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Frequently Asked Questions
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Q. I have a Honeywell L8148E limit control which came with my gas boiler. It has one 24vac zone for a thermostat. I want to implement the SR503 into the circuit, as I have two zone 120vac thermostats. I need to know what the output of the thermostat zones are, along with a n/o contact set I can use for the 24vac zone on the Honeywell. It will be used for a cold start boiler operation with continuous ignition.

Q. What are the ZC and ZR terminals on the SR506 and how are they used?

Q. I need technical details on how the ZR and ZC terminals interface with the aquastat on a boiler. I wire many boilers and all directions specify cold start or hot start, black box type instructions. I do not fully understand the inner workings, or what happens electrically with either application.

Q. I have a gas boiler with Taco controls that is short cycling. The problem seems to relate only to the 2nd floor zone. What can be causing this?

Q. I have installed a sr503-1 with priority in a primary secondary loop and an in direct water heater (priority. In total I have four pumps, one for my primary loop and one for each of three zones. I want my primary pump to come on for 2 zones but not to come on when my indirect water heat call hot heat. Can this be done?

Q. Hi Taco Rep. my question is why is it that in the Taco controller module the terminal 3 & 4 have to be jumped for 2 wire zone valves? Thanks for your help!
A taco user.

Q. If a ZC wire from the aquastat is wired to the SR board and the temperature of the boiler is low, will the indicator lights be on, and the circulator be on if there is a call for heat?

Q. Can a SR EXP control and a ZVCEXP control be used together?

Q. Can I use the screws of an end switch on a ZVC or SR board to check continuity?

Q. Can you prioritize a SR502/503 when used with an SR502/4/6 EXP?

Q. Can I use a PC700 with a SR board when I have a primary loop pump?

Q. I need to power my thermostat as there is C, R, W terminals on the thermostat. How do I get a C connection? I have a ZVC board.

Q. I need to power my thermostat as there is C,R,W terminals on the Thermostat. How do I get a C connection? I have a SR board.

Q. How to run a system pump on a SR504/506