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What would you do?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Jimxt88, Feb 19, 2008.

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  1. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    That you certainly don't need more than 140,000 btu. We can't know how much that boiler might be over-sized, but that sets a top bracket for how much heat your house is using.

    You'll need to find where the pipes go up to the second floor. That may be in the basement, but in an older house, it could easily happen inside the wall. Likewise, track down all the downstairs fixtures.

    Personally, I would buy "stop and waste" valves (a valve with one of those little drain caps). Install one on each of the first floor branches (again, after making certain that no second-floor fixtures are served by those same pipes). Then you can shut the water off, open the faucet, and remove the drain cap, letting the water drain out.

    If you have any low spots in the piping, you can install a drain there, as well, to let the water out.

    That takes care of the domestic. Next up is the drain piping.

    Use a wet/dry vacuum to pull the water out of the traps, and fill them with antifreeze. You don't need a lot of antifreeze - just enough to seal the trap so no sewer gasses back into the house. Make sure to flush the toilet first, to empty the tank, then vacuum out the trap and fill it. Splash a bit in the bottom of the tank, to protect the gaskets.

    Make sure to hit the shower trap, not just the sink traps (a lot of guys forget the shower trap). If you have a bathtub, the vacuum won't work because the overflow will let air in. You can try to seal the opening in the overflow so that the vacuum can pull the water out, but it's usually easier to just waste a bit of antifreeze and make sure that the trap water is well-diluted with it. That only works if you have 100% glycol - the pre-mixed stuff will be too weak if it is diluted at all.

    As far as the heating pipes, it may be best to simply fill the entire system with glycol, rather than trying to isolate the first floor. In order to do that, you will need to have a transfer pump with pretty decent capacity, and it's best to use 100% glycol (not the "RV and marine" or other pre-diluted stuff). Without seeing the actual piping, it would be hard to explain how to pump antifreeze into a heating system, properly. The simplest method is probably to shut off the water inlet, isolate the zones, then drain the boiler block itself. Use the transfer pump to fill the block with antifreeze. Then open the zones and hope you can purge the air from the system without wasting too much of the antifreeze.

    Joe

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  2. Jersey Bill

    Jersey Bill Member

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    As I mentioned before, you are looking for trouble if you freeze the downstairs apartment. Houses arent designed to do that. There is no insulation in the floor between the 2 units. This is where water pipes (probably also uninsulated) feed the 2nd floor fixtures. They are not designed to drain back when the water is shut off. Water in an OFF pipe will freeze in pockets and create holes which you will find when the water comes back on. If a live pipe freezes, it will turn into a gusher when it thaws.

    As for the boiler tag, It looks to me like you have a steam system. Jim, do you know the difference between circulating hot water and steam ? Does the boiler have a sight glass?
  3. Jimxt88

    Jimxt88 New Member

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    Joe, I didn't go. Because of the snow. We had a foot here in Mass where I am now. Just as well I. I'm going to look at this as a problem to be solved rather than an emergency. I hear what you are saying Bill, regarding the risk of disabling the downstairs and recognize I might make matters worse if I go at isolating the plumbing half cocked.

    The house is heated with radiant baseboard forced hot water and not steam. There is 3/4" copper pipe with fins all around the first and second floor. There are two zones, one up and one down each on its own thermostat with its own circulator. I don't know why the boiler says "Steam" and wonder if that could that be part of the problem? I don't know what "MBH" means on the boiler plate. and the H hight and L low difference, I wonder what that is?

    Right now I'm thinking, This summer I'll build a masonry heater in the cellar with integral hydronics. Yesterday I was determined to buy a GARN. But this masonry boiler is a beautiful heater - if I can build it so that it works the way I'm imagining. Building it myself I'll spend a lot less on it than even a regular gassifying, refractory, commercially-made stove and waterstorage tank. The EKO, Tarn, Greenfire and Greenwood all look like great stoves but I believe what I've been told by some people that these stoves need to be dumping into a storage tank to realize their full benefit.

