Tekmar 256 versus 260

ALH_4

I dont know if the indoor sensor will gain you a lot, but just for the cost of a relay, you should upgrade to the 260. Also if you decide to add dhw to your boiler, you have the option right there.

I think you are correct to be leaning toward the 260.

Al Roethlisberger

Tekmar 256 versus 260 - best application?

Based on some recommendations here, I have been researching the Tekmar 256 and 260 boiler controls to retrofit to my ca1991 gas hot water boiler.

I do not have Domestic How Water plumbed through my boiler, so although the 260 provides that function, I don't need it.

So, that might seem to indicate using the 256 alone, but it seems like the 260 is a more complete control, and also controls a circulator pump, which I do have on my system.

If I used the 260 instead of the 256 combined with my existing old controls, it might be a simpler/cleaner installation.

The 260 is about $100 more than the 256, but if my interpretation of the controls is correct, I could eliminate my old electromechanical based controls by using the 260, instead of piggybacking the 256.

But other than simplifying the system by not having two controls working together if I used the 256, I don't know if anything else the 260 offers might make sense to install it and spend that $100. Hence my post looking for thoughts and others experiences.

One other advantage the 260 may have is its ability to use an internal temp sensor to also regulate temps. But my question would be how useful is this if one already has a quality thermostat sending demand? Would they work together, or "compete" in regulating demand and output water temp?

What do you think? Would it make sense to "simplify" the contols for the system and do away with my old controls and just spend another $100 to get the 260, or would the 256 really be sufficient?

I have attached a photo of my current boiler, and the electromechanical controls currently attached.

Thanks!
Al

Al Roethlisberger

Can/Will the 260 control my damper correctly as well?

> I dont know if the indoor sensor will gain you a

> lot, but just for the cost of a relay, you should

> upgrade to the 260. Also if you decide to add

> dhw to your boiler, you have the option right

> there.

>

> I think you are correct to be leaning

> toward the 260.




Basically, my current "legacy" controls are doing three things:

1) fires boiler to set output temp
2) turns on circulator pump
3) open/closes damper accordingly

I know the 260 will do 1 & 2, but will it also perform the function for #3?

Thanks
Al

Al Roethlisberger

Can/Will the 260 control my damper correctly as well?


Basically, my current "legacy" controls are doing three things:

1) fires boiler to set output temp
2) turns on circulator pump
3) open/closes damper accordingly

I know the 260 will do 1 & 2, but will it also perform the function for #3?

Thanks
Al

Ross_7

Hi Al,
No, the Tekmar controls are not designed to open & close the damper on the boiler. The existing controls on your boiler will take care of that for you.
Ross

JaredM

You should be aware

that the Tekmar controls are not listed as 'Operating Controls' meaning that you must leave the Honeywell Aqustat Relay in place. You can operate the circulator with the tekmar though.

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Al Roethlisberger

How do prog thermostats work in concert with the controllers


Thank you very much for that clarification. That helps a lot.

So here's some thoughts and questions:

Yes, I am considering the 260. The DHW feature is a waste for me, as my boiler doesn't currently have the configuration to support that use.

The only advantage I can see with the 260 for me would be:

1) Use of inside temp sensor to aid in calculations of heating curve

2) Direct control of circulator pump from the unit

#1 seems like a "win", but beyond the function of the occasional exercising of the pump during off seasons, I don't know that the 260 would operate my pump any better/differently than my electromechanical Honeywell aquastat does today.

More directly, is there any advantage to having the 260 control my pump versus my Honeywell aquastat?

I think the 260 might seem to offer some "investment protection" if I ever install DHW functionality, but I'm not so certain that by the time I did that(i.e. replace boiler in a decade) that there may be something better anyway.

So I'm still thinking on the 256 versus 260 issue.


One other question, I am looking at the Tekmar 510 thermostat. Like many thermostats, it has an "early start" function and function to thwart short cycling the furnace. My currently programmable thermostat has the same function where it will learn the delta between starting the system and the target temp, and send demand early enough to reach that target. And it also has a function where it holds cycles to 20-30 minute intervals.

Now, the 260 boiler control also uses an automatic algorithm to control cycles on the boiler based on terminal(in my case, radiators) type.

My question is this: Will the thermostat(510, etc) "logic" to control early-start and cycles interfere, confuse, or reduce the efficacy of the "logic" in the control(256, 260, etc) since it seems they are both seemingly doing similar things?

It almost makes me worry that the thermostat will try to impose its own demand logic based on a relatively fixed algorithm, and then the 256 or 260 will then base its logic to control cycles on an incorrect demand assumption.

Or do they work together just fine...

Thoughts?

Thanks
Al


Al