The Day in the Life of a Rocket Mass Heater

Rocket Mass Heaters have fascinated me since the moment I first read about them. Some day I will build one, but until then I just learn about them and admire all the Rocket Mass Heaters others have built. Paul just published a nice video about the day in the life of a rocket mass heater (I love that title!). I the video Samantha goes through the whole day, measuring temperatures in different parts of the heater and the room:





It's really cool to actually see how the temperature goes up and stays up for so long time! We have a masonry heater, so I do know something about the amazingness of having a mass, but oh how I wished to have the rocket effect in out heater - we are once again wondering if the firewood we have will last to the spring.
Heated seating area sounds delightful too - although I do feel that our dog and cat would probably own it as their own..

It would be really cool to hear about people with Rocket Mass Heaters - is the day in your Rocket Mass Heater's life like the one Paul's heater has?

My days are nothing like that.  You have to burn a fire pretty much all day to warm the mass up and then you can get by with no fire at night, but you’ll need to burn all day again the next day.  With the temps getting here in the singe digits down to the negatives I expect to have to stay up extra late burning wood to keep the house warm

Eric Hammond wrote:My days are nothing like that.  You have to burn a fire pretty much all day to warm the mass up and then you can get by with no fire at night, but you’ll need to burn all day again the next day.  With the temps getting here in the singe digits down to the negatives I expect to have to stay up extra late burning wood to keep the house warm

Oh, Eric, I have seen your thread about the build! Your rocket mass heater is beautiful!
What kind of temperatures are you trying to keep in the house?

I have also read about the cold that has arrived to USA, it was with us here in Finland about a week ago and wow.. It was cold! Our Masonry heater was used a lot, multible hours in the morning and in the evening. The temperatures in the house in the mornings were around 16C/60F.

Saana Jalimauchi wrote:

Eric Hammond wrote:My days are nothing like that.  You have to burn a fire pretty much all day to warm the mass up and then you can get by with no fire at night, but you’ll need to burn all day again the next day.  With the temps getting here in the singe digits down to the negatives I expect to have to stay up extra late burning wood to keep the house warm

Oh, Eric, I have seen your thread about the build! Your rocket mass heater is beautiful!
What kind of temperatures are you trying to keep in the house?

I have also read about the cold that has arrived to USA, it was with us here in Finland about a week ago and wow.. It was cold! Our Masonry heater was used a lot, multible hours in the morning and in the evening. The temperatures in the house in the mornings were around 16C/60F.

Yesterday we got the house to around 76. The bench before bed was really hot 🥵 109-116 F. I measure 130 under a pillow. I think we stopped burning around 10 pm.  This morning it was about 63 by the bench and 60 at the other end of the room.

We lit a fire a little before 9 am and the house is now 66 2 hours later, the bench is about 82 F after burning 2 hours.  We will have a fire all day again today.  My house was built/designed for a rocket mass heater and has great insulation. I studied for years before I built mine.

I think our low last night was around 12 F, tonight is our coldest night, supposed to be -4

I love my rocket mass heater, but a lot of the claims around it seem pretty unrealistic to me.  I have no doubt that Paul’s are super awesome because he’s built tons of them, trialed and errored and has them down to a science.

Most people are just going to build one. So I wouldn’t expect the absolute best results.  I used one for my sole heat one winter and burned 1.3 cords of wood.  My buddy at work used a wood stove all winter and burned 1.5 cords

Eric Hammond wrote:
Yesterday we got the house to around 76. The bench before bed was really hot 🥵 109-116 F. I measure 130 under a pillow. I think we stopped burning around 10 pm.  This morning it was about 63 by the bench and 60 at the other end of the room.

Okay wow, that’s a lot of heat in the bench! I wonder where it all goes.

Was your RMH built next to a outer wall? I might be thinking about someone elses build but I remember seeing windows up the wall.

I have been learning a lot about heat and RMHs lately and I remember reading somewhere that a lot of heat can conduct to the wall if there’s no air gap between the bench and the wall. Just a thought.