    So I'm researching masonry heaters. I'm curious to know how stone rates as compared to water in its ability to absorb and give-up heat. I started to get into this with someone on another thread a few days ago and I was pretty well told that water is the best transfer medium for thermodynamics. I just can't help but wonder if that's the end of the story. When I think of a stainless steel tank full of steaming hot water sitting on the cold cellar floor all day as compared to a mountain of hot rocks on that same cold floor, I think that the hot rocks would hold their heat longer than the tank of water. Especially if the rocks are insulated layered with space between them one inside the other. I think that tank of steamng water would just cool off like a cup of coffee on a window sill in February in Maine.
  4. Eric Johnson

    Eric Johnson Mod Emeritus

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    On the steam vs. water question, my late '50s vintage cast iron Weil-McLain has a similar tag, in that both steam and water are listed. I gather that the older boiler vessels were designed to go either way. When I was thinking about buying the house, the real estate agent wasn't sophisticated enough (or too lazy) to realize it was an either/or situation, so the house was listed as being heated with both hw and steam. I scratched my head over that one until I got into the basement to see what was what.

    If you have hydronic baseboards, then obviously it's a hot water system.

    I don't know anything about masonry heaters, other than they're not really central heating appliances in the traditional sense. You can't pipe the heat to a remote location in the house, for example, or heat the garage or basement, or whatever, with a centrally-located masonry heater. But I hear they're a really nice way to heat the right space, which I suspect would be some sort of open floor plan. It's not going to work very well in an older house with a lot of walls and rooms.
  5. wdc1160

    wdc1160 New Member

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    Jim, I thought the expense of true masonary heaters are high 20G's +?
  6. Jimxt88

    Jimxt88 New Member

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    Eric, I found this article on masonry boiler besign for starters. The idea is to use the refractory like a water tank and circulate the radiant heating water supply through it using heat exchangers (not liquid to liquid) but radiant air to liquid heat exchange. Kind of like putting a pan of water in the oven to heat up.
  7. Jimxt88

    Jimxt88 New Member

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    That sounds about right, high 20s. But how much is a pallet of firebrick and a few bags of mortor. I'll use my 1974 pre-catalytic Vigilant as my fire box and some found steam radiators for heat exchangers. Of course the real art of the project will be piping air ducts for gasification, I mean, don't get me wrong, I know there's going to be a lot to it, but just now I believe I can manage it.
  8. Jimxt88

    Jimxt88 New Member

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  9. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    FYI, Baseboard is convective, not radiant.

    MBH means "mean btu's per hour." The actual btu capacity of water varies depending on temperature. A btu for 100-degree water is different than a btu for 200-degree water. MBH is an averaged rating which we use for hydronic heating systems. It also includes a multiplier of 1000, so "150 MBH" actually means "150,000."

    The H and L are ratings for two different nozzle sizes. Smith tests most of their boilers (then, and still) at multiple firing rates, so you can "officially" install it at a lower firing rate, to better match the heat demands of the building.

    The issue you will have is the heat output. Baseboard requires 180-degree water (approximately). The masonry heater is not going to realistically supply that sort of water temperature for an extended period.

    The tank isn't sitting on the cold floor. It's insulated. Think of it as a thermos bottle.

    Joe
  10. wdc1160

    wdc1160 New Member

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    Good point Joe. I have always heard people misuse the term. It occurs so often you forget its not correct. Sometime, I use the term radiant incorrectly, just so people will know what the heck I am talking about.
  11. Jimxt88

    Jimxt88 New Member

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    Thanks, Joe! That was fun to read. Alot of questions answered and explained. Thank you. Now, can you describe the difference between convection and radiant and there's a third form of heat too isn't there? Are the things I've always known as radiators really convectionators?
  12. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Baseboard is a convection system. Cool air hits the hot finned pipe, heating it and causing it to rise, which draws in more cool air. To do that requires a relatively-large temperature difference between the pipe and the air, in order to create efficient flow.

    Radiant works by heating a surface to slightly above the air temperature, causing it to radiate infrared energy, which directly heats the furnishings and occupants. As a result, it requires water only a bit above air temperature (supply is typically around 100 degrees on most radiant systems, which results in floor surface temperatures around 80 degrees).

    Radiators work on a combination of the two principles. Air near them is heated, causing convective flow. They also have a good bit of surface area to radiate heat. Running a small, hot radiator favors convection. Running a large, cool radiator favors radiation.

