Harman 52i just installed, some questions

[armstrom]

I'm a new owner of a 52i with OAK fired up yesterday for the first time. Just out of curiosity, has anyone seen this bronze color stove before? I have been unable to find any reference to it on the Harman website. I bought the stove as a showroom sample and was told it was a special order color... not sure... Either way, I like the look much better than the enamel. I've also included a picture of the service rails I built.

Regarding pellet consumption. When people say they burn "1 bag a day" or "2 bags a day" do they generally refer to a full 24 hour day? Or starting up the stove in the morning and letting it burn itself out during the night?

Yesterday I filled the hopper with a 40lb bag and the stove ran for just under 15 hours before running out of pellets. I've read the sticky thread on how the stove works so I was playing around with the settings quite a bit but it seemed to be running the feed motor pretty frequently. For the overnight I left the stove in Room temp Manual with a setting of around 60-65 degrees. My temp sensor is probably in a bad spot since it seemed to keep running at a steady state even when the room temp was 72. I also tried Stove Temp Manual for several hours and turned the stove temp all the way down but it seemed to feed pellets pretty frequently. My burning pellets never got close to the edge and were burning pretty far back in the burn pot (maybe 2.5-3" from the lip) Oh, I left my feed limit knob set to about 3 the entire time.

Is this normal? I will try to do a more consistent test once the weather cools off again and I can run a full bag at the same Stove Temp Auto setting.

Oh... and how does well does the stove shut itself down in different settings? Since I knew I would run out of pellets some time during the night I made sure to leave my stove in Room Temp Manual mode so it would not try to run the igniter for 30+ minutes before giving up. Does Stove Temp Auto try to re-light after running out of pellets?

Thanks!
-Matt

 

[bbone]

welcome, read how your Harman works in stickies, wealth of info there

 

[jackman]

All of what you describe sounds normal to me. I don't have the exact model as yours. I burn about one bag/24 hours. If the outside temps are in the teens I'll be up to 2 bags/24hrs but everyone's situation is different. I also keep mine in manual mode for the same reason as you, to minimize igniter usage when the hopper runs out.

 

[armstrom]

Thanks for the responses. I've read the stickies a number of times which informed my decision on how to run the stove. I was just curious if my burn rate was reasonable or not. I've seen some people claim that using an OAK increases pellet consumption somewhat, which I find strange but I suppose the cooler combustion air could be resulting in the pellets burning more quickly (more dense air charge).

Yesterday's temps were only in the 40s-30s so I was not expecting to use too many pellets. Today we're getting up to the 50's so I'm just letting my heat pump handle the heating load in the house. As soon as it cools down a little more I will run an experiment with a single bag in the hopper running in stove temp auto mode with feed limit set to 3 and stove temp all the way down to 1. That should give me an indication of my minimum steady-state consumption (without cycling you would get from room temp mode).
-Matt

 

[Paulinator]

You are going to need to play around with the sensor when trying room temp mode. My probe is behind the stove and to one side, don't place it where the warm air blows on or near it. I use the default feed setting of 4, and run the fan about 2/3 rd's up. That's a good looking setup, enjoy and you will find the sweet spot that works for you. Make sure you keep it clean, these stoves do like their maintenance.

 

[zrock]

Ok definitely increases pellet usage in the colder temps. -20 and I have yo turn my stove up yo maintain the same temps... almost wish I would have installed a manifold to I could switch from inside go outside air

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[rob.mwpropane]

Ok definitely increases pellet usage in the colder temps. -20 and I have yo turn my stove up yo maintain the same temps... almost wish I would have installed a manifold to I could switch from inside go outside air

I feel like using "inside" air would use just as many pellets if not more as you'd have to replace that air with cold air being drawn in from outside. Just my opinion. More dense does equal more fuel, but should get hotter faster. I would think that would be more efficient....right? All newer high efficiency systems use outside air for combustion, so it makes sense to me. I think pellets combust @ around 375F and I've read stoves can get up to 1100F inside (although I think that's around max if I remember correct). If both of those statements are fairly accurate, than the ~ 70F difference in combustion air really doesn't mean anything.

I would think that prolonged lack cleaning would cut down on efficiency way faster / more than combustion air temp. If the heat can't get to / through the exchanger, it wouldn't matter what combustion air is. I try to clean mine really good every 2-3 weeks.

I have the 52i (sole source of heat) in a 1500' sq rancher. It's been really cold (like record breaking cold), and I've been using the equivalent of 2-2.5 bags a day. I run mine in room temp connected to an electronic thermostat (with sensor in line). Temp set to never higher than 5, and feed rate on 6 (as I don't think feed rate matters as much in "room temp", but can hinder it if turned down to low). Saves a good amount of pellets because I tweek the stove to what I want, when I want, save it and forget about it. At around 9am it dials back to 65, and then again at 10pm. I have it ramp up at 4am just a little before I get up for work. Before I would have the issue where the kids / wife / me would forget to turn it down and I'd have gone through a lot by morning from running higher all night.

