I have two questions on my domestic hot water / in-floor heating system. I've attached a hand-drawn schematic for your reference. We just moved into this house four weeks ago and since it's summertime we haven't really put the heating system through its paces. The biggest load we've put on it is an extended shower and there's plenty of heat for that.
1) Both water heaters are high efficiency models less than four years old and both are equipped with White Rodgers Intelli-Vent controllers. Both are set to the same setting which, according to the manual, should keep the water temperature around 135F. Heater #1 is a 40 US gallon model and #2 is a 50 US gallon model. I've noticed that #1 fires a lot during the day but #2 fires rarely, if at all. Does this setup seem right? I was wondering if #1 should be set to a lower temperature in order to share the heating load across the two heaters.
2) I've also noticed that heater #1 usually takes several attempts to light. The fan starts, the ignitor gets hot, the gas comes on and lights and a couple seconds later the flame goes out - I've watched this happen through the sight glass. On occasion I've received error messages on the controller that it temporarily locked itself out for too many unsuccessful lighting attempts. I was wondering if the heat sensor (thermocouple) got bent out of position but it looks like it's in the right place to me (see attached photo). I'm wondering if the thermocouple is bad. Any ideas how to test that? Any other ideas what could be the problem?
Thanks for your help!