I'd like to add a separate zone heating to my 800 square foot basement. My house is heated by hydronic radiators. My boiler is a high efficiency boiler(195,000 BTU)and heats the water to 120F. Unfortunately the floors were just done when we bought the house so radiant pex is not an option. When I look at baseboard slant fin style heating it recommends 180F degree water. If I ran wall to wall slant fin would it be enough to warm in a cold environment like Chicago? If not what would you recommend? Multi cast iron radiators , steel radiators , multiple loops?
Thanks
John

If you're heating with 120* water, you must be running off an outdoor reset curve? If so, is your boiler capable of running multiple curves? You might be able to run a higher supply, and still condense. You need to do a heat loss calculation for the basement. Then look at output rating charts for different types of radiation. You want to cover the heat loss with the lowest supply temperatures possible. That ensures your return temperatures are low enough to keep the boiler condensing.



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Paul's right on.The Proper size radiation "Maybe even over sized" so you can keep that return temp as low as possible.It being a basement you mite get away with baseboard (lots of it!).A heat loss calculation is a must.

120 deg water will not heat a house in a cold climate via radiators ???
if the basement is well insulated without sliding patio doors and with only a couple of small windows then the chances are filling the exterior wall with baseboard heaters will work fine. some of the full length of wall will have heating elements inside the covers while some will have just pipe connecting the elements.
a picture of the boiler and its piping will be helpful in telling you where to cut in tees for basement feed and return.
there might be a set up for a future zone already there..
BTW, 195,000 BTU sounds like alot ???

packy..........Folks are heating their homes with 120* water, at 5* design day temperatures. It requires over-radiating, but that's what's needed to get you that 95% efficiency of a mod/con boiler. In many cases they are running without a thermostat in the house and running off outdoor reset only. To make sure the temperatures in the house stay balanced and not over or under heat an area, they must do a heat loss calculation, and properly size the emitters.

Thanks everyone I got some more details for you.

Here's some more info. I was able to borrow a infrared spot meter. So out going temp maxes out at 129F. The return temp was in the 70s/80s but jumped around allot. Radiators we're around 95/100F. 15 degrees outside , 73 inside. 54 in the basement and 45F on the basement exterior walls. I drew a simple diagram of the radiator layout. You can see how the outgoing and return have two inlet and outlets. The boiler is in the middle of the house. There is currently no separate zone(thermostats/pump)for the 2nd floor, just on main floor. I took a photo of the boiler model. I don't know if it's running on a curve, I'm no familiar with these boilers. Thanks

Posted more info

its always fun to sit here and spend other peoples money...
if it were my house i would...
get rid of the 2 and 3 inch iron mains leaving only the 1 inch risers.
i would set up 3 manifolds at the boiler. one for second floor, one for first floor and one for basement.
i would bring back all the risers separately to the boiler creating a zone for each floor.
you would be using probably less than 1/2 the water to heat the house.
each riser i would run with 3/4 pex from the manifold to the iron pipe.
so 3 circulators with internal flow checks (one for each zone)
one 3 zone relay for the thermostats and circulator wiring.
sounds like 10's of thousands dollars but it is not..
i think in the long run you would be more comfortable because you would have better control of the heat.
you would save money because of the amount of water you would be heaqting is less.
i have done a few jobs like this and the people are all very satisfied with the results.
bottom line here is to just add a basement zone you would need to make so many modifications to the existing piping that it would just not be a cheap nor easy job.
not to mention that firing 198,000 BTU to make 120 deg water is very inefficient. the harder a boiler works the more efficient it will be. yours is not working very hard right now..

Yes, the idea would be something similar to this.I would add a zone for the basement/upstairs. I've got a nest thermostat so I can tell you the boiler was running for 172 hours in Dec. all the pipes are original 1933 iron. Chicago hasn't totally caught up with pex but I really like the idea of it.

exactly..
so just picture a bunch of tees on the left of that picture.
each tee on one manifold would be a feed.
the each tee on another manifold would be a return.
pretty easy to pipe..
note that you buy manifolds all made up and solder copper x pex adapters on each branch..
so there would be four something like this. 2 feed and 2 returns. the basement would just be one feed and one return.

What is the make and model of that boiler? That's an 80% efficiency boiler, and I believe it's cast iron. If I'm right and you run it at those temperatures you'll rot it out, in short order. Check the manual.



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excellent point paul..

[www.bryant.com]

I posted earlier the Bryant model in the photo. It's BWB series 195k BTU
Looks like 82% effiency cast iron style. What are the temps you guys normally run in a water boiler ???

160-180

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Did not find anything helpful in manual pertaining to temps but in similar make I did find some info on return temps below 120F causing corrosion. I'm going to have it looked at. Thanks

Return temps below 130* will cause flue gases to condense. That condensate is acidic, and will rot the boiler quickly.If you look at the boiler input rating, compared to it's capacity, it's 80%. One of the primary figures used to figure efficiency is flue temperature. If you run it in such a way that your flue temps are colder than they should be, it's possible to get higher than 80%. For the short time the boiler will last.



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Looks like I had a faulty pressure regulator, system had almost no pressure and now is running allot hotter.

Gas pressure?

no this was water pressure. So before I posted my question there was a leak in the system which was repaired. The back flow pressure and regulator were not working so the system never got back up to 12 psi. It's repaired now.