Hi All,

Let me open by explaining that I am a novice when it comes to troubleshooting failed electrical appliances/components.

That said, this is my first time posting and I'm looking forward to whatever assistance folks are able to provide.

I am the owner (and original installer) of a no-longer-supported c.1998 Tamarack Technologies Inc. "HV500" Whole House Cooler (a.k.a "high efficiency attic fan") which, sadly, has ceased operating. The unit consists of a power relay, a synchronous motor (which is connected to two countering rotating pusher arms that, when operated, open and close the insulated hatch and actuate two limit switches, one of which cuts power to the hatch motor and sends power to the fan while the other of which, I believe, cuts power to the power relay to shut everything off), the aforementioned limit switches and the aforecited fan, all housed in a custom two-piece molded plastic (I'm guessing PVC) enclosure. Note: the above supplied links point to the currently available replacement components and don't necessarily detail the currently installed components. For instance, the synchronous motor currently installed in the unit was long ago discontinued which prevented me from supplying a link to it (so I supplied a link to the modern-day comparable part).

Having removed the unit from the attic, disassembled it, cleaned it, researched the availability of replacement components and done my best to test the existing components (all of which, I might add, are readily available off-the-shelf analog parts) I have determined the following:

• when everything is connected and the hatch in the 'closed' position (which results in one pusher arm pressing on one of the two limit switches) and I send power to the power relay, it actuates but nothing else happens;
• when everything is connected and the hatch is the 'open' position (which results in one pusher arm pressing on the other of the two limit switches) and I send power to the power relay, it actuates but nothing else happens;
  
• the fan, when isolated from the rest of the unit's electrical system and supplied independently with power, runs normally;
• the synchronous motor, when isolated from the rest of the unit's electrical system and supplied independently with power, runs but no longer has enough strength, via the 1RPM reduction gearbox (which I opened and all the nylon gears are in place and in excellent condition), to drive the interconnected pusher arms. IOW the motor runs but is not strong enough to oppose the weight of the hatch. However, if I lay the unit on its side (thus unloading the gravitational weight of the hatch from the motor) the motor is able to actuate the pusher arms and the hatch opens and closes.
• Both limit switches show continuity (or not depending on the position of the limit switch) implying to me that they are both functioning properly.

Note - I do not have the unit's electrical diagram and nor is one available. The unit was not supplied with one and Tamarack, which came under new ownership more than a decade ago, disavows any knowledge of this particular unit.

As I recall, the way that this unit is supposed to operate is that when the wall-mounted switch is toggled to the "on" position, the power relay energizes thus sending power to the synchronous motor which then activates to open the insulated hatch (the action of which, in the first second or two of operation, results in the de-actuation of one of the two limit switches, what I'll call Limit Switch "A"). When the hatch reaches the open position, the other limit switch (what I'll call Limit Switch "B") is actuated which simultaneously cuts power to the hatch motor while also sending power to the fan, the latter of which turns on [and cools our two story house via chimney effect - by drawing cooler outdoor air in through open windows and doors (which we open around dusk) - and also by pressurizing the attic (which causes hot air in the attic to be evacuated though the vents in each gable end]. Then, when the wall-mounted switch is toggled to the "off" position, the fan immediately shuts off (not sure what the power relay does in this moment) and the synchronous motor re-activates, this time closing the insulated hatch (the action of which, in the first second or two of operation, results in the deactivation of Limit Switch "B"). When the hatch reaches the closed position, this action, via the position of the pusher arms, results in the actuation of Limit Switch "A", the latter of which must then cut power to the power relay, thus removing power from the entirety of the unit. What I can't work out is exactly how Limit Switch "B" is able to force the power relay to cut power to the fan and synchronous motor, etc. but then allows the power relay to re-energize when the wall mounted switch is toggled back to the 'on" position.

