Hrman P61: Draft Adjustment: I don’t see any.

[lawlopez]

I was wondering if there is a draft adjustment on the Harman P61.
The stove is hooked up to a conventional chimney.
I have a Dwyer Magnahelic .5" vaccum gauge.
When the combustion blower turns on it pins in both high and low combustion motor settings.
So I suspect my draft is > .5".

The Adjustment for low voltage draft is absent.
Threre is a hole in the panel coveredby a label by no adjustment device exists behind the hole.
I don't immediately see any any mechanical draft adjustment.

Information on Harmans stoves seems to be sketchy and misleading.
I've had to go to three stove manuals to find out things.

My stove burns a bit more than I would like while idling but other than this I am happy with it.

Larry

 

[lawlopez]

I LL Bean catalog across the exhaust pipe seems to bring the draft down quite a bit.
Not very practical.
I suppose I could make a aluminum foil restrictor.

 

[djarseneault]

They are supposed to burn about .75lbs/hr on low. If you screw with it enough that it burns less, you could cause the ESP temperature to fall low enough that the stove shuts off. And using a restrictor of any type on the exhaust or intake will also cause less than desireable operation (read: dangerous!), such as creosote build up and possibly a "burn back". And their is a low draft adjustment. If yours is a P61 and not a P61A, the draft adjustment is not accessable without removing the control board.

 

[lawlopez]

I'm not screwing with it to get less than .75/hour.
I'm screwing with it to get less than 1.5/hour.

The restriction works fine.
But I don't like it.

Dropping the line voltage with a variac works.
But I had to drop it to 90 volts. No way I'm going to run the motor on that.

What I'm thinking is:

The stove is tight.
The draft is always more than .5" of water.
Turning on the vent fan over the stove doesn't change the draft by much.
The draft motor has one heck of a lot of headroom.
I don't think ther eis any way to adjust the draft.

I'm going to leave it alone unless someone knows how to adjust.

I think I'll talk to the local Harman guy and see what he says.
It's not their stove but they said they would help.

 

[lawlopez]

Couldn't I restrict the air intake ?

 

[djarseneault]

if it is burning that much on low, you probably have a bad ESP. About 35-45 bucks for a new one.
If you restrict the intake it will adversely effect performance at higher burn rates, and cause incomplete combustion.

 

[lawlopez]

I'm noticing that no one is telling me how to change the draft.
Does this mean that > .5 inches of water is ok ?

I like the idea that the ESP may be bad.

It would be much more convenient to have the stove shut down more at this time of year.

I wonder how you can check the ESP.

 

[djarseneault]

Are you measuring low draft or high draft? The control board has a potentiometer to adjust the draft. If yours is not a self igniting stove, IIRC the adjuster may be on the back of the control board, or on the front and not accesable without removing the control board.
To check the ESP you have to have a Harman DDM tool dealer tec should have one. It plugs into the control board and will tell you what temp the ESP is sending to the control board.

 

[lawlopez]

Are you measuring low draft or high draft?
Both high draft and low draft are above .5 inches of water.
What is your high draft and low draft measurements ?

The control board has a potentiometer to adjust the draft. If yours is not a self igniting stove, IIRC the adjuster may be on the back of the control board, or on the front and not accesable without removing the control board.
Do you have a P61 that you would be remembering from or do you have a P61A which we have one person who says it has this ?
They might be different you know.

I found a hole in the front panel which had nothing behind it.
I removed the two screws golting the front plate which has the board mounted to it.
There was a place for a potentiameter and there was nothing there.
I looked all over the board and found no potentiameter which wasn't which didn't have a front panel know on it.

To check the ESP you have to have a Harman DDM tool dealer tec should have one. It plugs into the control board and will tell you what temp the ESP is sending to the control board.
That's nice.
Normally sensors have simple measurement criteria to test if they are working correctly.
You know, like voltage or resistance at specified temperatures.
For some reason this information isn't available.

I didn't see a DMM connector.
I'll look again.

... time passes ...

No DMM connector.
No draft potantiameter.

No way to regilate draft.
No way to reduce burn rate down to .75 pounds per hour.

 

[lawlopez]

Spoke to Stove shop.
My stove is an orphan by the way.

Adjusting draft is not important
.75 pounds per hour is not always achieved.

My interpretation is:

it runs fine.
leave it alone.
.75 pounds per hour is completely bogus.
no draft adjustment.

SInce ESP is not marginal I'm leaving it alone.

I think draft quotes in manual are minimum.