Last fall, I built a small 5 room 1008 sq. foot patio home. Single level, slab on grade with hydronic radiant heat supplied by an Electro Industries 9kw mini boiler (model EMB-H-9). The entire house is on one zone. The home is located in Minnesota. I use a ductless mini-split for heat in the spring and fall and the hydronic heat for the coldest weather.
The hydronic system is currently being controlled only by the slab sensor using a Ranco single stage Electronic Temperature Control unit.
I love the in floor heat, but the one thing I am not crazy about is having to program the Ranco control unit slab temperature sensor setpoint frequently throughout the winter whenever there is a significant weather change. If I fail to do so, it results in either the air temperature of the house being too cold or too warm. This was particularly obvious when I left on vacation for a week and when I came back the outdoor temperature had risen significantly and because no slab setpoint changes were made during my absence, that resulted in a very warm house upon my return. And of course, extra energy consumed.
The installer of this system had originally told me that air thermostats are not a great way to control hydronic radiant systems because of issues like passive solar gain, overshoot, undershoot, etc. I kind of get that, but after Google searching and seeing frequent nods towards Tekmar controls, it appears that they manufacture stand-alone thermostats that utilize floor slab temp input plus the air stat input TOGETHER, along with the ability to control minimum slab temperature. I was wondering if a stat with the ability to control these three things instead of simply slab temperature might not be a better choice for my application.
In hindsight, I know that it would have been better if the system would have been designed with more sophisticated controls like a whole house unit and outdoor reset control, etc. But the house is built and my budget does not allow for a major upgrade at this time.
So while I do realize "optimum" and "budget" don't go well together, my question for you guys today is this:
If I replace the Ranco slab temp control with a more sophisticated hydronic thermostat like a Tekmar 552 and one of their slab sensors, do you think that would "improve" my control? I'm not looking for specific room control; I am fine with one stat for the entire house. If I feel that I have a shot at "improving" my control, I'm willing to try it. And I thought it would be best to get one of their higher end stats that would integrate with their whole house control unit network in the event that I am still not happy and want to make further upgrades down the line..
If any of you have any experience with Tekmar or can make any specific recommendations for my application that would be much appreciated!