Anyways, my question is: which - in terms of the existing components - do I need to replace? Without understanding the related PFM, it seems obvious that the synchronous motor needs to be replaced. However, do I also need to replace the power relay and/or one or both of the limit switches? The only component that makes any sense to me (again, as a novice) is the fan. When I power it up on its own, it works fine - so, I'm guessing that it doesn't need to be replaced. Does the power relay "sense" the problem with the synchronous motor and, accordingly, not send power to it? Is it "smart" enough to be able to function in this way? If so, do I only, therefore, need to replace the synchronous motor in order to return this unit to fully operable status?

Hoping someone with a better handle on the world of electricity and analog components can help me troubleshoot this (very effective and very much missed) appliance.

Thanks, in advance, for your kind assistance.

And, because a photo is worth a thousand words...(the Wago Lever Nuts are my addition - I gave up on the original wire nuts - and the scary-looking makeshift power supply cord was unplugged while I took pictures):

 

I was really hoping some kind soul would chime in with some advice. Still hoping this will happen!

 

From what I gather you have a geared synchronous motor that operates a hatch, if so I would think this is a poor choice for that application, most motors of this type are used for low load applications such as timers/clocks etc.
I would look at replacing with a small geared DC motor, even if you have to obtain/make a small DC supply for it.
The Fan looks like a typical AC shaded pole fan so all these usually require is a bearing lubrication after a long time of usage.
Max.

 

In the interest of moving this along, here are some additional photos of the attic fan which provide additional detail:

[This shows the aluminum operating arm which, in conjunction with the nylon operating arm) articulates the insulated hatch:]


[This shows what the fan looks like assembled:]


[This shows the fan housing being disassembled:]


[This shows the full-dimension foam seal on the inner face of the insulated hatch and the attachment point for the operating arm:]


[This show the piano hinge that the insulated hatch pivots on:]

 

From what I gather you have a geared synchronous motor that operates a hatch, if so I would think this is a poor choice for that application, most motors of this type are used for low load applications such as timers/clocks etc.
I would look at replacing with a small geared DC motor, even if you have to obtain/make a small DC supply for it.
The Fan looks like a typical AC shaded pole fan so all these usually require is a bearing lubrication after a long time of usage.
Max.

Thanks for your reply! FWIW the existing hatch motor functioned flawlessly for more than a decade. Given that, I'm fine with replacing it in-kind. If I get another ten years out of a replacement I'll be happy. I also wouldn't know where to start retrofitting a DC motor in place of the existing AC one. I'm trying to keep this as simple as possible.

Regarding the fan itself, it operates fine when powered up separately, though I do understand your point about needing to repack/replace bearings after a while. The good news is that this exact make and model of fan is still available so if it came to it I'd likely just buy a new fan and install it in place of the existing one.

 

Tell you what, I'm tempted to fabricate a mechanism to manually open and close the insulated hatch so that I can hardwire the fan directly to the wall switch and thereby eliminate the hatch motor, the limit switches and the power relay. This appliance is unnecessarily complicated!

 

Looks like there is a multi source still of Crouzet synchronous motor/gearbox etc.
Is there no equivalent, have you tried an Email to Crouzet for a current model?
Max.

 

What is the motor Wattage? With a bit of mechanical ingenuity it should be possible to substitute other gear-motor brands. There are plenty of 1rpm mains motors advertised.

 

Looks like there is a multi source still of Crouzet synchronous motor/gearbox etc.
Is there no equivalent, have you tried an Email to Crouzet for a current model?
Max.

Looks like there is a multi source still of Crouzet synchronous motor/gearbox etc.
Is there no equivalent, have you tried an Email to Crouzet for a current model?
Max.

Yes, Crouzet supplied me with the current comparable model which I linked to in the third paragraph of my first post. Here it is again.

 

What is the motor Wattage? With a bit of mechanical ingenuity it should be possible to substitute other gear-motor brands. There are plenty of 1rpm mains motors advertised.

According to the spec's for the modern day comparable motor, it's 3.5W.

 

Also have you already mentioned whether the hatch mechanism is operating freely?
Have you gone over all possible points of friction.

BTW, when posting a long OP-thread, it is much easier to read when paragraphs are used instead of a continuous tome.
Max.

