Harman Fan Speed and Pellet consumption

[Tonyray]

Mostly for Harman owners or any models with the temp probe:
example:
running room temp/auto or manual. Optimal feedrate # 4.. desired temp set at 72.
the stove calls for heat when the room temp drops,
the theory is that at a LOW fan speed, say 1/4 on,
the stove will take longer to hit the set temp thereby comsuming more pellets
as opposed to higher speed, say 3/4 hitting the desired probe temp sooner thereby
using less pellets..
I liken this to Air conditioning whereas the lower the blower speed, the longer it takes to cool off the room
causing the Compressor to run longer...
anyone have a definitive answer?
or are the're too many variables to this..IE: House plan, Insulation or lack of, type of pellets etc.
I would think even with variables thrown in,, the theory would be the same with just the pellet consumption level of less or more would differ due to variables mentioned in each household.

 

[HarmanManP43]

The way I have always felt is that you want to get heat out of the stove as quickly as possible.

With lower blower settings more heat stays in the stove and that means more heat out the exhaust being wasted.

It's an oversimplification of the process but I believe it still applies.

 

[Tonyray]

The way I have always felt is that you want to get heat out of the stove as quickly as possible.

With lower blower settings more heat stays in the stove and that means more heat out the exhaust being wasted.

It's an oversimplification of the process but I believe it still applies.

ok... I would agree with that so the question still remains.:
at the end of the 24 hr day, did we use more pellets or less pellets running at faster blower speed..

 

[HarmanManP43]

Would have to experiment to find out.

 

[tonyd]

How about? With a faster blower speed, you are cooling the heat exchangers to quick blowing colder air into the room. Take the decorative grill off the opening where the heat comes out.. You will be amazed at the amount of air being blocked by that pretty grill. I have taken mine off and the difference is amazing. BUT My wife likes pretty more then heat.

 

[Tonyray]

How about? With a faster blower speed, you are cooling the heat exchangers to quick blowing colder air into the room. Take the decorative grill off the opening where the heat comes out.. You will be amazed at the amount of air being blocked by that pretty grill. I have taken mine off and the difference is amazing. BUT My wife likes pretty more then heat.

Now that's an Interesting theory and Modification....
Off topic here but:
funny but I always though also that the AC in the car was colder if I dropped the blower speed to maybe 2 after the Initial 1st cool off.. same principal.. blowing cold air out Faster than can make it.
btw:
I open all my car windows for the 1st mile or so with the blower on high to quickly blow all the hot air out thru the back windows. It works!!

 

[tonyd]

Its not off topic. Its something to think about. Same principle

 

[Tonyray]

Its not off topic. Its something to think about. Same principle

I have read that theory posted in a discussion awhile back about possibly cooling the heat exchanger quicker at high fan speed...

Its not off topic. Its something to think about. Same principle

If that High blower theory is valid, then a higher pellet consumption might take place due to heat exchanger doing some " relative" cooling but I don't
know if the exchanger can cool down [lose some measurable heat sounds more realistic] if fire is still roaring in the stove.. but your saying the blower is doing that by pushing all the exchangers heat out too fast.

 

[tonyd]

The air needs time to be heated. Run your hand over a flame fast, No problem, Now do the same slow. The air is doing the same,

 

[Tonyray]

The air needs time to be heated. Run your hand over a flame fast, No problem, Now do the same slow. The air is doing the same,

ok.
still need to figure where the pellet consumption lies with low fan/high fan..

 

[moey]

In most heating appliances there is always a balance between comfort and efficiency. Usually what is most efficient is not most comfortable.

Most efficient would be having a larger blower fan with exiting temps around 100F. But you would be cold when you walked by from the stiff breeze.

 

[Tim_M]

There was an interesting post on here a few weeks ago (I think it was by Scott Williamson) related to this topic. I think It said that when running your Harman in stove temp, the ESP probe monitors and controls the exhaust temperature (based on the heat setting selected) by increasing or decreasing the feed rate. So if you have your fan on high, more heat is being blown into the room and less is vented past the ESP resulting in an increase in the feed rate and more pellets being used.

In room temp mode I don't think the ESP plays as big a role, but the fan speed is automatically varied to some degree depending on whether the room sensor is calling for heat, and how much of a differential there is in the room vs desired temperatures.

 

[mepellet]

Btuh = cfm x 1.08 x delta t(f)

 

[Peterfield]

Btuh = cfm x 1.08 x delta t(f)

Now I understand.

 

[harmandude]

I don't think you loose efficiency or heat between low fan speed and high fan speed.

It's true that at low, the air might be a little hotter than high, but i think we can describe the fan simply as it is written on the stove, a distribution fan.

The principal purpose of this blower is to distribute the heat.

I think they did not choose randomly the 150cfm capacity of the blower either. They probably determined that at that speed it is most efficient (or hotter) at the highest temp.

I mostly run the fan on my stove at 75% and notice that the blower motor run faster if the stove is on lets say 4-5 on stove temp than 2-3. So i let him decide.

I keep the low speed when its hotter outside and yes its is faster to heat the room at high speed on room temp.

By the way first post here! Been reading for a long time here. Got a lot of advice from all of you guys hope mine can help a bit.

 

[mikesj]

Even though these stoves are considered to be room heaters, most of us use them to heat multiple rooms or entire houses. As such, I think it's probably more advantageous to push as much heated air out as possible- for circulation purposes. Never really experimented with it. My fan is always set to max. I usually only adjust the temp or sometimes the feed rate.

Happy New Year!