Problem with my Harman PB 105.

[Tdiguy]

I hate calling the dealer to fix this thing because i have found for the most part its pretty easy to understand and work on. Also I think sometimes i understand this boiler better than the dealer.

This time though the thing has me a bit stumped. I have not taken my multimeter to it yet because i just got off my 12 hour work shift and we have a backup heat source.

My boiler powers up, all the lights will come on when i put it in test mode, but I cant feel any heat from the ignitor inside the burnpot ( i didnt take the cover off though so maybe it simply isnt getting hot enough to feel through the burnpot.. again just too tired right now to check ) but the feed motor and combustion motor are definantly not turning. I thought maybe a vaccume leak but that would only stop the feed motor the combustion blower would still be going.

What do all these components have in common that would cause such a failure where the control board is all light up but nothing is running? Monday i think i will have time to find my meter to really troubleshoot unless you guys can give me advice beforehand to help narrow this down. Thank you.

 

[velvetfoot]

Hi. Can't help you, but I think you should post a copy of this on the Pellet forum as well. Maybe by the time you wake up you'll have an answer.

 

[AndrewChurchill]

Check your large ash pan door. I had that same issue and it turned out the latch on my door wasn't tight enough to make a tight seal.

 

[Tdiguy]

Ok after some rest and some poking around with my meter i think its the exhaust fan. I am getting the 110 to said fan but its not spinning. I have pulled it out of the boiler and made sure it can spin freely but it does not turn on with the boiler.
I am betting without the exhaust fan the rest of the boiler won't run. It looks like the exhaust fan is what ends up creating the vaccume / pressure diff which ends up powering the feed motor and such.

I could be wrong on this, its mostly guesswork of mine.
Its also worth noting that i bought this boiler back in 2008 and the exhaust blower has not been replaced.

 

[maple1]

Can you hook it up direct to 120 when it's out & see if it turns? That should confirm.

 

[Tdiguy]

Not a bad idea. I don't have a way to do that right now but a stop at home depot and probably 5$ worth of cheap replacement power cord can cure that. Well worth it to confirm before spending over 100$

 

[maple1]

I've gone partly nuts before trying to get a fan to work - although that was 12v DC & not on a boiler. I could get 12v on a meter at the wires, but when I hooked the fan up it wouldn't work. Hook the fan right up to a car battery, & it worked fine. Partial break in a wire let the meter see 12v, but wouldn't carry enough current to start the fan up. Might not be relevant to your issue though.

(I pull wires/cords off appliances I throw out just for things like this).

Good luck.

 

[Tdiguy]

Well I am pretty sure it's the exhaust blower. Plugged it into the wall and nothing happened. Now to see if I can get that 30$ fan blade off of it.

 

[heaterman]

The draft inducer on the Harmon pellet furnace and the boiler are pretty common replacement parts. A couple of our customers with these have gone as far as keeping a spare on hand themselves.

 

[heaterman]

Well I am pretty sure it's the exhaust blower. Plugged it into the wall and nothing happened. Now to see if I can get that 30$ fan blade off of it.

If you succeed in getting it off without ruining it, put some anti-sieze compound on the shaft before you reassemble. It will come apart much better next time.
The copper based product is what we use for hi temp applications.

http://www.henkelna.com/industrial/product-search-1554.htm?nodeid=8797932355585

 

[Tdiguy]

Well looks like I will be getting a fan blade also. Man that thing was stuck. I guess that is normal for being the original with the boiler.

 

[BoilerMan]

You are correct in that the fan must be actually pulling a slight vacuum which is detected by the vacuum switch to start the ignition process. It's worth having a spare exhaust motor and a spare ignitor for a Harmon PB105. The thing is basically just a glorified pellet stove with water tubes. Nicely built and simple, for a price-point residential higher-maintenance boiler.

TS

 

[Tdiguy]

Well I just installed the new exhaust blower and it's back up and running. The new blower only has one side to the fan but it is so much quieter than the old one ever was.

 

[wil lanfear]

Well I just installed the new exhaust blower and it's back up and running. The new blower only has one side to the fan but it is so much quieter than the old one ever was.

What do you mean by "one side to the fan"? If the fan only has paddles on one side, it's not the right one for the PB-105 which needs the double paddle fan blade, part # 3-20-502221. The single paddle fan, part #3-20-40985 is used on the accentra.

 

[Tdiguy]

The old blower had 2 sides with fan blades. This one only has 1 side with a fan blade. The fan blade is double sided.

 

[Tdiguy]

Here is what they look like. The second one is the new one installed.

 

[wil lanfear]

Here is what they look like. The second one is the new one installed.

Okay, got it, not a big fan of these motors without the duel fans, I was lucky a couple years ago to purchase a duel fan off of ebay. IMHO, the outer fan helps to cool the motor, Maybe the reason Harman went with a single fan is because they were lasting to long or they were cutting manufacturing costs on their products.

 

[Tdiguy]

Okay, got it, not a big fan of these motors without the duel fans, I was lucky a couple years ago to purchase a duel fan off of ebay. IMHO, the outer fan helps to cool the motor, Maybe the reason Harman went with a single fan is because they were lasting to long or they were cutting manufacturing costs on their products.

Probably a bit of both. It blows me away that this thing sells for so much money. It's just a fan.

 

[Mr._Graybeard]

My boiler (installed in 2012) came with the single fan. So single has been OE for awhile.