Custom control schematic for older Pellet stove

[Snowy Rivers]

Here is a copy of a schematic that I have used to rewire a couple older Pellet stoves.

Had a member ask about it, so here it is for all to use.

Things can be tweeked a little here and there to suit the specifics of the stove being retro fitted

The timers came from Precision timer company (Find on the web)
The main burner control timer (heat control) is a series 646 and the one shot timer is a series 644

These are not expensive and will be made to suit at the time of the order.

120 volt input/output solid state and are about 2 inches square and about 3/4 inch high.

The main timer I used has a pot on the controller to set the feed motor on time (1.5 to 2 seconds) and the off time (heat range) is controlled using a remote panel mounted pot and can vary from 2 seconds off up to 10 seconds off.

Most all of the original stove components such as feed motor, fans and such including the safety snap switches (low temp and high temp) can be reused from the original parts.

The snap switches are a universal item and can be purchased in various temps to suit the need.

The speed of the convection fan can be controlled using a standard CassaBlanca fan speed controller that is available from the hardware store.

These are a basic Triac with a round Knob to control the speed.

This is a very simple control setup, and will work fine for many of the older stoves that have become a parts orphan.

Hope this helps

Snowy

 

[mattwade808]

Thanks so much Snowy. I've got plenty of info to digest this weekend!

 

[tjnamtiw]

I am majorly impressed, Snowy! Have you ever looked at the Cublok systems? Very inexpensive and can be programmed either in Basic or Ladder Logic Diagram (which I like better). http://cubloc.com/product/01_01.php

 

[Snowy Rivers]

I fooled with several different "off the shelf" boards and gizmos before deciding on the timers from precision.

The little precision timers are very robust and designed to handle the full power load.

The units I bought are rated at 120V 10 amps. The only power that passes through these is to run the feed motor ( maybe 2 amps on a cold day, but more like 1/2 amp)

My mind set on these stoves is to keep the controls as simple as possible.

The method of placing all the controls on a single board with a "chip" handling the entire process is just a recipe for failure.

HOW MANY TIMES HAVE WE READ A POST My stove is setting a code ???????

With the simple timers, they work or they dont, and its easy to figure out whats not working.

A pellet stove does not need to be a complicated device.

My Little whitfield cruises along happily with a 1.8 second feed time and between 7 and 10 seconds of Off time on the feed motor.

I can tweek the convection/ booster fan right down to the Gnats butt with the triac and sit back and LETERIP.

Proprietary boards are just a way to sell service and parts is all.


The timers I am using were used by a lot of the stove makers back some years.

The manuf's started contracting their controls out over seas and they get a complete plug and play unit for far less $$$$$$$ BUTTTTTTTTTT the end user does not see any savngs.

Add 10 to 20 years and so many of these really great older stoves are parts orphans, making a new controller simply out of the question.

The design I came up with uses all the factory safeties (plus some new ones) and is far more robust and very easy to use.

The schematic I have here can be adapted to just about any of the older stoves that is a manual light type.

Some stoves use an exhaust fan that pulls the air through the fire pot and some have a small booster fan that adds air to the fire pot. These can all be wired in accordingly.

The little whitfield has an exhaust housing blower that runs at a steady speed to keep the exhaust gases moving out of the stove, plus a single fan thats used as a convection/booster.

As the heat range "was" raised the convection booster fan would increase in speed to handle the increase in heat output as well as add additional combustion air.

This is a rather interesting design, but works quite well.

Sadly once the original board takes a leave, the cost and availability of a new one can be an issue.

The original boards were subject to failures due to fan issues. The retro fit I have is pretty bomb proof.

The fan is handled with a stand alone triac (hardware store item) and the feed system is run with the timers.

The feed motor has its own Fuse thats not shown in the drawing that is after the timer and will protect the timers from a shorted motor.

The two high temp snap switches that I used were replacements for the ones that were there.
I swapped in two manual reset types.

My feeling is simple here, if the high temp snaps POP out, I dont want an auto reset, I want the thing to STOP and to be examined before a resart.

With the manual resets, it will be obvious that something happened and not just a stove thats out.

I also installed a STACK overtemp snap switch. This snap switch allows the stove to be shut off if the exhaust pipe between the stove anad the wall should exceed 250F

Again this design can be adapted to just about any of the older Pellet stoves.



Now the little whitfield used a "Hall effect" sensor on the covection/booster fan. This setup allowed the control board to have just a "Heat" setting knob to handle the feed and fan speed.

