What you can do if you don't want your lye solution to get too hot, is to use a water bath. Cold tap water should be enough if you're in Canada.
You can leave some ice cube nearby and drop a few ice cubes in your water bath as needed. As you mix your lye you can add and remove your lye solution from the cool water bath as needed to keep the temperature of your mix cool, but keep it warm enough to disolve the lye properly.
You can use a thermometer or monitor by the amount of fumes to know if your lye water is getting too hot.
Just make sure the Citric acid is well disolved like I had mentioned, before mixing in the lye.
I have had to warm up part of the lye solution to disolve the Citric acid. Then I add the Citric acid water to the rest of the water, mix well, and then add the lye. If you add sugar, you may have to warm it up to disolve separately as well.
I'm in Ottawa, the temperature varies so much that if you soap in the summer or winter months , I need different approaches to make the soap based on the weather