Harman XXV general questions/concerns

[aqualab]

Hi,
I posted this in the wrong forum this morning - cold and only on my first cup of coffee, so reposting here. I have had my Harman now for four seasons now and have a couple of questions regarding some potential “issues” that I have noticed this past season. One or both of my labs decided to eat the manual that came with the stove, some of these questions or concerns may have been answered in it. I run the stove on auto ignite, room temp and 24-hrs a day - it is my primary whole house heat and my propane furnace acts as my backup if outside temps drop below zero.

1. The blower starts to rev up and then shuts down several times in a row before it will finally go up to and maintain RPM’s. Doesn’t happen all the time but I never noticed it before this season. I keep the blower set at full. I have to play with the blower knob and sometimes that corrects immediately. Could it be that the potentiometer control knob has dirty contacts or is going bad or is it just that the temp set and the surrounding house temp are too close for it to go full blast? It doesn’t run below full speed - it is full or nothing at all.
2. The thermostat is not that accurate - almost always having to adjust up and down depending on room/house temp (gets too hot or not maintaining at the set temp). The temp probe is located behind and slightly below the stove, not in contact with anything but air. Is the wire thermistor bad maybe?
3. The door’s glass is always dirty after an hour after being cleaned it gets black/brown with very limited visual of the blast furnace inside - has happened since day one. The door gasket appears in fine shape and the dollar bill check was perfomed several times. Dirty glass is usually indicative of an air leak - yes? Should I change out gasket and if so, is it hard to do?
4. I get a grinding/laboring noise every once in awhile that I believe is coming from the auger, loud enough that it can be heard easily over the TV and has us all looking at the stove in subdued fear. I have never seen any evidence of metal grindings etc… in the burn pot area or the ash pan when cleaning.
5. Does the electronic control panel need periodic maintenance, calibration and or a disassembly and cleaning? Seems I remember the stove rep/salesman where I bought the stove from mentioning that they should perform this monumental task in addition to a complete stove dissassembly and cleaning (internals) for me yearly at a somewhat substantial service fee - thanks but no thanks. I dissasemble the back plates and clean/vac the stove’s mechanical internals every spring as suggested by the manufacturer.

I like the stove, no regrets, other than the pellets price increase and lack of availibilty up by me. I think the pellet manufacturers/retailers and the major oil companies must be one in the same because they follow the identical “supply and demand” practices when it comes to price gouging. Maybe I should have looked at a multiple source stove - pellets, grass, corn, cherry pits, etc.....?
Thanks for any feedback/suggestions, appreciate your help.
Bill

 

[lecomte38]

try cleaning / replacing the ESP probe. That is what is controlling the blower fan. I was told that they get weak with age.
Try moving the room sense probe around to different locations.

 

[aqualab]

Forgive my ignorance, but where is the ESP probe located, I don't ever recall hearing about that - is it built into the control panel? I'm sure it is in the manual - I will have to try and locate the owner's manual online and download it for printing.

Thanks

 

[slink]

Check out my site for the manual. Click on the products page then on harman heating to find the info. you can download directly from there.

 

[aqualab]

Thanks, I downloaded the manual. I looked up the ESP probe and all I could find was the entire electronics control system shown in the manual. It also mentions the ESP probe in the cleaning section but does not illustrate it. Am I still missing something with the location of the probe, I'm starting to think you need ESP to find it!

Bill

 

[GVA]

ESP exhaust sensing probe...It is located in the exhaust pipe of your stove about 3" before the starter collar and flue piping

 

[aqualab]

Thanks - would that control the blower that delivers heat inside the house or just the exhaust discharge blower? I was not clear in my initial post which blower was giving me the run problems. To clarify better, it is the blower which delivers/throws the heat into the room. It will start to ramp up and then it dies, this goes on for a few more times before it finally stays running at full speed. I think the control potentiometer for the blower max/min is dirty or defective. I just noticed this happening this winter. Sometimes if I adjust the knob it will go to full power, sometimes it does absolutely nothing in correcting the problem.

 

[GVA]

first....The ESP if it senses a high temp condition will kick the (room) distribution blower speed up to keep the stove from overheating, it can cause strange things to happen ( I won't get into it though).....
second....the potetiometer can be dirty or defective...
third.... The hysterisis on the control board could be off a bit....
The next time you hear the blower ramping up and down don't turn the blower knob...... turn the temp knob, see if this cures the problem.
if it does try moving the room temp thermister to a different location...

 

[aqualab]

Okay, I will move the temp knob to see if it corrects the blower ramping problem. I noticed that when the blower acts up the front top of the stove is pretty hot to the touch - makes sense from what you described about the blower working to keep the stove from overheating. I might just order a new ESP sensor and temp probe and install both this spring. A dirty potentiometer or incorrect hysterisis setting would require a house call I guess to correct/repair - makes sense since i am out of warranty. I just inspected the temp sensor probe and noticed the protective covering is missing, looks like either the cat or one of the dogs may have gotten to it too. The bulb appears to be intact, hard to say if it is damaged - time for a new one none the less. Appears the wife or kids protected the animals and just put the wire back behind the stove before dad found out. If one of the pets chewed on it and then put it back so nobody would find out, I will just ask them to fix the rest of the stove's issues since they are obviously smarter than me.

Thanks GVA for your help

 

[JNixon]

I had a similar unpleasant grinding noise in my XXV when new. It turns out that the auger motor was touching the exhaust shroud and setting up a vibration. There is a cutout in the shroud that is supposed to keep this from happening,but obviously in my case was not successful. I solved the problem by wedging a piece of cardboard between the auger motor and the shroud which worked like a charm. (The parts I am referring to are on the right as you face the rear of the stove).Good luck. Jon