Help with Harman PB105

[CallMeAl]

I have a Harman PB105, heating water for baseboard heat. (Not home's hot water.) Going into my 3rd winter with the furnace, and still learning how it works!

I've been having issues with the pellets falling into the ashpan before they can burn. I did a deep cleaning, but still having issues.

My main questions:

-What are ideal settings for the furnace for this use (baseboard heat)? I know that it depends on your variables, but how does one decide when to make adjustments? I had the temp range pretty high, like 170-185... but thinking I should lower it, maybe 140-175? I always felt like the furnace struggles to heat the house on very cold days, which is why i set it so high. Feed rate was about 0.5 but didn't seem to slow the pellets enough to burn them all. From other threads, it sounds like people generally use a higher feed rate with these?

-What can I look for to indicate low draft? I looked at the air intake pipe, all the seals seem ok, exhaust motor is operational and exhaust pipe seems clear...

Thanks in advance!

 

[bogieb]

Hey @Don2222 - any suggestions? I see you were just working on one of these.

 

[Don2222]

Just sounds like there is not enough air to burn the pellets. Check all the holes in the burnpot to make sure they are clear and also remove all the ash under the burnpot. Did you take out the combustion blower and clean the impeller blades?

 

[CallMeAl]

Just sounds like there is not enough air to burn the pellets. Check all the holes in the burnpot to make sure they are clear and also remove all the ash under the burnpot. Did you take out the combustion blower and clean the impeller blades?

yup cleaned all the holes, the cleanout under the burnpot and the fan blades too.

I did discover the fines cleanout under the hopper, the one by the auger, which i also cleaned out last night. Not sure if that contributes to my issues here, but it needed to be done!

My furnace guy did mention the seal on the door to the secondary ash chamber, which seems to be holding pressure still when the fan is on... but probably time to replace that sooner than later. He said the main door (viewing window) seal looked ok, but wondering if now that needs replaced. Is that difficult to do? Looks like its just a stick-on type of seal?

PS This is an older furnace, We've owned the house 2 years but it was here when we bought it. So finding all kinds of maintenance and parts to replace! I've already had to replace the fan and the pressure release valve.

I also reset the temp to 140-175, that seems like a common setting mentioned in other threads here. And i set the feed to 4, as i just found in the manual that's the recommended start point. I checked this AM and the ash pan was free of pellets! So maybe it was just the setting s needed tweaking, ill be monitoring closely in the coming week.

thanks for the help so far!

 

[Mr._Graybeard]

I keep my temp settings at 180 at the max and 175 on min. You want the boiler to start the ignition cycle very quickly after the circulation pump starts running and sending cooler water into the boiler. The boiler takes time to light. If the water temp in the boiler drops below 140 there's the potential for condensation to occur, producing creosote. You don't want that.

I make a point of cleaning the combustion fan and the housing it sits in once a month when I'm burning hardwood pellets. I use a toothbrush to clean every surface of every vane on the fan, and scrape the backing plate behind it with a putty knife. When I neglect that, I can get an ignition failure, which can cause an explosive ignition and spill smoldering pellets into the ash pan.

I keep the feed at 4 at all times.

 

[CallMeAl]

the furnace has been working a bit better with the new settings, though i did discover some slightly charred pellets in the ashpan. (Where before it was completely unburned pellets.) any thoughts there?

I also had a heating company come by to look at the hot water side of the system, make sure everything was working right over there. The guy said he's never seen this (pellet boiler hooked up to a hot water heater) and it wasn't a very efficient way to heat a house. Suggested a tankless water heater with propane would be more efficient. any thoughts there?

I was reading most places suggest 180 for hot water heaters, so u bumped the max up to 180. i bumped the min up to 160, to avoid getting too close to 140 as @Mr._Graybeard suggests. Feed still at 4. So far it seems to be working well with these settings.

 

[Former Farmer]

The slightly charred pellets could be from when the boiler starts up. It may be feeding more pellets than needed for startup. What are the dip switches set at on your control board?

 

[johneh]

Funny you should ask about a tankless on-demand water heater
My youngest son is an HVAC tech here in Ontario the company he
works for installed quite a few Propane fired units at least they did
They have had more people complain about them than not and just this week
taken 4 units out and reinstalled propane-fired hot water tanks.
They found that the water did not get hot enough for things such as dishwashers, showers/baths
or just hand-washing dishes. My best friend just pulled his unit out after a year and a half
and again found it not hot enough for his liking and took too long to get hot water at a consistent temp

 

[Mr._Graybeard]

the furnace has been working a bit better with the new settings, though i did discover some slightly charred pellets in the ashpan. (Where before it was completely unburned pellets.) any thoughts there?

I also had a heating company come by to look at the hot water side of the system, make sure everything was working right over there. The guy said he's never seen this (pellet boiler hooked up to a hot water heater) and it wasn't a very efficient way to heat a house. Suggested a tankless water heater with propane would be more efficient. any thoughts there?

I was reading most places suggest 180 for hot water heaters, so u bumped the max up to 180. i bumped the min up to 160, to avoid getting too close to 140 as @Mr._Graybeard suggests. Feed still at 4. So far it seems to be working well with these settings.

First question: Do you have a finned igniter with this unit or a pressure igniter? BTW, I agree with Former Farmer that you should check the position of the dip switches.

Second question: Is the hot water heater hooked up so that heated water that ultimately flows to the baseboards passes through the heater tank? If so, that may be an effort to add some BTU storage so the boiler isn't overwhelmed by cooler water from the return piping. I recall another PB105 owner on the forum having a similar setup.