Adding a basement radiator

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  #1  
Old 01-29-03, 08:08 AM
Brewbeer
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Adding a basement radiator

Hi folks, I am adding a bathroom to the unfinished, unheated basement of my ranch house, and would like to install heat in the new bathroom. Heat to the house is supplied by a diverter T hot water system, pump away, 1 inch supply main, 1/2 inch branch connections to 7 cast iron baseboard radiators, with diverter Ts on the return side, serving the main floor.

I would like to install a 6 foot cast iron baseboard radiator in the basement bathroom. Will 2 diverter Ts cut into the 1 inch main loop serving inch supply lines work for this application, or should a new zone be added to the boiler (Utica USC4 w/ taco 007 circulator)? The supply line from the main would be 4 feet horizontal and 7 feet vertical (down), and the return from the radiator would be 7 feet vertical (up) and 20 feet horizontal. Thankx.
 
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Old 01-29-03, 02:15 PM
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If accurate temperature control is not important, you can use the 2 diverter tees. I would highly recommend another zone though. You have areas with dissimilar construction factors and now add a random (?) length of cast iron baseboard and you have a pretty good shot at an uncomfortable bathroom. The only saving factor I can see is, if you take off of the existing loop, the new bathroom will probably need less heat than you are putting in and the bathroom being below grade will need even less than the room upstairs where the thermostat is. So you will likely overheat the new bathroom and could throttle one of the pipes going to the new baseboard.
 
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Old 01-30-03, 06:35 AM
Brewbeer
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Thank you for the reply KField. The 6 foot length is a "random" guess. There is one unobstructed wall 7 feet long, and cast iron baseboard radiators come pre-assembled in lengths up to six feet (any longer and they require assembly). Could easily go shorter, but would much rather it be too warm than too cold. The door could be left open some what if it got too warm.

There is a single-pane metal frame basement window in there. The floor slab is cold concrete, and figured that a warmer room would help compensate for the cold slab, and also help dry out the shower.

Next winter I'll be finishing the entire basement anyway, so perhaps I should just add the additional zone. I was just worried that one radiator on a zone would not be too good for the boiler.

Do you have any recommendations on how to size the radiation for the basement zone? I want cast iron the in bathroom, actually I'd love it for the whole basement, but at about 30 bucks a foot, I guess it is cast iron in the bathroom only and fin tube for the rest

Thankx again.
 
  #4  
Old 01-30-03, 08:55 AM
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The only right way to know how much baseboard to put in the room is to do a heatloss calculation. There is someplace on the internet where you can do it but I do mine with a program I bought just for that. There would be no problem having a small piece of baseboard as a single zone. We routinely put bathrooms on their own zone and usually there is only 4 or 5 feet of baseboard in there. Be careful about mixing cast iron baseboard and finned tube on the same zone. It is not a comfortable mix. They heat up and cool down very differently and cannot be balanced.
 
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Old 01-30-03, 10:28 AM
Brewbeer
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Is the heat loss calculation difficult? How would I go about doing it?

The basement is 23 ft. by 39 ft. I will be heating most of this space, a little over 800 sq. ft. (not heating 10 ft. by 14 ft. mechanical room where boiler/ hot water heater are, or laundry room, 10ft. by 7 ft.) Ceiling is 7 feet high. Bare concrete slab without insulation under it.

There is about 1.5 feet exposed concrete in the front wall, and 2.5 feet exposed on the back wall.

There are 6 single glaze metal frame windows having a total surface are of approximatly 20 sq. ft. There will be one insulated metal door 36 inches wide up to the bulkhead.

The rim joist is insulated to R-15 with caulked extruded polystyrene. The finished basement insulation will be R-10 extruded polystyrene glued to the concrete interior wall followed by fiberglass bats in a 2x4 stud wall. No insulation in the ceiling.

The bathroom is approximately 8 x 8.
 
  #6  
Old 01-30-03, 12:23 PM
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For what it's worth.

I did a quick runthrough of your basement using the following specs. 2 ft. above grade with r-23 insulation. 6 windows 1 X 3 with uninsulated metal frames. 1 door 3ft. insulated steel. (not in the bathroom) 7 ft. room height. Heated living space above.

Used 570 btu/hr output for baseboard and a 0 outdoor design temp. and 70 degree indoor temp.

I figured the bathroom with 2 outside walls and one window and the balance of the heated space was 23 X 30.

The bathroom calls for 1.6 ft of baseboard and has a heatloss of 894 btu.

The rest of the basement calls for 10.8 ft. and has a heatloss of 6167 btu.

This is probably in the ballpark and because most of the room is below grade and well insulated, any small differences in what values I used won't affect the outcome a whole lot.

No warranty expressed or implied.
 
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Old 01-30-03, 01:11 PM
Brewbeer
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Thankyou very much, KField. I appreciate your efforts on my behalf.
 
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Old 01-30-03, 06:04 PM
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Initiative is contagious.
 
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