The main control know setting would set a predetermined fan speed and the Hall effect sensor would supply fan speed data to the board and keep the fan speed at the proper setting.

Ok speed forward in time 20 + years and the Hall effect controlled fan is not available, sooooooooooo yet another issue can surface.


A standard fan thats available readily is quite capable of doing the job, it just needs to be connected to a triac and the speed set to match the burn rate.

Took a few minutes at each feed rate to get the fan speed right and the panel marked accordingly.

The whole process is not rocket science, just took some "surfing" on the net and some thinking was all.


The timers Cost me $108.22 with shipping.
A remanufactured board (if you can find one) was nearly $400.

I only paid $200 for the stove, including the floor pad.

The same components are being used on the Large Whitfield we have too.

I have a spare set of timers on the shelf (just in case) and these can be swapped in within about 5 minutes if need be.

A fan speed triac can be swapped out in about the sale length of time.


I love off the shelf technology thats cheap and rugged.

A friend recently bought a used Pellet stove and it had the touch pad controls.

According to the fellow he bought it from, it was a returned item (big box store) and the guy bought the stove as a NON OP unit.

Well the cost of new controls was $$$$$$$$$$$$$$$$$$$$$ so we got together, orderd a pair of timers, some wire and within a saturday Afternoon, rewired the little stove and it works sweet.

The more they overthink the plumbing, the easier it is to stop up the drain.

I must add here, this stuff is not for everyone to do. I have wired a couple new homes, done industrial controls and wiring on 460 3 phase stuff, so I am no stranger to dealing with electrical goodies.

The voltages inside a pellet stove, although only 120V can KILL and do other nasty things if not dealt with properly.

The safety features of the stove in question must be kept in working order and or enhanced.
Never remove any safety switch or device, your well being is at stake.

If you are not familiar with electrical work, please leave it to someone who is.

I do not want to come here and read that someone has burned their house down with a half baked conversion on their Pellet stove.

We have all seen some of the Chimney installs that make us shudder, so please be safe.

Best for the coming stove season.

Snowy

 

[Snowy Rivers]

One thing that few people realize is that the control boards in their stoves are very sensative to Static electricity.

Last fall a friend installed a new stove and all was well. The weather was cool and dry and the kids were having a really fun time scurrying around the house, shuffling on the carpet and zaaaaaaaaaaaaaaaaaaapppppping the cat with all the static.

The Missus walked over to check the stove, added some pellets, bent down to reset the controls and ZAP a little arc jumped from her fingers to the stove controls.

Aside from the major squeal that she let out, the stove instantlly started flashing some error code and the fire went out.

The static discharge had killed the control board.

I would certainly think that the controls would be set up to prevent this, but obviously not in their case.

Two days and several Hundred $$$$$ later, the stove is working again.

I never heard exactly what the service tech did to prevent this from happening again, but if you have carpet, touch the stoves shell first before the controls to get rid of any static discharge.


Snowy

 

[tjnamtiw]

There is NO WAY to argue with the KISS principle, that's for sure, Snowy. You've taken it to a very down to earth level. I like the idea of a stack temp sensor too. You wonder why the manufacturer wouldn't include that. It would sure stop people from over firing and possibly warping their stove.

I just mentioned the Cublock technology because I'm in love with technology. The last plant I built before I retired has incorporated PLC's for the entire assembly line and I was the 'go to' guy to modify and upgrade the equipment as we improved the design. We used Automation Direct equipment that has worked without one failure for going on probably 15+ years. Of course, that's industrial grade stuff.

I was looking at using the PLC to give more feedback to the home owner on what's wrong. For instance, a light bank showing what things are running, what switches are made or not, etc. You could go one step further and add a text screen to actually show in words what's going on. Like I said, I'm a sucker for toys! But at the same time, I can't fault your approach for actually getting the ole 'girl' to come back to life and put out heat!

 

[Snowy Rivers]

I too love technology. Toys like the new iPhones are way cool.

I grew up with stoves that the only mechanical parts were the door latch and the damper control lever.

The key to what you are saying is "Industrial grade controls)

Its like the difference between the engine controls that are used on the large class 8 truck engines with Cats, Cummins, Detroits as compared to whats on the consumer vehicles stuff.

My feeling is that a Pellet stove does not need a lot of fancy logic controls to work well and live a long useful life span.

