Harman's Room Temp and the fan

I am with you on this, the fan shutting off is a waste of heat, we should be able to override the fan settings.

this should only happen to you if you have the stove running really low and the fan pretty high. this can also happen if your feed adjuster is set too low. the fan shuts off when the ESP senses temps below 165 on the combustion side, so a dirty ESP could also do that.

Delta-T said:

this should only happen to you if you have the stove running really low and the fan pretty high. this can also happen if your feed adjuster is set too low. the fan shuts off when the ESP senses temps below 165 on the combustion side, so a dirty ESP could also do that.

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The room fan should run based on the heat exchanger being hot, and keep blowing until the heat of the heat exchanger is below the room temp set, that way the heat isn't being wasted.

Is the fan supposed to be variable speed, or just on and off ? mine is on or off and it does kind of bug me too, it's seems a variable speed would be better.

the fan is variable speed. you do need a certain amount of heat to keep the exhaust from condensing in the pipe.

Delta-T said:

the fan is variable speed. you do need a certain amount of heat to keep the exhaust from condensing in the pipe.

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We're talking about the Room heat Distribution Fan, not the combustion fan.

What are guys using for temp control? Just the probe? Works well?

lordgrinz said:

Delta-T said:

the fan is variable speed. you do need a certain amount of heat to keep the exhaust from condensing in the pipe.

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We're talking about the Room heat Distribution Fan, not the combustion fan.

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yes, I know, it is variable speed.

Delta-T said:

lordgrinz said:

Delta-T said:

the fan is variable speed. you do need a certain amount of heat to keep the exhaust from condensing in the pipe.

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We're talking about the Room heat Distribution Fan, not the combustion fan.

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yes, I know, it is variable speed.

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Yes, but what does that have to do with condensing pipes? I can be standing right in front of my XXV while its blowing hot air, then all of a sudden it stops blowing. Its not like the stove just went cold, so why is the fan shutoff? Its a waste of heat to shutoff like that.

lordgrinz said:

Delta-T said:

lordgrinz said:

Delta-T said:

the fan is variable speed. you do need a certain amount of heat to keep the exhaust from condensing in the pipe.

Click to expand...

We're talking about the Room heat Distribution Fan, not the combustion fan.

Click to expand...

yes, I know, it is variable speed.

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Yes, but what does that have to do with condensing pipes? I can be standing right in front of my XXV while its blowing hot air, then all of a sudden it stops blowing. Its not like the stove just went cold, so why is the fan shutoff? Its a waste of heat to shutoff like that.

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I agree, that would be a waste of heat. Let me put it this way...there are normal instances where the fan shuts off because the stove thinks its is not warm enough (exhaust temp below 165 would indicate that the stove is not generating enough heat, and so, it shuts off the fan to allow the heat exchanger to re-heat up to an appropriate temp, and then it turns the fan back on). If your feed adjuster is too low, the stove does not feed enough pellets per cycle to get the temps to an acceptable level (there is a benchmark temp range that the ESP probe is looking for based on what you've told the stove to do), an you'll be stripping off more heat than the stove is making (thats how the exhaust temp is related to the distribution blower). If the probe is dirty it can also be insulated from the actual temp of the exhaust and it will believe that it is running too cool and shut the fan off. The stove will also default to a high blower speed (distribution) if the stove is burning at a very high rate, even if you have the fan set fairly low, to prevent over heating and wasting heat out the exhaust.

Delta-T said:

lordgrinz said:

Delta-T said:

lordgrinz said:

Delta-T said:

the fan is variable speed. you do need a certain amount of heat to keep the exhaust from condensing in the pipe.

Click to expand...

We're talking about the Room heat Distribution Fan, not the combustion fan.

Click to expand...

yes, I know, it is variable speed.

Click to expand...

Yes, but what does that have to do with condensing pipes? I can be standing right in front of my XXV while its blowing hot air, then all of a sudden it stops blowing. Its not like the stove just went cold, so why is the fan shutoff? Its a waste of heat to shutoff like that.

Click to expand...

I agree, that would be a waste of heat. Let me put it this way...there are normal instances where the fan shuts off because the stove thinks its is not warm enough (exhaust temp below 165 would indicate that the stove is not generating enough heat, and so, it shuts off the fan to allow the heat exchanger to re-heat up to an appropriate temp, and then it turns the fan back on). If your feed adjuster is too low, the stove does not feed enough pellets per cycle to get the temps to an acceptable level (there is a benchmark temp range that the ESP probe is looking for based on what you've told the stove to do), an you'll be stripping off more heat than the stove is making (thats how the exhaust temp is related to the distribution blower). If the probe is dirty it can also be insulated from the actual temp of the exhaust and it will believe that it is running too cool and shut the fan off. The stove will also default to a high blower speed (distribution) if the stove is burning at a very high rate, even if you have the fan set fairly low, to prevent over heating and wasting heat out the exhaust.

