and HP of my fan motor. Maybe it would extend the life of the fan and I would be able to control the speed. No?...........or just run the fan and get a new one when it goes?

A faster motor runs cooler than a slower motor I would save my money and run it as is... The important thing is to keep the bearings lubricated unless they are sealed.. The windings will be fine...

Ray

 

[Singed Eyebrows]

Frank; This was more for my Atmos than your Tarm. What everybody is saying is correct, that it won't hurt the motor to run it on 60 hz. The problem is about 20 percent more airflow as the moderator mentioned. I've seen pictures of the Tarm & I believe the fan is in a housing with an air inlet. I would choke off the air about 20 percent & run without the capacitor if Tarm won't supply the 60 hz motor without charge. No one that I have talked to is enthused about the capacitor idea. My guess is the cap will get the motor to fight itself down to proper speed. This is all kind of a moot point though Frank as you said were promised a new motor. Hopefully Bioheat will follow through on this & then you won't need any halfway solutions. Good luck, Randy

 

[pybyr]

Let me confess up front-- I am the un-annointed king of over-thinking things.

And, with that disclaimer out of the way, really, don't sweat the difference between the 50/60 Hz motor or the cap; if Bioheat will send you a cap that they say is better, say thanks and put it in.

they're not offering a cap to "choke" the motor; it's almost assuredly a capacitor-run motor that needs a cap anyways, and they're likely just supplying a cap that will be more efficient at 60 Hz than the"stock" cap that was meant for 50 Hz.

Put your frets and sweats somewhere else, as you are almost sure to get more return on your investment anywhere else in your overall big-picture system- whether it's getting further ahead on your wood for the following year, or doing some more insulating or air sealing on your house.

 

[ohbie1]

The problem is about 20 percent more airflow as the moderator mentioned. I've seen pictures of the Tarm & I believe the fan is in a housing with an air inlet. I would choke off the air about 20 percent & run without the capacitor if Tarm won't supply the 60 hz motor

My fan is mounted on the boiler flue pipe, with no air inlet. It sucks the air through the boiler flue and up the HX tubes and pushes it into the chimney. I have a B damper on the flue pipe, suppose I knock the draft from .o4 (what they call for) to say .03. Would that be a compensation?
I guess the other choice is I could put a brick in the bottom of the flue duct in the boiler, cutting off about 20% of the suction area, but I think this would just cause a venturi effect, speeding up the air flow???

 

[ohbie1]

Let me confess up front-- I am the un-annointed king of over-thinking things.

And, with that disclaimer out of the way, really, don't sweat the difference between the 50/60 Hz motor or the cap; if Bioheat will send you a cap that they say is better, say thanks and put it in.

they're not offering a cap to "choke" the motor; it's almost assuredly a capacitor-run motor that needs a cap anyways, and they're likely just supplying a cap that will be more efficient at 60 Hz than the"stock" cap that was meant for 50 Hz.

Put your frets and sweats somewhere else, as you are almost sure to get more return on your investment anywhere else in your overall big-picture system- whether it's getting further ahead on your wood for the following year, or doing some more insulating or air sealing on your house.

Sounds good. I only brought up the question bcause I was thinking in terms of how long the fan motor would last being run overspeed, not really the efficiency of the setup.

 

[raybonz]

Let me confess up front-- I am the un-annointed king of over-thinking things.

And, with that disclaimer out of the way, really, don't sweat the difference between the 50/60 Hz motor or the cap; if Bioheat will send you a cap that they say is better, say thanks and put it in.

they're not offering a cap to "choke" the motor; it's almost assuredly a capacitor-run motor that needs a cap anyways, and they're likely just supplying a cap that will be more efficient at 60 Hz than the"stock" cap that was meant for 50 Hz.

Put your frets and sweats somewhere else, as you are almost sure to get more return on your investment anywhere else in your overall big-picture system- whether it's getting further ahead on your wood for the following year, or doing some more insulating or air sealing on your house.

Sounds good. I only brought up the question bcause I was thinking in terms of how long the fan motor would last being run overspeed, not really the efficiency of the setup.

If you want to put your mind at ease borrow an amprobe from an electrician and check your amperage to see if it is at or under nameplate rated amps... If it is then all is OK...

Ray

 

[kabbott]

I may be wrong but I would think the value of the cap needed would change with a different frequency. It still will not change the speed the
motor runs methinks. As most have stated I wouldn't sweat it.

 

[Singed Eyebrows]

Pbyr; The only way a cap is going to slow the motor down is to choke it. I though most everybody understood that choke meant shifting the phase etc. some. I'll be more explicite next time. This has nothing to do with efficiency, this is just an attempt to slow the motor down & not have the expense of a new motor in my opinion. I don't feel this is a good fix, an engineer friend I talked to didn't feel it was a good fix, Stratos did not feel it was a good fix even though it might slow it down. It's easy to not "fret" about someone elses boiler. I still think Frank deserves what he said he was promised & thats a 60 hz motor, Randy

 

[ohbie1]

At this point(It's been a year.), I don't have much hope that Bioheat intends on keeping their promise. It seems like this band aid fix lets them off the hook, as they see it. At least I have this thread to use as my argument; I will complain to my salesman and headquarters, but I have no leverage, except a lot of word of mouth publicity. Just about everyone feels that there is no " conversion" by replacing a capacitor, which is what Bioheat is claiming. You would think that for 7K+, they could at least provide the proper fan for USA use.

Thanks to all who are taking the time to weigh in on this question!

 

[jebatty]

Before putting much money into a fan speed controller, keep in mind the fairly long lag times between flue temp change and burn rate. IMO you want to maintain a consistent high and even burn rate throughout the entire burn in a gasifier. I don't think you want your fan speed to be bouncing up and down very much in an effort to control flue gas temp, as each bounce will result in significant unburned gases being exhausted or condensing somewhere. A "smart" controller that is on high speed when the fire is started, and then when knows to cut back well in advance of the early high burn to a speed that maintains the high burn at the target flue temp, and then ramps up again to high speed as the wood load burns down, could be helpful.