Avalon PS 900 Switch Problem?

[stoaf88]

Hi guys I have 2 stoves and both are acting up right now, aahhhhh waht a pain!

Anyway I have a 1990's Avalon PS 900 pellet stove.

I have pretty much replaced every part of this stove.

Here is the new problem I am having. This problem has happened around 4 times over the past 2 months.

The stove seems to put itself on non stop high. The auger motor is less than 1 year old. It makes the auger turn non stop, and overheats the stove. This thing looks like it could catch fire when this happens.

It also sets off the thermal switch in the convection motor because it gets so overheated. So pretty much I cant run the stove unless I am in the general area of the room where the stove is.

I need to be able to run the stove at night when I am sleeping so I need to fix this.

I just replaced the motherboard last year because of a different problem. The only part that is old on the stove at this point are the dials that control feed rate and the convection fan speed. Is this a common problem when the dials go? Is this a part that I can even find?

Thanks in advance to any replies.

 

[stoaf88]

A few more details.

Stove has new exhause motor, OAK installed and the exhaust has 2 foot horizontal then outside 4 ft vertical. Everything has been cleaned less than 1 month ago.

Burning Somerset premium pellets. The air flow in the stove is perfect and it runs great except for when it decides to shovel pellets into the burn pot for no reason. The fire gets HUGE!

 

[SmokeyTheBear]

Have you cleaned the crud out of the convection blower and if that one can be oiled lubricated it with the proper lubricant?

A lot of convection blowers need regular lubrication.

 

[stoaf88]

The convection blower is totally clean and was replaced less than 2 years ago. This is not a convection blower problem it is either a motherboard problem (the motherboard is less than a year old) or a problem with the actual control knobs.

I have read topics where people have had similar stoves overfeeding, but it actually put out their fire. My fire unfortunately does not go out when the over feeding happens, it goes completely out of control and look like it will catch fire!

 

[SmokeyTheBear]

The convection blower is totally clean and was replaced less than 2 years ago. This is not a convection blower problem it is either a motherboard problem (the motherboard is less than a year old) or a problem with the actual control knobs.

I have read topics where people have had similar stoves overfeeding, but it actually put out their fire. My fire unfortunately does not go out when the over feeding happens, it goes completely out of control and look like it will catch fire!

You could find the values of the pots connected to the knobs and replace them.

I've had pots get messed up by spending too much time in one position and when hit with tuner cleaner and moved back and forth several times go back to normal (not do not use tuner cleaner unless the stove is unplugged, off, and cold, also you need to make certain that you allow the residual cleaner to evaporate before applying power).

You could also have a flaky triac on the control board.

My mention about the convection blower was because even a auger running full time can normally be handled by the stove provided the convection blower is in proper shape and the high temperature limit operates.


A failing motor can also damage the triac it is connected too.

 

[stoaf88]

Thanks for the reply Smokey! What do you mean by values of pots connected to knobs?

 

[SmokeyTheBear]

Thanks for the reply Smokey! What do you mean by values of pots connected to knobs?

There are two types of items that are connected to knobs on a stove one is a switch, these respond to tuner cleaner, and the other is a potentiometer (pot) that varies its resistance when rotated, a pot has a lower and upper resistance value and a tapper (how it changes as the knob is turned). If you are looking at a switch you need to know its contact configuration, for a pot its low (usually 0 ohms) and high values and tapper. Frequently this of a set of numbers is stamped unto the case.

 

[stoaf88]

So these pots can be replaced?

Maybe I should just buy a new control box with new knobs then? Do you think this is what is causing the problem?

 

[SmokeyTheBear]

So these pots can be replaced?

Maybe I should just buy a new control box with new knobs then? Do you think this is what is causing the problem?

I don't know what is causing the problem. Short of bench checking things and getting actual measurements when the stove is failing it is a crap shoot.

I'd get some tuner cleaner at radio shack and give that a shot before spending big bucks.

ETA: Every single component on that board can be replaced if you have the time and equipment to do so. I'm out of here until I can do something about my mouse this like having a root canal and no pain killer.

 

[stoaf88]

So do I just pull off the knobs and spray the cleaner in there?

