There are basically four ways to do storage:"BrownianHeatingTech"

[Sawyer]

I did not think of a Garn as a pressurized system until I saw this post. Is the pressure from the storage tank the pressure referred to?


[quote author="BrownianHeatingTech" date="1218953266"][quote author="WoodNotOil" date="1218952864"]Very well put! People can start second guessing themselves in reading posts here and think they have chosen the wrong method. I think the choice has a lot to do with the space the storage is going in and what skills and materials each person has available to them. The encouraging thing is that so many people on this forum are coming up with different methods that work![/quote]

Not to get too far afield, but there are basically four ways to do storage:

1. Pressurized - pumped
2. Pressurized - gravity (we'll include the Garn system in here, since it's an odd duck)
3. Atmospheric - immersed heat exchanger
4. Atmospheric - external heat exchanger

Each has a place, and each has benefits and drawbacks.

Joe[/quote]

 

[BrownianHeatingTech]

I did not think of a Garn as a pressurized system until I saw this post. Is the pressure from the storage tank the pressure referred to?

No, I was just sticking it in a category, since it could go in either the "pressurized, gravity," or the "atmospheric with external heat exchanger" category, depending upon the installation.

For example, if you put a Garn in a shed next to your two-story house, you would need an external heat exchanger to operate the upstairs zone. Assuming that your first-floor piping and basement zone were located fully below the water line of the Garn, you could install them without heat exchangers, as if the Garn were pressurized (albeit, it's only pressurized with the height of water column from the top surface to the bottom).

I just didn't feel like creating a fifth category for a potential hybrid system like that...

Joe

 

[Sawyer]

Thanks Joe, I nderstand. Now I can move on with my schematic and not worry about changes due to this thought.

 

[atlarge54]

What about pure thermal mass? I'm going into my fourth winter and things get better every year. What I sacrifice in rapid response I gain in ease of temp. control. My OWB must weigh 3000 to 4000 pounds (filled with pea gravel & 300' of copper) plus the weight of all the floor joists and two layers of flooring. Outdoor temps can swing 25-30 deg. F and I'm lucky to see indoor temps move from 68 to 71 deg F. This is with 800' of 1/2" pex and a 1200 sq. ft. home. When temps really dip a water to air HX and fan pick up the slack. With temps in the 20's and 30's the "boiler" calls for heat about 20 min. every 2 hrs. If you have a modest home I'd recommend looking for an OWB that has had a water jacket failure. I paid $300 for mine and have under $3000 in my entire system.

 

[BrownianHeatingTech]

What about pure thermal mass? I'm going into my fourth winter and things get better every year. What I sacrifice in rapid response I gain in ease of temp. control. My OWB must weigh 3000 to 4000 pounds (filled with pea gravel & 300' of copper) plus the weight of all the floor joists and two layers of flooring. Outdoor temps can swing 25-30 deg. F and I'm lucky to see indoor temps move from 68 to 71 deg F. This is with 800' of 1/2" pex and a 1200 sq. ft. home. When temps really dip a water to air HX and fan pick up the slack. With temps in the 20's and 30's the "boiler" calls for heat about 20 min. every 2 hrs. If you have a modest home I'd recommend looking for an OWB that has had a water jacket failure. I paid $300 for mine and have under $3000 in my entire system.

"Mass" isn't relevant. Energy storage is. A few gallons of water store more energy than many pounds of gravel.

Joe

 

[atlarge54]

What about pure thermal mass? I'm going into my fourth winter and things get better every year. What I sacrifice in rapid response I gain in ease of temp. control. My OWB must weigh 3000 to 4000 pounds (filled with pea gravel & 300' of copper) plus the weight of all the floor joists and two layers of flooring. Outdoor temps can swing 25-30 deg. F and I'm lucky to see indoor temps move from 68 to 71 deg F. This is with 800' of 1/2" pex and a 1200 sq. ft. home. When temps really dip a water to air HX and fan pick up the slack. With temps in the 20's and 30's the "boiler" calls for heat about 20 min. every 2 hrs. If you have a modest home I'd recommend looking for an OWB that has had a water jacket failure. I paid $300 for mine and have under $3000 in my entire system.