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I guess I would be fine with what they are doing, but I would like to override that distribution fan. I really want it on full high constantly, until the heat exchanger is below the set room temp, not the ESP probes heat settings.

are you using room temp or stove temp? in room temp you'll have less control, but in stove temp, so long as the stove is running above 3ish the fan should run full bore all the time without shutting off (make sure your feed adjuster is above 3 at the very least).

if the distribution blower ran until the heat exchanger was the same as the temp you've set (say 70) then the exhaust would be cooler than that and it would cause all kinds of problems as far a measuring safety, combustion ratios, and the differences in pellet qualities would become much more obvious. Trust me, these guys who make these things do know what they are doing.

Delta-T said:

are you using room temp or stove temp? in room temp you'll have less control, but in stove temp, so long as the stove is running above 3ish the fan should run full bore all the time without shutting off (make sure your feed adjuster is above 3 at the very least).

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I'm using Room Temp, but I'm going to guess they have this thing setup to stay in a narrow band when using room temp, thus wasting heat. I would rather the fan ran on high even if the heat in the room got too high, as long as it starts to shutdown, but I never want it to go below my set room temp. I'll have to give Stove Temp a try, maybe thats what I am really looking for here.

I have seen this too. The room comes up to temp say 77 degrees and the stove will slowly lower the feed rate and the distribution fan. I have mine hooked through a thermostat so that in manual mode and room temp the stove goes into 4 blink alarm (Open Thermister) when programmed at night and when not at home. This completely shuts down the distribution fan and drops to minimum feed levels. I would love to have the distribution fan on at its lowest set point for this so that we do not waste that heat.

If the stove is in manual mode and room temp then the only time I have ever seen the distribution fan completely shut off is when the room actual temp was significantly above the set point (Say 3 to 5 degrees) This can be solved by moving the thermister probe to a more thermally stable location (away from the stove). Just my thoughts.

Delta-T said:

the fan is variable speed. you do need a certain amount of heat to keep the exhaust from condensing in the pipe.

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Any Idea why mine runs between full speed and off with no in between?

Running in room temp mode, feed set at 4 1/2.

BJN644 said:

Delta-T said:

the fan is variable speed. you do need a certain amount of heat to keep the exhaust from condensing in the pipe.

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Any Idea why mine runs between full speed and off with no in between?

Running in room temp mode, feed set at 4 1/2.

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Do you set the fan on high and it switches between high and off? or do yo set it on low and it only runs on high or off?

Delta-T said:

BJN644 said:

Delta-T said:

the fan is variable speed. you do need a certain amount of heat to keep the exhaust from condensing in the pipe.

Click to expand...

Any Idea why mine runs between full speed and off with no in between?

Running in room temp mode, feed set at 4 1/2.

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Do you set the fan on high and it switches between high and off? or do yo set it on low and it only runs on high or off?

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I have the room temp knob set 1/2 to 3/4 towards high, when the fan is on it's full blast then when (i'm assuming) room temp is met the fan shuts off. I have never noticed the dist. fan run at a slow speed only wide open.

i notice on most units (Harmans that is) that at slightly above 50% on the fan control it seems to be running at full, and just at or a hair below 50% you can notice the difference. Even at that, the fan does change spped slightly as you approach the high possition, but the sound of the turbulence doesnt change much, giving the impression that there isn't much difference (i've watched the volts to the motor change and not heard or felt much difference, but it must be so, cuz the volts are changing). If you set the fan at about 50% the stove will turn the fan up when it goes to high burn, and then default to the mid speed after that, and off when the stove goes to shut down of course.

I have ran my stove 95% of the time on stove temp just for this very reason. I can't stand the up down and off of the fan. My feeling it's a complete waste of heat. I just adjust feed rate and monitor the pellet consumption. I also feel this helps me keep better control of the operation of the stove.

Somethin' ain't right, here. My stove doesn't act like this at all. The only time the fan shuts down is if it gets really warm outside suddenly, or something else causes a sudden change in the heat load on the house, like turning on the oven.

Sounds to me like your thermostat probe needs to be moved farther away from the stove. Its not getting an accurate picture of the load on the house. Either the temp probe is too close, or there is something else causing inconsistent air circulation...lots of rooms with doors, people coming and going a lot (opening an outside door)...something like that.

Stove temp can't be more efficient, by definition. it is a constant state; the load on the house isn't. In stove temp, you're either going to get more than you need, or less; you'll never be able to match the heat load on the house.
The only time stove-temp is really appropriate is when you want a fire without the fan on, for ambiance. That fan won't come on until the stove's temp gets so high, it'll blow me out of the house.
Even if you're artificially setting the stove to a higher setting, because you're trying to heat some distant area, (i.e. heating the living space from a basement stove), you should still get the same output from the stove by simply setting the room temp higher...unless there is some reason that the stove can't sense the load.

the fan will come on, like normal at 165 in room or stove temp mode...unless you put the igniter switch to manual in stove temp, then the stove is in "ambience" mode. I never use room temp and I have no control problems. I may have to tweak the knob every now and again if theres a big swing in temps outside, but I dont find that to be very inconvenient. Stove is pretty much equally efficient in either mode.

Delta-T said:

... I may have to tweak the knob every now and again if theres a big swing in temps outside, but I dont find that to be very inconvenient.

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perhaps not "inconvenient", but it can't possibly be done as accurately as the computer can do it. The extra heat you will get at times may be "acceptable" to you, but it is not as efficient.