 

Also have you already mentioned whether the hatch mechanism is operating freely?
Have you gone over all possible points of friction.

BTW, when posting a long OP-thread, it is much easier to read when paragraphs are used instead of a continuous tome.
Max.

My apologies - I tried to keep the wording and formatting clear and concise but I obviously failed in this regard.

As an aside, when I didn't get a response here I posted my inquiry on another forum:

https://www.electronicspoint.com/fo...hooting-crouzet-synchronous-motor-etc.291487/

Perhaps referring to the discussion that took place over there might help expand on what appears here? While the assistance I received over there is a little hard to follow, all of my entries are hopefully clear.

Now, as it pertains to your question, I go into a lot of detail regarding my troubleshooting the hatch motor. In particular, I wrote:

"The hatch motor, at least in its present state, is not able to push past the two 'top dead center" positions. IOW were it working normally, it would be able to push through these two positions. When testing as part of the troubleshooting, I had to provide the additional force necessary to assist the motor to make it through these two "restrictions". Moreover, something I didn't include earlier is the fact that the motor can't even hold the hatch open when the hatch is going through the closing portion of its travel. The weight of the hatch just totally overpowers the motor and the hatch slams shut (not sure if the weight of the hatch forces the motor to run in reverse or if one or more of the nylon gears slip). All the more reason (I assume) to replace the motor."

I also wrote:

"Yes, the hatch does have some modest weight to it, though it consists only of the weight of a) the plastic lid, b) the full-dimension open cell foam gasket (which air seals the hatch) and c) the full-dimension 2" thick aluminium-tape-covered closed cell foam 'top' (which insulates the hatch). In this respect, it is quite lightweight, all things being equal. Plus, before the unit failed, the motor worked flawlessly for over a decade. So, if I can get another decade-plus from a replacement motor, then that's a small price to pay for having been able to refurbish the unit myself."

In addition, I wrote:

"Regarding [the hatch motor and gear box] I had a look inside when I removed the motor to look more closely at it (and the gear box). The cover for the gear box is plastic and pops off easily. The gears inside (there are several) are all made of nylon/plastic and everything turns smoothly when spun by hand. I made sure to mark the resting position of the flat on the spindle before I opened the gear box to ensure that I would be able to return it to the correct position before reinstalling the motor. And you're right, the reduction gearing is quite pronounced. But the gear box and the gears/teeth are immaculate; even the original factory grease is intact - it hasn't separated. I did power the motor/gearbox when I had it out and I waited a full minute for the spindle to make a complete rotation. However, I didn't try to load the spindle in this condition. I suppose I could have held the motor in one hand and with the other (and a wrench bearing down on the flat on the spindle) tried to prevent the spindle/axle from rotating. But I don't think I'd realized at that point that laying the unit on its side (IOW un-loading the weight of the hatch from the motor) allowed the hatch to open and close. Said another way, I think I figured this out only after I'd already reinstalled the motor and gear box assembly.

Now, I guess another question is: is there a failure mode in a small synchronous motor of this type that can limit its original ability to offset the weight of the hatch? Not knowing, I assume that if an electric motor runs when powered then all is fine. But perhaps a motor like this can fail partially such that when unloaded it runs normally (or at least appears to run normally) but then, when loaded, it bogs down and will refuse to move what, in the past, it was able to move. I don't know - this is where my knowledge of these things runs out."

I also describe in further detail my limited understanding of the operating sequence as it involves the power relay, the two limit switches, the hatch motor and the fan. I also ask additional questions related to the failure mode(s) of an AC synchronous motor and I request guidance on how the power relay works in conjunction with the other components. Basically, I try to gain insight on what else, in addition to the hatch motor, I should replace. Again, because I don't fully understand how the relay works in conjunction with the limit switches and the wall switch I am stuck on knowing whether or not it is working properly (and, thus, whether or not I need to replace it).

 

While the assistance I received over there is a little hard to follow, all of my entries are hopefully clear.
.

Yes he his replies do get a little convoluted.

