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  1. #1
    Join Date
    Dec 2008
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    4

    Default Tekmar 256 install

    looking at the schematics for my systems at first i think i understand it and than i look further and i feel im totally lost.

    Anyone wire the 256 up to a honeywell L8148E yet?

    I stuck with the boiler demand and the boiler contact inputs.

  2. #2
    Join Date
    Feb 2008
    Posts
    555

    Default Re: Tekmar 256 install

    Jeff:

    The mechanical and electrical schematics for the Tekmar 256 can be seen at the site below---scroll down 9 items for the 256---after the mechanical & electrical schematic is listed, there is a "system operation" commentary on how the different versions are wired---most boiler rooms also have a "switching relay" box to route the wiring, such as a Taco SR 501, which further complicates things.

    Also, there are 3 or 4 different applications listed for the Tekmar 256, depending on if you have an indirect HWH, a tankless coil, zone valves, zone circulators, etc.

    IIRC, the L8148A is a cold start that often has an indirect HWH coupled with the boiler.

    PM also issued.

    http://www.tekmarcontrols.com/literature/a.html
    Last edited by NashuaTech; 12-12-2008 at 04:40 PM.

  3. #3
    Join Date
    Dec 2008
    Posts
    4

    Default Re: Tekmar 256 install

    Yes i looked at those diagrams for hours. The 256-1 diagram shows you somewhat of the right way to hook it up but the only problem is that the 256 would always see the call for heat since the relay is always energized.

    I actually called Tekmar and spoke with there tech dept. Those guys rock! what i have to do is to is this. Since my thermostats on the wall carry 24 volts they supply the zone valves the power to turn on when there is a call for heat. When the motor on the zone valve reaches its full swing it hits a switch. This switch is wired to the T and TV on teh L8148E box. once those to contacts meet the boiler is told to fire if neede, and the circulator pump starts to run. What i have to do is to take the wires from the zone valves off teh T and TV terminals on the relay box. Than hook them to the 7 and 9 terminals on teh 256. Next take wire and runn teh 5 and 6 terminals on the 256 to the T and TV lugs on the relay box.

    So now what happens is as the thermostat calls for heat the motor hits the switch. The switch than tells teh 256 we need heat. the relay closes in the 256 and makes the connection on the relay box.

  4. #4
    Join Date
    Feb 2008
    Posts
    555

    Default Re: Tekmar 256 install

    Thanks Jeff.

    I'm sure your post will help lots of others who want to put in an ODR.

    Please post back later in the heating season to give an update on the unit's performance.

  5. #5
    Join Date
    Dec 2008
    Posts
    4

    Default Re: Tekmar 256 install

    Will do. Maybe i will try to work on some schematics to show what i did as well.

    Thanks for the quick responses and help.

  6. #6
    Join Date
    Mar 2009
    Posts
    2

    Default Re: Tekmar 256 install

    Quote Originally Posted by Jeffz View Post
    Yes i looked at those diagrams for hours. The 256-1 diagram shows you somewhat of the right way to hook it up but the only problem is that the 256 would always see the call for heat since the relay is always energized.

    I actually called Tekmar and spoke with there tech dept. Those guys rock! what i have to do is to is this. Since my thermostats on the wall carry 24 volts they supply the zone valves the power to turn on when there is a call for heat. When the motor on the zone valve reaches its full swing it hits a switch. This switch is wired to the T and TV on teh L8148E box. once those to contacts meet the boiler is told to fire if neede, and the circulator pump starts to run. What i have to do is to take the wires from the zone valves off teh T and TV terminals on the relay box. Than hook them to the 7 and 9 terminals on teh 256. Next take wire and runn teh 5 and 6 terminals on the 256 to the T and TV lugs on the relay box.

    So now what happens is as the thermostat calls for heat the motor hits the switch. The switch than tells teh 256 we need heat. the relay closes in the 256 and makes the connection on the relay box.
    Jeff, your wiring is almost right but doing it this way will shut off the circulator before the thermostat is satisfied, Have you noticed that yet?

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