# What would you do?



## Jimxt88 (Feb 19, 2008)

Here's my situation.  Two family home in Central Maine.  Approximately 5,000 sq ft., 2,500 per floor.  Two chimney's, one unused the other used by an oil fired tankless boiler located in the full cellar, which is not used for living space.  Two single brick unlined chimneys.  The chimneys are in the middle of the house and about 20' apart.  The unused chimney doesn't have a flue in the basement.  The flue opening inside this chimney begins at the first story level of the house. The unused chimney has capacity for one six inch liner but not an eight inch liner when clearance from cumbustibles are taken into consideration.   Two zones, two thermostats, baseboard radiant heat.  One zone heats up stairs, where people are living and the second zone heats down stairs currently unoccupied but heated to 50 degrees to keep the pipes from freezing.   The domestic hot and cold water supply is not seperated, upstair from down stairs.  There is no propylene glycol in the radiant system.  I believe this is called a two zone, closed, pressurized, hydronic oil-fired system.  Correct me if I'm wrong.  The house is attached to a two and a half story barn with a dirt floor. The cellar has a dirt floor as well.

My goals is to heat the house independent of fossil fuels with the primary incentive of saving money.  One possibility I am considering is  to seperate the two floors making them thermally independent with the option of shutting one floor down completely while heating the other with wood, pellets, or other biomas.  This would require buying and installing two boilers.  I am also considering a water storage tank charged by a high energy short burst boiler.   It may be more economical to retain the current plumbing arrangement and install one monster boiler in the barn with an underground hot water transfer storage tank that can hold a charge for 24 hours and requires less attendance. I am open to all suggestions including designer referrals.  

What do you recommend?


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## wdc1160 (Feb 19, 2008)

1.  Does fossil fuel independent mean "home grown" electric for the pumps too?
2.  Do a heat analysis.  I have learned a ton from it.  You wouldn't believe what you'll learn  heatinghelp.com
3.  Do you have access to wood??


> I believe this is called a two zone, closed, pressurized, hydronic oil-fired system.  Correct me if I’m wrong.  The house is attached to a two and a half story barn with a dirt floor. The cellar has a dirt floor as well.


  4. Saying closed and pressurized is redundant, but no big deal.
5. why would you need two boilers?
6.  Why is there "Monster" demand heat for 5000 ft of house?


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## Jimxt88 (Feb 19, 2008)

1.  I have not taken electricity into consideration.  My electric bills are not what's killing me.
2.  I have not done a heat analysis, but I will.
3.  I have access to wood.

4.  Thank you for the correction: pressurized and closed is redundant.  But is open and nonpressurized?  Gravity?  Please explain this.
5.  Two boilers would serve to make each floor independent of the other.  The family living upstairs would be responsible for their own heat.
6.  One monster boiler would heat the entire house without seperating the floors.  I use the word monster to describe a boiler like the Garn or other boilers I have seen that use gassification and solid logs creting an enormous output of heat in a very short time.   This would only be efficient with a water storage tank to hold the otherwise dumped energy and use it to heat the house when the boiler is not breing fired.


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## Jersey Bill (Feb 19, 2008)

Jim,
you need to paint a better picture of your goals. It sounds like we are talking about an owner-occupied 2 family, and you are living on the 2nd floor. Separating the utilities to have the 1st floor tenants pay their own way is a good thing, but if you really want to heat the whole house with wood you would be better off to leave the system intact and put a wood fired boiler and a storage tank as you suggest. Probably outsite, or in your barn.
If you really want to separate utilities, tackle that problem first, then consider alternate fuel stratagies. for you and your tenant.

I dont think that you can do much with an unlined chimney that would take a 6" vent max. Maybe a direct vent pellet stove fireplace insert. I think they might be available with a 4" exhaust. If you have a local source for pellets and dont want to deal with cord stock, that might be an option.


