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HVAC Guru
HVAC Guru, HVAC TECH
Category: HVAC
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Experience:  15yrs in the HVAC industry with certificates and degrees.
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On a Sola R7910A control, what do the J9 's #1 & 2 terminals

Customer Question

On a Sola R7910A control, what do the J9 's #1 & 2 terminals marked for DHW connect to (field connections)? Are they positive and negative compared electrically to each other? What sensor (part number) should be used for DHW temp control and how is it wired to the Sola?Thanks for your help.Mark***************
Submitted: 3 months ago.
Category: HVAC
Expert:  HVAC Guru replied 3 months ago.

Hello and thanks for using this service! If you are a JA Member I would like to personally thank you and welcome you back! I am HVAC Guru an extremely experienced tech on the site and I try to get to as many customers as I can. NOTE it takes time for me to type research and add links so please wait for me to respond back I can only do this so fast. Secondly, I do not know your skill level so please try and let me know if I am going beyond your knowledge or comfort zone thanks! I strive for a 5 star rating from everyone especially our JA members.

Are you just trying to hook up the two wires?

Customer: replied 3 months ago.
Well yes, it is just 2 wires. Right now we've got a normally closed aquastat wired to it. The DHW field on the SOLA display shows "Short" when there is a demand and "Open" once the setpoint is reached. Problem is even though the aquastat is doing what it's designed to do, the SOLA controller is ignoring its' inputs (or lack thereof when it opens) and is instead operating based on the DHW setpoints programed within the control. We assumed once the DHW circuit opened the boiler would stop running but it's not.Our concern is even if we get a different sensor are those terminals actually going to control the boilers operation? As of now they seem to be more for informational purposes rather than a control feature. This is a lead/lag setup with a two and a 3 way valve operation to redirect flow thru a shell & tube heat exchanger for DHW so we need the ability to correctly input the DHW demand.
Expert:  HVAC Guru replied 3 months ago.

So they are not controlling it at this point correct? The board is not seeing the input or responding correct right?

Customer: replied 3 months ago.
Correct.
Expert:  HVAC Guru replied 3 months ago.

OK on that unit normally that is a controller issue nothing to do with the sensor at all. The controller should be changed out to really fix the issue.

All I ask is please use the Star Rating Link at the top of your page before leaving, that is the only way I am paid anything through the site and that will also get you a DIRECT LINK emailed to you to get back to me!.....tips are greatly appreciated so thank you very much for using this service. If you have any other questions just post back to me here anytime!

Customer: replied 3 months ago.
Thanks - I'll re-contact you if problems continue or change.
Expert:  HVAC Guru replied 3 months ago.

OK sounds good!

All I ask is please use the Star Rating Link at the top of your page before leaving, that is the only way I am paid anything through the site and that will also get you a DIRECT LINK emailed to you to get back to me!.....tips are greatly appreciated so thank you very much for using this service. If you have any other questions just post back to me here anytime!

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