Home>Discussions>PLUMBING>cast radiator /headscratcher
4 posts / 0 new
Last post
cast radiator /headscratcher

Greetings to all and many advance thank you's for your help. Over the last several days,I've searched and have not been able to nail down an affirmative answer to my question: Is it possible to use a cast iron steam radiator on a hot water system? and; Is the basic difference between the two types of radiators a bottom connecting manifolds on steam rads, and a top and bottom manifolds on hot water rads? thanks, Larry

Re: cast radiator /headscratcher

First let me say I have never worked on a steam systems.
As I understand it steam systems usually have one pipe feeding the bottom of the radiator. The steam rises in the radiator and as it condenses it runs down and out the same pipe. There is an air bleeder and pressure release valve on the top side.

In a hot water system there is an inlet pipe at the bottom and a return pipe on the bottom of the other side. An air bleeder valve on the top side . The air is bleed out and the radiator fills with water. The hot water comes in the inlet side and rises to the top of the radiator as it cools the cooler water drops to the bottom and goes out the outlet pipe.

So the difference in the radiators- a steam radiator has a single pipe connection and a plug on the other side, a water radiator has a pipe connected to each side at the bottom and the bleeder valves are different but the cast radiators are the same.

I'm sure one of the techs will be along and correct me if I'm wrong.

Re: cast radiator /headscratcher

jack has it perfectly correct, any steam radiator can be adapted to accomodate a hot water system.

Re: cast radiator /headscratcher


It depends on the configuration of the steam radiator.

The steam rad has to have an inlet hole to allow the hot water INTO the rad and an OUTLET hole (usually on the other side) to allow the hot water out.

Many steam rads have only an inlet hole, but I've seen even THESE modified for hot water.

Another problem is that the steam vent on a steam rad is almost always in the middle of the rad--this would have to be plugged up & a 3/8" hole drill-tapped at the top to let the accumulated air out (air vent/bleeder).

Other steam rads are not connected along the top spine of the rad, which would allow air to get trapped in all the sections---bleed valves would have to be drilled & tapped into each section, which wouldn't be worth the trouble.

The site below explains it further.


Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.