The auto ignitor systems require more input from the stove to allow things to work, but aside from that the extra tech is really a burden IMHO.

My stove has a Master Power lamp (on any time the main switch is on) A feed motor lamp that indicates when the thing is feeding and thats it.

If the main lamp is not on, its either a tripped breaker, blown fuse or the latchout relay needs to be reset, or the High side snaps have tripped

Beyond that its going to work.

If the feed motor lamp does not blink then the timers are not working.

If the lamp blinks and no fuel comes out, the motor is not running or the thing is out of fuel or the presure switch has failed or there is an internal stove issue such as a plugged vent or draft fan not working.


Really basic and easy to trace back any issues within a few minutes.

A few extra lamps wired into the system can make dagnostics even better if one feels the need to do it.

My hatred for the high tech stuff in some places stems fro the fact that something I need under the worst possible conditions, if equipped with too much high tech will fail and leave me SOL.

A fireplace has never flashed a trouble code, Know what I mean?? (Grinnng)

So if the high tech stove flashes a code, then what, generally the codes meaing is not readily available to the owner and can in many cases mean that there is an issue in the controls themselves, and thats beyond the scope of most home owners to fix.


Snowy

 

[slls]

Well you can't get much simpler than your Quad 1000, no code there.

 

[Snowy Rivers]

No the Quad is pretty simple, looking in from the outside.
Now, this said, if the quad stops working and the issue is not with a feed motor, fan, temp switch, vacuum switch or a few other little items then the controller is likely the cause.

The controller is a costly part to have stashed on the shelf though. I do keep a spare ignitor and a couple other goodies laying around for that stove.

Ignitors have been the only part that has been needed for the most part.

The warranty changed out the fire pot and ignitor during a factory update campaign.

(Read this "The ceramic pot and ignitor were junk and they had to do something")

The factory changed out the original pot and replaced it with a fabricated steel pot and a better heavier duty ignitor about a year after we bought that stove.

Service was great from Quad. I got a letter and it asked if we wanted the upgrade.
Yeh buddy, you betcha. About a week or two and a box showed up on the door step with the parts and ZERO instructions.

OOOOOK this can't be too difficult. Ripped the thing apart, looked over the pieces and made what I felt were the right Mods to install the stuff and Poof, worked great.

About two weeks later an envelope showed up with the Instructions inside, AHHHHHHH OK

Looked pretty much like what I did so that was that.

Kit was a new pot, pot gasket, clean out trap door latch linkage and a new ignitor.

Had to drill a hole in the fron of the lower panel of the stove for the clean out rod to go through, drop in the new pot, drill a couple holes in the fire box floor to secure it, use the existing wire nuts to attach the new ignitor to the system.

OHH yeah, had to use my die grinder and clean out the weld pimples from the ignitor housing so it would fit. (not in the intructions though)

Now I was never asked If I needed assistance ????


Snowy

 

[pellet]

Snowey,
I have studied your thread and have questions if you wouldn't mind. The part I am not sure about is how to modify it for my stove. I have studied the schematic. My stove is a Martin Venturi and the control board can be viewed here, it's the 3rd post down:
https://www.hearth.com/econtent/index.php/forums/viewthread/32216/

A schematic for the stove wiring is available in a manual here on page 15:
http://www.api-assembled.com/support/martin/martinservice.PDF

I do not have the following:
-pressure switch (would you just run the blue wire from the timer directly to the feed motor eliminating the burner off/on switch, pressure switch, and burner lamp? Would the components on this work with a 6 RPM auger motor which is what my stove has? Doesn't your stove have a 4 RPM auger motor?),
-burner on/off switch (addressed above hopefully),
-momentary switch to start (would you just run the red hot wire directly to the timer L1 and the neutral to the timer N to eliminate this switch?),
-latch out relay (would the L1 and neutral just go straight to the power chord/120v outlet?),
-low limit snap switch (would the pink hot wire just go straight to the L1 on the timer?),
-door switch (would the yellow hot wire just go straight to the triac speed control?). I have a rotary speed control for the room air fan but not sure if it is a TRIAC speed control, it is separately mounted from the board with wires to it from the board and on to the fan.
-And finally, if these things were all ok, I assume the t-stat feature isn't going to work?

LOTS of questions…hope you have the patience to answer them.

 

[Snowy Rivers]

I am not at all familiar with the operation of the stove model you have.

