sizing new boiler for existing systems

heatmizer

I  am taking  a steam  class ,Today we  where covering  sizing  all class long talked about  how  everything  was over sized  by about 75%  when these  where  installed   . After  saying that  i was told that i would  size unit   to match the existing  radiators  that i know   are 75%  to big   . so i asked   why  would i  size to somthing i know  is too big   i got a  confused looked and  no answer . could  somone plz  help me to understand . and  also  my instructor   had  no good heat loss formula  for steam systems   this would be nice too . ty  bob  form  boston

Mark N

Steam boiler sizing

On this website under resources, then hot tech tips, read the article titled How to replace an Old Steam-Heating Boiler.

heatmizer

sizing new boiler for existing systems

ty , found that  to  be very helpful 

Rod

Steam Links

Hi- Basically you've answered your own question -"Sizing a new boiler for the existing system" . You're matching the boiler to an already installed system. If you undersize the boiler, the overall operation seriously diminishes with some radiators getting steam and other not.  If you were installing a complete new steam system you would take into account actual heat loss but in the case of a retrofit boiler it really is irrelevant, However there are things that can be done to adjust for the oversize system.

The following are link to articles that might be of interest to you. Pay special attention to the third link which is written by Dave Bunnell, a very experienced steam pro in the Chicago area, which has some ideas about the issues you raised.

You also might want to look at other articles in the Resources section at the top of this page. There a lot of info on steam heating, it's history and practice. Once you get into it, Steam Heating is really neat and I must warn you, learning about it tends to be addicting !

- Rod



http://www.heatinghelp.com/article/11/Hot-Tech-Tips/180/How-that-steam-boiler-got-to-be-so-big



http://www.heatinghelp.com/article/11/Hot-Tech-Tips/186/How-to-replace-an-old-steam-heating-boiler





http://www.heatinghelp.com/article/11/Hot-Tech-Tips/1551/Taking-Another-Look-at-Steam-Boiler-Sizing-Methods-by-Dave-Boilerpro-Bunnell 

Dave in QCA

Oriface System can be sized for load

Great Links Rod,

Here is another......

It is a link to an artical by Henry Gifford.   https://869789182725854870-a-energysavingscience-com-s-sites.googlegroups.com/a/energysavingscience.com/www/articles/henrysarticles/BSEOrifices.pdf?attachauth=ANoY7cpMKt2xR1nn_zRevEAqQwce2HTJfOiyrEKf3snG5RpFYPeuO94KD6IiuWLxfJ28tX9JZeXKYJRlnPpEmZWCTuFLjLSGmdiXnP2RsDVNtevRuBDMPXXAzJbdzkO9_FRQasqvzoPOTZKDIVgZcTX3uyHSkwZuu4VI3GOqdAff4SkiYltmbW_9v574YPri3CzugymiCVTlvacRyczWhoT7WHTjyvvlQHFhQtwmEWXmLIa2xwiqaBY%3D&attredirects=0

Henry explains how a 2 pipe system can be fitted with orifaces, which will even the distribution, even if the boiler is sized smaller than the connected radiation.

heatmizer

sizing

  i understand ,   I need  to match the systems   ablity  to condense  steam  more then the  heat loss , and  from there  can regulate   the  radiator  with thermistatic  valves  .on  radiators

Rod

Systems

 You are matching the existing system radiators. When dealing with radiators you also have to consider with what type of system it is.  Dave gave you a good article of orifices. This applies only to two pipe systems. TRVs can be used on both 1 pipe and 2 pipe systems however each system uses a different model TRV. On the 2 pipe system the TRV is installed on the inlet pipe and on the 1 pipe system, between the radiator and the radiator vent.  Changing the venting capacity/speed on each radiator is also a way of controlling the radiator's heat output.

Another website you might be interested in is Gerry Gill's as it has a lot of really good info on steam heating.

http://www.gwgillplumbingandheating.com/

Gerry Gill is a very experienced steam pro in the Cleveland area and is on the cutting edge of steam heating. Another post on here mentioned that he has posted some new videos on mains vents on his sight so you might want to take a look at those too.

- Rod

http://www.heatinghelp.com/forum-thread/134221/Main-Vent-Videos