Radiant Efficiency

Trapper_Dave

So we finally got our system up and running this year. Lots of careful planning and help from several on this forum. Wow, I am amazed how well it works and how comfortable this old house can be.

I am, however having a debate with myself as to the most efficient way to run our Buderus wood boiler. Normally, I keep making small hot fires throughout the day and try to maintain the return temp at the boiler in the upper 70's. Seldom do I need to make fire at night, but of course my return temps are down in the morning. No problem because it is nice to sleep with it a bit cooler. The question I have arises when we are going to be away for the day or sometimes the weekend. If I don't fire somewhat consistantly I get behind and have to really get busy feeding the boiler to get caught up.

So my question is, do I somehow loose efficiency by letting the temps sag down and then accelerating the system when we get back? Is this similar to speeding and slowing down your car on the freeway, which we are told is a waste of gas?

Probably a simple question.

Jamie Hall

Maybe... particularly with a wood boiler, though, it will be very hard to quantify in either direction. Even measuring the efficiency of a wood boiler (BTU out vs. BTU in) is problematic, since the BTU in is very hard to measure (even quality pellets have a wide range of BTU per pound, never mind chip or solid feeds). There may be some loss from the floors having to be a bit hotter to recover -- but then, there may be some gain from there being a bit cooler part of the time...

Gordy

I think you answered your own question. Think of it as "system efficiency". Steady state when needed for radiant is always a better approach. However if you like the cooler temps at night, and are gone for long periods then let it set back. What is the emitters you have? I'm assuming radiant since that is the title.

hot_rod

Actually the cooler the return, the higher the efficiency of the boiler, any boiler really. With wood you need the return to stay above 130, however to avoid condensation

I don't think that is a gasification type boiler? Those like to stay hot to keep them in gasification mode, and cold starts bother them more than non gasifiers. I've run both types at my place.

A buffer tank can really smooth out a solid fueled boiler. Run it hot, long, charge the tank to carry through a day

As you discovered wood boilers are pretty operator intensive when you try to match them to ever changing loads.