Timer for boiler fan

[goosegunner]

I have been using a spring wound timer with good success to shut down my econoburn fan so I have coals left to start the new fire.

The one thing I don't like is the play in the spring wound timer. I found this digital timer that I might try.

http://www.auberins.com/index.php?main_page=product_info&cPath=16&products_id=290

I might go the next step and tie in a relay to the linear actuator so fan and make up air are controlled by the same timer.

gg

 

[wrightk20]

How inaccurate would you say a spring wound timer would be? I just bought a 12 hour spring wound timer from reedsburg true value to shut down my boiler. I haven't installed it yet though. Would you suggest the digital one over the spring wound timer? Kevin

 

[jebatty]

You might consider a K-type sensor temperature controller with reset which functions similar to the shut-down control on my Tarm. The sensor could be installed in the smokebox (the area above and between the hx tubes before the exhaust flue fitting) or probably even on the flue at the exit point from the boiler. On fire start, use the reset to close the controller circuit and power up the boiler. Set the temperature (depending on location of the sensor) at a temperature that when it falls to this point the controller shuts down. For my Tarm, a bulb sensor is in the smokebox and is set at 100C. This temperature is a temperature at which the fire probably has burned out. This might not function well if you experience long idle periods, brief periods should not cause a problem.

Alternatively, a set-up like that used on the new Garn controller -- a differential controller with reset that shuts the boiler down when flue temperature is less than xF higher than the boiler output water temperature, with x being about 5F (or higher).

Depending on the location of the sensor, you might not need the reset function and instead use a manual bypass switch. Turn the switch on to start the draft fan, start the fire, temperature of exhaust gases rise rapidly above the setpoint of the controller and the controller turns on, turn off the manual switch, when temperature falls to the controller set point the controller shuts the boiler down.

 

[henfruit]

Jim,
Is the temp on your bulb sensor fixed at 100c or can you change it to adjust how much coals are left at the end of the burn?

 

[goosegunner]

How inaccurate would you say a spring wound timer would be? I just bought a 12 hour spring wound timer from reedsburg true value to shut down my boiler. I haven't installed it yet though. Would you suggest the digital one over the spring wound timer? Kevin

For the most part the spring timers are plenty accurate. There is some play so you have to make sure and turn it lightly back to the left to see the actual time. My wife starts fires 2 or 3 times per week. An accurate digital display would be nice for her as she sometimes does not give the boiler enough time. Not a real big deal, I just think the digital would be nice.

gg

 

[goosegunner]

You might consider a K-type sensor temperature controller with reset which functions similar to the shut-down control on my Tarm. The sensor could be installed in the smokebox (the area above and between the hx tubes before the exhaust flue fitting) or probably even on the flue at the exit point from the boiler. On fire start, use the reset to close the controller circuit and power up the boiler. Set the temperature (depending on location of the sensor) at a temperature that when it falls to this point the controller shuts down. For my Tarm, a bulb sensor is in the smokebox and is set at 100C. This temperature is a temperature at which the fire probably has burned out. This might not function well if you experience long idle periods, brief periods should not cause a problem.

Alternatively, a set-up like that used on the new Garn controller -- a differential controller with reset that shuts the boiler down when flue temperature is less than xF higher than the boiler output water temperature, with x being about 5F (or higher).

Depending on the location of the sensor, you might not need the reset function and instead use a manual bypass switch. Turn the switch on to start the draft fan, start the fire, temperature of exhaust gases rise rapidly above the setpoint of the controller and the controller turns on, turn off the manual switch, when temperature falls to the controller set point the controller shuts the boiler down.

My econoburn controller has the ability to do flue temp shutdown. I have not installed the probe yet, I am not sure I will. I want to get the actuator installed that you picked up for me, Thanks again Jim! But, I am not electrically skilled enough to determine where to tie it to the on board flue sensor. Putting it with a timer/fan circuit is a little easier for me.

gg

 

[jebatty]

Is the temp on your bulb sensor fixed at 100c or can you change it to adjust how much coals are left at the end of the burn?

The temp is adjustable. Usually just a few burned out coals are left, occasionally more. The "more" seems to happen when a split or two fails to fall to the center and is left on the side of the firebox. Not really a problem, as the burned out coals aid a quick gasification start.

 

[stee6043]

I love how this board is constantly providing me with ways to waste my money. Now my old fashioned analog fan timer is not good enough? Son of a biscuit.

A digital display would be cool. Someday...when I'm really bored and have money falling out of my pockets...I'd consider moving the boiler controller to a new "panel" and have my tank gauges and a digital timer on the same panel. It wouldn't be as slick as something like the nofossil setup but it would look nice having everything together?

Share pics once you put something together!