Adding longer baseboard steam radiators

Paradox

There are three rooms in my house that the existing cast iron baseboard radiators just aren't sufficient enough to heat them properly during the winter. I was thinking about replacing them with slightly longer baseboard radiators and see if that will improve the comfort in each room. I would be replacing a 3' cast iron and making it a 4'. And a 6' and making it a 8' or 9'. My question is will the addition of just those 3 or 4 extra feet of radiators affect the system negatively or be any type of strain on the existing system? All the existing radiators do get hot, and I had a brand new gas boiler (100,000 BTU output) installed less than a year ago. Thanks for any and all input in advance.



Will

Jamie Hall

Well...

Really isn't enough information here to say yes or no.  If there is enough capacity in the boiler to handle the extra radiation, that wouldn't be a problem -- so the first thing to do is to add up all your existing radiation in EDR, and compare it to the rating of the boiler, also in EDR.  If that indicates you have the capacity to add some more radiation, at least that won't be a problem.



Then there is the question of pipe size feeding the radiators.  You don't say whether this is one pipe steam or two pipe steam, but in either case you will want to be sure that the pipes feeding the radiators are big enough to handle the bigger ones.  There are tables for that; it depends on what size the pipes are and the EDR of the baseboards.



But... before you do all that, it would worth finding out if the system really is performing as intended.  Do you have adequate venting on your mains?  Are these baseboards getting hot as fast as the rest of the system?  If they are one pipe, are their vents really correct?  Then too, is there some reason why these rooms need more heat than was installed?  Leaky windows?  Worth looking at those things, too...

BobC

More heat

Do the radiators in the cool rooms get hot at the same time as other radiators in the house? Is this single pipe or two pipe steam?  Do they get hot fully across? Where is the thermostat in relation to these radiators in the cool rooms?



Getting longer cast iron radiators will not be cheap, don't try and use anything but cast iron. The pipe feeding a radiator has to be large enough to feed the surface area of the radiator. Can you tell us the size of pipe (circumference of the pipe would be fine) that feeds each radiator?  Do you know wht the EDR (surface area) of the radiators is? Do you know if there is insulation behind the baseboard radiators and are they recessed into the wall?



Bob

nicholas bonham-carter

Unbalanced system

Those baseboards are probably the right length, (unless you know otherwise from a heat-loss survey).

I am assuming this system is unbalanced due to bad main (not rad) venting. All radiation should receive steam at the same time, and these three baseboards are probably the last on the line for steam. As a result, they have only just begun to heat up when the thermostat shuts off the boiler.--NBC

Paradox_

Additional Inormation

Thank you so much to everyone for your expert input. Here is the additional information:



1)This is a one pipe steam system

2) The size of the pipe going to the radiators I wish to add length to (A 3ft baseboard and two 6 foot baseboards) is 1' pipe.

3)The thermostat is located in the kitchen (which has no radiators in it) but is adjacent through an open floor plan to the dining room (13x10ft room which has the 6' baseboard in it) and that room is adjacent through an open floor plan is the master living room. The master living room is the biggest problem. Its a 12x13 foot room with a 12 foot cathedral ceiling. Room also has sliding glass doors, and 4 windows. The only radiator in that entire room is a 6' baseboard.

4)All radiators get hot and heat up all the way through. They do not all heat up at the same time, the ones in the master bedroom heat up last - which i have the valves set that way because if they heated up sooner that room would be 90 degrees while the rest of the house was 60 degrees. The one in that cathedral ceiling room does heat up last, it is the furthest one away from the boiler.

5) The EDR of all radiators is 264.5 which I believe is 63,480 BTU's.

6) Not sure the EDR of the boiler but it is a Weil-Mcclain SEG35, these are the tech specs.

Maximum Input Capacity (BTU)100,000Input Capacity Range

DOE Heating Capacity (BTU)83,000Net I=B=R Capacity (BTU)62,000Efficiency (%)82.9



7) They are not recessed into the walls. Walls have normal insulation behind them.



I did use to have some problems with water hammer but I had the pipes repitched to a greater slope and that diminished most of the water hammer. I also do not have any other valves of any kind anywhere in this system except on the radiators themselves.



There is a huge lack of steam knowledge in my area so any and all help is very much appreciated! Thanks in advance!



Will

nicholas bonham-carter

install main vents fiurst

I am assuming that the baseboard radiators were sized to the rooms long ago when steam knowledge was more prevalent in your area. if that is so, then getting the air out easily from the system will result in all radiators getting a few ounces of steam simultaneously. the thermostat is probably also letting the system run longer than necessary as it is far away from a radiator.

the radiator vents will not be able to do the main job of air removal, as they are just too small.--NBC