Tekmar 256 Wiring help

ehonig7

I have been looking this over for a while now and looking for affirmation that I am wiring this correctly. I am looking to install a Tekmar 256 onto my current propane fired Utica Boiler. I have three zones w/ circulators that are each controlled by a separate R182c relay. I also have an indirect WH as a zone. I realize that there are better products out there for this but I have the tekmar in hand so I am trying to make it work.
The aquatstat on my boiler is a Honeywell L8148E. Right now I am planning to use the Tv from this as my trigger and cutoff.
I realize that the IDHW system needs to ignore the tekmar. For this, I am adding a relay that will bypass the Tv out of the tekmar.

Right now my thoughts are to wire as shown.


The left side is my relay that is bypassing the Tekmar. The "Boiler Demand Block" on the top right is the terminal block I have that is triggered from all the zone relays.

I appreciate any advice in making sure this looks right!

GGross

Tekmar offers a nice application guide for this control, Page 7 shows an application for 3 zone circulators, a single stage boiler and an indirect heater.

https://www.watts.com/dfsmedia/0533dbba17714b1ab581ab07a4cbb521/81346-source/256-a-06

109A_5

Hello @ehonig7,
Your wiring diagram seems to co-mingle 120 VAC with 24 VAC stuff, probably not good for something.

I agree with @GGross.

However, if you want the extra security of the Honeywell L8148E aquatstat high limit that could be wired in too, since it is already there.

ehonig7

Thank you! I will take a look again. Nothing is 120v past the Honeywell R182c zone relays. I do not touch that at all. It is all 24v. The High limit still applies since it is after the thermostat on the aquastat. I will take a look again and compare. Thank you as I did not see this exact document on tekmar's site.

109A_5

Hello @ehonig7,

I Think terminal 1 on the R182c relay is on the 120 VAC side of the transformer.




Also The DHW aquastat contacts going to R182c relay's 7 N/C and 8 Com contacts also does not make much sense either.

ehonig7

Ahh I get, I was not clear. I am not touching the R182c at all. The relay I have not labeled in the image is a Tekmar 003 (Not exact but same thing). I am really sorry, my fault for not being clear.
The diagram @GGross put is very close to what I am doing. The DHW aquastat is my signal to the 003, that is triggering the relay to bypass the Tekmar 256 and pass the Tv signal on directly to the Aquastat on the Boiler.
I am hoping that is a bit more clear.

109A_5

Hello @ehonig7,
Well what powers the 003 relay coil ? Tekmar terminals 7 to 9 should be isolated switching like in the Tekmar diagram. Not connected to the L8148E, possible phasing issues.

109A_5

Hello @ehonig7,
Maybe something more like this, but I get a bit foggy towards the boiler since I don't know what you have. And the closure needed from Tekmar terminals 7 to 9 should be from the extra isolated paralleled contacts of the R182c zone relays.

ehonig7

Alright, I had it planned out exactly as @109A_5 said. I just had to figure out the trigger for #7. I was able to successfully get it installed and working. Now, I just need to see if it makes a difference. Hard to tell at this point. I can say that my boiler burner cut out and the tekmar still said call for burner. The probe on the intake side is what throws me. It drops as low as 90 and only hits in the 120's. Does this device take this into account? I have it strapped to the 1" line that enters the boiler. It is about half in. half out.
Am I missing something? Just seems it will not do what it is made to with the temp probe like this.

109A_5

Hello @ehonig7,

ehonig7 said:

The probe on the intake side is what throws me. It drops as low as 90 and only hits in the 120's. Does this device take this into account? I have it strapped to the 1" line that enters the boiler. It is about half in. half out.
Am I missing something? Just seems it will not do what it is made to with the temp probe like this.

I think the 'Universal Sensor' wants to be on the boiler supply side. Sounds like you have it on the return side.



https://www.watts.com/dfsmedia/0533dbba17714b1ab581ab07a4cbb521/81348-source/256-d-09

ehonig7

Yup... that would be it.. I read supply only and that was it...
Will have to move it. I have to figure out a better attachment system. They give you one zip tie. Which really does not feel secure. I assume it is a high-heat one, but who knows. At the ver least two would be better. Any suggestions would be appreciated. Thank you so much for your help!

109A_5

Hello @ehonig7,
In the short term most any zip tie may work, and could be replaced with a better temperature rating type later, if needed. Also once the insulation is placed around the sensor and the pipe it probably won't go far. However the zip tie may help maintain good contact area with the pipe.

You probably could use tape, but that may turn into a gooey mess.

GGross

ehonig7 said:

Yup... that would be it.. I read supply only and that was it...
Will have to move it. I have to figure out a better attachment system. They give you one zip tie. Which really does not feel secure. I assume it is a high-heat one, but who knows. At the ver least two would be better. Any suggestions would be appreciated. Thank you so much for your help!

You could try an appropriately sized hose clamp, or 2