Now this said, the schematic I drew up should work fine. The lack of a pressure/vacuum switch is not a reall biggy, just run the wiring beyond and go with it.

If there is not a door safety switch, just eliminate that from the loop and continue as though it were there.

Your stove no doubt has some snap switches to prtotect from over temps and it should have a low temp switch that has to be satisfied to keep the stove running once the firs is burning.


The Whitfields use a 1 RPM fed motor, many stoves use two feed motors and some use a 4 or a 6 RPM motor.

You can tailer to timer adjustments to make your feed motors run at whatever speed you need.

I did my rewires as a stand alone, replacing the switch panels and all with new parts that I put together from scratch.

Your stove is going to have an exhaust fan, a room air fan, a feed motor/motors and some temperature sensative snap switches.

As long as your over temp switch is wired to shut the stove down if an over fire occurs that part is fine.

The low temp switch must be wired into the loop pretty much as shown.

What is the normal on off times for the different heat settings on your stove ?? (feed motor)

Is this a top feed or a bottom feed auger system ? two feed motors or one ??

You may have to do some imagineering to adapt the system I have drawn out.

What I drew will work for the Whitfields and several other top feed stoves with a single feed motor.


Give us some more specifics about your stove and then we can move ahead.

The original control board/panel aperaed to be pretty simple.

The idea behind having a BURNER switch is a simple one.
The switch shuts off the fuel feed and allows the room air fan/s and the exhaust fan to continue to run.

This allows you to cool the stove down until the fire has burned out completely and then shut the master switch off to finish the shut down.

Some stoves like the Larger whitfields (adv 2 and 2T) had the low temp switch controlling everything.


When the stat button was pressed all the feed power was run through the start timer and then to the fans and such.

The burner switch controlled only the feed motor.

Once the burnr switch was shut off the ehaust fan and the room air fan would run until the low temp switch dropped out and then the entire stove would shut down.

This could be done easily too simply by changing things a bit.

Keep us posted

Snowy

 

[whit]

The controller is a costly part to have stashed on the shelf though. I do keep a spare ignitor and a couple other goodies laying around for that stove.

Said to be cheaper here, direct from the manufacturer for the Quad boards. Also offers "customized" boards.

 

[pellet]

Snowey,
Let me see if I can describe my stove’s operation. I’m going to do my best (been working on it a couple of days) to get all the information you have asked for so please bear with me.

These are the controls: Main power switch, room air speed control, and pellet feed adjustment. There is also a red LED indicator light. I have also installed a remote wall mounted thermostat connected to the two control board thermostat terminals with standard thermostat control wire. That’s it.

The main power switch is mounted on the control board. When it is off, there is no power to anything in the stove. The pellet feed adjustment is also mounted on the control board that controls the time the auger motor runs and can be adjusted from low, 2, 4, 6, and hi, and anywhere in between (It is continuously variable, does not have “clicksâ€). As mentioned above there is also a red LED indicator. Here is a description of what happens when the feed control is set at the indicated points, but first some definitions:

(NOTE - all times are approximate, I did my best with a stop watch.)
• Fast blink-the LED is blinking so fast I can’t time it. A casual glance might leave the impression it is just dimly lit, but it is actually blinking very fast if you look closely.
• Slow blink- the LED is blinking on and off at about ½ second intervals. Much slower than the above fast blink
• On- the LED is on for aprox. 13 sec. continuously.
• Off- the LED is off for aprox. 13 sec. continuously.
• Idle mode- when the remote wall mounted thermostat is off or open and not calling for heat but the pellets are being fed just enough to keep the fire going or “keep fire†mode. A jumper is factory installed on the two thermostat terminals and replaced with the wire to the remote wall mounted thermostat if you decide to use one, which I did. If you just leave the jumper off the stove STAYS in “keep fire†mode.

So here is what happens at different settings of the pellet feed control:
-Setting = Lo: "Fast blink" LED and auger running = 3/4 second. "Slow blink" and auger not running = 36 seconds. Total cycle = 38 seconds, then the whole cycle repeats.
-Setting = 2: "Fast blink" LED and auger running = 2 seconds. "Slow blink" and auger not running = 36 seconds. Total cycle = 39 seconds, then the whole cycle repeats.
-Setting = 4: "Fast blink" LED and auger running = 4 seconds. "Slow blink" and auger not running = 36 seconds. Total cycle = 40 seconds, then the whole cycle repeats.
-Setting = Hi: "Fast blink" LED and auger running = 6 seconds. "Slow blink" and auger not running = 36 seconds. Total cycle = 43 seconds, then the whole cycle repeats.

