connecting cast iron radiator

Rich_44

When using a cast iron radiator in a water system, What is the best way to connect to the radiator...In on the bottom, out on the bottom...In on the bottom, out on the top...In on the bottom, out on top same side....etc

What is the best configuration for the connection?

Jack P.

In on the bottom, out on the top...opposite side

Unknown

JEPProperties

Are you sure about that? I was always taught that as the water cooled it will become heavier, hence "falling-out" the bottom helping natural circulation through the rad.

Dave

Eric Johnson

In the bottom and out the bottom

Is how I always do it. The only times I've seen the top tapping used on a conventional hot water system is when somebody couldn't get the plug out of one side on the bottom, and went for the top instead. I'd cut the old plug or bushing out with a Sawzall and a hacksaw blade and cold chisel before doing that.

Unknown

Agreed Eric,

bottom to bottom is the norm, but when installing TRVs on each freestanding CI rad, do you not think having the control-head at the top(flow side), is better?

Dave

Jack P.

If you send in supply water on the bottom and out at the bottom, only the bottom of the radiator gets warm. You are sending the supply water straight through at the bottom. The supply water will not rise to the top as you might think. When supply water enters at the bottom and exits at the top the supply water will heat the whole radiator uniformly. That way you forcing the supply water to the top of the radiator and not just hoping it gets there.

Unknown

JEPProperties

I would re-think that statement, many a CI rads are installed this way. Are they all wrong?

Dave

Eric Johnson

My experience is limited to working on systems installed in houses I've owned, all of which had cast iron radiators piped bottom to bottom. And when installed correctly, they get nice and hot, top to bottom.

I'm not saying it's wrong to do it bottom to top, because I don't know enough about it, especially when you're talking TRVs. All I'm saying is that it's not very common (I'm not aware of any such installations, and I pay attention to that kind of thing).

Seems to me you'd want to be returning cooler water to the boiler whenever possible, and water exiting from the bottom of the rad is going to be cooler than water exiting from the top.

Tim_41

Bottom to bottom

After I hooked up some rads, I used a infrared thermometer. I pointed it to the bottom and than to the top on all 3 rads. Once the water got heated and circulating, the top was hotter across the whole radiator than the bottom by 10 too 12 degrees on avg. Each one was piped to a manifold via homerun.

Tim_41

burnham brochure

check out the tappings and connections from a burnham brochure http://www.burnham.com/PDF/Baseray.pdf
Its on the last page (page 8) on the right side.