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I believe coldjensen is making some misstatements about the relative heat trnasfer efficiency of copper & cast iron / baseboard fins vs old style radiators. Copper is far more efficient, and because of that efficiency can be assumed to result in a greater "delta" from the hot side to the return side. In a drafty old house that can be perceived as making the swings from hot to cold more pronounced, but that is not a fault of the copper, it is fault of the poor insulation. In fact if they do have a drowsy old house that lacks insulation they may want to investigate adding thermal mass to the areas above the copper tube/ Al finned baseboard units specificallynto moderate the swings in temp. I believe there are even some firms that sell soapstone specifically for this purpose...
At the end of the day / heating season it does not make much sense to spend big money on a high end heating plant if your home is poorly insulated.
If the OP can get the work done to improve the insulation and air sealing in their home that is priority NUMBER ONE. A ten year old boiler is probably at about 50% or less "used up" and I would really runnthe numbers about how much I would "save" in fuel cost before I would replace it.
I might also factor the relative costs of switching to hot water hydronic heat as being MUCH easier to integrate with solar and/ or geothermal BUT only after doing the costs...
I believe coldjensen is making some misstatements about the relative heat trnasfer efficiency of copper & cast iron / baseboard fins vs old style radiators. Copper is far more efficient, and because of that efficiency can be assumed to result in a greater "delta" from the hot side to the return side. In a drafty old house that can be perceived as making the swings from hot to cold more pronounced, but that is not a fault of the copper, it is fault of the poor insulation. In fact if they do have a drowsy old house that lacks insulation they may want to investigate adding thermal mass to the areas above the copper tube/ Al finned baseboard units specificallynto moderate the swings in temp. I believe there are even some firms that sell soapstone specifically for this purpose...
At the end of the day / heating season it does not make much sense to spend big money on a high end heating plant if your home is poorly insulated.
If the OP can get the work done to improve the insulation and air sealing in their home that is priority NUMBER ONE. A ten year old boiler is probably at about 50% or less "used up" and I would really runnthe numbers about how much I would "save" in fuel cost before I would replace it.
I might also factor the relative costs of switching to hot water hydronic heat as being MUCH easier to integrate with solar and/ or geothermal BUT only after doing the costs...
20 years, 10 was a typo. sorry.
the insulation and weather sealing will be done as part of this project. it's really a question of whether i am keeping current system, or converting to baseboard for the supposed higher efficiency gain. some i spoke to have said that the baseboard systems appear to run more often than the steam radiator system which stays hot longer. i don't really know. i know my gas bill goes from around $25 in the summer to about $400 in the winter. i could pull the exact numbers.
anyways, i'm not sure what hot water hydronic heat is, and if that's an option for this work.
I believe coldjensen is making some misstatements about the relative heat trnasfer efficiency of copper & cast iron / baseboard fins vs old style radiators. Copper is far more efficient, and because of that efficiency can be assumed to result in a greater "delta" from the hot side to the return side.
At the end of the day / heating season it does not make much sense to spend big money on a high end heating plant if your home is poorly insulated.
.
No copper baseboard radiators are not more efficient. Cast iron is. Do the research. We had some sales people tell us that copper was better becasue that is what they sell. We foudn some university studies and called some physics professors and learned that this is untrue. When we confronted the salespersons with the data, they suddenly changed their tune and tried to argue that copper baseboards look better and distribute heat more evenly. The first is opinion with which I disagree and the second is somewhat true, but really makes no difference. Radiated heat spreads from the source through walls, floors, furniture and is very even heat. Extensive Copper radiators can heat up the house more quickly, but at least for us, that is not really an issue. Once the heat is on for a few hours, it is warm and stays warm. Radiated heat does not heat up, cool off, heat up, cool off like forced air. It just stays warm. When the temps graudally and evenly drop, the system kicks back on and warms up the zone that has cooled and you never notice anything but steady comfortable heat. Notwithstanding poor insulation we do not get drafts, but we do get big bills and some walls/floors are cold to touch at times.
