Hot wtr zone from steam w/vacuum

Rodney Summers

Try <a href="http://www.heatinghelp.com/newsletter.cfm?Id=29">here.</a>

-Michael

Fred Almeida

Hot water zone off steam with vacuum

I have a situation that requires a hot water baseboard heating zone on a 2nd floor that must be supplied from a steam boiler.
I was told that there is a method of piping and purging that creates a vacuum to accomplish this task. Do you have any material or comments on this?

Fred Almeida

So, does vacuum play a role in this?

don_52

Vacuum...

> So, does vacuum play a role in this?

don_52

Vacuum...

insofar as the common reference to "vacuum",sort of.

place a straw in a glass of water, put your
finger over the end and lift it out.

viola! a "vacuum seal" if you will, i believe this
is explained in the article.

cheers, db

Rodney Summers

vacuum

I think the "vacuum" part you're interested comes into how/where the water comes from out of your steam boiler to your FHW system. Let's say there are two fundamental options:

1) Use the boiler water. Push it around your hot water system.

2) Use a heat exchanger. Basically, have a separate, closed system completely filled with water (no air), and push it around. The piping for this separate system will be, for lack of a simpler description, partially submerged in the boiler water, so it gets hot, but it will be different water.

Now, #2 is likely more expensive to implement, but hey, you've got a closed system of water.

A cursory though about #1 might sound good, too, but the thing that you might notice is that your hot water baseboards/radiators will be a higher elevation than the water in the boiler. Hey! Doesn't water always seek its lowest point and so forth? Why doesn't the water in the hot water radiator sink down into the boiler?

As an example of the above, try (or imagine, it's not that hard) the follow. Fill your sink with water. Now, take a handful of water and gently place it on top of the water in the sink and let go. Plop. The water sinks. The water, in fact, does not stay, magically suspended above the water level in the sink. (Duh!) So why doesn't your radiator water plop down to the basement, since it's connected to the lower boiler water level?

The answer is that the radiator water can't fall because there is no air (ding ding! vacuum!) up there to replace the water. If you, say, had a small hole in your radiator where air could leak in, then in fact the radiator water would fall down into the basement and your system wouldn't work. But if your radiators don't leak (and they shouldn't), then the straw analogy comes into play, and once the radiators are filled with water, the water will in fact not all slosh out into the boiler. This works so long as your radiators aren't more than about 32-33 feet higher than your boiler.

Goodness; once of these days I need to work on the fact that I'm so darned verbose.

-Michael

Fred Almeida

Thanks!

Mike, thanks for the response. I was thinking there was something that I was not aware of on this one. Your analogy confirms anything I've ever understood or done in the past.