Help setting thermostat (and expectations). new Harman p35i

juneaubugg · Dec 25, 2013

we just fired up our new p35i on Monday. (We live in NW New Jersey) We are having trouble regulating our thermostat. The first bag lasted almost 18 hours. The second bag we put in at around 6:00 last night left the hopper empty by 9:30 am. The stove was blasting all night long. It seems like it goes on for a long time, and then shuts down for over an hour. The room temp falls noticeably before it goes back on. How much should it drop before it kicks back on?? We have the ceiling fan going on low (our living room has a big high cathedral ceiling that opens above to the kitchen/dining area (which is like a balcony).

The installer from SOS put the thermostat right under the control panel, which seems a bit drafty since we don't have the shroud on yet (it's being custom made). It just seems like almost a full bag of pellets (The hopper is small and doesn't hold a full bag) in 18 hours is a lot. Is it??
Can someone give me some direction? We are using hamer pellets. at $260 a ton we are hoping they might burn a bit longer. Is that realistic?

And what is a setback and how do we set this up as well???

Hoot23 · Dec 26, 2013

Sony know the size of your house or the layout, but 18 hours is not bad on a bag. I've got just over 2000 sq ft to heat and I get anywhere between 15 to 24 hours on a bag. It depends on the temps outside. The colder it is, the more she'll eat. Also, your insulation in your home is a big factor.

Sounds like your running in room temp/ auto. Try running in manual or stove temp and she won't shut down on ya.

Madcodger · Dec 26, 2013

Hello, and welcome. Let me answer a couple of things, comment on a couple more, and then others will fill in as well (great folks here).

The setback is just the amount by which you reduce the temperature at night or when the area is unoccupied. For example, our daytime temp (thermostat setting) is 73, which allows the overall temp in adjacent rooms to be 68-70 even on a cold day. But at night we SET BACK the temp to 67, so our setback is 6' (' is abbreviation for degrees). We set the tstat to start heating up the house about 1 - 1.5 hours before we get up, and that works well.

Another important term if DIFFERENTIAL. This is the amount below your tstat setting that the temperature is allowed to fall, before the heat turns on (i.e., stove reignites). I keep mine at 1', so the temp can fall to 72 during the day or 66 at night, before the stove kicks on (1' degree below set temp). Some folks go as high as 3', but those swings are too wide for me.

I suspect these isues could be part of your problem in that your stove is set too high at night (not enough setback) and your differential might be too great, forcing the stove to really ramp up and consume lots of pellets rather than having a smaller, more controlled (and possibly more efficient) burn.

I'm not quite clear on the location of your tstat as described, probably b/c my one stove doesn't have a control panel (newer stove and all done from tstat) and the other has only a control panel (old stove with no tstat). But the location of the tstat is important, and installers are sometimes just lazy (our original one was awful). If not happy with it, call and get the dealer back out there, without charge! The best way to tell is whether or not the room overheats. If so, the tstat is not optimally located.

Finally, it's hard to say whether your pellet usage is excessive, at least yet. Hamer's are, IMO, one of the best pellets you can buy (I'm currently trying to test several, and so far they're by far the best). And for this time of year that's not a terrible price (may be $250/ton or lower in off season, which is when you will want to buy). Let's see where things are with a decent setback and differential, and others will also chime in.

Justin M · Dec 26, 2013

1 bag in 18 hours may be appropriate for you. It depends on how big of an area that you are heating, how much heat loss you have, and how warm you want the house to be. Running the stove in room temp. manual will keep the fire from going out so the stove won't cycle on and off. "Setback" is simply setting your thermostat to a lower temperature setting. Most people do this a night or when out of the house. This can be automatically accomplished with the use of a programmable thermostat. Please be sure to read the "How you Harman work" sticky at the top of this forum.

tsmith · Dec 26, 2013

Run it on room temp manual and it will always maintain your set temp within 1 degree and will not shut off.

