Harman PF100 vs Oil furnace

[Ncon]

I have a Harman pf100 connected to the same forced hot air ducting as my oil furnace, thermapride.
When comparing the heart output of both at the registers the oil is way hotter then the air from the pellet furnace.
It makes me think my pellet furnace isn't working as it should.
Before I go trying to fix something that isn't broken should there be such a big difference?
Thanks for any input it help

 

[rickwai]

Your PF100 has a max capacity of 100k btu. That would be maxxed out, feed set to high. You probably have your feed set between 3-4? So you are running at probably 60k btu? How many btu is your oil burner?

 

[Ncon]

Your PF100 has a max capacity of 100k btu. That would be maxxed out, feed set to high. You probably have your feed set between 3-4? So you are running at probably 60k btu? How many btu is your oil burner?

I have it set to 4, I did try higher settings recently and didn't notice any major difference.
Perhaps I need to figure out a way to accurately measure the air temp.
I will check on oil furnace model.
Everything was here when we bought property last November.

 

[rickwai]

Also blower fan speed will affect air temp. Slower fan = warmer air but less volume. Btu output is what more matters as opposed to temp at the vent.

 

[Ncon]

I have the fan speed set at medium, is that best? Or is it a bit more situational specific

 

[Mr._Graybeard]

Keep in mind that high-efficiency gas furnaces pump out a lot of lukewarm air. The fact that your PF100 isn't blowing as hot as the oil burner doesn't mean it isn't getting the job done.

 

[Ncon]

Keep in mind that high-efficiency gas furnaces pump out a lot of lukewarm air. The fact that your PF100 isn't blowing as hot as the oil burner doesn't mean it isn't getting the job done.

Unfortunately on the cold nights it's not getting the job done and I need to turn on the oil.
I've a lot of other work to do on house regarding insulation, etc.... So I'm sure once that is done it'll work a bit better.

 

[gutlo]

I'm running a P43, not a furnace, but I have noticed a big difference in heat output depending on the brand of pellets. Barefoot are the best available in my area. They're high heat with very low ash and fines. Green Supreme are much less heat with high ash and fines.

Stove Chow are pretty good too. Almost as much heat as Barefoot, low ash and fines.

Run some tests with different brands before going back to oil to see if there's any difference in your system.

 

[zrock]

Never really run a pellet furnace but have seen them in action... To me they are more of a constant run at a set temp so they are always pumping warm air unless you have it controlled by a thermostat. where a oil furnace comes on when the thermostat calls for heat and quickly heats up the room so they are by design to hun hotter for a short amount of time...

 

[Mr._Graybeard]

Never really run a pellet furnace but have seen them in action... To me they are more of a constant run at a set temp so they are always pumping warm air unless you have it controlled by a thermostat. where a oil furnace comes on when the thermostat calls for heat and quickly heats up the room so they are by design to hun hotter for a short amount of time...

Yes, that's how my friend has his Fahrenheit Endurance set up -- it's always running, but it's rated at only 50K btu. He regularly calls on the propane furnace to supplement heat. The newish propane unit blows cooler than the pellet burner, though. If the oil burner's output seems warmer, I'd guess that it's a relatively low-efficiency unit, and the Harman is there to take the sting out of the oil bills (That's why I have my boiler).

A lot of things to consider, including the size and energy efficiency of the house. I'm in an old farmhouse, and the PB105 keeps up pretty well unless the polar vortex has landed and we're looking at below-zero daytime temperatures with blustery wind. The PF100 and my PB105 are pretty similar as far as the pellet-burning parts are concerned.

These units take some experimenting to get the most out of them. I would try stepping up the feed to 4 1/2. Turn the distribution fan to "low" to see if it makes the air flow a little warmer. One thing to consider is that these pellet burners like to burn hot. Burning pellets produce moisture, and you want to avoid condensation, which makes creosote.

Make sure your burn chamber is tight with no air leaks. Seek a picture of a strong-burning pellet fire and compare it to what you see in your furnace. Lazy, licking flames are not what you want.