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## Jimxt88 (Feb 19, 2008)

Bill,

Heating the whole house with wood is primary to having the tenants pay their own way.  So, weather I seperate the plumbing or not, My main goal is to heat both parts of the house with wood, even if it means some of the heat would be used to keep the pipes in an empty apartment from freezing.  If the plumbing were seperated, I could pump the downstairs with glycol and not worry about the tenants.  One day, I hope to have the entire house occupied year round.  Right now the tenant is upstairs and I am out of town.  So it is my apartment that is unoccupied and heated at fifty degrees to keep the pipes from freezing.  When I got into this I had no idea the rent, $300/mo which included heat would pay for less than half the cost to heat the house per month with oil. 

I am inclined to go with the wood fired boiler and storage tank in the cellar of the barn and leave seperating the two floors for later, if ever.  Wood is plentiful and cheap here, so I'm told though I've never bought any.  I had a few dead poplars felled, and split and they are stacked in the barn right now.  I think you're right that the barn would be a good place for a boiler and storage tank.  The cellar of the barn is accessible to a vehicle for deliveirng the boiler, parts and unsplit logs.  Because the floor is dirt, I can dig a hole for a water storage tank.   

If I buy two wood pellet boilers from Harmon, put one up stairs for the tenants and one in the cellar for the first floor, I will still have to seperate the plumbing and use electric heat tapes to keep the pipes that pass through the down stairs from freezing up.

I see you have a two hundred gallon storage tank and are upsizing to 1,200.  Why is that?


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## BrownianHeatingTech (Feb 19, 2008)

Jimxt88 said:
			
		

> I see you have a two hundred gallon storage tank and are upsizing to 1,200.  Why is that?



I assume for longer run-time.  The storage tank is like a thermal "battery."  The larger the battery, the longer it takes to charge, but the longer it will run for, until the next "recharge."

An accurate heat loss will be important to designing a system like this.  Until then, do you know the output rating of the oil boiler (check the rating plate, and also check the service log to see if it mentions nozzle size, since sometimes techs change to a smaller nozzle)?  It may be significantly oversized (many are), but would at least give us a ballpark idea of your heat demands...

Evergreen Heat in Old Orchard has a pellet boiler and a wood boiler running in the shop.  I'd recommend giving him a call and chatting about your needs and what you hope to get from your system.  He's very good at talking people out of using wood... if he can't talk you out of it, then you're actually serious about doing this.  I like that policy.  He may also be able to recommend an installer in your area who can look your actual system over and give you a more accurate idea of what is involved in doing this conversion.

Joe


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## Jimxt88 (Feb 19, 2008)

I'm not at the house so can't check out the rating plate.  Why would a tech change to a smaller nozzle on the boiler and how would that affect the cost of running the boiler.  Likewise, would would be the affect of an oversized nozzle?  I will call Evergreen and have a talk with them.  There is no way of talking me into sticking with oil.  It is prohibitively expensive.  Thanks for the advice.


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## BrownianHeatingTech (Feb 19, 2008)

Jimxt88 said:
			
		

> I'm not at the house so can't check out the rating plate.  Why would a tech change to a smaller nozzle on the boiler and how would that affect the cost of running the boiler.  Likewise, would would be the affect of an oversized nozzle?  I will call Evergreen and have a talk with them.  There is no way of talking me into sticking with oil.  It is prohibitively expensive.  Thanks for the advice.



If a boiler is very oversized, it will run inefficiently.  Often, a smart tech will realize how oversized a boiler is, and (since he can't easily change the boiler) will install a smaller nozzle.  Within reason, a smaller nozzle in a larger boiler will be more efficient, in terms of combustion parameters.  Typically, after that, each subsequent tech will just replace the current nozzle with exactly what was in there, so the earlier tech's change usually ends up being preserved.

It sounds like you have a potential interest in pellets, and Mark (the guy at Evergreen) can give you a good comparison of wood versus pellets versus oil.

How many gallons of oil are you actually using per year?

