Post by kymetro on Nov 1, 2023 9:05:10 GMT -8
Hi folks,
I've been studying masonry heaters, particularly Peter's designs. I want to build one to heat our new house, which is still in the planning phase. About 2/3 of the house will be within range of the heater, but I'm worried that the back bedrooms will get little or no heat from the mass. Additionally, we will have a full basement and so I'd like to install radiant PEX tubing in the slab to keep it warmer down there. I therefore need to incorporate some hydronic heating within the masonry. There are a few designs I will reference here:
A shop heated by a hydronic masonry heater, No storage tank, just the slab itself. He notes that a significant amount of heat comes off the masonry itself (desirable in my use case): heatkit.com/html/lopezs.htm
I want to use a DSR2, for the black oven element and its compact nature. It appears to be an excellent design. Reference here: batchrocket.eu/en/designs#dsr
And my plan is for a dead end bench to one side, based on this design: www.mha-net.org/docs/v8n2/wildac15f.htm
The novel element in my design is the storage tank. I haven't seen anyone put that inside a bell. I would like some feedback from folks here, you have a very keen sense of thermodynamics and ideal smoke paths. Will this work and what are the pitfalls?
Please note this is not to scale. Bells may be too large/small and the core is just a rough mockup. I'm validating the concept first of all, if it's worth pursuing I'll refine the dimensions.
The small two-chamber unit in the center is the DSR2 core. Hot gases exit the top front slot, into the first bell. Gases circulate in the bell, giving up heat to the top masonry first, as they cool they will fall to the bottom near the rear exit. The water heat exchanger is in this section to pick up the most heat, yet be outside the combustion area and so not influence the burn at all. This exchanger is plumbed in as a thermosyphon to the storage tank above it.
Cooler gases reaching the bottom will flow through the rear gap and up behind the first bell into the second larger bell. It contains a large uninsulated water storage tank. Gases will transfer heat to the masonry first, then to the tank - but only if the water is cold. When the water is warm, it will not absorb heat, but won’t lose any either. If the water becomes too hot, it should begin to shed heat to the masonry. I will of course have safety valves etc. This water will then circulate out to the radiant flooring system.
The gas continues down the side of the second bell, into the bench. Flow once again has reduced, increasing residence time. It is a dead end, meaning gases will flow in the top left, cool, then back out the bottom left. The bench should get warm but not too hot to sit on. Gases once cooled enough will drop to the bottom, to exit via a slot near the base. This concept was proven by the MHA double bench build linked above.
Behind the stove, you can see the slot admits gasses into a manifold, which goes to the final flue pipe. You can also see a bypass valve, which connects back to the first bell. This should improve cold starts if necessary, by shortening the path and drawing directly from the flue. This idea was taken from Peter's notes on the MHA double bench design.
Here’s the Sketchup model if anyone wants to get a better view (from Sketchup Web): drive.google.com/file/d/17nurPFCjFnXPbQgltkK7eGLX-u7YQNHF/view?usp=sharing
I greatly appreciate any feedback you can provide. I'm new to masonry stoves but not to burning wood or DIY engineering. Thanks in advance!
I've been studying masonry heaters, particularly Peter's designs. I want to build one to heat our new house, which is still in the planning phase. About 2/3 of the house will be within range of the heater, but I'm worried that the back bedrooms will get little or no heat from the mass. Additionally, we will have a full basement and so I'd like to install radiant PEX tubing in the slab to keep it warmer down there. I therefore need to incorporate some hydronic heating within the masonry. There are a few designs I will reference here:
A shop heated by a hydronic masonry heater, No storage tank, just the slab itself. He notes that a significant amount of heat comes off the masonry itself (desirable in my use case): heatkit.com/html/lopezs.htm
I want to use a DSR2, for the black oven element and its compact nature. It appears to be an excellent design. Reference here: batchrocket.eu/en/designs#dsr
And my plan is for a dead end bench to one side, based on this design: www.mha-net.org/docs/v8n2/wildac15f.htm
The novel element in my design is the storage tank. I haven't seen anyone put that inside a bell. I would like some feedback from folks here, you have a very keen sense of thermodynamics and ideal smoke paths. Will this work and what are the pitfalls?
Please note this is not to scale. Bells may be too large/small and the core is just a rough mockup. I'm validating the concept first of all, if it's worth pursuing I'll refine the dimensions.
The small two-chamber unit in the center is the DSR2 core. Hot gases exit the top front slot, into the first bell. Gases circulate in the bell, giving up heat to the top masonry first, as they cool they will fall to the bottom near the rear exit. The water heat exchanger is in this section to pick up the most heat, yet be outside the combustion area and so not influence the burn at all. This exchanger is plumbed in as a thermosyphon to the storage tank above it.
Cooler gases reaching the bottom will flow through the rear gap and up behind the first bell into the second larger bell. It contains a large uninsulated water storage tank. Gases will transfer heat to the masonry first, then to the tank - but only if the water is cold. When the water is warm, it will not absorb heat, but won’t lose any either. If the water becomes too hot, it should begin to shed heat to the masonry. I will of course have safety valves etc. This water will then circulate out to the radiant flooring system.
The gas continues down the side of the second bell, into the bench. Flow once again has reduced, increasing residence time. It is a dead end, meaning gases will flow in the top left, cool, then back out the bottom left. The bench should get warm but not too hot to sit on. Gases once cooled enough will drop to the bottom, to exit via a slot near the base. This concept was proven by the MHA double bench build linked above.
Behind the stove, you can see the slot admits gasses into a manifold, which goes to the final flue pipe. You can also see a bypass valve, which connects back to the first bell. This should improve cold starts if necessary, by shortening the path and drawing directly from the flue. This idea was taken from Peter's notes on the MHA double bench design.
Here’s the Sketchup model if anyone wants to get a better view (from Sketchup Web): drive.google.com/file/d/17nurPFCjFnXPbQgltkK7eGLX-u7YQNHF/view?usp=sharing
I greatly appreciate any feedback you can provide. I'm new to masonry stoves but not to burning wood or DIY engineering. Thanks in advance!