-Idle mode (not on the feed control, just the t-stat is open): The wall mounted thermostat is open. This is pretty complicated so bear with me…. (In this mode the auger will always run for aprox. 5 seconds no matter when it begins to run.)
If you start the “Idle mode†cycle, the red LED "on" (the LED may be "on" or "off" when it starts) you will hear the auger begin the 5 second run. The LED will finish that 13 second "on" or "off" period and begin to "slow blink". There will now begin alternating 13 second cycles of "slow blink" (4 each) and "on" (4 each). There will only be "fast blink" of the LED if the auger runs for the 5 seconds during a "slow blink" 13 second period, however the auger may run for 5 seconds during "on" or "slow blink" periods. If the auger runs during the "slow blink", the LED will begin the "fast blink" until the auger stops the 5 second run, then back to the "slow blink".

There will be a total of 3 separate, 5 second runs of the auger during the 13 second cycles of "slow blink" (4 each) and "on" (4 each).

After the last run of the auger a period of alternating cycles between "off" and "on" modes begins. I counted 12 of these cycles at 13 seconds each. 12 x 13 = a total of aprox. 156 seconds. Then the whole process begins again as above where you hear the auger run again.

Note the manual also has info on what the LED and settings do and a WIRING DIAGRAM for the stove (not the control board). It is located on page 15 of the manual. The manual is for the FS-31 but uses the same board as my FS-3 and the stoves are virtually identical, just trim differences. This website: http://api-assembled.com/support/martin/martin.htm has the manual that can be downloaded with one click. On the website scroll down about one page and the pdf file link is on the right side about half way down in blue. Click on it and when the pdf file is finished loading go to page 15. The wiring diagram is the bottom half of the page and worth more than many words I could type here. Please take a look at the diagram if you would.

It is a BOTTOM feed auger and has only one auger motor that is 6 RPM. It has 1 (one) over temp snap disk switch and no other snap disk switches what so ever. I note your diagram shows 2 high temp switches. There is no low temp switch on my stove.
It has a combustion air blower that is on all the time when the stove is on and there is no speed control for it.

There is a fan for room air circulation and a speed control for it mounted separately on the stove just above the control board. Here is the info for the speed control: KB Electronics (HK) LLC. Model KBMS-13 BVNS 3.0 amps FL 6.0 amps LR 120 volts AC

Power for both fans comes to them from the control board, but only the room air blower goes through the speed control. The two fans are 120 volts and 2.5 amps (room air blower) and 1 amp (combustion blower). Total about 3.5 amps.

(CONTINUED ON NEXT POST)

 

[pellet]

I understand the lack of a pressure/vacuum switch just means running the blue wire on from the burner on/off switch directly to the feed motor. And the same applies to the door switch. Just run the yellow wire from the power bus directly to the rotary speed control. Thanks.

There is a High Limit snap switch, but no Low Temp switch. Not sure if I need the low limit since it wasn’t there from the factory. It isn’t on the wiring diagram or on the stove. The “one shot†device is not on my stove either and I don’t think it is built into the control board. There is no button to push there and nothing in the manual involving it in the starting procedure. You just start this stove with a match and some paper or fire starter. These two items seem like just something else with the potential to fail if added. Would you please advise???

My stove has only one feed motor and it is 6 RPM. When you say to “tailor the timer adjustments to make your feed motors run at whatever speed you needâ€, I’m not sure how to do this. They currently are just on or off for a timed period. Maybe that is what you are telling me, varying the amount of time they are on or off. If so, I am not sure how to adjust the timer. Is there a pot on it, dip switches, or some way to get the on/off periods to match what I have now? Would you please advise???

“The low temp switch must be wired into the loop pretty much as shown. When the start button was pressed all the feed power was run through the start timer and then to the fans and such.â€
If the low temp switch HAS to be in place I think I can wire it in. I guess its purpose is to shut the feed motor off if the fire goes out. And the one shot gets the fire going before the low limit switch closes? Why would I want the stove to run before I light the fire in the burn pot with a match and paper or fire starter? Please advise???
Sounds like a nice idea but wouldn’t these two things be above and beyond the original features of the stove? This sounds like more complexity with potential to fail but maybe there is a safety benefit I am not seeing. If the fire went out I guess the only problem would be having to shovel all those pellets out of the ash pan area and back in the hopper after making sure there were no live sparks or fire. I have never had the fire go out unless I ran out of pellets or shut the stove off. When I turn the stove off the pellets in the burn pot just finish burning and it goes out. I usually just turn the feed to its lowest setting (or turn the thermostat down) for a while before turning the master switch off as a cool down mostly for energy efficiency. Gotta get the last BTU out of those pellets! With this process in mind, is there still benefit to having the burner on/off switch too?

