Radiant in lieu of extending Steam

tommyg

I need some opinions/advise.
I'm living in a 1930's colonial in NJ which has a one pipe steam system. I'm in the middle of constructing a 2 story + basement addition of 26'x12' off the back of the house. So far, I've done everything myself with the help of some family except dig the hole.

When I started, I figured I would simply have the steam lines extended out to the new back of the house and have longer radiators put in. This was one of the few things I figured I would leave up to a "pro". Unfortunately or maybe fortunately for me, one of the contractors I've talked to has proceeded to confuse me and make me wonder if I shouldn't go with radiant heat.

While the radiator option is viable, it's not easy to maintain pitch and get the radiators located properly. The room locations where the rads can be brought to are not prime, and they really can't get to the new master bath without some major surgery.

So, one of the local contractors suggested that since I've got perfect access, to the undersides of the floors, why not go with radiant heat and replace the water heater with a combination water heater (he quoted a 75 gal Bradford White Combicor). At the time, he told me it would cost me roughly the same as doing the steam work, but the nice thing was that I'd have separate control. He also told me he could install a HX off the the existing WM Boiler, but didn't recommend doing that because anytime I needed heat in the addition, I would be firing up the 200,000 btu boiler.

Everthing sounded great until I got the quote for $10k to heat a total of 600 sf of space.

1. Am I nuts or is this proposal out of line?

2. Is there real merit in not using a HX off the steam sytem? Would this be more affordable?

3. I definitely want to separate potable and radiant systems, but it seems the combo water heaters are not in favor among the pros here. What would you suggest?

Thanks for your help/opinions

steve_6

condensate heating

Check out Heating Q&A, Condensate heating on this web site. this will answer a good part of your question.

T.J.

I have similar situation

Tom,

Boy its good to hear someone with a similar situation debate the issues. Now is certainly the time to commit one way or the other. My situation is a little different but I too went thru the same process. My new construction floorspace is roughly double the existing house,so I decided to change everything over to hot water. 90% will be radiant floor and 10% will be Runtal radiant panels.

Instead of changing out the existing HW heater, leave it and get a deicated HW heater for your radiant floor. You probably only need 18-25,000 btu/hr. With a dedicated HW heater, no need for HX, or worry about your potable water, or what your local building inspector will say. Good luck and let us know what you decide.


Tim

TJ_2

Heat Exchanger vs Direct boiler water

Running a hot-water loop directly off of a steam boiler is pretty straightforward and is explained quite well on this site. In addition, you could check to see if you boiler is oversized for the current connected radiation load. If it is, you will have some heating capacity in addition to the 30% pickup.

It seems to me that the one consideration with connecting directly to the boiler as opposed to using a heat exchanger is that the boiler water is somewhat corrosive because it absorbs CO2 from the air over time and becomes acidic.

A radiant heat expert should be able to comment on whether or not this is a problem with radiant systems.