Controller Question

[WoodNotOil]

I have a Tarm Solo 30 that is a few years old. I have noticed that the newer EKO's have the RK-2001 controller, I think BioMax uses it too. I also noticed some of the new boilers Bioheatusa offer have newer controllers. I was wondering if any of these controllers could be used with my Tarm to add features the older controller doesn't have. I notice that some control the speed of the fan (perhaps I would need a different fan for that), others have O2 sensors and so forth. Anyone thought about better controlling there Solo boilers? Just curious if I am missing out on some more efficient or convenient features that could be added.

 

[chuck172]

I've wondered the same thing, I added a variable speed manual motor control to my fan but I wish it could be throttled automatically.

 

[WoodNotOil]

Here is the manual for the RK-2001UA http://www.newhorizoncorp.com/PDF/RK-2001UA-ENG1.pdf

I wonder if it can vary the speed of the existing fan in the Solo?

 

[Eric Johnson]

The RK2001U has some nice features, including a "FUEL OUT" mode, which preserves a nice bed of coals when it works. Sometimes it activates prematurely and that's a bit of nuisance. The fan speed control feature is also really nice, as it allows you to tune your draft from 50% to 100% in 10-point increments. I've found that it really extends burn time and saves wood when you get it right. On very cold nights, for example, I fill the boiler and throttle it down to 50%. Since I don't have storage, it helps keep the boiler from idling, and as numerous other threads here have mentioned, you can achieve better gasification by modifying the draft to suit conditions.

 

[WoodNotOil]

Do you guys think these features matter more if you don't have storage? What about flue temp sensors and O2 sensors? What controllers are available with those? What does the Froling use? What about Econoburn?

 

[Eric Johnson]

Does the fan on the Tarm modulate at all? If so, then I think it's a variable speed fan and should work with the RK2001U, though I doubt Tarm would endorse it. Bear in mind that the fan is the only thing that the EKO controller controls. Actually, that's not true. It's the only thing the controller controls on my setup. You can also run a pump and connect the controller to an indoor thermostat if you like.

 

[WoodNotOil]

The Tarm fan does not modulate at all. It is simply on/off from the controls.

 

[cguida]

Hi WoodNotOil,

Ever since I heard about the Froeling Boiler and the lamda sensor (now I know why I can't find the carborator on my wife's car!), I've been wondering about the possibility of a Trachiotomy on the Tarm -- kind of 'cathatarize' its bronchial tubes, and replace the fan with an air supply you could control with the Arduino. If you could control the air, and you had a target heat output, and you knew the appropriate stack temperature and o2 reading, it seems like you could get the Arduino to optimize the system, and adapt to changes in weather and wood and such. I know I'm making it sound simpler than it is, but it isn't rocket science.

A good first step might be to figure out some kind of data logging with the temperature sensors.

 

[DaveBP]

A while back there was a thread about varying the speed of fans and there was a photo of the fan from an EKO ( I think ). Same fan as in the Tarm Solo. It will vary speed with a 3-position fan speed controller. Standard PSC motor.

 

[jebatty]

I have a fan speed controller on my Tarm, which I tend to only use to slow down the fan at time of intense burns with very dry wood (typically pine), which occurs about 1 hour into a burn. I then may turn the fan down and leave it down to reduce stack temp and then I leave it down to end of burn, unless I happen to be around the boiler when it is getting close to mostly coals, when I will turn the fan back to max speed again.

While speed controls on PSC motors work, PSC motors are very inefficient when operated at less than full speed, according to this source, a disadvantage not present with an ECM motor.
(broken link removed to http://www.nailor.com/pdf/ECM_1.pdf)

 

[WoodNotOil]

A while back there was a thread about varying the speed of fans and there was a photo of the fan from an EKO ( I think ). Same fan as in the Tarm Solo. It will vary speed with a 3-position fan speed controller. Standard PSC motor.

Are the fans the same for EKO and Tarm Solo Plus? If so, then the RK controller should be able to change the speed of the Tarm fan?

Here is the description of the RK controller from the Manual:

1. Application
RK-2001UA controller is a device designed for temperature control of solid
fuel fired boilers. The temperature of the boiler is kept on level set by user,
by controlling the speed of the pressure fan. The controller monitors
temperature of water in the boiler, displays it on the display, and controls
circulating pump. To enable more precise temperature control of heated
rooms, the controller is equipped with input for room thermostat.
The controller is equipped with additional multipurpose output which allows
connecting mixing valve, alarm signal or additional gas or oil boiler.

So this controller could technically control fan speed (which is currently not done on my Tarm) and control my boiler circ. It seems to only have a sensor for boiler temp to make most of these calculations on. I know there is also a place to plug in room temp sensors, but in the case of storage that doesn't seem needed. The Froling from what I can tell has two sensors in the storage tank and an O2 sensor at least that it uses to adjust fan speed and circ. Also, I don't understand the overheat function in the RK controller. Yes, it turns the fan off and the circ on, but it would take a long time to draw the heat down just by circulating water unless there was a big heat demand to draw it off. I think in the Tarm application the overheat protection would have to be left as it currently is with an aquastat to dump zone and power failure gravity zone and automag.

I guess my question still is: Who makes the best controllers now and can they be adapted to use with a Tarm Solo Plus?

 

[chuck172]

Here is the link to a thread I recently started:
https://www.hearth.com/talk/threads/33919/

Seems to me someone with a technical background familiar with this would be able to design an add-on to the Tarms. and others.

 

[WoodNotOil]

Here is the link to a thread I recently started:
https://www.hearth.com/talk/threads/33919/

Seems to me someone with a technical background familiar with this would be able to design an add-on to the Tarms. and others.

Thanks. That clarifies a few things for me. Does anyone know how much the RK controller costs? I know a couple of guys on here have upgraded their units to it. Just curious. I could probably add all of these features with my arduino controller I built and may do that instead anyway. Just trying to understand the different controls available, the costs, and benefits of using them. There is always something that can be tweaked...

 

[DaveBP]

jebatty Posted: 06 March 2009 07:43 AM
PSC motors are very inefficient when operated at less than full speed, according to this source, a disadvantage not present with an ECM motor.

Just a basement lab report on efficiencies of these draft fans.
My Tarm Solo 40 came with an EBM M2E 068 90 Watt fan. Plugged into the wall outlet, 119 volts.

Without going through the Hunter brand fan speed controller (bought at Lowe's) it drew 90 watts with a power factor of 99%.

Through the speed controller:

High speed, 84 watts, PF 99%
Med. speed, 23 watts, PF 48%
Slow speed, 7 watts, PF 27%

The medium speed was noticeably slower and the slow speed didn't even seem like it would blow against any kind of resistance.

I have to admit that I never have been able to wrap my mind around all the implications of Power Factors and the CFM output is not a linear function of power consumed, but I think you are right, Jim. They are a lot less efficient when slowed down by these cheapo controls. Hopefully the ECM technology will become more affordable when they start being manufactured in mass quantities. And I think they will need to lose some of their "green" cachet. There's an opportunity to save some long term electrical costs but at their current prices that's a mighty long term.

 

[chuck172]

We have to ask ourselves why do we want to slow the fan. To save the electricity that the fan uses or to improve the efficiency of the boiler. Will a auto fan increase burn time, idle less than what we have now. It may not improve performance for someone with storage, but may be a God-send for someone without.