Comparing Heat Pumps and the Rocket Mass Heater.. And an apple poll about heat!

The heating system in our house includes a masonry heater, a mini split and the electric radiators we have in some of the rooms. We mainly heat with wood, but when it gets really cold (like now!) we have to turn the radiators on.

Paul just published a new video about the comparison between a heat pumps and the rocket mass heater:



Paul makes a good point in the video about the best option being having both of them, the heat pump and a Rocket Mass Heater.
Our mini split gets rarely used. In fact, we have not used it for the whole winter. At the moment the outer unit is basicly frozen and snowed in so even if we wanted to use it we would not be able to.. Oh well, we cannot leave the house empty anyways, we have a cat, so there's always someone around heating with wood. The electric radiators would end up costing a lot as the only source of heat.

The video was born from the Heat Infographic Paul, Uncle Mud and Andrés made last year. Super useful and pretty!

I feel like doing an apple poll about heating systems.. So here it goes!




PS. Does anyone know where the word "mini split" comes from??

Oil boiler but it is pretty much the same category as a furnace.

Timothy Norton wrote:Oil boiler but it is pretty much the same category as a furnace.

Oh oil, I totally forgot that one. I will add it so your apple can go to the right basket!

Oh by the way, your apple polls inspired me to do this one.

I'm so happy to hear! I like polls and seeing how everyone differs. I think people appreciate being able to share (At least I do).

Saana Jalimauchi wrote:

Timothy Norton wrote:Oil boiler but it is pretty much the same category as a furnace.

Oh oil, I totally forgot that one. I will add it so your apple can go to the right basket!

Oh by the way, your apple polls inspired me to do this one.

Haha, does it show that I don't really know the terminology?? Okay central oil furnace is now central oil boiler. Or does it have the central in it??

Actually, it should be both as options if you want to be picky.

Oil boiler and oil furnace are two used but different systems.

Oil boiler goes to hot water or steam baseboard to radiate heat.

Oil furnace sends hot air.

Timothy Norton wrote:Actually, it should be both as options if you want to be picky.

Oil boiler and oil furnace are two used but different systems.

Oil boiler goes to hot water or steam baseboard to radiate heat.

Oil furnace sends hot air.

Thank you Timothy! As always, hanging out at Permies.com means learning new things!

Unfortunately the impractical design of my current "modern" house locks me into a centralized forced air system.

I would love to be able to tie in an outdoor wood furnace to reduce my gas consumption -- maybe employing mass to deliver an even temperature over time.

Douglas, I am in the same boat.

So far I've concluded that an outdoor solid fuel fired boiler with indoor mass, in the form of buffer tanks(s) is what might work for me.
To distribute the heat, an water to air heat exchanger in the return air duct should work automatically as the thermostat calls for heat.

I am enamored of water centered space heating.
Water it is both a storage and a transportation medium, and it can accept many different inputs, for example, a dump load from a solar pv array.

I am sad as I can't vote.

None of the options fit our house.

Am I the only person with a propane space heater for the living area and an electric space heater for the bedroom?

I came here to comment about the inground heat pump.

I never thought of a heat pump as something in the ground.  Wish I had learned about the years ago.

An inground heat pump is the next best heater the RMH being first.

Anne Miller wrote:I am sad as I can't vote.

None of the options fit our house.

Am I the only person with a propane space heater for the living area and an electric space heater for the bedroom?

Oh Anne, of course I will add an option for you so you can vote too! Maybe "space heaters"?

Douglas Alpenstock wrote:Unfortunately the impractical design of my current "modern" house locks me into a centralized forced air system.

I think that this means I have to add "centralized forced air system" to the poll too..? Yes? Is that the.. Name of the system?

Indeed, learning a lot. I know nothing!

Space heater would be great, thanks.

Saana Jalimauchi wrote:

Douglas Alpenstock wrote:Unfortunately the impractical design of my current "modern" house locks me into a centralized forced air system.

I think that this means I have to add "centralized forced air system" to the poll too..?

No need, that's just a reference to my natural gas furnace. They all have powerful blowers that move heat from a central location to the rest of the house.

You could add "natural gas/propane fireplace/heater" instead, since they typically heat one room instead of a whole house. I have a NG fireplace for our sitting room and it saves a lot of money/emissions in the shoulder seasons, compared to starting up the furnace beast in the basement.

Saana Jalimauchi wrote:Paul makes a good point in the video about the best option being having both of them, the heat pump and a Rocket Mass Heater.  Our mini split gets rarely used. In fact, we have not used it for the whole winter. At the moment the outer unit is basicly frozen and snowed in so even if we wanted to use it we would not be able to.. Oh well, we cannot leave the house empty anyways, we have a cat, so there's always someone around heating with wood. The electric radiators would end up costing a lot as the only source of heat.

I am actually surprised by your logic.  When I first designed my home, I had planned to install a mini split system plus a woodstove as a backup.  I later dropped the mini split entirely as redundant, for huge cost savings.  Perhaps if I were in a more seriously cold climate I might reconsider.  But the thing is, a wood stove is something one burns "when the mood strikes you," to paraphrase Paul in the video.  Not so with an RMH, which is most practical to run continuously during at least the coldest stretches of the heating season.

Understand that when I say "run continuously," I don't mean that you would burn a fire 24/7, but rather that you would burn a fire before the mass completely cools from the last fire.  However, while I once helped to build one, I've never actually lived with an RMH.  Is my presumption correct?

Saana Jalimauchi wrote:PS. Does anyone know where the word "mini split" comes from??

My understanding is this...  A regular air source heat pump has an outside compressor/fan unit that produces hot or cold refrigerant. That refrigerant is pumped inside to a central heat exchanger/air handler.  This inside unit distributes the heated or cooled air throughout the house via ducts.  Whereas, in a mini split heat pump, the function of the central heat exchanger/air handler is split throughout the house by pumping refrigerant to multiple miniature heat exchangers/air handlers, one for each room.

Anne Miller wrote:I am sad as I can't vote.

None of the options fit our house.

Am I the only person with a propane space heater for the living area and an electric space heater for the bedroom?

I came here to comment about the inground heat pump.

I never thought of a heat pump as something in the ground.  Wish I had learned about the years ago.

An inground heat pump is the next best heater the RMH being first.

When living in a trailer, I took everything propane out. The possiblity of leakage concerned me and the price of refilling is outrageous where I live. I had to use compressed oil heaters during the winter. It kept it in the upper 60’s during the day. In the morning, I turned on the hot plate on my way to the bathroom. By the time I washed up, it was toasty, but not hot and the fire was perfect for making breakfast.

gir bot wrote:Last vote in apple poll was on August 22, 2024

By golly, that’s today! I vote rocket mass heater.

Anni Miller said:
I am sad as I can't vote.

None of the options fit our house.

Am I the only person with a propane space heater for the living area and an electric space heater for the bedroom?

I came here to comment about the inground heat pump.

I never thought of a heat pump as something in the ground.  Wish I had learned about the years ago.

An inground heat pump is the next best heater the RMH being first.

But the best is what I found, look up Hydrothermal instead of Geothermal heat pumps. As many others said the use of water to store or transport energy is much more efficient than any dirt. Thanks for the thread.
SE Oklahoma

Last vote in apple poll was on August 23, 2024