"Mass" isn't relevant. Energy storage is. A few gallons of water store more energy than many pounds of gravel.

Joe

Brownie you've no doubt forgotten more about HVAC than I'll ever know, but........ There is little doubt in my mind that a large "thermal mass" inside the insulated envelope of a structure will go a long long way to both increasing the comfort and decreasing the size of heat storage required. The cost, size and complexity of some of the systems described at the boiler room are just unbelievable to me. In my mind anyone starting from scratch would be foolish to overlook this in their design. JMVHO

 

[BrownianHeatingTech]

There is little doubt in my mind that a large "thermal mass" inside the insulated envelope of a structure will go a long long way to both increasing the comfort and decreasing the size of heat storage required. The cost, size and complexity of some of the systems described at the boiler room are just unbelievable to me. In my mind anyone starting from scratch would be foolish to overlook this in their design. JMVHO

Having a large thermal mass, will. But thermal mass relates to energy storage, not "weight."

It takes a lot of concrete to offset a small amount of water.

This goes double when we're talking building materials, so the temperature swing is small. Let's just compare apples to apples, and pretend that we're using the same material for building and for mass in our storage tank. Our floor can't swing more than (for example) five degrees, without causing discomfort to the occupants. Our tank can swing maybe 100 degrees (for example). That means that every "unit" of material is 20 times more effective, if it's in the tank instead of the floor.

Now, we factor in that concrete (for example) is many times lower on the specific heat capacity than water, and you need an awful lot of concrete floor to store the same heat as a small amount of water.

You will certainly get some effect from "heavy" construction. But the amount of water to get the same effect is much lighter (weight-wise), and much smaller (volume-wise).

Joe

 

[pybyr]

There is little doubt in my mind that a large "thermal mass" inside the insulated envelope of a structure will go a long long way to both increasing the comfort and decreasing the size of heat storage required. The cost, size and complexity of some of the systems described at the boiler room are just unbelievable to me. In my mind anyone starting from scratch would be foolish to overlook this in their design. JMVHO

Having a large thermal mass, will. But thermal mass relates to energy storage, not "weight."

It takes a lot of concrete to offset a small amount of water.

This goes double when we're talking building materials, so the temperature swing is small. Let's just compare apples to apples, and pretend that we're using the same material for building and for mass in our storage tank. Our floor can't swing more than (for example) five degrees, without causing discomfort to the occupants. Our tank can swing maybe 100 degrees (for example). That means that every "unit" of material is 20 times more effective, if it's in the tank instead of the floor.

Now, we factor in that concrete (for example) is many times lower on the specific heat capacity than water, and you need an awful lot of concrete floor to store the same heat as a small amount of water.

You will certainly get some effect from "heavy" construction. But the amount of water to get the same effect is much lighter (weight-wise), and much smaller (volume-wise).

Joe

so assuming that one was building a structure from scratch and wanted the ultimate in both efficiency/effectiveness and simplicity, you'd build a really good masonry heater that also incorporated some chambers for water thermal storage, or even better, chambers for something that does phase change storage at an optimum temperature?

 

[BrownianHeatingTech]

so assuming that one was building a structure from scratch and wanted the ultimate in both efficiency/effectiveness and simplicity, you'd build a really good masonry heater that also incorporated some chambers for water thermal storage, or even better, chambers for something that does phase change storage at an optimum temperature?

Well, combustion efficiency on a masonry heater isn't going to be as high as a gasification boiler. And pricing (if you hire it out) would, I assume, not be all that much less.

Incorporating space for water tanks sounds like a good idea to me, though! I'm working on a system for a customer who planned for wood heat, and included both space for water tanks, and wood storage: the 2-car garage is actually on a suspended slab, and there is a hatchway in the garage floor leading to the basement underneath, where they will store their wood. Just dump the wood through the hatch, and it's into the storage room. There's a ramp from the garage basement into the house basement, so they can winch carts of wood right into the boiler room.

Joe

 

[Nofossil]

I've seen designs for 'water walls' - essentially huge vertical pipes (think culvert sections) filled with water behind a glass wall on the south side of a house. Heat them with the sun during the day, and get heat back during the night. You'd want thermal shutters to control heat flow, maybe.