Joe


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## Jimxt88 (Feb 19, 2008)

Since November 1st I have purchased 1,045 gal. of number 2 heating oil.  I probably have enough oil stored to make it through the end of March.  So, I'm guessing I'll average 220 gallons/mo. for the entire seven month heating season, October through the end of April.  Add another 300 gallons for the rest of the year and it brings me to about 260 gallons per month per year on average for this year.  Keep in mind the first floor of the house was maintained at 50 degrees all winter.  If it were occupied and heated at 65 degrees, the amount of oil consumed would have been much greater.  The short answer to your question: How many gallons sof oil are you actually using per year?  1,345, this year.  Next year when both floors are occupied, probably 1,800 gallons - just a guess.  At the current price of oil in my area that translates into $5,960!


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## BrownianHeatingTech (Feb 19, 2008)

Jimxt88 said:
			
		

> Since November 1st I have purchased 1,045 gal. of number 2 heating oil.  I probably have enough oil stored to make it through the end of March.  So, I'm guessing I'll average 220 gallons/mo. for the entire seven month heating season, October through the end of April.  Add another 300 gallons for the rest of the year and it brings me to about 260 gallons per month per year on average for this year.  Keep in mind the first floor of the house was maintained at 50 degrees all winter.  If it were occupied and heated at 65 degrees, the amount of oil consumed would have been much greater.  The short answer to your question: How many gallons sof oil are you actually using per year?  1,345, this year.  Next year when both floors are occupied, probably 1,800 gallons - just a guess.  At the current price of oil in my area that translates into $5,960!



Sounds like you could see a pretty realistic payoff with either wood or pellets.  There are plenty of other reasons to get away from oil, but it's nice when it also makes good economic sense...

Joe


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## heaterman (Feb 20, 2008)

Regarding a heat loss calc. A real benefit of an accurate heat loss in your case will be that you can accurately determine the percentage of the total load each floor provides. Use this as a hypothetical situation; assume the total heat loss for the structure is 100,000 BTU's. The heat loss may reveal that the bottom floor represents 45% of that total and the upper floor requires the remaining 55%. You now have concrete data which will enable you to split heating costs on a very fair basis.......all other things being equal. This can help you make an intelligent decision as to whether you really need 2 separate heat sources or a single larger one.


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## wdc1160 (Feb 20, 2008)

Jim,  Please post a heat calc.  They are very helpful here is mine.  this is 4200 sq ft in a ranch.  
Oddly, this calc also helped me with this CAD which helped me with a home wiring and construction prodject.


http://www.innovativesolutions.cc/boiler/images/heatloss.jpg


http://www.innovativesolutions.cc/boiler/images/housestuff/layout.jpg


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## Jimxt88 (Feb 20, 2008)

Thanks guys.  These are impressive calculations.  What is the factor for single-pane wooden double-hung windows with aluminum storms outside?/per sq. ft.  I'm not sure I understand how I can better calculate heat loss the differential heat loss between the two floors in the house using room height, and width, etc.  It seems the other variables are more determinitive.  For instance, that one floor is vacant most of the time and heated at 50 degrees or that the tenants crank up the heat to 80 and open the windows to let in fresh air (not that they do).


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## wdc1160 (Feb 20, 2008)

Jim,  



> What is the factor for single-pane wooden double-hung windows with aluminum storms outside?/per sq. ft.


goto heatinghelp.com they have software that give you a heat loss table and all the things that come with it.  It is really to hard to do in your head.  


> I have purchased 1,045 gal. of number 2 heating oil.


You know that is like 10 cords of wood, 15 if you start keeping the temperature at higher levels. (in a gasifier)


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## Jersey Bill (Feb 21, 2008)

For 2 layers of glazing, an average number is U=0.55.

I would not lower the temperature of the 1st floor apartment below 50. Most likely, the heat load on the 2nd floor apt was figured with the heat on below. Its not worth the risk of freezing pipes. 

Based on the ammount of energy being consumed, it seem to me that a full energy audit would be worthwile. How many degree days per year up by you Jim?


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## Jimxt88 (Feb 21, 2008)

1,045 gal of oil is equal to ten cords of wood?  I figure that's a ball park.  I mean if I had a gasifying boiler and buffer storage, i.e. 2,000 gallon water storage tank, do you think I'd need ten cords of wood?

What is a degree day?  I mean how do you calulate that.  I am in Piscataquis County, Maine.