I would attempt first to reverse-engineer the whole system if you are able to and try to lay it out in some form of schematic format.
This will help not only you but any posting you make for assistance.
All the synchronous motors I have trouble shot in the past are mainly friction or bearing problems.
Max.

 

I am making the assumption that the motor only rotates in one direction and stops at two positions about 180 degrees apart corresponding to the up and down positions of the vent flap.

I can think of two ways that the unit can operate.

1 The wall switch will have three wires going to it. The feed will be to the common terminal. The contact for the up position will feed the motor via the up position micro switch which opens when the up position is reached so the motor will stop when the up micro switch is actuated. (It's contacts will open when actuated.) The contact an the wall switch for the down position feeds the motor via the down position micro switch. So with the wall switch in this position the motor runs until the down position micro switch contacts open.

2 The wall switch only has two wires going two it and it just feeds the relay coil. The relay has a set of change over contacts one of which feeds the motor via the up micro switch and the other feeds the motor via the down limit micro switch. The common contact on the relay has a permanent live feed to it.
From the way you describe the symptoms I think version 2 is the most likely. I suspect that this permanent feed to the common contact on the relay is missing.

Are there two or three wires connected to the wall switch ? Is there a permanent live feed to the vent unit and if so is there power on this connection ?

Edit. After re reading post #12 it looks like the motor is being powered but is not providing the required torque.

Les.

 

I am making the assumption that the motor only rotates in one direction and stops at two positions about 180 degrees apart corresponding to the up and down positions of the vent flap.

I can think of two ways that the unit can operate.

1 The wall switch will have three wires going to it. The feed will be to the common terminal. The contact for the up position will feed the motor via the up position micro switch which opens when the up position is reached so the motor will stop when the up micro switch is actuated. (It's contacts will open when actuated.) The contact an the wall switch for the down position feeds the motor via the down position micro switch. So with the wall switch in this position the motor runs until the down position micro switch contacts open.

2 The wall switch only has two wires going two it and it just feeds the relay coil. The relay has a set of change over contacts one of which feeds the motor via the up micro switch and the other feeds the motor via the down limit micro switch. The common contact on the relay has a permanent live feed to it.
From the way you describe the symptoms I think version 2 is the most likely. I suspect that this permanent feed to the common contact on the relay is missing.

Are there two or three wires connected to the wall switch ? Is there a permanent live feed to the vent unit and if so is there power on this connection ?

Edit. After re reading post #12 it looks like the motor is being powered but is not providing the required torque.

Les.

It's a three wire feed - hot, neutral and ground. I had the option when I originally roughed it in of using four wire Romex which would have allowed for illumination of an optional LED bulb which can be fitted to the wall switch plate. I opted against the LED. So, said another way, it sounds like your Scenario #2 is the correct one.

So, when you say that the common contact on the relay is "missing" do you mean that this subcomponent of the relay has failed or are you supposing that the related hot wire has come loose (or comparable)? FWIW the first task I completed once I had the unit apart was to check all the connections. Everything is cinched down tight.

Regarding your edit, yes, it appears that the motor is no longer producing the required torque. The caveat is that I only know this because I happened to isolate the motor from the rest of the system and power it up on its own and it worked. When it is wired back into the system the only thing that occurs when power is applied to the relay is an audible "click" but then nothing else happens. And this remains the case regardless of how I manually manipulate the limit switches. Back to torque - this is what I was alluding to when I requested more info on how these little motors can fail. With my basic understanding I assume that if an electric motor spins when power is applied to it then it is fully functional. IOW I assume that an electric motor like this either works or doesn't (with nothing in between). But maybe they can partially fail such that they still spin when powered up but because of a failed subcomponent inside the motor are no longer able to produce their rated torque?

 

But maybe they can partially fail such that they still spin when powered up but because of a failed subcomponent inside the motor are no longer able to produce their rated torque?

A shorted turn of the motor coil might result in reduced torque. Dried up bearing lubricant is a more likely cause.

