Questions

Bob Workman

Qustion: Are steam heat and hot water heat the same thing? And how do I tell the difference?

Mark Eatherton1

Differences...

are usually found at the boiler.

A steam boiler will have a sight gage showing the water level in the boiler. A hot water boiler will not.

A hot water boiler will have an expansion tank somewhere in the system, a steam boiler will not.

A steam boiler controls it's burner operation based on PRESSURE. A hot water boiler runs its burner based on TEMPERATURE.

Although rare, some hot water boilers can be installed with a one pipe system. Most one pipe systems are steam. Both steam and hot water use a 2 pipe system.

Why do you ask?

ME

etp66

type of connection for copper to steel pipe?

What type of connection would be used for connecting copper pipe to iron/steel pipe?

Mark Eatherton1

Yellow brass...

is neutral to both metals.

ME

Canuck

Dissimilar materials

Dielectric unions

Larry Weingarten

dissimilar metals

Maybe brass is OK in a closed system with steel, but in potable water that isn't the best quality, I'd use plastic lined steel nipples to put distance between the different metals. With 3/4 inch lines where I need to tie new copper to old steel, I use a lined nipple out of a steel fitting and then a copper flex line to get to the copper pipe. The flex can be had with a true dielectric that doesn't have any steel exposed to water, as normal dielectric unions do. We have some pretty bad waters around here in central CA, but I've seen brass/steel connections fail in about a year.

Mark Eatherton1

Probably true with red brass...

That's why I specifically said yellow brass.

As far as dielectric unions and plastic lined nipples are concerned, I've seen both of them fail and clog up after less than 5 years. In our water conditons, I've never seen a yellow brass nipple fail.

I guess it depends on where you're at and what you're doing with it.

I actually got a local building code authority to outlaw the required use of di-electric unions when I took a box of failed, plugged di-electric unions in to a city council meeting. I proved to them that a direct connection between the copper adapter and the steel tank did less harm during the life of the heater than did di-electric unions.

Does the code in your jurisdiction recognize plastic lined nipples as a true means of dissimilar metals disconnect? To the best of my knowledge, none of the codes allow the use of unprotected mild steel nipples in potable water applications.

I know most codes do accept the use of yellow brass.

As for the use of di-electric unions in truly closed systems, they're a waste because the majority of the free oxygen needed to complete the battery of electrolysis is removed in the process of heating. This excludes non barrier tubing applications.

Also, it has been my experience that the rubber washers in typical dielectric unions start leaking when the system cools down, and no leak is a good leak.

Just My Humble Experiences speaking:-)

ME