Webinar: Heating Greenhouses using Rocket Mass Heaters with Uncle MUD

Will purchasing the webinar include a recording??

I am planning to build a greenhouse over an old swimming pool. I would like to heat it with wood heat so I am very interested in this webinar. Unfortunately, I will not be available to watch it. Is it possible to watch a recording of it later.

I have the old furnace out of the house that we replaced 10 years ago and thought about using it. But I think a rocket heater would be more efficient. How do you feed the rocket heater during the night or when you are away all day?   Thank you for all your information. Trying to get my ducks in a row before I start

Saralee Couchoud wrote:... How do you feed the rocket heater during the night or when you are away all day?   Thank you for all your information. Trying to get my ducks in a row before I start

The point of a rocket mass heater is to heat the thermal mass enough that it can "coast" for hours without keeping the stove fired constantly. I've built a lot of mass into the stone-filled bench made from patio slabs (that came with my house) and hope my new rocket stove will be able to warm it enough to at least keep the greenhouse above freezing (under a tented part) on the occasional -30 night without 1 AM stoking. Time will tell if it works as I hope.

I don't know how cold a climate Uncle Mud deals with, but I'm in eastern Ontario.

Emily Limaye wrote:Will purchasing the webinar include a recording??

We will more than likely have the recording available a few days after the webinar.

Sometimes this doesn't happen for various technical reasons outside of our control so I cannot guarantee a recording at this time.

I will be attending this webinar if at all possible as we have a greenhouse in need of a Rocket Mass Heater. It is built, from salvaged double pane windows and roofed with double panes from sliding patio doors, as a lean-to on the side of a high-cube shipping container and measures about 40' long by 12' wide by 11' high at the back. We keep it just frost-free and, this time of the year, it is always packed full of plants; tender plants, hardier plants which are still in pots awaiting planting out and salad crops, such as swiss chard and kale, also in pots.

There is no need to keep it warm, only to keep the frost out, with outside temperature in winter often above freezing during the day, with occasional lows of around  minus 20C. At the moment, I aim for a minimum of just 2C but wouldn't mind pushing that up to 5C. Heating is electrical for now. The shipping can is roofed over and the top and the weather-ward end are insulated. The other side forms the wall of a workshop (which I hope will soon have its own RMH) and, as the can contains large machine tools weighing many tons, it acts as a useful heat reservoir.

I want to avoid spikes in temperature while the greenhouse RMH is being fired, with as much heat as possible being stored, and I have recently been inspired by this Sand Battery https://www.bbc.com/future/article/20221102-how-a-sand-battery-could-transform-clean-energy, which contains 100 tonnes of sand, heated electrically to 600 degrees C and which stores 8 Mwh of heat energy, equivalent to 80 kwh/ tonne. Heat is extracted as required by fans and hot air ducts at a rate of 200 kw to feed district heating systems.

I am considering a long mass, low enough to fit under the staging, containing two sets of ducts: one for the hot gasses as per usual and the second for air to be driven in by a thermostatically controlled fan when the greenhouse needs more heating. The mass will be well insulated to retain stored heat the rest of the time. A temperature of 600C seems to me to be somewhat ambitious and maybe 300C is more realistic. Our soil contains no clay and is unsuitable for making cob so, for the mass, I am inclined to use pit run: a sandy mixture of everything from 3" rocks downwards, dug straight out of the terminal moraine of the local glacier and screened only to remove to larger rocks. It is cheap, heavy and packs down well and 5 tonnes of this should store about 200 kwh of heat, according to the above figures, which looks reasonable for an extraction rate to average about 5 kw,

I would be most interested in the views of those who know about these things as to whether this sounds feasible and what sort of storage temperature I could achieve. By the way, we have solar power with a large back-up battery bank, so I don't have to worry about losing power on some particularly cold night.

Emily Limaye wrote:Will purchasing the webinar include a recording??

If it is like the last webinar, the recording were available afterwards as an upgrade option.

Hey everyone. Mud here. I'm excited about Saturday's webinar.

Among the things we will cover:

Sizing a Greenhouse Rocket Mass Heater (Very Important!)

Storing the Heat (mass options)

Tips on how not to kill your plants

Fuel

Redundant heaters and why you should use them

Please keep your questions and comments coming. I will keep them in mind when I choose what to go over quickly and what to get deeper into. Greenhouses have some special circumstances that make them challenging but rewarding.