 

[Ncon]

Thanks for the replies all.
The basement the furnace is in might as well be outside, no insulation and lots of air leaks.
So the ducting is probably losing a lot to that climate.
I did give it a very thorough cleaning today and that has seemed to push the heat output up a bit. I'll get a video of flame posted but it does look pretty good to me.

 

[Ncon]

Yes, that's how my friend has his Fahrenheit Endurance set up -- it's always running, but it's rated at only 50K btu. He regularly calls on the propane furnace to supplement heat. The newish propane unit blows cooler than the pellet burner, though. If the oil burner's output seems warmer, I'd guess that it's a relatively low-efficiency unit, and the Harman is there to take the sting out of the oil bills (That's why I have my boiler).

A lot of things to consider, including the size and energy efficiency of the house. I'm in an old farmhouse, and the PB105 keeps up pretty well unless the polar vortex has landed and we're looking at below-zero daytime temperatures with blustery wind. The PF100 and my PB105 are pretty similar as far as the pellet-burning parts are concerned.

These units take some experimenting to get the most out of them. I would try stepping up the feed to 4 1/2. Turn the distribution fan to "low" to see if it makes the air flow a little warmer. One thing to consider is that these pellet burners like to burn hot. Burning pellets produce moisture, and you want to avoid condensation, which makes creosote.

Make sure your burn chamber is tight with no air leaks. Seek a picture of a strong-burning pellet fire and compare it to what you see in your furnace. Lazy, licking flames are not what you want.

Check leaks with the dollar bill technique?

 

[Mr._Graybeard]

Check leaks with the dollar bill technique?

That's a good place to start. There are magnehelic gauges that measure differential pressure if you want to get anal about it. My boiler has a test port in the burn chamber door, but it looks like the PF100 is different -- looks like an inner and outer ash door? My boiler is a fairly late model, from 2012, and it has just one door, along with the door for the ash pan and the swing-out hopper/burn pot assembly. I replaced the gasket at the hopper a year ago -- it's the opening I use most for cleaning.

I would expect to see flames in the Harman blowing like they would in your oil burner, only fewer of them. My old oil dragon is 160K BTU, and I'd say the flame group in the pellet boiler is maybe half as big as the oil burner's. But the character of the flame is similar. If you can see black tips on the flames, you're feeding too much fuel for the available air flow. There is no adjustable damper on a Harman.

When cleaning, be sure to go over the combustion fan and its housing thoroughly. A dirty fan can impede ignition -- that's when you'll get explosive startups and smoldering pellets in the ash pan. On the furnace, it seems like you need to remove a couple of baffles in the firebox to get at the heat exchanger for a thorough cleaning. Keeping that heat exchanger clean is crucial to getting decent heat output. Do you have a maintenance manual for this unit? If not, here's a link to one: https://www.manualslib.com/manual/626795/Harman-Pf100.html?page=32#manual

 

[Jeremy6500]

You mentioned the basement being very open and drafty. Is the duct work insulated? If not I would suggest that. It can make a large difference over time.

 

[zrock]

ya if it was me i would go buy one of those home spray foam kits and insulate all the ducting you can get to. Probably increase your heat output by 20% or more... Also use it to seal off any drafts you can find in the basement

 

[Ncon]

Here is a video of flame if anyone has opinions

 

[Jeremy6500]

Here is a video of flame if anyone has opinions

Do you have the ability to adjust the draft settings on yours? To me the flame looks a little over active.

In general if the draft is running higher than needed it can pull alot of the heat out of the burn chamber and cause the room air to be cooler.

I might have missed you saying it, but is yours hooked up to or have the ability to be hooked up to a room thermostat?

If it is not then it will simply run at a constant predetermined heat setting regardless of room temps. If you can hook it to a thermostat then it could ramp up when heat is called for and then back down when it is not.

I have a USSC 6500 which is designed to hook to duct work. With it it moves a whole lot more air (2 x 800cfm fans) than my PP130 stove, but the air is cooler....especially on the lower heat settings. I used an infrared temp gun to measure the metal room air plenum. On my lowest heat setting it read 65*, so the actual air coming out was a little over that. On medium for 30 minutes the plenum was 96*. On High for 30 minutes it was 126*.

