Harman PF100 Questions.

[Labrat]

I am investing in a PF100 this fall. The wife and I are tired of the rising oil prices and my Quad Castile in the basement helps offset the oil but we want something better.

My questions are:

How many of you hooked up your PF100 directly to your trunk line of your existing furnace or directly to the plenum of the existing furnace?

Is it really needed to hook up the return to your existing furnace return? or will the air in the basement it will be in OK?

What about the the damper? Do you need to put one in if one or the other furnace is off (as in the breaker is off)? Is it a matter of heat spilling into the other unit and causing damage with out a damper?

Im sure I will have other questions, and thanks in advance.

By the way I have been lurking of this forum for months and think the advice is great.

 

[freeloader]

Hello,
First, Welcome! I am shopping for a furnace at current. I totally like the PF-100 but I was wondering why you came to that choice.

Regarding the ducting connections for a 'back-up' furnace... i know dampeners need to be installed to reduce the risk of running exhuast from one furnace to the other and potentially back into your home. On a different thread i asked some of the same questions you were looking for also, regarding connecting the ducting work. When I look at the cold air returns I have now they do go to different rooms than the room the furnace is - one cold air vent goes to another room in the basement and one goes to a room in the first floor -

I have seen responses from several installers in the forum so hopefully some insight can be gained from future posts regarding this..

 

[Labrat]

Thanks Freeloader. I came to the Haman conclusion as it seems they have fixed most of the burn pot issues and I have 3 dealer/service places all within a half hour drive. I have an Endurance dealer but he is a 2+ hr drive one way. I looked at both furnaces and liked the Harman better for the BTU output and the dealers for Harman really liked how Harman treated everyone with a problem. The Endurace guy was not overly informative and really couldn't speak of the customer service side of things.

 

[freeloader]

I have been having a terrible time with locating a dealer. I talked to a few locally and it seems they have specific stoves they like to sell and install. With choosing to install a furnace, most the dealers I have talked to (aside form a few very helpful guys on this forum) don't seem to enthusiastic about (installing) em.

Some of the recommendations i got so far were, find a good dealer, and review as many furnaces as possible. I found a great article a week or so ago on some pellet/biomass furnaces that were reviewed.

I think discussing or consulting a experienced and qualified HVAC guy on the particulars of the project is gonna be essential to get everything to come together efficiently..

Good luck on your project

link on pellet furnace reviews
http://www.hvac-for-beginners.com/biomass-furnace-ratings.html

 

[jtakeman]

Is it really needed to hook up the return to your existing furnace return? or will the air in the basement it will be in OK?

It is more efficient to use the return air. Using the basement air will cause the house air to get pulled into the basement. This warms the basement air so your heating it. Most basements aren't insulated so there is heat loss. Think of the return as closing the loop. Not to mention the basement air is cooler so you have to spend more energy to heat the cooler air.

 

[Labrat]

Freeloader thanks for the website I will check it out.

J-takeman I hadn't really thought of the return pulling the heat down to the basement. My basement is mostly finished but I'm sure the heat loss would still be more than if it were completly finished. I may do a loop upstairs and one down as I am thinking about completing the basement and add a little more heat to go with my Quad I already have down there. Thanks for bringing up the point.

 

[DexterDay]

Would definitely put in a cold air return and Back Draft dampers.. They are necessary. Unless you want to loose all your central air. (If u have it?). I just bought a Fahrenhiet Endurance. Don't have mine "hooked up" yet. But when I do, I will post the pics. Should be within a week or 2. Said this a week or 2 ago.. Can't get enough help to get in the basement. My buddy just bought a Magnum bay countryside. So we are gonna rent an appliance dolly and knock'em both out.
Harmans are great stoves. There botton feed is a great system. The shop that sells the Fahrenhiet I have , has one heating there whole shop. Like a converted barn. 16ft ceilings, over 3,000 sq ft, and they keep it at 73. With just the Endurance with a diffuser on the top. Its a good dtove and sccording to them, and the amount of pellets it eats per hour. Its a better than the 50,000 BTU's its rated at.
Whatever you buy, keep us updated!

 

[Delta-T]

according to the installation manual of the PF100...the cold air return is a MUST DO. Honestly, even if it wasn't a MUST DO...it would be silly not to.

 

[exoilburner]

I connected my PF100 to the hot air trunk line and the cold return air trunk line. Get good air circulation through out the house and good air pressure at all the duct registers.

Installed manual dampers in the hot air plenums of both furnaces down stream of both furnace's Fan/Hi limit switchs according to the PF100 install manual. (damper down stream from the Fan/Hi Limit Switch is a safety must)

Ran the 120vac power cables of both furnaces to a transfer switch (3 way light switch) so the two furnaces (oil & pellet) could not both get power at the same time preventing them from ever running at the same time.

From the Harmon Install Manual:
The Harman PF100 may be connected to a gas or
oil-fired central furnace or heat pump duct system. Prior
to installation, determine whether all requirements for
installation including all clearances can be met.
The PF100 warm air supply and the cold air return
must be installed in a parallel arrangement. EXAMPLE:
The warm air supply duct from the PF100 is to be connected
to the warm air supply of the existing furnace.
Also the cold air return duct from the existing furnace is
to be connected to the cold air return duct of the PF100.
Isolation dampers (2) should be installed in the ductwork.
(1) in the warm air supply duct for the existing furnace
and (1) in the warm air supply duct of the PF100 after
or “downstream†of the high limit/fan control. These
dampers can be manually operated or fully automatic.
In either case, the unit that is not being used must be
prevented from being operated. (This also can be done
manually or automatically.)