 

[atlarge54]

Mr. Brown would you care to share any info. on your heating and cooling system? Any solar involved? I look at some of the homes (mortgages) built around here lately and can't believe the total lack of concern for energy consumption. The focus seems to be on pretty pretty pretty not sane and sensible. Do you know of any websites that look at homes designed with energy consumption as their main priority?

 

[BrownianHeatingTech]

I've seen designs for 'water walls' - essentially huge vertical pipes (think culvert sections) filled with water behind a glass wall on the south side of a house. Heat them with the sun during the day, and get heat back during the night. You'd want thermal shutters to control heat flow, maybe.

Yup. Best way I've seen to do this is to build a sun porch, and have the water tanks against the back (ie, the wall shared with the house, not the glass wall). The entire sun porch becomes a greenhouse, and heats the water tanks. Vents between the sun porch and the house open at night to draw heat into the house when it's cool, or pumps can utilize the water with radiant floors/panels. The roof of the sun porch is installed so that summer sun misses the water tanks, but winter sun hits them.

You can also use them as an accessory to a solar thermal collector - size the collector for winter conditions, knowing that it will overheat your storage tank during the summer. Then install a heat exchanger so that the water tanks in the sun porch become a giant dump zone in the afternoon, when the solar storage tank wants to overheat.

I've seen it done with tanks in the floor, as well. Or with a combination, using piping in the floor to capture the heat (due to the location where sun will hit it), and gravity convection into the large tanks. Heck, I've heard of folks using that sort of system with patios, driveways, and the like. Capture the energy for several clear days, then use it to assist a snowmelt system during the stormy days!

Joe

 

[BrownianHeatingTech]

Mr. Brown would you care to share any info. on your heating and cooling system? Any solar involved? I look at some of the homes (mortgages) built around here lately and can't believe the total lack of concern for energy consumption. The focus seems to be on pretty pretty pretty not sane and sensible. Do you know of any websites that look at homes designed with energy consumption as their main priority?

We bought this house recently, so I haven't torn the existing system out (beat up old forced-air), yet. The eventual system is going to be fairly crazy, because I'm what they call a "boiler geek." 95% certain I'll be using a Fröling boiler, with two or three 305-gallon pressurized storage tanks. The boiler is actually going in my sun porch (living space), because it's quieter than a dishwasher, so why not?

Of course, there will be plans for some additional boilers, in the future, because I like to tinker. Looking at a design that can use switchgrass pellets, if we can get them burning cleanly enough. I'd love to have a biomass backup for the wood boiler, rather than using oil or propane.

The sun porch is also getting an indoor wood hot tub, with a heat exchanger off the boiler. The south-west roof of the attached barn will eventually be covered almost entirely with evacuated-tube solar collectors, tied into the heating system using several large "sidearm"-type heat exchangers.

We'll be converting most of the house over to in-floor radiant, and the others will get panel radiators.

Cooling will be with geothermal. Not sure if I'll be using a heat pump, or if the sizing (radiant, plus in-duct coil) will allow for ground loops to be used, directly. Thinking maybe something using a pair of large cisterns - pump water from one, through the heat exchanger, to the other, where it can cool back down overnight. Need to do some insulation and radiant barriers before we can get the cooling load down to the level where that can possibly work.

Putting up greenhouses in a few years more, and they'll be far enough from the house to get their own system - probably a Garn.

I know I've seen some websites that sell "green" homes, specifically. Can't remember them, off the top of my head. There are also some building contractors that specialize in this sort of thing, but they are few and far between. Probably 90% of those advertising "green ______" are anything but...

Joe

 

[Willman]

95% certain I’ll be using Fröling boiler,

Joe, Do you know if the dual fuel ( pellet/round wood) Froling boilers are coming to the USA ?
Will

 

[BrownianHeatingTech]

Joe, Do you know if the dual fuel ( pellet/round wood) Froling boilers are coming to the USA ?

The pellet boilers will be here this spring, in all likelihood. They aren't really "dual fuel," though - the ability to burn round wood is purely an emergency backup measure, not something that can be done on a regular basis. I'm not sure whether they will even be importing the grates that let you do it.

Joe