“Once the burner switch was shut off the exhaust fan and the room air fan would run until the low temp switch dropped out and then the entire stove would shut down.â€
Maybe I’m lost again but looking at the diagram, wouldn’t the combustion and exhaust fans keep running? Isn’t it just killing power to the timer L1 connection? How does this kill power to the pink wire? I’m not sure how that kills the whole stove unless the low temp switch is relocated to the black main power wire? Maybe this is what you mean by “This could be done easily too, simply by changing things a bit.†Maybe put the low limit in the black main power line to the main power switch? Please advise???

I’ve tried to be through and detailed here. If you have more questions or need more info just let me know. The link above to the wiring diagram should help you see the functions and how the parts are connected and interact better than anything. Hope you have time to go there and look it over.

Some of this is magic to me! The timed sequences at the top above like the “keep fire†mode are pretty complicated from my perspective. It amazes me what they can do, but that said, I absolutely agree with you about the KISS principle. If it is simple, it usually will work when needed. I think it is pretty obvious the thermostat control cannot be kept if I put this control system in place….or could it? Could that be done somehow?

I will keep you posted! Hope you can find the patients to deal with this novice and all my questions. I think this is interesting. I have had this stove apart, changed both fans because the originals are not available anymore, pulled the auger out, rebuilt the auger feed motor, rewired the stove, added a remote thermostat and know I can do what you have started me on. I really want to finish this. If we can get through this with my stove, I bet most any stove can be operated with your general ideas and a little adaptation. You’ve done something here I have been trying to find for a long, long time and I KNOW others have too. This is one of the best postings I have seen and will be very valuable to a lot of us older stove owners. I know WY.MINER is having a problem right now that may very well be his control board and this would be a solution.

MAYBE THE MODERATORS COULD START AN ARCHIVE REFERENCE THREAD LIST. This thread would be a great one to start it!

Many thanks!

Sorry about the long post. I think its well covered though.
Pellet

 

[Snowy Rivers]

This is a far more complicated set up than the whits or some of the others.

The timers are definately different than what I have designed around.

 

[pellet]

I can live without the t-stat "keep fire" mode and the LED indicator. It looks to me like the rest can work... Can we get there?

 

[Snowy Rivers]

Precision timer company is the company that I got the timers from.

They have many types and ranges to choose from.

The one shot timer does not start the stove before the fire ???

The one shot timer is in the system when there is a low limit switch, to bypass the low switch until the fire is going well enough to get heat built up and to close the switch.

This cycle usually lasts 15-20 minutes.

The idea of the low switch is that if the fire goes out for ????? reason the auger will stop and not stuff the entire contenets of the hopper into the fire box on a dead stove.

You can make this setup work for sure.

You will just have to spec out the timers to give you the auger on and off times you need.

The whitfield has a standard on time on the feed motor of about 2 seconds and the off time is what is regulated by the "heat control"

Your info indicates that the on and off times vary with each setting.

I think you could just use a single feed time of maybe 2-3 seconds and then just vary the off times as the Whitfields do and get things working happily.

You can order the timers with remote adjustment "pots" for both the on and off times or you can have the on time adjustement as an on board pot (built into the timer)

I would definately shy away from trying to vary both the on and off times for each heat setting.

A little testing of the timer settings should allow you to find a "sweet spot" where the little beast will work well.

My large Whit is rarely run above the low setting (on for 2 seconds and off for 7 seconds)

There are times that I may run it on the 2 setting that is on for 2 and off for 5 seconds.

The actual on and off times don't have to match the original, just get things dialed in so you can have a reliable fire that will not go out or get too large.

The original Whitfield settings were very easy to match with these timers.

The door switch, vacuum switch and other such items were added by several manufactures as safety devices.

If the exhaust fan stopped for ???? the lack of vacuum in the fire pot would shut the stove off.

Some stoves use a pressure switch to measure excess pressure in the vent to do the same thing.