It does make sense if you are going to upgrade the insulation (or already contracted for it which we did, the insulation guy just turned out to be a crook and did not put insulation in some of the walls). Parts of the house are extremely well insulated (ICYNENE) however the parts that could not be accessed where they were supposed to blow in insulation had some completely empty walls or portions of walls. I found and filled some of them, some still need to be found and filled. It is hard to find them. An IR camera was not helpful.
No copper baseboard radiators are not more efficient. Cast iron is. Do the research. We had some sales people tell us that copper was better becasue that is what they sell. We foudn some university studies and called some physics professors and learned that this is untrue. When we confronted the salespersons with the data, they suddenly changed their tune and tried to argue that copper baseboards look better and distribute heat more evenly. The first is opinion with which I disagree and the second is somewhat true, but really makes no difference. Radiated heat spreads from the source through walls, floors, furniture and is very even heat. Extensive Copper radiators can heat up the house more quickly, but at least for us, that is not really an issue. Once the heat is on for a few hours, it is warm and stays warm. Radiated heat does not heat up, cool off, heat up, cool off like forced air. It just stays warm. When the temps graudally and evenly drop, the system kicks back on and warms up the zone that has cooled and you never notice anything but steady comfortable heat. Notwithstanding poor insulation we do not get drafts, but we do get big bills and some walls/floors are cold to touch at times.
It does make sense if you are going to upgrade the insulation (or already contracted for it which we did, the insulation guy just turned out to be a crook and did not put insulation in some of the walls). Parts of the house are extremely well insulated (ICYNENE) however the parts that could not be accessed where they were supposed to blow in insulation had some completely empty walls or portions of walls. I found and filled some of them, some still need to be found and filled. It is hard to find them. An IR camera was not helpful.
so do you vote to keep cast iron radiators over replacing with baseboard heaters?
The thermodynamic properties of a the "room end" of the swap are not the only thing one needs to consider. You can't change the fact that copper has a thermal conductivity of about 360 W/(mK) {Aluminum is about is about 220 W/mK, so very close and used in many low-end slant fin baseboard setups...} and cast iron is about 55 W/(mK). Of course the fluid that carries the heat is water which has a thermal conductivity of about 0.6 W/(mK) and air, which ultimatelly is how your skin feels the warmth from the heating plant, is down around 0.024 W/(mK). What any decent hydronic heating specialist would do is use the DATA from a test run of the heating plant to adjust the boiler run time AND the circulator pump to extract as much heat from from the WATER into the AIR of the home out of the hot water. The key is to size the circulator and hot water branches so that the slant fin (copper) radiators OR cast iron radiators are making up for the approx 6X better rate of thermal conductivity. In a well insulated house the ability to MAINTAIN comfort may require the circulator runs much longer with iron radiators. (It is important to realize that modern boilers, with low mass heat exchangers and forced draft condensing flue gas exhaust systems, are based on the idea that since the "combustion" is as efficient as theoretically possible on "room air" the only area for improvement is to shorten the whole burn time AND prevent as much heat from going "out the flue" as possible BUT the burner is OFF for most of the time the circulcator is running with cast iron radiators while it is running less time with slant fin /copper radiators...)
Additionally the "boiler end" of the system has to be considered too. In a theoretical sense the hotter the water that is delivered from the boiler to the radiators and the greater the delta in temperature the better total heat transfer per input of energy BUT it takes more input energy to heat the water to a higher temp SO the best heating plants have a little computer built in so it will calculate the OPTIMAL temperature to heat the water to BASED ON INDOOR TEMP, OUTDOOR TEMP, LEARNED TIME TO HEAT THE HOUSE to the asked for the temp and even the rate of heat loss / gain. In practice this means that a SMART furnace will be able to run the burners and circulator pump the EXACT time needed to achieve the lowest total system cost with the EXACT mix of underfloor hydronic, slant fin AND cast iron radiators all factored in. Of course if it set up wrong it does not work...
Last edited by chet everett; 09-30-2011 at 02:25 PM..
