tN2 House Control

This definitely reduced the fuel use and improved performance. The system not only accounts for outside temp, but also the diff in the zone actual and set temps via tn2 thermostats. I've seen some short-cycling on rare occasions, but big improvement over the last setup with mechanical aquastat. I like that this has post-purge to remove the excess heat in the boiler and pump exercise features. Install is fairly straightforward. Keep the aquastat for a safety limit. The temp sensor works fine at the boiler outlet as a strap-on but the DHW sensor as a strap-on is unusable. It really has to be in the sensor well inside the tank. I ended up plumbing in a well for the boiler and replaced the aquastat on the DHW with the tekmar sensor. It would be nice if the software could "learn" the sensor delay, but the boiler is protected by the original aquastat. There's no overshoot with the DHW. The only other real improvement I would have liked is in the DHW control. There are times when the tank runs out of hot water. The problem is the DHW differential is fixed at 6 deg. Since the boiler may be starting at 120-140, it takes time for it to heat the DHW. It would be nice to have an adjustable DHW differential, and also have the software sense the rate in drop of DHW temp, so if the temp drops rapidly, reduce the differential. Not all installs are the same, and this would be a nice feature to have.

I bought the 401 because of the modulating output necessary to operate a Burnham Alpine condensing boiler. Prior to this system, I had a Tekmar 370 controller running an oil fired Burnham series 7 cast iron boiler. The 370 was impressive however just not the optimal controller for my new heating system. The 401 controller works very well and the documentation made installation very simple. The ability to use a temperature sensor in my indirect DHW tank further optimized my systems energy efficiency. The temperature control in my home is rock steady with no discernable variations as you typically get using conventional on/off thermostats.