David Wieland wrote:

Saralee Couchoud wrote:... How do you feed the rocket heater during the night or when you are away all day?   Thank you for all your information. Trying to get my ducks in a row before I start

The point of a rocket mass heater is to heat the thermal mass enough that it can "coast" for hours without keeping the stove fired constantly. I've built a lot of mass into the stone-filled bench made from patio slabs (that came with my house) and hope my new rocket stove will be able to warm it enough to at least keep the greenhouse above freezing (under a tented part) on the occasional -30 night without 1 AM stoking. Time will tell if it works as I hope.

I don't know how cold a climate Uncle Mud deals with, but I'm in eastern Ontario.

I'm in Cleveland. Hello Neighbor!

  ~This sounds like a good way to utilize the dead wood i have in my forest?~Ive been looking at different greenhouse designs~It doesnt get severely cold here, usually the 30s, occassionally the teens~Id love to see a video on this, too?~

How are we to access this webinar? I presume a link will be posted somewhere?

As a backer of the Garden Master kickstarter at the $100 level, I thought I should either be seeing a way to access this webinar in 'my stuff' or else would have received a link...I don't see it either place. It's possible I was sent something and inadvertently deleted it in a recent email cleanup. Could this be sent (re-sent?) please? I'd really like to see this webinar, or at least the recording.

Hello everyone,
Due to several things happening at once I'm going to have to postpone. We will reschedule very soon. --Mud

That's alright with me....I totally thought it was next week anyway 😅

I'm sure there's a better place for this post than here but I don't know where that is. It does concern heating greenhouses over the winter, so here's the link: - https://www.cbc.ca/news/canada/british-columbia/british-columbians-subtropical-fruit-1.6689079
I'd love to be able to pick home grown avocados!

We had a cold spell for over a week and the lowest temperature was about minus12C. Our heaters still kept the greenhouse above freezing but with a large spike in electricity consumption, so I'm looking forward to having a Rocket Mass Heater in there!

Thanks for scheduling at an hour that works in my timezone (UTC+1)

Hey everyone. I'm looking forward to our webinar at 11am MST on January 14 2023. Don't forget to post your last minute questions here I will try to get to them.
--Mud

Saralee Couchoud wrote:I am planning to build a greenhouse over an old swimming pool. I would like to heat it with wood heat so I am very interested in this webinar. Unfortunately, I will not be available to watch it. Is it possible to watch a recording of it later.

I have the old furnace out of the house that we replaced 10 years ago and thought about using it. But I think a rocket heater would be more efficient. How do you feed the rocket heater during the night or when you are away all day?   Thank you for all your information. Trying to get my ducks in a row before I start

If your pool can still hold water, use it as a mass...I have ducts held in place with sandbags at the bottom of my pool, the duct has a fanned air intake at the high point of my green house, when it's hot, the air is blown into the ducted pool...I do have many sunny days in winter.

For the people that are going to be in the event today, can you see the zoom link in the first post?

paul wheaton wrote:For the people that are going to be in the event today, can you see the zoom link in the first post?

Indeed, and it works!

I do have one tiny question for the discussion;

Are there (or maybe be there is, and I just need to listen) be any needs for a Condensate trap, and/or is there a a potential to put one in to recover and use the water vapor from the heat stack. (Possibly other exhaust gases as well).

Thanks in advance.

I have purchased a 30 x 40 greenhouse.
Location i want to place is against a hill i have, so I might have to support the hill inside greenhouse by terracing 1 side inside greenhouse.

I am excited for this project, and think you may answer my questions during the zoom call.

Question.
The Cobb does not have strength or does it for a wall?

I'm thinking the heater should be inside greenhouse?
Or outside and pipe inside?

Many thanks to Uncle Mud & Paul & Christine & everyone else concerned for putting on this webinar. Most informative! I might need to build a test bed of some sort before I build the proper thing in the greenhouse.

If we are cooling the exhaust below about 150 degrees (f) at any point there is going to be liquid water in the exhaust . The water recovered will probably kill any plants you use it on just from the chemicals in the exhaust from the wood gasses.

Cob is plenty strong for a wall, just insulate the outside of it with light clay straw or plastered straw bale. I prefer to put the heater in a vestibule in case it backdrafts so it doesn't smoke out the plants.