 

[mrfjsf]

I just helped a friend install a PF 100 today. Connecting into existing return air duct is essential for optimum performance. Its not really an option. You will need to install dampers in the duct system. A damper that will block the hot air that the pellet furnace is putting out from getting back into the return air system and vice-versa. I would put this damper in just below (main furnace side) where the pellet supply air dumps into the main trunk. This will stop the hot air from the pellet stove from short cutting down through the main furnace and right back into the return air on the pellet furnace. When you are not using the pellet furnace, you will also need to stop the main furnace hot air from short cutting back through the pellet furnace and into the main furnace return air. This can be accomplished by simply bloacking the supply coming from the pellet furnace.

Feel free to pm for any specifics on the install.

 

[Ejectr]

Because of my existing ductwork being as low as it is in my basement and having to install a back draft damper that took up some of the useable height, my blower control is not mounted 11 inches above the furnace output.

Is there any detriment to efficient operation of the PF100 if the blower control cannot be mounted 11 inches above the output duct of the furnace?

 

[exoilburner]

Because of my existing ductwork being as low as it is in my basement and having to install a back draft damper that took up some of the useable height, my blower control is not mounted 11 inches above the furnace output.

Is there any detriment to efficient operation of the PF100 if the blower control cannot be mounted 11 inches above the output duct of the furnace?

The PF100 install manual says "approximately 11 inches". (I assume you are talking about your fan/HI limit control location on the duct above the PF100.) The fan/HI limit control detects the heat level in your duct at 11 inches above the top of the PF100. It provides 2 functions. 1) It starts and stops your distribution blower when the hot air duct temperature is at a certain point, and 2) it is a safety that shuts down the PF100 if the hot air in the duct gets too hot. If the hot air duct temperature over heats this control interrupts the circuit to the auger drive motor, stopping the fuel flow, and shutting the PF100 down. (I know this works because it has happened on mine. Worked great.)

I assume you mounted your fan/HI limit control closer than 11 inches from the top of your PF100. If that is the case your distribution blower may come on a bit sooner and the same with your duct over temp. shut down. May not be a problem.

If you mounted the fan/HI limit switch further away that could be a safety problem with the PF100 shutting down at a hotter duct temp.

 

[Ejectr]

Because of my existing ductwork being as low as it is in my basement and having to install a back draft damper that took up some of the useable height, my blower control is not mounted 11 inches above the furnace output.

Is there any detriment to efficient operation of the PF100 if the blower control cannot be mounted 11 inches above the output duct of the furnace?

The PF100 install manual says "approximately 11 inches". (I assume you are talking about your fan/HI limit control location on the duct above the PF100.) The fan/HI limit control detects the heat level in your duct at 11 inches above the top of the PF100. It provides 2 functions. 1) It starts and stops your distribution blower when the hot air duct temperature is at a certain point, and 2) it is a safety that shuts down the PF100 if the hot air in the duct gets too hot. If the hot air duct temperature over heats this control interrupts the circuit to the auger drive motor, stopping the fuel flow, and shutting the PF100 down. (I know this works because it has happened on mine. Worked great.)

I assume you mounted your fan/HI limit control closer than 11 inches from the top of your PF100. If that is the case your distribution blower may come on a bit sooner and the same with your duct over temp. shut down. May not be a problem.

If you mounted the fan/HI limit switch further away that could be a safety problem with the PF100 shutting down at a hotter duct temp.

Yes, I meant the fan/high limit control. It had to be mounted closer than 11". Everything seems to function OK. I figured it would trigger the distribution fan sooner. Don't think I've run into a high temp shut down issue though.

 

[exoilburner]

Because of my existing ductwork being as low as it is in my basement and having to install a back draft damper that took up some of the useable height, my blower control is not mounted 11 inches above the furnace output.

Is there any detriment to efficient operation of the PF100 if the blower control cannot be mounted 11 inches above the output duct of the furnace?

The PF100 install manual says "approximately 11 inches". (I assume you are talking about your fan/HI limit control location on the duct above the PF100.) The fan/HI limit control detects the heat level in your duct at 11 inches above the top of the PF100. It provides 2 functions. 1) It starts and stops your distribution blower when the hot air duct temperature is at a certain point, and 2) it is a safety that shuts down the PF100 if the hot air in the duct gets too hot. If the hot air duct temperature over heats this control interrupts the circuit to the auger drive motor, stopping the fuel flow, and shutting the PF100 down. (I know this works because it has happened on mine. Worked great.)

I assume you mounted your fan/HI limit control closer than 11 inches from the top of your PF100. If that is the case your distribution blower may come on a bit sooner and the same with your duct over temp. shut down. May not be a problem.

If you mounted the fan/HI limit switch further away that could be a safety problem with the PF100 shutting down at a hotter duct temp.

Yes, I meant the fan/high limit control. It had to be mounted closer than 11". Everything seems to function OK. I figured it would trigger the distribution fan sooner. Don't think I've run into a high temp shut down issue though.

Sounds like you are okay.
My hi temp shut down was not a PF100 fault. I had a blockage in my main hot air duct; the PF100 detected the over temp and shut itself down.

 

[Skippydo]

exoilburner:
You should hide your money someplace else.
Couldn't remember where you hid it?
Thank god it did not catch on fire. haha