Making boiler controls smart

[Jersey Bill]

Down here in NJ, we had some good weather for burning. For me, thats below 40, preferably below 20 when I can push it hard without hitting the upper temp limit. Since I have less than 200 gallons of water storage, for the most part I have to match boiler output to load, on average. Getting through the night without the gas boiler coming on has been a challange. When its 20 or below, I have to get up twice at night to fire the boiler.
The KP Pyro stock control is probably as simple as it gets. There are 4 capilary bulbs in a well at the top of the boiler- temp display, pump, hi-limit, operating limit. When the fire runs out, the fan stays on until the main power is shut off. This caused the coals to burn out forcing me to re-light each time. I spoke with Zenon about this and he sold me an additional stat for the stack. This would shut down the fan when the fire died off and the stack temp dropped. This worked OK, but not great. After a hot run, the stack temp was maintained until the wood is gone, not helping much there. It was incompatible with the existing operating stat. If they were both set and the operating stat shut off the fan, the stack temp would drop and the stack stat would open, preventing the fan from resuming when the operating stat re-called. If the stack stat was set too high, some ebb and flow of the fire might kick out the fan with a half of a firebox filled with wood. If its set too low, I will have no coals left.

So, until now I have resisted trying to "improve" the controls. I removed the stack stat and put in a control relay to my PLC. the boiler controls are 120v. I also needed a signal that the loading door is open. There is an existing switch, but I need a low voltage signal so I put in a control relay there also. I used 1 set of contacts to do what the switch did, which was to force the fan on if the door is open. Another set of contacts went back to a PLC input. Finally, I installed a manual/auto switch which basically jumped the PLC relay closed in manual. I tucked the relays in (on pigtails) and put the box cover back on.

Then I sat down to write the PLC program. For now my goal was to run the fan for a time, about 3 hrs, after the loading door is shut, then shut down the fan until the loading door opens again.
When I get a chance I want to use time OR stack temp to shut down the fan, or maybe time AND stack temp.

The other feature that I was thinking about is hibernate. Say I load the boiler all day and I get near my max limit. Before bed I stoke the boiler, then have the fan shut down for 2 or 3 hours. Then I should get a 3 hour burn which should get me 6 or 7 hours before I need to re load.

How does everybody else do it? I realize that I am at a disadvantage compared to you guys with gobs of storage.

 

[Eric Johnson]

The EKO controller does a good job of maintaining a bed of coals, but I had that problem with my previous boiler. I thought about wiring the fan through a timer so that I could anticipate the burn time and set the timer accordingly. But I never did it.

You might want to ask Zenon if the RK2001U controller will work on your boiler. It has all kinds of control settings, including a user-adjustable FUEL mode that shuts off the blower when the boiler water temp drops to a setpoint and then doesn't recover after a specified period. I think they run about $250--maybe less.

 

[steam man]

Thinking out loud here I guess you want the fan to shut off when the fuel is near depletion. I would say that if you measured the input and output temp to determine if there is positive heat output. Possibly combine it with a positive indication of flow (pump on?) and a minimum temp setpoint. Shutting down the fan while there is still a slight heat output would ensure there would still be hot coals available.

Mike

 

[skidsteer]

I feel your pain with relighting your boiler every time. I have a Econoburn eby 200 I have been burning it now for almost
three years now and this past July I finally hooked up my storage I'm using three 500gal propane tanks all stacked one
on top of each other on a steel rack that I had help fabricating . that solved a lot of issues.
But it did not solve the issue of not having hot Cole's for the ease of relighting or what would absolutely drive me crazy would be the
fan running on high for most of the day or night seeing I Would only get a four hr burn time.
This past January I finally did what I been saying I was going to do for the last 2 1/2 yrs I installed a thermostat with a remote probe
that controls the boiler cirk. Then next I installed a 24hr fifteen min increment time clock and broke the fan circuit.
So far its been great it solved even Moore issues that bothered me about my boiler now I have Cole's for the ease of relighting.
I also hve the ability to fire the boiler when I most need the heat . What I do because I'm in bed so
early most of the time my last filling is at 8pm the tanks usually are charged to ware I'm happy 180+- so I will fill the boiler set
the time clock run one to one in a half hrs to make sure the fresh load of wood gets a Chance to start burning
then I shut the boiler down for one to two hrs then start it back up for two Moore hrs that gets into around the 2am range
now when I reload at 5am my tanks have a decent temp around 150+ temp and that's been during the recent cold snap that we all
have been feeling and I'm heating 5000sqft house a 30x50 garage and last but not least a 400gal hot tub. The clock has been great
saves wood & electricity .

 

[Piker]

I just developed a simple timer control that I will be installing on systems with storage. It's pretty simple... just a timer and a relay. Light the boiler and set the timer to shut the boiler down before your load is fully burned. WHen the timer shuts off, the relay is energized and turns on the circulator that only flows water through the boiler... those of you with mixing valves instead of boiler circs won't find this timer control all that handy... but for folks with boilers that have tempering circs controlled by water temp you might like the idea. Being able to turn the circ on before the fire goes out will keep a good coal bed for your next firing, plus it prevents the boiler from making steam if you short change the burn time a little too much and have too big of a coal bed left.

you can check it out on my website if you like.

cheers