1950's Baseboard

I am trying to get information about the baseboard units in my 1950's house. They are heavy steel about 8" tall with a kind of looped fin arrangement. I am wondering what the BTU radiation rating is. The fins are about 5" tall. Any help would be appreciated as I am trying to determine the current EDR for the house.
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picture of interior fins?
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is there a separate element under a cover with a pipe with aluminum or steel fins? There were some styles of fin tube baseboard with covers (that may or may not come off) that looked similar to cast iron baseboard.
If they are fin tube then the output will be similar to modern fin tube baseboard. Why do you need to know? That will determine how precise an answer you need. Are they set up as steam?
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Catching up.. The reason for this is I need to replace a 30 Yr.old boiler, and I want to be fully knowledgeable about the heating system before I call in contractors for quotes. I am measuring everything up (walls, windows, doors) to calculate the load, and the baseboards to get the radiation area.
Here are pictures of the fins and one end.
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you size hot water by the heat loss of the house. 500 btu/ft is a conservative guess at the output of fin tube baseboard. if that isn't more than what your heat loss calculations show each room needs then you can look for an old catalog with an exact spec. Does it adequately heat the house now?
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The current radiation is fine. 143 Ft x 500 = 71,500 BTU/Hr. The current boiler (old Dunkirk PW51) is 150,000 BTU input / 103,000 Output. Looks oversize, especially considering my calculation of a boiler size based on actual gas use for this heating season is 37,000 to 40,000 BYU/Hr. But I am no professional so I will be interested to see what the local contractors say,
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Steam boilers are sized based on the connected EDR (Equivalent Direct Radiation) measured in Square Feet.
You do not have a steam boiler by the looks of that radiator. Do not select the replacement boiler size based on the size of the radiators. If you have more radiators than you need as a result of improvements to the home like new windows or insulation upgrades, then you have too many radiators and you may select a boiler that is too big for the house as it stands. You can install a smaller boiler when you have too many radiators and save $$$
One of the nice things about water radiators is that If you have too many radiators, you can make your home more comfortable using a lower water temperature. This will come in handy if you select a modulating condensing boiler that can accept lower return water temperature. By heating the water temperature to 140°F on a cold winter day, you will use less fuel and the home will be comfortable.
When the home was built in the 1950s and the boiler was installed, the plumber may have set the high limit at 180° which causes the room temperature to go above the thermostat set point, then the burner stops when the thermostat is satisfied. As the home cools off, the thermostat will call for heat again using all 150,000 BTUh’s of gas to overheat again. This may actually be uncomfortable. This is a result of oversizing. I would tell my customers this story:
Have you ever been sitting in your easy chair relaxing or reading a book and at some point you feel a chill? Then just about the time that you feel compelled to go to the thermostat to see if it is set too low, you hear that click and the burner turns on. Then you know that the heat is on its way and you forget about it. But a short time later, you feel a little warm. Just about the time you feel the need to see if the thermostat is set too high. You hear that click and you know that the thermostat just shut off the burner. You know that the temperature will be cooling back to the comfort zone shortly.
This is an unconscious reaction to the poor thermostat design and oversized heating system. This may also happen several times an hour because of the short cycling and oversizing resulting from the radiators going up to 180° then cooling off to below 100°. By selecting the proper size boiler with a modulating gas input, the boiler will never react like an oversized boiler and keep your home comfortable with radiator temperature ranging between 100° and 140°
If you are going with a conventional On/Off cast iron boiler the you may be better off with the next size smaller.
This is why I am measuring all the walls, doors, windows, ceilings and floors, and asking about what kind of insulation is in the walls and ceiling. This way I can plug in all those measurements to a heat loss calculation. You may find that you only need a 58,000 BTU boiler and not a 71,000 BTU boiler. That will save you over $$$ on the cost of the replacement boiler and will turn into big savings on your gas bill over the next 20+ years.
I hope this story helps you to decide on a HVAC contractor or plumber that will do the Load Calculation to select the right size boiler.
Edward Young Retired
After you make that expensive repair and you still have the same problem, What will you check next?
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Thanks for the insightful comments.
I have been thinking along those lines and will be looking for a contractor who also can provide that level of understanding.0 -
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What Edthehearterman wrote about lots of radiation. Fortunately, lots of people are in a good position that way with increasing their insulation and air sealting their homes
I have a problem with some of the other advice. I don't see How can a load calculation can come closer to boiler capacity needed than a determination based on fuel use, boiler efficiency and heating degree days. There is, of course, the problem of calculating in the DHW and cooking contribution if the same fuel is used for those things. With an old house, expecially without an energy rating for the structure, infiltration is a guess. Insulation quality may also be a guess
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Yes, infiltration is a guess without some type measurement like a blower door score. Both EdTheHeaterMan and bio_guy have good points. Ideally, you could use the heat load calculations and the fuel use calculations to produce the most educated guess that is closest to the true heat load.
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The average from the fuel use could miss the load on the coldest couple days. You probably need the bigger of the 2.
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but you don’t size for the coldest days of the year! You size for the average?
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you size for the coldest period but not the peak lowest temp. I can see where if you have 2 or 3 days in a row that are the design temp in an otherwise warmer month you would miss the actual peak sustained load you need to cover.
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Thanks for all the thoughts and comments. This gives me much to think about.
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Right, you might get your data from the coldest weeks not average over several months. On the other hand, the relationship between fuel use and heating degree is directly proportional and is often used. The only other figure that you need is furnace or boiler efficiency. It has to work, otherwise how do fuel oil, propane and kerosene (and I might assume coal deliveries work). People delivering fuel don't want to come too often because it costs them money and people get really angry when the fuel companies allow them to run out. The latter rarely happens. My parents had the same fuel oil supplier for over 50 years and they ran outonly once, in the summer. The explanation was that the supplier switched their computer system and software. The customer information had to be inputted by hand and they use the wrong setting for DHW putting my parents on someting other than the heating boiler when it was, in fact. a hot start combination boiler.
I am familiar with how this works but very rusty. I once did a calculation for my parents' house. My aunt recorded max/min temperatures on her front porch for decades to get degree days for their family liquid fuel delivery business. She then would have calculated when each customer might be running low because she did not have any stinkin computer.
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A wise person posted on a forum, maybe this one, that the heat loss (Manual J) calculation is the hypothesis and fuel usage is the experiment that tests that hypothesis. Fuel use is much more direct data than even careful testing of the structure and detailed knowledge about the construction.
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