steam

brad johns

I was looking at an 8 floor apartment building that has some steam leaks and water hammer noises the other day and found something I had never seen before. This is a 100 year old building that used to be heated by a coal boiler, now it is heated by city steam and runs on 3 psig, that part is normal, the strange part is that the main travels all the way up to the 8 th floor and then feeds the apartments on the wqay down. We havent been in every apartment but the ones we were in didn't have any traps in them, all the returns come into the basement and then the pipeing is trapped before it is sent to the condensate meter. The pipeing has not been changed in the building except where the boilers were disconnected and the condensate meter was added. We found it vey strange that the main goes up 8 floors and feeds down, any suggestions or knowledge on this type of system would be a great help.

Fred Harwood

Sounds

like a parallel -flow down-feed system, or Mills System, see page 92 of Dan's The Lost Art of Steam Heating, available from this site.

t. tekushan

overhead system, traps

I've seen quite a few Mills overhead systems in industrial buildings here in Cleveland. Overhead is the best way to go in tall buildings. As D.H. would say, it is an "express" route to the roof, but from there on, steam and condensate are traveling in the same direction.

If this is single pipe, there would only be return loops at the bottom of the downfeed risers going into a dry return.

If it is two pipe, those elbows may not plain old el's. They might have orifices in them, which were really only appropriate if the pressures are extemely low (as in a vapor system) and in conjunction with radiator inlet orifices or special orifice type valves. If this is the case, that might explain the water hammer, as pressures might be to high for this type of set-up.
Also look carefully at any of the remaining original radiator valves. If they look unusual or have orifice plates between the valve and radiator, then replacement radiator valves elsewhere in the system will wreak havoc, causing steam to flow through the dry returns. More water hammer.

I highly recommend "The Lost Art of Steam Heating." I have a collection of old and priceless books on steam heating but Dan's book is the most complete and concise single volume I have ever seen. I've learned so much more about a subject I thought I knew a lot about.