    The third sort is conduction, which is what happens when you grab the hot pipe and get heat transfer directly to your hand.

    The need for relatively-high water temperatures is why baseboard does not work as well with these systems.

    Joe
  13. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    It's further confused because there is radiant baseboard. It looks like molding, but has pipes embedded in it. The output isn't really all that high, compared to a whole floor, though.

    Joe
  14. Jimxt88

    Jimxt88 New Member

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    Joe, I came across this statement in an article on masonry boilers. It appeaers to be saying that the masonry mass can serve as the thermos you referred to for the hot water.

    7. Location of heat exchanging coils in multifunctional stoves and boilers outside of the firebox. Such placement maintains high combustion temperatures, thus enabling to use energy of the fuel in full.

    8. Heating of the thermal mass rather than the heat medium (water) in the boilers and multifunctional stoves. Mass of the thermal receiver can be heated 5.5 to 6 times better than water thus considerably increasing the accumulating capability of the system.

    What do you make of this? Alternately, how do you describe or design the thermos in the hot water storage systems you are familiar with?
  15. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    I'd be interested to see where they get this "5.5 to 6 times better than water" number. Sounds like it was invented, since fluids have dramatically better heat-loading properties than solids (due to convection within the fluid medium) and water has a dramatically better specific heat than most things out there.

    Take a large tank of water, and insulate it with foam insulation.

    nofossil has 880 gallons of water outside, under his deck in Vermont, and loses about one degree per day (I think I'm recalling the numbers accurately - hopefully, he will chime in if I didn't). If you put your tank in your basement, the loss will be smaller (less temperature difference between the water and the surrounding air), and any heat lost will percolate up into your house (provided you do a good job of insulating the bottom of the tank).

    Some tanks are pressurized (part of the system), and others are atmospheric, with coils immersed in them.

    Joe
  16. Jimxt88

    Jimxt88 New Member

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    Joe, Water boils at 212 degrees farenheit, far below the thermal absorption capacity of stone. So with heat output X from a hot burn, water (as liquid) can only absorb so much heat before turning into steam where stone will continue to absorb and hold heat. I am guessing that is what they are referring to.

    With equal volumes of water and stone as Y, total heat output X will in the end transfer more efficiently to stone than to water. Water heats up more quickly and is a better transfer medium up to the point that it changes into steam at which point for our purposes, (water storage tank systems) water is maxed out as a heat transfer medium.

    I can transfer more Btus into a firebrick than I can into the same volume of water (and have it remain water).
  17. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Yes, but that assumes an ideal transfer. In other words, transferring heat into microscopic pieces of brick suspended in the flue gas. Since brick doesn't flow like water, the larger you make the brick chunks, the more the inside of the brick is insulated by the outside of the brick. If you were going to heat it very slowly, it wouldn't matter, but trying to heat it during the course of a fire, time becomes a factor.

    Additionally, the hotter the brick's surface (the smaller the temperature difference between the flue gas and the surface of the brick), the slower the heat transfer. The outer surface of the brick will quickly heat, and thereby reduce the heat transfer efficiency. That's why firebricks are such a good insulator in stoves, protecting the steel firebox.

    And, of course, you also want to be able to extract the heat, as well. The same issues apply. Since the brick can't flow past your heat exchanger pipe, it can't transfer heat to it effectively. Only the bricks in direct contact with the pipe are going to dump real heat into the pipe. The further ones will have to heat the bricks near them, which will heat the bricks near them, etc... eventually heating the pipe, but no where near as fast as water which will form currents internally and flow past the pipe.

    Joe
  18. slowzuki

    slowzuki Feeling the Heat

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    It has been pretty well discussed that you need much more masonry or rock to store heat. Think of this, I can stand on beach sand heated to what 140 F in the sun and within minutes its cool enough to be comfortable. I can't dangle my feet into 140 F water and be ok, I would burn my feet and the local water temp would hardly change.
  19. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    I like that description. I think that explains it rather well.

    Even though there's a whole beach of sand, the heat doesn't flow well enough through it. That's why you can be cool in the shade, and burn your feet on the sand a few inches from the edge of the sunlight.