 

[SmokeyTheBear]

So do I just pull off the knobs and spray the cleaner in there?

No, you spray the cleaner into the pot or switch and move the knobs back and forth. If you have to take the knobs off to remove the controls to get to the parts you spray then remove them and the controls put the knobs back on and spray the part, turn the knobs and then remove them and remount the controls. My bet is you can likely do the spraying without needing to remove much if anything. but I don't have a picture of your controls. It will depend upon several things.

 

[stoaf88]

This is the part. The stove is running fine right now, but the problem could happen at any moment.

The knob on the left is the feed rate. I always keep it on as low as it can go and it still feeds the pellets pretty fast. I barely ever have to turn it up at all. It seems to just do what it wants to.

 

[smwilliamson]

What are you talking about when you say motherboard? This stove does not have one. There is the control box which is pictured and there is another box underneath to the left side. Nothing digital in there. You will have two timing boxes and a phase control. Your problem is either the auger timing box or a bad pot from the heat control.

 

[stoaf88]

I replaced the box underneath to the left side last year. I called it a motherboard because every component that the stove has is plugged into that box which has some circuits in it. In my mind that is a motherboard. But anyway, can I mess with the timing in the mother box or whatever you want to call it? Or is the problem just the knobs pictured?

 

[imacman]

This is a shot in the dark, but are you sure the knob is tight on the pot shaft? If not, you might think it's turning, when actually the knob is just spinning on the shaft.

If not, then open up the control box and spray the contact cleaner directly into the pot while you're turning it back & forth.

This it typically what they look like....you have to get the contact cleaner inside the round metal cover:

 

[stoaf88]

I assume that the knob is tight on the shaft because the problem only happens once the stove has been running after about 10-12 hours. It goes from low to non stop feeding and no one touches the knob.

So I guess Ill try what you suggested with the contact cleaner.

I remember whan i replaced the mother box I saw a few adjustments in there. I just left them how they were from the factory, and checked my old box and the settings were the same.

Maybe I need to mess with these settings?

I can post a picture of that later, I am off to work now.

Thanks for the help so far everyone!

 

[stoaf88]

The problem just happened again
It seems to happen when the stove reaches a certain temperature
So now i have no idea what could cause this but it seems like some sort of sensor or electronics
Any help would be great i need this stove to work

 

[stoaf88]

I think Smokey might be onto something with the convection motor.

The convection motor failed a few times last year before the feed problem ever existed.

No I get the over feeding problem. The last time the stove did the overfeeding a few hours ago I went over to it and actually turned off the feed rate. I can actually shut off the feed with the knob it clicks off.

When I turned the knob back to the on and low position it still fed the pellets at a non stop rate. The problem only seems to happen after the stove reaches a certain temp after a certain amount of time.

Now I know that the on off clicking selection still works on the knob but am not sure what is causing this problem. Could the stove reach a certain temp and then the convection motor tells the auger to start turning non stop because of some short circuit or something? Keep in mind the last few times the stove did the problem the convection blower was still working, but if I left it unattended it would eventually overheat and shut down.

Here is my plan for the afternoon. Take out the mother box that everything connects to. Put the old one that still works back in. Take apart the knobs and clean the pots with contact cleaner.

Then if the stove still continues with the problem could it be the convection blower causing the auger feed problem?

I tried to call travis themselves but they are on vacation until JAN 3.

 

[smwilliamson]

What are you talking about when you say motherboard? This stove does not have one. There is the control box which is pictured and there is another box underneath to the left side. Nothing digital in there. You will have two timing boxes and a phase control. Your problem is either the auger timing box or a bad pot from the heat control.

To test the pot you need to determine whether or not there is a phase control running with it. If you open the the control box up you want to look at the wires coming off of the pot. If there are only two, then you do not have phase control. Phase control is the process of raising and lowering the resistance of the pot to change voltage to the sending leads. One set will go to the auger timing box and the other set will go to a phase control which raises and lowers the voltage to the combustion motor. I forget if the PS900 has this or not.

