Recent Harman Combustion Blower Upgrade! but why?

Hello

After working on a few Harmans, I found the new Harman Combustion blower is now 1.75 Amps and the older blowers are only 1.50 Amps. Harman does change the part # on upgrades and sure enough, the new blower does have a new part number!

If anyone has any insight as to why this upgrade was done, please let us know.
Did Harmam put out a Service Bulletin that explains it?

See pics below for proof!

Pic 1 - Old Star date 12/12/2008 1.50 Amp Part # (BM)2524-A1506T-1204
Pic 2 - New Star date 11/05/2013 1.75 Amp Part # (BM)2524-A1756T-1371

Time to update the Harmy's again! LOL

 

hey, Don....just spied your post!
the new blowers are a lot more adjustable than the old ones......the old ones were adjustable to like =/- 5 volts, where the new ones have quite a lot more range........

 

Wow, Thanks for the info LW, sounds like a better heat curve for different temp settings! Now I really want to try one! I have one in stock and 2 more on order. (= Is your shift key broken?)

 

yea, Don, old keyboard....lol......and I cant type.....more to make it easier to vary the draft tho.....more adjustibility

 

Does the Circuit Board automatically increase or decrease the exhaust blower speed with the heat level?

 

no, Don, all the voltage adjustments are made via the potentiometer, manually, on the set screw on the circuitboard

 

LW, I have the old blower. Would tweaking that adjustment potentially increase air to my burn pot?

 

You mean the small white screw next to the Ignighter light used to adjust the combustion fan to make up for voltage irregularity?
According to the instructions I have attached, the white set screw is only to adjust the combustion blower when the Circuit Board automatically sets the combustion blower to low draft in test mode. (Draft should be between 0.30 and 0.35 WC)
Turning it to the left will increase the exhaust blower speed/voltage.
So it seems to me that the stove does vary the combustion blower between low and high draft.
If not automatically does it vary with the Temperature knob?
My guess is that the combustion blower speed would be automatically set in room temp mode as the heat ramps up or down and manually in stove temp mode as the heat level knob is turned up?

Therefore, in room temp mode, getting the right set temp on the temp dial would be much easier since adjusting the knob would not be so coarse and difficult to do as it is now. Sounds like a really nice upgrade! I want one!

Sounds like we got the answer to the question Why Upgrade? Thanks

One other side note is that the circuit board if old, would also have to be upgraded to have the wider voltage control over the blower. I already noticed a difference when I did mine!

 

if youre set screw is already maxxed out, Sub, then no, that's just full voltage to the combi blower (cant increase itmore if its already set to full)....line voltage.....the beauty of the higher range is that it allows a guy (or gal!), to DECREASE the voltage to more of a degree, thereby actually lowering draft.....which is a good thing when your chimney has one of those killer draft issues......

 

lotsa times the draft pegs out on high OR low draft.......I just got a new digital draft meter which has a range of +/- 20 inches of water, broke down into the hundredths......no more pegging out of me!

 

Nice, Thanks again for your comments. I will have to do a manometer check at low draft to make sure it is in the range!
Did you get a manometer like mine? See pic below. I used it to help diagnose the problem on a Magnum 6500 furnace the other day. Not enough draft to keep the vacuum switch closed so I installed the recommended higher CFM blower. It works great now!

 

don- its EXACTLY like yours.....or, yours is like mine........how do you like it?

 

I like it. It works fine. Easy to use.

 

I believe I will get one of these manometers. I always question if my stove is set correctly. How do you use the meter?? When the stove is under normal opt ? I understand the vent hole in the bottom of my Harman but at what stove settings and or opt.

 

It is in you Harman Manual. (RTFM)
A simple draft test should be performed after completing the flue pipe installation.
To record the results for future reference:
1. Plug unit into a 120VAC, 60 HZ outlet.
2. Close the hopper lid, front view door, and the ash pan.
Neither pellets or a fire are required for this test.
3. With the mode selector in the "OFF" position, turn
the feed adjuster to "TEST".
4. Record the high draft_____in W.C. (Normal is -.50
to -.60) The control will be on the High Draft for a total
of 2 minutes.
5. After 2 minutes is up, the combustion motor will go
down to low draft and the distribution blower will go
on high. Allow approximately 15 seconds to pass for
the combustion motor to slow before checking the low
draft.
6. If the low draft is between -.35 and -.45, record the
reading _____ in W.C. If the reading is higher, slowly
turn the set screw counter-clockwise until the draft
lowers. If the reading is lower, very slowly turn the set
screw clockwise until the draft increases.
NOTE: The test mode alternates from high to low
draft every 60 seconds. If more time is needed for
draft adjustment, wait until the next low draft
cycle.
NOTE: In some cases, the draft may not go as low
as -.35 to -.45 even with the set screw completely
counter-clockwise.

 

Thank You for the details. Stove has been in 2 years now so the flue pipe installation is long gone ago. I will do this before next season heating season after all is cleaned... Thanks again.