    Joe
  20. Jimxt88

    Jimxt88 New Member

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    I am thinking of a firebrick chamber containing a 250 gallon water storage tank, the tank serves as a heat cell for a coil of water which is part of a pressurized hydronic baseboard loop. The masonry shell containing the water storage tank is built into the exaughst system for the boiler which heats the bricks to X degrees as the fire gases pass through it.

    I know this is nothing less than a masonry boiler I am describing. This appears to be more efficient than an insulated metal water tank which is cooled as it circulates and while insulated not heated. In my system the inner coil both heats and then is heated by the water "fuel cell". The radiating firebrick (heated to seven or eight hundred degrees or more) keeps the water in the tank hot after the fire is gone out. I am able to take advantage of the thermal properties of firebrick, high temperatures and slow release, which will not boil the water in the tank. The heat loss from the inner circulating coil is less than if the entire contents of the tank were circulating and returning to an unheated tank. My storage tank would be smaller and occupy less space.

    I am dealing with baseboard level 3/4" copper pipe. I have learned from you it is necessary to maintain a water temperature of 180 degrees for baseboard to convect heat. I know that water boils at 212 degrees. That leaves me thirty degrees to play with, (180-210) and I want to stay within that thirtiy degree range for as long as possible, ideally, twnety-four hours. If I can slow the heat loss to one degree per hour, I can go from 210 to 180 in twenty-four hours. I am trying to come up with a system that can achieve that. Even the GARN, the work horse of water tank heat storage systems requires two charges per day in normally cold winter weather.

    My plan applies the properties of fire, water and stone to achieve and maintain a water temperature range for as long as possible from a single fire that will heat the air in the rooms of the house using the existing hydronic baseboard system.
  21. BrownianHeatingTech

    BrownianHeatingTech Minister of Fire

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    Almost. 180 is for "properly-sized" baseboard, at peak load. Your peak loading is probably calculated for -10 or -20 outdoor temp (so, call it 80 or 90 degrees colder outside than inside). When the difference between the indoor temp and the outdoor temp is half that, the btu requirements are half that. That doesn't halve the water temp, but it does reduce it dramatically.

    Additionally, depending on who did the installation, the baseboard might be significantly oversized. A lot of guys just guess at how much baseboard, and "play it safe" by installing too much. You need to do a heat loss calculation, and measure the existing baseboard, and then you can determine what water temp is needed to produce the required heat from the known length of baseboard. It might only be 160, or even 140. (140 is pretty much the minimum at which baseboard convects effectively).

    Without the actual numbers, we're just making wild guesses.

    Joe
  22. Nofossil

    Nofossil Moderator Emeritus

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    Interesting discussion. My $.02:

    First of all, stone / masonry is far from ideal for storing heat. The only exception I can think of is if you make it in the shape of your floor, so that it serves a structural purpose as well - much easier for most of us to walk on concrete rather than water.

    If you have a tank of water and fill it with stones (letting the water overflow), it will store LESS heat than if you stayed with straight water. Not intuitive, but true.

    If you have an extremely high temperature source, you MIGHT be able to store more heat in stone by raising it to a much higher temperature. However, it would be easier, cheaper, safer, and more effective to simply increase the amount of water and raise it to a lower temperature.

    I'll echo the comments about storage, convenience, and efficiency. In all but the most extreme cases, storage probably won't buy you much in the way of efficiency improvements. However, storage can absorb excess heat during boiler operation and supply heat when the boiler is out. I skipped two days in the last week, and the house temperature stayed within a 2 degree range the entire time. I have a window of many hours - often 12 or more - for when I build a fire. I lived without storage for a season, and the result is that either you idle a lot or the house temp fluctuates a lot. Idling for more than a small amount of time WILL affect your efficiency.

    This ties back to the whole conversation about baseboards vs. radiant and minimum useful temperatures. If I don't resort to heroic measures, I can get about 350,000 BTU of usable heat in my storage tank. I use the tank down to 120 degrees. At that temperature, the baseboards don't put out much heat at all. If it's cold outside they won't be able to keep up, so my effective storage capacity is less when I really need it most. I'm adding a radiant zone under the main floor to allow me to use the storage tank down to 100 degrees or so.
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