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## wdc1160 (Feb 21, 2008)

Well, I think the concensus is that storage may not increase effciency (cause you to use less wood).  You can check about 500 posts on this site and still be in wonderment as to whether that is true.  I assume until I see a consensus that it isn't a fact.


I think that you will find that a 100 gal of heating oil can be replaced with 1 cord-- all things being equal.   Keep in mind you'll be a rookie with wet wood the first year.  


> What is a degree day?


http://en.wikipedia.org/wiki/Heating_degree_day


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## slowzuki (Feb 21, 2008)

The storage is two things, how often you want to have to add wood to the boiler and somewhat related to efficiency.  A massively oversized boiler will like storage.  Storage can let you go down a boiler size in some cases if you have enough storage but it doesn't really help efficency as much in that case.


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## Jimxt88 (Feb 21, 2008)

The house is big but not that big.  I mean, it's about 1,500 upstairs and 2,000 feet down for a total of (I'm guessing) 3,500 sq ft. with maybe 8 floot ceilings.


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## Jersey Bill (Feb 21, 2008)

in your area, my map shows 7200-9000 heating degree days per year.
based on your information on oil consumption, I backed into your design heat load which is 126,000 btu/hr, or 25 btu/sqft.
Thats high, but not crazy high considering how cold it is there.


I don't think that storage will increase efficiency by much, if at all.

From what I can think of, any increase would be in the system efficiency because the boiler is running long, so the startup losses are minimized. Also, the boiler is working at a lower water temperature so the heat exchanger will be working better to extract more energy from the flue gas.

This is offset by the storage losses. Nofossil claims 1 deg per day standing loss for his 880 gallon tank. Thats a loss of about 7 MBH per day, or about 1.4% per day loss.

The real benefit from a decent size storage tank is the human factor. Without storage a wood boiler would have to be tended every 2-3 hours, at least my wood boiler. This can be a pain in the neck when its cold and its nicer to be in bed sleeping through the night.
A storage tank would allow a normal person to come home from work, fire the boiler until bed time, then coast on the storage until morning. This is quality of life, not efficiency.


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## Jimxt88 (Feb 21, 2008)

7,200-9,000 heating degree days per year in Piscataquis, Maine.  With my oil consumption for this year I'm looking at 126,000 btu/hr, or 25 btu/sqft.  Jersey, Bill, can you define what you mean by efficiency when you say "I don't think that storage will increase efficiency by much, if at all."?  And "system efficiency", can you define that?

I've under stand combustion efficiency to mean how efficiently did you combust the wood in the first place, i.e., what percentage of the chemical energy that's locked up in that piece of wood was released as heat energy vs went up the chimney uncombusted?  That's the combustion efficiency.  Transfer efficiency is what percentage of that heat that you produced is then released in to the living space?  It seems from what you are telling me, correct me if I have misunderstood, is that storage won't directly improve my combustion efficiency or transfer efficiency but indirectly it could.  And that will be because I will be able to have hotter, cleaner burns and store the energy I can't use during the burn time for later, via my storage tank.  But it doesn't necessarily mean I'll be burnnig less wood.  But of course, importantly I will have less burden of tending the fire.  So storage means, cleaner emmissions, better combustion efficiency, good but probably not better transfer efficiencies, but definitely less fire tending burden.


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## Jersey Bill (Feb 21, 2008)

sorry, I meant "system " efficiency, not "storage" efficiency


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## wdc1160 (Feb 21, 2008)

Jim,  all of our deductions are great, but if you put in the work with a heatloss calc you'll likely not be disappointed.
It is entirely possible that your system is ineffcient and so we are overestimating your needs,  It would be nice to check estimates against a heat loss.


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## Jersey Bill (Feb 21, 2008)

Right, a formal heat loss calculation has to be done. Then this can be compaired to the "field" measured heat loss derived from energy consumption.
If they are close, you are OK. If not then you have to start looking for either an inaccuracy in the calculation, or, maybe a lack of insulation in the house, or a hole in the thermal envelope.
The ammount of money spent on energy could definately justify an energy audit on the house, including an infra red scan. I would not wait until next year. Get it done while its still winter.


