One pipe steam to individual boilers

Howwen

I have a customer who has a 4 unit apartment building with a one pipe single steam boiler. He wants to seperate the utilities for each unit and add hot air furnaces to each unit. I am trying to keep him steam (I am a plumber!) Is it possible to split the apartments on the feed side and still use the common return along the floor to go to each boiler? Each units rads are feed from a common feed so reconnect them to an indivdual branch header should not be difficult. I am sure someone else has ran into this problem, any ideas?

Howard Bromberg
Smith Plumbing, Inc (New Jersey)

DanHolohan

There would be problems with that.

Please read this when you have a chance:

Zone valves and steam heat

Steamhead (in transit)

But if you used four small boilers

you wouldn't need zone valves.

I'd still run separate wet returns for each apartment, in addition to separate steam mains. Completely isolate each from the others. That would eliminate the need for a boiler-feed pump.

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Garret

If you ran separate wet returns, would it be possible to put a condensate meter on each and get the usage ratio for each apt? Not sure how accurate those are...

Then put thermostatic vents on all the rads in the apts, so they get zoned heat...

Maybe this is a nutty idea... but if the current boiler is in good shape, it seems a shame to pull it just to be able to account for the usage apt-by-apt.

Here's the best idea... give each apartment control of someone else's temperature. Then just divide the total bill 4 ways evenly... everyone wins, especially the sweater manufacturers.

Howwen

So with 4 boilers I would need to pipe each apartment as if it was completely independent. My fear is that the cost of this amount of work will give the landlord an "easy" choice of 4 hot air furnaces. I realy wanted to keep him steam but the more I work on the bid the higher the price goes, and although I see the benefit it will be hard to sell comfort to a landlord who only wants to dump the utility bill on his tenants. Thanks for the ideas.

DanHolohan

He's not buying a heating system; he's buying a way to sub-meter the apartments.

Steamhead (in transit)

Another benefit of steam

all the work is done in the basement. No ducts to fabricate and install, bulkheads to build etc.

Dan, if you know a way to sub-meter one-pipe steam, we're listening.

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Christian Egli_2

A no pressure sale

This one is very interesting, it is a twist on the zone valve scheme because it uses four boilers worth one quarter each of the old boiler.

So, of all the problems we get from zone valves on one pipe at least we won't be getting the one of gross radiation mismatch. The main problem I see with having a common gravity return to four boilers is when one boiler is on and the three others off.

One boiler will steam up to pressure it's main is then sealed off from the atmosphere. In the other boilers with their mains still wide open to the atmospheric pressure, we see the water pile up the way Pascal discovered it would in a series of communicating water columns. 1 PSI of operating pressure will cause a water level step of 28 in. Even at 0.5 PSI, we're still talking about a good foot. And there is nothing you can do about it, check valves do not make the pressure differential disappear, they only loosely prevent water from one specific place to step into the differential (but water from somewhere else will do so). So, with even a foot of differential, you're playing dangerously close to the ends of the water level sight gauges and you're playing dodge ball with your water feeders.

Each of the three boilers will have to see their level go up by one half of the pressure step, thus guzzling up three half boiler unit volumes of water. The operating boiler will see its level go down one half the step, and it will give up one half a boiler unit volume. We got one amount of water while we needed three. We need stretchable water.

Why is it so difficult to add in new returns? With a new boiler, new returns are a good idea anyways? Is it a wet return that links all the bottoms of the risers?

Perhaps there is some novel piping method to think of along the lines of the trapped bottle scheme but in reverse. Not for maintaining a steady system level, but for maintaining a steady boiler level.

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The real idea is submetering, as already mentioned. Are there common areas to the building? who will heat those? It seems some form of electronic data acquisition spread into each radiator and apartment should be more suited to pleasing the tenants and the owner. There are firms that specialize in this, they can submeter the electric, the water and the gas all on one computerized system. One such firm is:

http://www.emon.com

Here is some of the gadgets Viessman makes for that specific purpose. They are available in Germany. They are like stop watches you stick to your radiator, they only have hot water stuff though. Sorry it is in German, but you can look at the picture.

http://cgi.ebay.de/Viterra-Waermezaehler-Waermemengenzaehler_W0QQitemZ6066280242QQcategoryZ32280QQrdZ1QQcmdZViewItem