retrofit a tekmar 256 or something easier????


Old 11-07-12, 05:52 AM
Thread Starter
Join Date: Nov 2012
Location: usa
Posts: 35
retrofit a tekmar 256 or something easier????

I have good electrical skills but limited plumbing/mechanical skills.

1. I want to have my hydronic boiler shut down on warm days,

2. and if it is not too difficult, adjust boiler temperature
according to outside conditions.

what choices do I have? I guess the tekmar 256 will need a temperature sensor at the boiler?

What other choices are there for an outdoor sensor product, without changing aquastat or adding a boiler temperature sensor?
Can the Tekmar 256 be used without adding a boiler temperature sensor? Will adding a temperature sensor to the boiler be a big job involving disassembling the boiler?
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Old 11-07-12, 06:02 AM
Join Date: Nov 2011
Location: USA
Posts: 401
You don't need to remove the current a'stat when you install the Tekmar 256 control.

And, the Tekmar boiler sensor is a "strap on" type, which means you don't need to take apart the boiler. You just need some space on the supply pipe to strap the sensor against.

Check out the 256 specs and manuals from HERE.
Old 11-07-12, 06:41 AM
Join Date: Jan 2012
Location: Canada
Posts: 2,612
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I'm guessing you have a warm start boiler setup currently (always maintain hot water)?
Are you pulling DHW off the boiler?

If you are not getting your hot water from the boiler, might be worth considering a new aquastat.
I was looking at replacing mine and found they where not all that expensive (<$100 I think).

What aquastat do you currently have?
Old 11-07-12, 08:02 AM
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Join Date: Jul 2007
Location: Pennsylvania
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As N Mike asked what control but also what boiler, oil, gas.
How do you make your hot water?
Old 11-07-12, 11:28 AM
Thread Starter
Join Date: Nov 2012
Location: usa
Posts: 35
details requested

I have natural gas boiler, separate natural gas hot stand alone water heater.

My boiler is a Weil Mclain pcg-5.

Aquastat really old discontinued White Rogers 8f42a-5, which seems to have single settable high temp cutoff and fixed 7 degree differential... i cant find a manual for it.

I have 3 floors with hydronic baseboard heat about 60 feet on each floor.
attached townhouse with heat almost never used in 1/2 below ground basement with garage occupying half of basement.

My heating/gas bills are $100-200 a month, and only $30 in spring/ summer (hot water and stove).
I am guessing I can cut alot of the November and April gas usage with
the Tekmar 256, and it would pay for itself.

Thanks for any more advice you can provide on this on whether a new aquastat would make much improvement compared to Tekmar 256,
Also how to replace 8f42a-5 with Honeywell replacement for it I saw on this
board... There is a "well/sensor" and I have no idea how hard to replace/install. The electical part I am sure I can handle.

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