 

[Mr._Graybeard]

Here is a video of flame if anyone has opinions

The flame looks OK to me. It's a little hard to gauge how much flame you have, but it should be blowing pretty much like that. I do think I'm getting more of that bright core flame out of my boiler. Make sure all the holes in the burnpot are clear by running a stout piece of wire through them.

Looking at the manual, it appears that you have a feed-control dial and a "temperature" dial. Do you control temperature with a room thermostat or the thermostat on the unit? I might try raising the feed rate to 4 1/2 or even 5 to see if heat output improves. If you start seeing black tips on the flames it's getting too much fuel.

 

[Ncon]

Do you have the ability to adjust the draft settings on yours? To me the flame looks a little over active.

In general if the draft is running higher than needed it can pull alot of the heat out of the burn chamber and cause the room air to be cooler.

I might have missed you saying it, but is yours hooked up to or have the ability to be hooked up to a room thermostat?

If it is not then it will simply run at a constant predetermined heat setting regardless of room temps. If you can hook it to a thermostat then it could ramp up when heat is called for and then back down when it is not.

I have a USSC 6500 which is designed to hook to duct work. With it it moves a whole lot more air (2 x 800cfm fans) than my PP130 stove, but the air is cooler....especially on the lower heat settings. I used an infrared temp gun to measure the metal room air plenum. On my lowest heat setting it read 65*, so the actual air coming out was a little over that. On medium for 30 minutes the plenum was 96*. On High for 30 minutes it was 126*.

View attachment 288676
View attachment 288677

No ability to alter draft.
It is hooked up to a thermostat.

I think I need to get an IR therm and get accurate readings of temps so I can compare.

 

[Ncon]

I have bumped up to a 5 on feed setting and have noticed a slight increase in temp, not substantial.

 

[Jeremy6500]

No ability to alter draft.
It is hooked up to a thermostat.

I think I need to get an IR therm and get accurate readings of temps so I can compare.

So how does yours work with the thermostat?

Does ramp up to a higher setting when the thermostat is calling for heat?

An IR thermometer is handy. Your readings could be a lot different than mine because mine is a different unit, but you could at least insure that it is increasing heat output when the thermostat is calling.

Have you insulated any of the duct work yet?

 

[Ncon]

So how does yours work with the thermostat?

Does ramp up to a higher setting when the thermostat is calling for heat?

An IR thermometer is handy. Your readings could be a lot different than mine because mine is a different unit, but you could at least insure that it is increasing heat output when the thermostat is calling.

Have you insulated any of the duct work yet?

Thermostat is a the non programmable Harman one, so when temp drops there is a call for heat.

I haven't insulated any of ducts yet. Torn between doing them now or doing full basement insulation next summer

 

[Jeremy6500]

Thermostat is a the non programmable Harman one, so when temp drops there is a call for heat.

I haven't insulated any of ducts yet. Torn between doing them now or doing full basement insulation next summer

Does the furnace completely shut down when the thermostat isn’t calling and then light when it is, of does it burn at a lower setting when not calling and then ramps to a higher setting when the thermostat calls?

When I light mine from cold it can take a bit for the room blower air to warm up. Longer than my other stove. A combination of the stove mass to heat and the volume of air the room blowers move.

Either or both of the insulation ideas would help. For me personally I would start with the ducts and do them now if possible. Even if you insulated the basement, I would still recommend doing the ducts.

 

[Mr._Graybeard]

I would go back in and clean the heat exchanger baffles thoroughly. That's the most critical point of your furnace's heating efficiency. The manual has instructions for removing the plate that covers them. The manual recommends doing a cleaning once a month; I'd probably be in there every other week.

As the manual states: "Keep in mind that the cleaner the heat exchanger surface is kept, the higher the heat transfer efficiency will be."

 

[Ncon]

Does the furnace completely shut down when the thermostat isn’t calling and then light when it is, of does it burn at a lower setting when not calling and then ramps to a higher setting when the thermostat calls?

I believe that it goes on a low heat setting for a time and if there is no call for heat it will then turn off. I think it is 30min