The door switch shuts the stpove off if the door gets left open or gets accidentally opened by a pet or children.

You can pretty well get creative with this stuff and have good success, and as long as you keep the safety items in place you should be fine.

I am not sure on your stove if the exhaust fan runs at a constant speed or varies with heat settings.

This can also be managed.


Snowy

 

[tjnamtiw]

Hi Snowy,
One quick question about the latch out relay. Usually they would be held in by a holding contact so that when power is lost, they open. Is that the reason for the relay?

 

[Snowy Rivers]

yes, thats it.

The idea is to prevent a restart after a power outage.

If the power was off for, say 5 minutes the fire can die out completely, but the stove could still be hot enough to keep the low temp snap switch locked..

Then the power comes back on and the auger starts feeding again and there is no fire, or worse yet the fire pot fills up with pellets, then smolders and in the mean time the low temp switch unlocks and the stove shuts off completely and the pile of pellets smolder and smoke up the house.

The best latchout relay is a solid state one.
A mechnical relay is a bad idea as its powered on all the time the stove is plugged in.
The solid state units have zero moving parts and basically dont wear out.

You can use the same relay as the one shot, just do not connect a pot between the terminals that are used to regulate the on time.

This will allow the timer to be activated by the push button/momentary switch, but due to the pot not being in the circuit the timer will never unlatch unless power to the stove is lost.

The timer uses a resistance across the "pot" terminals to activate the time value.

Then its just a case of press the "reset button" and its off to the rodeo.

The "latchout" can be wired into the primary side of things before the master on off switch if you like.

Just place your fuse before the latchout in the L1 line.

Wiring it this way fuses the entire stove and also shuts off everything in the event of a power outage and then repower.

Almost all stoves have a latchout built into the board in some fashion.

The usual reset method is to turn the on off switch to off then back on again.

I am not a fan of the "all in one" control boards.

This practice is a $$$$$$$$$ maker for the stove companies.

They get their boards mae overseas for CHEAP and sell them for huge $$$$$$$$$ as a replacement part if you need one.

The system I have drawn out is pretty basic and is almost identical to what many stove builders used back in the early days of Pellet stoves.

The only reason they went away from the relays was to cut costs, to make parts proprietary.

Once the stove bcomes a parts orphan you just have to get creative.

Snowy

 

[tjnamtiw]

Great logical explanation and design. I researched your timers. I really like them! That site went into my 'Electrical' bookmarks immediately! The on/off timer is really a jewel for this purpose. That solves all the problems in a simple brick!

 

[Snowy Rivers]

Yes, the little cube timers are just the ticket for this sort of application.

Sadly the demand of our society for ever more "USER Free" Controls in just about everything, the manufactures have turned to the microprocessor controls to do it all.

The new stoves, although they can pretty much take care of themselves, with auto lighting, full thermostate controls and a whole host of other things, fall short in my opinion of what is really needed in a stove.

Simple, reliable are the words that come to mind when I think of the ideal stove.

I have to light a fire in my stoves, set the heat setting and tend to things.

The plus side of this, is that those things will not fail or stop working and flash a trouble code in the middle of a cold winters night when I really need things to work. (I might grumble though)

The all in one control boards are handy for those who do not want to be bothered with having to set adjustments or fiddle with stuff, but when they fail (and they will) the entire reason for havng a simple heating appliance becomes a moot point.

The timer cubes are the most basic of electronic controls and unless wired wrong and subjected to a severe static discharge are pretty much bomb proof.

Their cost is low and once you have your setup working you can keep a couple spares on the shelf, and in the unlikely event of a failure, you can quickly plug in a fresh one and be up and running, even in the weeee hours of the night.

A little history.

Back in early 1991 I bought my first pellet stove because I wanted to heat my house as economically as possible.

I had been introduced to the idea of using nut shells as a fuel source.

Being in the dump trucking business made this very easy, simply get a truckload of shells, store them in 50 gallon drums with removable lids and Pooof, good economical heat.

Been doing this ever since.


The shells take more wotk, in that I have to handle the stuff more, each fill up of the stove requires me to scoop the shells from a drum, dump them through a screened bottom bucket to insure that there are no STICKS or other debris that can jam the auger.

Two full 6 gallon pails full, pack them upstairs to the Stoves. My philosophy is that 2 or more stoves in the living quarters are much better plan than one central unit.

We have a tiny stove in the living room to use in the moderate season, then a large stove in the family room for the colder weather, and during winters deeper cold we can use both stoves if need be.