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## Jimxt88 (Feb 22, 2008)

I found a photograph of my cellar and was able to zoom in and crop out the boiler plate.  I have put $2,838.00 US into this piggy bank since November 1, 2007 and I'm never going to see that change again.  Is there someone who could translate the numbers on the boiler plate?  What do they suggest as to the heating needs for the house when I transfer to a wood boiler?  Thank you.

I will take your advice Bill and get it done this winter.  I am not at the house now but will probably head up there today with my tape measure, ten gallons of glycol and a pipe cutter.  Wish me luck.  I will stick around till I hear back from someone regading his post.  Any advice on pumping propylene, anticrossive glycol into the system and isolating the downstairs fixture branches would be appreciated too.


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## BrownianHeatingTech (Feb 22, 2008)

Jimxt88 said:
			
		

> I found a photograph of my cellar and was able to zoom in and crop out the boiler plate.  I have put $2,838.00 US into this piggy bank since November 1, 2007 and I'm never going to see that change again.  Is there someone who could translate the numbers on the boiler plate?  What do they suggest as to the heating needs for the house when I transfer to a wood boiler?  Thank you.



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.



			
				Jimxt88 said:
			
		

> I will take your advice Bill and get it done this winter.  I am not at the house now but will probably head up there today with my tape measure, ten gallons of glycol and a pipe cutter.  Wish me luck.  I will stick around till I hear back from someone regading his post.  Any advice on pumping propylene, anticrossive glycol into the system and isolating the downstairs fixture branches would be appreciated too.



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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## Jersey Bill (Feb 22, 2008)

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?


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## Jimxt88 (Feb 23, 2008)

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.


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## Eric Johnson (Feb 23, 2008)

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.


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## wdc1160 (Feb 23, 2008)

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


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## Jimxt88 (Feb 23, 2008)

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.


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## Jimxt88 (Feb 23, 2008)

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.


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## Jimxt88 (Feb 23, 2008)

A paper on masonry boiler design with diagrams.  Almost comprehendable. http://www.stove.ru/index.php?lng=1&rs=109


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## BrownianHeatingTech (Feb 23, 2008)

Jimxt88 said:
			
		

> 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.



FYI, Baseboard is convective, not radiant.



			
				Jimxt88 said:
			
		

> I don't know what "MBH" means on the boiler plate.  and the H hight and L low difference, I wonder what that is?



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.



			
				Jimxt88 said:
			
		

> Right now I'm thinking, This summer I'll build a masonry heater in the cellar with integral hydronics.



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.



			
				Jimxt88 said:
			
		

> 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.



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

Joe


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## wdc1160 (Feb 23, 2008)

> > Jimxt88 - 23 February 2008 11:10 AM
> > 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.
> 
> 
> ...



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.


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## Jimxt88 (Feb 23, 2008)

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?


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## BrownianHeatingTech (Feb 23, 2008)

Jimxt88 said:
			
		

> 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?



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


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## BrownianHeatingTech (Feb 23, 2008)

ABGWD4U said:
			
		

> > FYI, Baseboard is convective, not radiant.
> 
> 
> 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.



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


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## Jimxt88 (Feb 24, 2008)

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?


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## BrownianHeatingTech (Feb 27, 2008)

Jimxt88 said:
			
		

> 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.



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.



			
				Jimxt88 said:
			
		

> Alternately, how do you describe or design the thermos in the hot water storage systems you are familiar with?



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


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## Jimxt88 (Feb 28, 2008)

Jimxt88 said:
			
		

> 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.





			
				BrownianHeatingTech said:
			
		

> [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.



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).


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## BrownianHeatingTech (Feb 29, 2008)

Jimxt88 said:
			
		

> 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).



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


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## slowzuki (Feb 29, 2008)

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.


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## BrownianHeatingTech (Feb 29, 2008)

slowzuki said:
			
		

> 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.



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


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## Jimxt88 (Mar 1, 2008)

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.


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## BrownianHeatingTech (Mar 1, 2008)

Jimxt88 said:
			
		

> 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.



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


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## Nofossil (Mar 1, 2008)

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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