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Relay Control Panel for heat system complete finally!

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by mpilihp, Jun 10, 2009.

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  1. mpilihp

    mpilihp Feeling the Heat

    Joined:
    Apr 22, 2008
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    Coastal ME
    Finally got it done, so now all heating of the house and DHW is automated to heat from wood when the wood boiler is running or heat from Oil when its not. Also have lower temps for the heat zones for the oil to kick in than when the wood boiler is running.

    Also the DHW can only call for heat from the Oil boiler during the wee hours of the mornign which gives us a chance to build a fire in the evening and heat the water with wood boiler, if we dont then the oil will kick in and heat it.

    Heres the control panel, outside view, the relays have LEDs in them so I can see whats on.
    [​IMG]

    Inside view 120v blocks are insulated from the backboard. each 24vac fed item is individually fused so a failure of one item cannot kill the power supply for the entire sytem.
    [​IMG]

    There are a couple of timers, the delay timer prevents the oil boiler from kicking on in between the wood boiler circulator kicking off while the wood boiler re-heats, IE if the house was really cold but was heating from wood I didnt want the oil boiler to kick on in between the wood boiler circulating cycles.

    The other timer only allows the DHW to kick on the oil boiler from 11pm to 1am.
    Heres a line diagram of the connections.
    [​IMG]

    This is the physical relay layout and individual connections to the relays, im not used to this relay setup so I created a view of this to help me wire it.
    [​IMG]

    Last here is a diagram showing all the input and output connections. Probably overkill but I like things documented so I can look back at them for trouble shooting.
    [​IMG]

    Im planning on adding a second DHW boilermate in series so when we do a firing in the summer it will last two days. One does us one day so hopefully a second will go for two. Ill wire it so the aquastat on the one outputting to the house to the oil boiler, IE it will only heat one tank on the Oil boiler. THe second one that feeds the output one will have its aquastat wired up to heat when the wood boiler is running.

    ~ Phil

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  2. WoodNotOil

    WoodNotOil Minister of Fire

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    Great job! Can you supply some links to some of the relays and other parts you used? I would be particularly interested in the sizing of your relay on your oil boiler. Lots of diagrams. I will have to take some time to look it over thoroughly...
  3. pybyr

    pybyr Minister of Fire

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    I am going to want to come back and look at this more closely later to try to tune into the details, but initially, just wanted to say

    BRAVO!
  4. Dune

    Dune Minister of Fire

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    I concur with the other posters, most impressive. Thank you for posting your schematics.
  5. mpilihp

    mpilihp Feeling the Heat

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    Thanks guys I will post links to the relays the source is in a thread here somewhere by nofo my unknowing mentor.
  6. Nofossil

    Nofossil Moderator Emeritus

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    Nice job on the design and especially on the documentation. That's always the hard part to get done. I like the inclusion of the timer.

    It's pretty cool what you can do with relays, switches, timers, and aquastats (or snap-action thermal switches, if you're cheap like me).

    Interesting - looks like you're using the same relays that I use. Are those the Schrack units? I like them because they give you a visual indication of when they're activated as well as a manual lever to activate them by hand for test purposes. Here's a picture of a box full:

    Attached Files:

  7. pybyr

    pybyr Minister of Fire

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    By the way, my compliments on the craftsmanship of design and layout, too.

    It'd be easy to have the inside of your box end up looking like a bird's nest, but yours looks first rate.
  8. mpilihp

    mpilihp Feeling the Heat

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    Hi all thanks for your comments, NoFo, nope those are not the relays I used, but I do like the idea of a manual switch on relay for testing. I got the relays, sockets and DIN rail from www.digikey.com I think you steered me to them. THeu are DPDT relays except for one is a quad contact relay, the wood boiler ON relay. Alot depends on if the wood boiler is or or off so needed a relay with alot of poles to run them through.

    PB1148-ND RELAY MINI DPDT 12A 24VAC W/LED
    PB1153-ND RELAY MINI 4PDT 6A 24VAC W/LED
    SOCKET FOR PT2S MINI RELAYS
    ADR3515-S0700-ND DIN RAIL 35X15MM SLOTTED 7IN

    Thats all the parts I got for relays, need the sockets and rail to mount them, screw holes in sockets are too small to do anything onto wood.

    THe mounts for the 120v rails are made from snowmobile hi-fax slides. they make great insluated mounts.

    The box is a throwaway from my company.

    The delay timer was found on Ebay simple unit, there is bleed current allowed through unit to activate the timer once voltage is applied but the current isnt enough to activate the relay, once timer counts down it applies full current and turns the relay on.

    The 24 hr timer I think I found on 1001lights.com or something like that.

    My next plan is to add a digital thermostat/controller to the wood boiler flue pipe with a high temp prob and have it operate a motor to close the draft damper if the temp gets too high, as long as it stays say under 700d it will let the mechanical damper control draft door based on water jacket temp, but if it goes over 700 the electronic one will close the door.

    Issue is on cold starts the mechanical draft controller lets the fire get too hot and out of control, once the water jacket comes up to temp and is cycling between its operating range the bi-metal draft controller works fine.

    ~ Phil
  9. jebatty

    jebatty Minister of Fire

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    My electrical control system is a growing, mutating alien. The time is likely to come when I will re-design and build a control box, like yours, that has an appearance other than a discombobulated and dismembered octopus.

    Good work.
  10. stee6043

    stee6043 Minister of Fire

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    That thing is a beauty.....do you guys have beds and toilets in your boiler rooms? I'd never leave mine if it was this tricked out....
  11. mpilihp

    mpilihp Feeling the Heat

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    You'll notice you can't see any of the basement in the pictures is it's A mess....
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