P68 Blower Speed?

[Shield1561]

Hi all.

I'm trying to understand my Harman P68. I have the feed set at 4, temp at 74, in room temp mode. What exactly does the blower motor speed do? I have it set to max at the moment. But i hear people talk about blower speeds and some people say set to medium. What is the optimum setting for the blower motor? Does the speed affect the amount of fuel burned?

-Justin

 

[pkitfox]

Hi all.

I'm trying to understand my Harman P68. I have the feed set at 4, temp at 74, in room temp mode. What exactly does the blower motor speed do? I have it set to max at the moment. But i hear people talk about blower speeds and some people say set to medium. What is the optimum setting for the blower motor? Does the speed affect the amount of fuel burned?

-Justin

You can vary the blower speed with this control. The blower speed will still change as the control board tries to maintain your set temperature (in room Temp mode). In fact, the control board will at times shut the blower off if it is getting too hot. It is trying to not shut the stove down. In stove Temp. mode, the blower is set where you set it. The control board does not vary the convection blower speed in stove Temp mode. I leave mine at Max., trying to get all the heat I can out of the pellets. It also helps to circulate the heat around the house better when on Max (it is a bit noisy).

As far as higher convection blower speeds causing more fuel to be burned, I have to guess. With the blower on low, the heat coming out of the stove is hotter, but less volume. On high, I don't think the circulating air is as hot, but there is more of it. Overall, I think more heat gets into the room with the blower at higher speeds (I have no proof of this). If you are getting more heat out of the stove with the blower on high, I think you will burn more fuel if you are in stove Temp. mode because the control would have to burn more fuel to maintain the same EGT (you have extracted extra heat that normally would be available for exhaust heat). In room Temp mode, the end result is the same, the stove maintains the rooms temperature. I would guess that in room Temp mode, the fuel usage is close to the same. I am kinda guessing on this, but it makes sense to me.

 

[kinsmanstoves]

Hi all.

I'm trying to understand my Harman P68. I have the feed set at 4, temp at 74, in room temp mode. What exactly does the blower motor speed do? I have it set to max at the moment. But i hear people talk about blower speeds and some people say set to medium. What is the optimum setting for the blower motor? Does the speed affect the amount of fuel burned?

-Justin

The Distribution blower has nothing to do with burning pellets faster, slower, or at all.
The Combustion blower runs a one speed and never should change while the stove is running.

Eric

 

[TomPajak]

Not to sound mean but I'm just curious how many people actually read the manual with their stoves...heres what it says about the fan speed in Room Temp Mode

In the Room Temperature Mode, the distribution blower speed can be increased or decreased by adjusting the Room Temp/Off/Stove Temp dial between L and H. As output of the stove increases, the speed of the blower will increase automatically to insure that more heat is transferred out into the room. The distribution blower will shut off as the room reaches the set temperature, this will prevent overheating of the room

 

[pkitfox]

Hi all.

I'm trying to understand my Harman P68. I have the feed set at 4, temp at 74, in room temp mode. What exactly does the blower motor speed do? I have it set to max at the moment. But i hear people talk about blower speeds and some people say set to medium. What is the optimum setting for the blower motor? Does the speed affect the amount of fuel burned?

-Justin

The Distribution blower has nothing to do with burning pellets faster, slower, or at all.
The Combustion blower runs a one speed and never should change while the stove is running.

Eric

Does the distribution blower speed have any effect on how much heat is transferred to the room?

 

[Steve NH]

Eric[/quote]

Does the distribution blower speed have any effect on how much heat is transferred to the room?[/quote]

Think of it as wind chill in reverse - the more wind (faster blower) that passes the heat tubes the more 'chill' applied to the heat tubes.
The blower 'chills' the heat tubes by moving the heat into the room.

Good test:
put stove on 'stove temp' (temp of stove will remain same)
do not change the temp setting - but try different blower settings.

You will defiantely see that higher blower settings produce higher room temps.

 

[pkitfox]

Eric

Does the distribution blower speed have any effect on how much heat is transferred to the room?[/quote]

Think of it as wind chill in reverse - the more wind (faster blower) that passes the heat tubes the more 'chill' applied to the heat tubes.
The blower 'chills' the heat tubes by moving the heat into the room.