 

A shorted turn of the motor coil might result in reduced torque. Dried up bearing lubricant is a more likely cause.

Inspired by your assessment I did a quick web search and watched the following:

My Crouzet motor is a little different in that its self-contained gear box is piggybacked onto the back of the motor (instead of being encased inside the motor shroud) but I'm tempted nonetheless to take the motor itself apart to see if I can see/feel anything obvious/suspect.

 

If the unit is only fed with a neutral and switched live (Ignore the earth as this is only for safety and does not play any part in the functioning of the unit.) then when the switch is in the off position there will be no power to move the motor so the unit would not work. So there must be power to it both when it is opening and closing. In post #12 you say that the unit works when it is on it's side it works as there is much less load on the motor. Have you measured the voltage across the motor while it should be opening and closing. As the motor label in one of your pictures indicates it is a 115 volt motor you should get a reading of about 115 volts. I think the problem is with the motor and I think it is caused by a gear that was a press fit on a shaft is now slipping. I think the actual motor is probably working normally but something is slipping in the gearbox part. If the construction was the same as the one in the video then the two places where the problem could occur are the pinion on the actual motor shaft and the plastic gear on the output shaft. (The plastic gears are all moulded each being two gear wheels that just rotate freely on a shaft.)

Les.

 

If the unit is only fed with a neutral and switched live (Ignore the earth as this is only for safety and does not play any part in the functioning of the unit.) then when the switch is in the off position there will be no power to move the motor so the unit would not work. So there must be power to it both when it is opening and closing. In post #12 you say that the unit works when it is on it's side it works as there is much less load on the motor. Have you measured the voltage across the motor while it should be opening and closing. As the motor label in one of your pictures indicates it is a 115 volt motor you should get a reading of about 115 volts. I think the problem is with the motor and I think it is caused by a gear that was a press fit on a shaft is now slipping. I think the actual motor is probably working normally but something is slipping in the gearbox part. If the construction was the same as the one in the video then the two places where the problem could occur are the pinion on the actual motor shaft and the plastic gear on the output shaft. (The plastic gears are all moulded each being two gear wheels that just rotate freely on a shaft.)

Les.

Les - I am going to bet that you're on to something. I did as you suggested and, yes, when isolated from the rest of the system and supplied with power, 120 volts (123 volts to be exact) crosses though the hatch motor.

Prior to your post, I didn't think about the interfaces between the round metal shafts and the nylon gears. Absent as they are of any mechanical means to hold the gears fast to the shafts I expect that the problem is as you've speculated.

Now, with that out of the way, what are your thoughts on the relay? Knowing as we now do that the motor (not including the gearbox) would operate normally were it to be sent power by the relay, then it would appear that there is something wrong with the relay. To reiterate, with all of the components properly hooked up, when I send power to the relay there is an audible "click" but then nothing else happens. What should happen is that the "click" (which is the electromagnet closing the contact in the relay) should be followed immediately by the operation of the hatch motor. That isn't happening. This is the same regardless of how I manually manipulate the limit switches.

As was suggested by another poster, I put together a rough wiring diagram to hopefully clear up any confusion I've caused:


The big blue component is the relay; the red donut is the fan; the two yellow rectangles are the limit switches; the orange cubes are the lever nuts; and the purple cylinder is the hatch motor. The layout of the posts on the relay mimic real life as do the posts on the limit switches. You will note that one of the posts on the relay is unused (this is for the optional LED indicator that I mentioned in an earlier post) as is one of the posts on one of the two limit switches. This also mimics real life. The color of the various wires also mimics real life. The relative placement of the limit switches also mimics real life. To lessen the complexity of the image I omitted the various ground wires.

My apologies for not providing this before now. Hopefully this helps!

 

I thought I'd also show the two modes of the relay - unpowered and powered.

Here's "unpowered":



And here's "powered":



With the relay in the "powered" scenario I checked the voltage at the post where the orange wire connects and it showed 1 volt. I'm assuming that were the relay working properly it should show ~120V. This condition remains regardless of how I manually manipulate the limit switches.