The stove is a way of life around here, not an obscure appliance that's tucked away in the mechanical room.

If the stove quits, the house is going to get cold fairly fast. Thursday eavening the power went off due to a tree falling across the power lines just up the road.

The house was 71 F at 11:30 pm and by 5 Am when the power came back on it was 62 F in here.

Took maybe 5 minutes to get both stoves up and running once power was restored, and about 3 hours to get the house comfy again.

Guess I am sort of like a mother hen with her chicks when it comes to the pellet stoves.

Smple, and reliable, Oh and cheap to feed too.


Bought the stoves off craigs list for $200 each and did the installs with new pipe.

All together the two stoves and related items to install them did not cost even half the price of a low end new stove.


Last heating season, the entire cost for heat from Sept - to June was under $200

This is heating a 2400 Sq ft ranch style house.


The design for the rewire using the timer cubes was the result of owning stoves that are basically parts orphans, even though the whits are still serviced well by the aftermarket.


The Cost for one new control board could cost me more than the entire cost of the stove in the first place.

I love off the shelf technology that's rugged and simple.

Back in the 90's many of the Pellet stove manufactures used these very timers from Precision to do this very task.

The companies started using proprietary controls that are made over seas to save $$$$$ and to keep the parts business.


The initial cost of a factory board (to the manufacture) is cheap as compared to using the timers and hard wiring everything.

I will say this in defense of the manufactures, the new boads with minimal user accessable controls keeps a lot of user complaints to a minimum. Just press a button and set the desired heat level and walk away.


There are too many folks that do not have a clue and will louse up their stove in a jiffy, then call the dealer or manufacture to complain that it does not work right.

Far too many people that buy a pellet stove do not comprehend the concept of having to clean out the ashes and doing service work such as lubricating the motors and such.

All in a days work eh ???

Good luck with things.


Snowy

 

[tjnamtiw]

I enjoyed your letter, Snowy. Well written and very interesting. Thanks!

 

[pellet]

Snowey,
Here are answers to the questions you’ve asked and some follow-up questions. I appreciate the response.

-This is a positive air stove. It pushes air into the burn pot unlike most other pellet stoves that suck the combustion air. The burn pot is a bottom feed with 6 rpm auger motor.

-This stove (and the Pellet Master if anyone out there has one) has a very basic control board. It only controls feed times to the auger and the idle mode if the stove is connected to a thermostat. It does not control any other function or change voltage to blowers but just turns the unit on when you turn on the power switch. There is a separately located speed control in the wire to the room air blower only, not the combustion blower. The combustion air blower runs at a constant speed all the time the stove is turned on. The feed control has no effect on either blower speed.

-I read the manual again and the latch-out relay is something I definitely want to add. Thanks for pointing this issue out. You’re right, it should have been in the original design but wasn’t. What were they thinking

-I also noted the manual says the auger should turn 2 to 6 seconds (varies with feed control) every 40 to 45 seconds which is pretty close to the times I posted above. The Precision timers should work fine. I think I could even get the thermostat “open mode†to work if I really wanted to just by adding another timer to the circuit with a connection to the thermostat. I wonder if the complexity is worth it? Hum, have to look at that.

-Any idea what the temperature rating is of both the low (Is looks like 120 degrees F on the schematic. Is that a zero?) and high temp snap switches? I currently don’t have a low temp. and definitely see your point on its need. Again, thanks for pointing this issue out. Do you have any ideas where it should be physically located on the stove? My high temp is a bear to get to. It’s located between the hopper and fire box and on the back wall, outside of the fire box. Inside there are fire brick around the burn pot, but are maybe 3 inches away from the back wall of the stove (although this is the secondary burn area) so there is some thermal buffer there.

- You indicated some stoves like the larger Whitfield’s (Advantage 2 and 2T) had the low temp switch controlling everything. Is this the better way? This isn’t the way you have it wired in the diagram. Is the diagram method better? Pros/cons?

-Would you identify the Latch-out Relay and Triac Speed Control you used? Do you have a good source for them?

-Last question, just to be certain. You are using 2 each high limit snap switches. I guess just to make SURE one of them DOES work if necessary? Do you have a good source for them?

Thanks,
Pellet

 

[pell it]

Precision timer has a $250 min order. Anyone know of another source for the timers?

 

[pellet]

Come on Snowey, help me out with this and I will quit. Thanks.