My experience is that the payback for switching out a heating plant is far longer than the relative fast payback for improving the insulation / weather sealing.
For coal it depends on where you are as the price per ton varies from $150 per ton to $350 per ton. The $150 is the lowest local cost delivered into your basement. Around the $300 mark natural gas becomes becomes competitive in most areas but that is limited because you need a gas line from the street. Natural gas should remain for very competitive well into the future because of all the new sources especially here in PA. You need to do price comparison using your local rates.
With coal because it's so much cheaper than most fuels the payback is considerably short time even with the high expense for some installations. With a small stoker for $2K stoker similar to pellet stove you'll see return in about year or two. More expensive installation like EFM boiler in the $9K range will be a few years. One thing I'll note is if you install EFM boiler it's once in a lifetime purchase, there is units in operation now they maufactured 60 or 70 years ago and there has only been some very small changes to the design over those years to address minor issues.
May be surprising but the demographics for those that use coal are in the middle income bracket, generally well educated and know how to do things themselves. The insulation, new windows and other things you might do is already done deal.
to get the credit and the loan, you need to improve your efficiency by 25% or more.
A another surprising fact is coal boilers are already very efficient, there is 50's design they tested back in the 50's over a 2 year period that's at 87%.
There's new one coming out and preliminary testing is 93%.
They were able to get these high efficiencies because of how they could design them. Going back to the picture I posted previously the round circle on the left hand side about a foot off the ground is the exhaust for the gases. Note all the surfaces that can extract heat. Only the coldest gases can escape from the boiler. They could proabaly make them 100% efficient but with coal you need to maintain a minimal draft.
As far as what is more efficient at transferring heat it's really irrelevant as long as it will transfer enough heat to the space you want to heat. Having said that copper will most certainly transfer heat faster. Whether it's copper or cast it is not going to increase the overall efficiency, makes no difference for fuel consumption.
You have X amount of BTU's in the water and it wants to go where it's colder. Whatever is not transferred to the room will go back through the return lines to the boiler, the boiler has to work less to raise the temperature again so there is no loss. The only argument you can make about what might increase your overall efficiency is any loss you might incur through the return lines since one setup may have less heat to lose through them. Those should be insulated, for me personally they are all in areas I want to heat anyway.
Last edited by thecoalman; 10-02-2011 at 07:57 AM..
so do you vote to keep cast iron radiators over replacing with baseboard heaters?
Yes. In fact, after researching it, I paid considerably more to replace the steam radiators with antique hot water radiators instead of copper baseboard. However maintaining historical integrity was also a factor. We needed specific sizes of radiators and we needed a lot of them, so it got pretty expensive. If you get the really pretty fancy ones, it can cost an arm and a leg.
Just google "are cast iron radiators more efficient than copper baseboard. "
Most responses are similar. Cast iron is better, copper is not very efficient. Lots of different explanations. One example:
Baseboard, although fairly economical to install is the least efficient form of hot water heating out there. If you want to replace your cast iron radiators i would consider Steel Panel Radiators. The may cost a little more but you can get more BTU's at lower water temperatures than baseboard. The best things is that you don't take up all of that wall space. Some of the better steel panel radiators are made by a company called Pensotti. (may not be the best example, the guy maight be a Penscottie rep, but just the first thing that popped up.).
Some responses are better than others. There are also some scientific studies out there, but they are not easy to find. Once we made our decision, I did not keep any of them, but I spent a few hours a day for about a week and a half finding and reading various answers and theories. Explanations vary, but one thing that is universally consistent, except for people who sell or install copper baseboard, almost everyone seems to agree that cast iron radiators are superior. People can pick at various responses for days and days, but if you do your own research and get around the sales people trying to tout their products, you will find an answer. Or, you cna ask your friendly neighborhood physics professor. If he or she is nice, they may even do a test in class if they do not already know the answer. It makes an interesting problem for them to bring to students. However as in every instance CD will not provide a definitve answer, but only some ideas or direction. You will have to satisfy yourself from actual knowledgeable sources.
Either way, you will be warm and comfortable, especially compared to forced air.
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