fmsm · Dec 28, 2013

Sorry to be late chiming in here, as the owner of 2 P35i's I can say once you learn your stove you will love it! Start by reading the sticky on how your Harman works, once you have read that a few times you will have a good understanding on how to run your stove. My main stove is located in a room with a cathedral ceiling. I do not have a fan in the room but the heat floats up and "rolls" off the ceiling heating the upstairs rooms. I have my stove set (the probe hangs 4 feet above and 2 feet to the left of the stove) so that the temperature on my oil thermostat (located about 18 feet away from the probe on the opposite wall) is 74 degrees (I know way to hot but my 88 yr old mother in law live with me) during the day. Based on the location of the probe and the wall thermostat I can tell you that the stove will cycle down (I keep it at room temp auto about 74 degrees) when it hits 74 on my thermostat, it will swing about 3-4 degrees and fire back up when my thermostat hits 70-71. Keep in mind it is keeping the temperature AT THE PROBE within 1 degree, when the temperature at the probe has been satisfied for about 5 minutes or so it will go into a maintenance burn (very low fire but if you burn hot pellets the blower will remain on and you will still get some heat) for about 30 minutes. If the stove is not calling for heat the unit will then shut down. On cold days I will flip from room auto to room manual so that the fire never goes out. I do flip it while running every 3-4 days to stove/auto so that it heats up good as my stove runs low a lot and I want to "blow it out" here and there.

My second stove was installed in a basement family room, it replaced an old manual Whitfield that I had for many years. The surprising thing is that the Whitfield would heat up the room too fast and blow you out of it, the Harman has a much stronger blower and is blowing heat out of the family room into my office, laundry room, crawl space, and down the hall (keeping this level at about 70) making my floors warm and boosting my kitchen a couple of degrees. All for about 1/2- 3/4 a bag per day. Probably be a little higher usage when we see single digits but who cares!

If you want to do a setback I am attaching a diagram another member was kind enough to send me along with the parts I needed. The parts should be available at Radio Shack etc. Instead of using a setback and putting your board into a 4 blink status this allows you to use a thermostat as a timer and a thermocouple to set the set back amount. Works great on my stove!

Enjoy your P35i, it's a great stove.....

CBL · Dec 28, 2013

I like running my p35i in stove temp mode bouncing it between 1 and 2. You get a more consistent heat coming out of the stove and a bit better pellet economy--- unless you're ultra anal about keeping a certain temperature in the room.

juneaubugg · Dec 30, 2013

fmsm said:
Sorry to be late chiming in here, as the owner of 2 P35i's I can say once you learn your stove you will love it! Start by reading the sticky on how your Harman works, once you have read that a few times you will have a good understanding on how to run your stove. My main stove is located in a room with a cathedral ceiling. I do not have a fan in the room but the heat floats up and "rolls" off the ceiling heating the upstairs rooms. I have my stove set (the probe hangs 4 feet above and 2 feet to the left of the stove) so that the temperature on my oil thermostat (located about 18 feet away from the probe on the opposite wall) is 74 degrees (I know way to hot but my 88 yr old mother in law live with me) during the day. Based on the location of the probe and the wall thermostat I can tell you that the stove will cycle down (I keep it at room temp auto about 74 degrees) when it hits 74 on my thermostat, it will swing about 3-4 degrees and fire back up when my thermostat hits 70-71. Keep in mind it is keeping the temperature AT THE PROBE within 1 degree, when the temperature at the probe has been satisfied for about 5 minutes or so it will go into a maintenance burn (very low fire but if you burn hot pellets the blower will remain on and you will still get some heat) for about 30 minutes. If the stove is not calling for heat the unit will then shut down. On cold days I will flip from room auto to room manual so that the fire never goes out. I do flip it while running every 3-4 days to stove/auto so that it heats up good as my stove runs low a lot and I want to "blow it out" here and there.

My second stove was installed in a basement family room, it replaced an old manual Whitfield that I had for many years. The surprising thing is that the Whitfield would heat up the room too fast and blow you out of it, the Harman has a much stronger blower and is blowing heat out of the family room into my office, laundry room, crawl space, and down the hall (keeping this level at about 70) making my floors warm and boosting my kitchen a couple of degrees. All for about 1/2- 3/4 a bag per day. Probably be a little higher usage when we see single digits but who cares!

If you want to do a setback I am attaching a diagram another member was kind enough to send me along with the parts I needed. The parts should be available at Radio Shack etc. Instead of using a setback and putting your board into a 4 blink status this allows you to use a thermostat as a timer and a thermocouple to set the set back amount. Works great on my stove!

Enjoy your P35i, it's a great stove.....

Thanks so much for the post - but I'm not sure what parts would be needed.. 2 Y adapters, a Termisotr Probe a adjustable resistor, and a time clock.? Is that correct?

fmsm · Dec 30, 2013

juneaubugg said:
Thanks so much for the post - but I'm not sure what parts would be needed.. 2 Y adapters, a Termisotr Probe a adjustable resistor, and a time clock.? Is that correct?

You already have the probe, the timeclock is simply a setback thermostat. You basically need the y adapters, resistor, and the thermostat. Show this to your installer, he should be able to install it in less than 20 minutes.

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Help setting thermostat (and expectations). new Harman p35i

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