Boiler controller

Discussion in 'General Electronics Chat' started by mpooley, Apr 10, 2010.

  1. mpooley

    Thread Starter Active Member

    Mar 3, 2010
    35
    0
    Hi
    I am thinking of controlling my oil boiler via a PC ethernet port.
    I need a board that will have an ethernet connection and some (4?) inputs with at least 1 output to control a relay.

    I am going round and round looking at the various boards,
    eg arduino types and PICaxe etc but to be honest although I'm certain I can get to grips with any one of these once I have one. I am totally confused which is the best /simplest/cheapest solution for my job.
    Or maybe I can build something from scratch?

    Could someone here with experience of something like this help me with a push in the right direction please. Just to get me started.

    Thanks in advance

    Mike
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Hello Mike,

    This project sounds like a disaster in the making. I have warning bells clanging in my brain. :eek:

    It would be one thing to simply monitor the boiler's temperature, water level, fuel flow, and pressure - but to actually control it is something completely different.

    Boiler controls are designed so that if/when they fail, they will fail in a safe manner - that will not result in a boiler explosion. High-quality components are used that will have a long and reliable service life.

    The fact that one of your requirements is the "cheapest" solution makes me even more nervous.

    This is simply not a beginners' level project.

    Just to become a competent boiler technician would require a somewhat lengthy course of instruction and certification - but that would still not qualify one to engineer boiler controls.

    I've been in electronics for many years, but I'm not even at a level of "certified boiler technician"; therefore I'm not qualified to recommend anything more to you than have someone who IS certified to maintain your boiler in the as-designed configuration.
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,766
    2,536
    The other thing is most boiler controllers are local, mechanical, and attached to the device in question. There is a pretty good reason for this. Goes to the fail safe Sgt Wookie was talking about.
     
  4. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    I am a boiler tech and I have a question.

    If you were to ONLY control the thermostat wire, thereby controlling the when, it could be done. Most boilers thermostat controls are 24v(logic 1) and 0v(logic 0). If you JUST wanted to replace your thermostat, It would be no problem.

    If you want to control fuel solenoid, fuel pump, and aquastat control... you need to find a safer hobby.

    If you want to keep ALL safety equipment in place, and just control boiler cycle times, this can be done. I would recommend buying a programmable thermostat with wifi or USB connectivity. These come with the software to report temperature and status signals, as well as cycling signals between the PC and the t-stat.

    However, MOST boilers use local, (as Bill said) aquastats to keep the water temperature at a set level regardless of the home thermostat settings.. You would actually control the circulation pumps. This would also be done simply thorough the homes t-stat.
     
  5. mpooley

    Thread Starter Active Member

    Mar 3, 2010
    35
    0
    OK Maybe i didn't make myself as clear as I should have.

    I dont want to get inside the boiler controls at all.
    Basically I want to be able to replace the timed thermostats that i have at present so really just a simple relay as in the thermostats.

    I am building a wifi heating sensor array which will be connected to my network server and am going to write my own program to run the zones and the "call" to turn the boiler and pump on and off.

    I will work out a way when i get round to it to make sure the default always failsafes to boiler off.

    Hope this makes it a bit clearer.!!!

    also I am hoping that will stop my boiler cycling which is a major problem at the moment.


    Mike
     
  6. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    If your boiler is cycling too often, your water temperature is too low.

    This is a user set-able on the boiler itself. You most likely have the boiler set too low. You do-not want to set it over 190 deg f. But my guess is yours is around 140.

    Having the temperature too low means it cools too quickly and causes the boiler to cycle too often to keep the temp up.

    By raising the temperature of the boiler water (not the house) it takes much longer for the hot water to drop to level where it needs to be heated. Also, At higher water temperatures, your fans and circulators dont need to run as long to bring the building up to proper temperature.

    What you want to do is called zone control. Each room will have a thermostat and a valve. The thermostat will report the room temp to the PC. If is starts to become too cool, the valve opens, allowing hot water from the boiler through to the coil or radiator.

    By setting each room as occupied or unoccupied, the computer can limit the boilers hot water to rooms that need it. This keeps the water in the boiler hotter, longer. In turn the boiler needs less fuel to keep the water at temperature.
     
  7. mpooley

    Thread Starter Active Member

    Mar 3, 2010
    35
    0
    I have only one control on my boiler which is set to a max of about 42kw which is not the max output of the boiler!

    As I understand it if i want to increase this i will need new jets.

    I have this control set to maximum.

    my boiler is a brand new grant condensing.

    thanks

    Mike
     
  8. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    Hrrmmm.. You should have a water temperature control. Its called an aquastat. The device you are speaking of determines thermal output of the fuel gun. The aquastat runs the burner for as long as needed until the water reaches the aquastats setting. The aquastat has the safety inside that kills the fuel supply if the water reaches boiling or a preset.


    They usually look like this:
    http://www.google.com/products/cata...DxPKK22ATErdThBw&sa=image&ved=0CA0Q8gIwATgA#p

    and are located inside the front panel of the boiler.
     
  9. mpooley

    Thread Starter Active Member

    Mar 3, 2010
    35
    0
    I suspect your boilers in the USA are different to those in the UK

    thanks for your help

    Mike
     
  10. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    Ahh... I didnt know your location.. sorry.
     
Loading...