Using a multimeter, you want to measure the ohms of the pot by testing the leads from low to high. You can test either set of there are more than two leaving the pot but they have to be the same color wires. If you have two black and two white...pick which pair you want to check....each pair will be the same value. Your low value measurements will between 800-900k and your high value will be about 73k without phase control and half of that (36k) with phase control. There will be a gradual sweep from low to high and back to low. If you get a spike to a higher or lower value during the sweep then your pot is bad.

If the pot tests fine, you then want to test the auger timing box. It s a blue or black square box inside the "mother board".

Infitech Typical Timer Control

You need to measure the time on and the time off rates for high and low fire, there should be a difference. Simply run the machine and count the seconds on and off. If the pot tests fine and the timing is not varied, replace the timing box. Travis will only sell you a new "motherboard" which is another full box but if you post a pic of the timing box you have I can part it out for you. If it is an Infitech and most likely is, the serial will start with TRS...I need that number.

Do you have auto ignition with this stove? If not, a modification needs to be made inside the motherboard to dead end the hot lead to the igniter. I doubt that has anything to do with your issue.

 

[stoaf88]

Scott Thanks so much!

What I did so far was to take off the box with the knobs on it and spray contact cleaner while turning the pole.

I dont really know how to test the voltage, but I do have another motherboard available.

If the stove still does the problem I will replace the motherboard and if that dosent work then I will assume that it is the pot.

The stove does have an igniter and there were only 2 wires coming out of the pot for auger feed.

Also I am pretty sure I need a new convection blower because it keeps shutting off for no reason. Anyone know where to get a good one cheap?

I sent you a PM Scott.

Thanks to everyone that has helped so far.

 

[smwilliamson]

Scott Thanks so much!

What I did so far was to take off the box with the knobs on it and spray contact cleaner while turning the pole.

I dont really know how to test the voltage, but I do have another motherboard available.

If the stove still does the problem I will replace the motherboard and if that dosent work then I will assume that it is the pot.

The stove does have an igniter and there were only 2 wires coming out of the pot for auger feed.

Also I am pretty sure I need a new convection blower because it keeps shutting off for no reason. Anyone know where to get a good one cheap?

I sent you a PM Scott.

Thanks to everyone that has helped so far.

you need a new pof switch or the whole wiring set looked at.

 

[stoaf88]

Scott what do you mean by "you need a new pof switch or the whole wiring set looked at"

Do you mean new pots for convection and auger feed? Or do I need that whole box that the knobs are on?

I think the problem might have something to do with the convection motor like smokey suggested.

Today the stove did the problem again after about 6 hours of running. After about an hour of running I turned the auger feed knob to high and the auger sped up, then I turned it all the way down and it went to low like it is supposed to do. Keep in mind I cleaned the pots with contact cleaner earlier in the day. I watched it close, and noticed around 3 or 4 times the convection motor kicked off like it was overheated even though the auger feed was on low and the fire was not big at all. Smokey suggested a failing convection motor can cause some kind of problems like this but I don't know, obviously I need to get one anyway. The stove just seems to decide to kick the auger on non stop after around 6-10 hours of running.

There is a shop near me which has convection blowers so I will go there Firday and install the new motor and see if that fixes the problem. If not then I will install my other motherboard box that I have and if that does not fix it then I will know for sure I need at least new pots or a whole new control box.

Anyway thanks for the help so far and if anyone else has any ideas let me know.

 

[SmokeyTheBear]

No Scott is likely thinking that a faulty pof (proof of fire) snap disc is responsible for at least part of your problems. This isn't a pot it is a temperature sensitive switch that closes when it sees a certain exhaust temperature and then opens when the temperature drops below the close temperature by at least 20 degrees (or something, switch dependant). These switches are used to turn off blowers when the stove has been told to shutdown or runs out of fuel. They have to close to tell the controller there is fire in the stove and to start the convection blower.

Some stoves have several switches that are similar some also use a photo cell for this purpose.

 

[stoaf88]

Yes my stove has only 1 snap disc that has a vacuum line attached to it.

So many things to replace........

 

[SmokeyTheBear]

Yes my stove has only 1 snap disc that has a vacum linke attached to it.

So many things to replace........

Not likely. It will have two wires. Not a vacuum line.