We've been burning since November sometime and I've gone through about 1.75 tons of Energex Pellets (out of 4), but like I said the past 3 weeks have been brutal dropping into single digits. Today I'm in a "T" shirt and Sunday they say back into the 20F's.

 

[zrock]

Technically yes and no... it takes a lot of energy from the fire to take air that is -20 and heat it to the output energy. Part of the reason we all turn our stoves up in this temp. That and drafts coming into the house. Now if you take part of that outside air and mix with warm air inside u will regain some of that energy... I plan to redo my oak so I have shutoff at both outside and inside. This way I can crack outside enough go keep a semi positive pressure in the house and side some of the preheated air to mix.... Also to help cut the cold air when stove is off I can shut the outside air off... in theory you should regain a few btu back.... but hey km no expert just things iv noticed on other projects... we did the same concept on a wood furnace. Quite a noticeable difference

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[dotman17]

There are a lot of questions here so I'm going to try and be brief and touch on one or two. First, I own a 52i and I run in automatic mode all year round. That means the stove is going to handle most things for me and it also means there are only 2 dials left I can fuss around with -- the "Maximum" feed rate and the desired temperature dial. If I run in manual mode, well then it's going to burn at a certain rate regardless of temperature and that seems for the most part, a lot more work and less efficient if I want to achieve maximum efficiency. I let the computer handle it. The second thing is I have my sensor exactly 2 feet from my stove and simply made adjustments to the "Max" feed rate and temperature dial to reach my ideal temperature upstairs. If you want temperature X upstairs or wherever in your house, that means you'll have to reach temperature Y at your sensor. So while placing your sensor further away from your stove might help you achieve your ideal temperature and keep the difference between X and Y low, I found tweaking those 2 dials accordingly was easy to achieve my desired reading on my thermostat upstairs -- regardless of where my sensor was. Third, the quality of pellet makes a major difference in a couple areas -- how hot they burn and how clean they burn -- both of which will impact your heat output.

So what does it all mean? Well unless I hook a thermostat up to my stove (which can be done but my stove manual does not promote this and I don't have this configuration), it means to achieve my desired temperature, I set my desire temperature in automatic mode and I set a maximum feed rate to 3 or 4. As mentioned, the temperature and feed rate are based on my own calculations depending on where my sensor is. This feed rate may vary depending on your pellet fuel and/or where you live as well as the temperature you have set. For me, living in the Pacific Northwest, I set my stove temperature to like 66, have a max feed rate of 3+ or 4 (the most common settings), and burn Douglas Fir pellets -- and that heats my entire 2200 sq/ft house to a temperature upstairs of 68 on a single bag of pellets or less. During outside temps in the 30s or temps approaching freezing, I may burn through a bag and a half, and on real, real cold days, maybe two bags -- yes -- within a 24 hour burn cycle.

 

[armstrom]

Ok, well I figured out my problem. The guy who sold me the stove was kind enough to lend me his DDM tool and I confirmed my suspicion that the room temp sensor was faulty. Oddly, it behaves PERFECTLY as a 5K thermistor (all the temps I tried match the resistance curves within 5-10%) but once I plugged in the DDM tool it told me my 75 degree room was actually 53 degrees. Hence my massive pellet consumption the first time I ran the stove. Luckily the seller supplied me with a replacement room sensor and now everything checks out. Maybe my stove was an oddball built during a phase-in of different parts? Manufactured in 2014. It has the red ESP sensor and the stove reads it properly.

One strange thing was that I had to replace the connectors on my stove. The temp sensor that came with the stove had insulated male spade connectors and the stove harness had matching female connectors on the twisted blue wires. The replacement temp sensor had un-insulated female spade connectors so it would not plug in. I happened to have the correct connectors on hand and swapped them out. Is this common? Did Harman change the connector style at some point?

At some point I need to reverse-engineer this DDM tool's serial protocol. $500 for an LCD and maybe a basic 8-bit microcontroller seems a bit crazy. They REALLY don't want people seeing whats inside that thing considering they rivet it shut!
-Matt

 

[dotman17]

They REALLY don't want people seeing whats inside that thing considering they rivet it shut!
-Matt

The DDM tool?

 

[armstrom]

The DDM tool?

Yeah, rather than just screw the enclosure shut they pop-rivet it. My guess is that there's basically zero processing power inside. There are 6 pins, power and ground are obvious. There's at least a TTL serial TX and I wouldn't be surprised if the button just grounds one of the other pins to signal the controller in the board to change the contents of the display. There MAY be a small microcontroller in there decoding the serial data for display purposes, but that's probably it. Maybe $30 worth of parts if they pay a lot for the heavy steel enclosure.

If I can find a used one I will buy it and open it up. The one I have now is not mine so it will not be molested
-Matt