How to optimize heating curve in outdoor reset

[cjo13]

Hello all,

As of three weeks ago, my house is heated by a Buderus GB142 boiler with AM10 outdoor reset, running liquid propane. The house is approx 1900 square feet. We've got 3 heat zones and we keep all of them at 60-62 degrees 24 hours/day (no set back).

Right now the AM10 is programmed for the Buderus default values for cast iron baseboards: the top of the heating curve is 167 degrees (corresponding to an outdoor temp of 14 degrees), and the bottom of the curve is set to 115 degrees (corresponding to an outdoor temp of 68 degrees). This maintains a very even temperature indoors per our heat requests for 60 to 62 degrees.

So, the question is, how does the heating curve relate to energy efficiency? If I lower the curve (say to 150 and 100) and my heat requests are still satisfied ... have I succeeded in conserving propane.

In other words, is a lower heat curve always more energy efficient, as long as
it's satisfying the home heating requests? And - does a lower heating curve help in keeping the boiler in condensing mode?

Thank you for any help you can provide - I appreciate it.

- C.J.

[Freezeking2000]

Lower return water temps equal savings

[cjo13]

Lower return water temps equal savings


And the best way to ensure lower return water temp is to lower the heating curve as much as possible while still being comfy. Correct?

Thanks for your response.
-CJ

[hockey]

The highest efficiency (lowest cost) is achieved by lowering the boiler temperatures (high and low) until it does not satisfy. The less propane you use, the more effificient it becomes. I have a Munchkin with outdoor reset, and I bumped up the higher temp to get the house warmer quicker at the low outside temperatures. So, I changed the slope. You want to move the curve downward.