Good test:
put stove on 'stove temp' (temp of stove will remain same)
do not change the temp setting - but try different blower settings.

You will defiantely see that higher blower settings produce higher room temps.[/quote]

So you might agree that if the stove temperature (EGT) remains the same, and the room temperature is higher because of a higher distribution blower setting (room blower), the extra heat in the room came from somewhere (more fuel being consumed?). On some models of pellet stoves with fixed feed rates, if the room was warmer with the higher distribution blower setting, the EGT would be lower, and the fuel used would be the same. I'm not sure this is true with Harman feed control. The control board will increase feed rate to maintain EGT when the Harman stove is in Stove temp mode. Room temperature mode seems more complicated. What do you think?

Somehow I messed up the quote feature.

 

[GVA]

You will defiantely see that higher blower settings produce higher room temps.

yes but the higher temp is short term only.

there is a point where you remove too much heat from the exchangers and start to blow cooler air into the room, thus the feed rate will need to be turned up to maintain the temp on the exchangers.

I always kept mine in the middle and let the stove turn it up or down as needed......

 

[GVA]

Hi all.

I'm trying to understand my Harman P68. I have the feed set at 4, temp at 74, in room temp mode. What exactly does the blower motor speed do? I have it set to max at the moment. But i hear people talk about blower speeds and some people say set to medium. What is the optimum setting for the blower motor? Does the speed affect the amount of fuel burned?

-Justin

The Distribution blower has nothing to do with burning pellets faster, slower, or at all.
The Combustion blower runs a one speed and never should change while the stove is running.

Eric

The combustion blower on the Harmans have a high and low draft speed.... but is controlled by the board..

 

[Shield1561]

Not to sound mean but I'm just curious how many people actually read the manual with their stoves...heres what it says about the fan speed in Room Temp Mode

In the Room Temperature Mode, the distribution blower speed can be increased or decreased by adjusting the Room Temp/Off/Stove Temp dial between L and H. As output of the stove increases, the speed of the blower will increase automatically to insure that more heat is transferred out into the room. The distribution blower will shut off as the room reaches the set temperature, this will prevent overheating of the room

Thanks for the reply. I don't actually have the manual, it was installed in the house when I bought it in august, and I've been going by what people have been telling me to do. Can you get the manual online somewhere?

So I'm best to leave it on med?

-Justin

 

[Steve NH]

yes but the higher temp is short term only.

there is a point where you remove too much heat from the exchangers and start to blow cooler air into the room, thus the feed rate will need to be turned up to maintain the temp on the exchangers

When the heat exchangers start to cool - since it is in stove mode the stove will start feeding more pellets to keep the stove at the pre-set temp. The higher room temp will be maintained.
Yes you will probably burn more pellets.
Also since more of the heat in the combustion chamber is actually being drawn thru the heat exchangers - whatever xtra heat drawn thru the heat exchangers does not go out the exhaust. The exhaust will be cooler which equals more effecient stove.

Room temp is more complicated since once room temp is reached pellet feed and blower both turn down automatically. But turning your blower on high will still get the room up to room temp faster than blower on low.
(I've actually done this experiment more than once - get up in AM - room at 59. Turn on stove (room temp) and time how long it takes to get to 72. Blower fan on high has the record.)

 

[TomPajak]

Not to sound mean but I'm just curious how many people actually read the manual with their stoves...heres what it says about the fan speed in Room Temp Mode

In the Room Temperature Mode, the distribution blower speed can be increased or decreased by adjusting the Room Temp/Off/Stove Temp dial between L and H. As output of the stove increases, the speed of the blower will increase automatically to insure that more heat is transferred out into the room. The distribution blower will shut off as the room reaches the set temperature, this will prevent overheating of the room

Thanks for the reply. I don't actually have the manual, it was installed in the house when I bought it in august, and I've been going by what people have been telling me to do. Can you get the manual online somewhere?

So I'm best to leave it on med?

-Justin

I leave my fan on high and let the stove decide how much speed it should use..the stove in room temp mode will automatically adjust your fan speed for you..YOU just have to set the maximum speed and the stove will adjust itself between the low speed and your speed you just set...
....the manual needs adobe reader to read it because its in .pdf form

http://get.adobe.com/reader/
http://www.harmanstoves.com/doc/p68m.pdf