Steam heat aquastat

Xray

For the second time I have seen a steam boiler in an apartment building controlled with an aquastat strapped on to a return near the boiler.  Strikes me as kinda rube goldberg, but the landlord doesn't want a thermostat.  Can anyone recommend a temperature setting?

Jamie Hall

Does sound a bit Rube Goldberg...

but perhaps the professionals have a handle on this.  Just out of curiousity, though, I was inspired by your post to investigate the returns on the system I supervise here, which was running happily on a small setback recovery.  Hadn't tripped on pressure (it rarely does).



One small return -- which is really just a drip off a big steam main -- was a little warm.  The principal return (collects all the dry returns (3) and all the drips from the steam mains (also 3) was cool.  I wouldn't say cold, but basement floor cool.  I'd have to run poor Cedric all day, I think, to get them even faintly warm...

Pumpguy

I have

seen this many times on 2 pipe vacuum systems.  The aquastat is wired in series with the control circuit to the vacuum switches.  The idea is to cut the vacuum function out of the circuit when the return line is cool, thus preventing the vacuum pump from running  when no condensate is returning.  The unit would still operate off the float switch(s) to return any condensate that does come back.



The setting was around 90 or 100 degrees F. 



I don't like this arrangement because vacuum pump operation should not depend on condensate temperature, but outdoor temperature.  I would much prefer an outdoor thermostat used instead. 



For either arrangement, it's best to have an override switch for the 'stat when you want to test the vacuum pump's operation.

Xray

Just a One-Pipe

That sounds more logical than what I'm seeing.  This is just a one-pipe gravity-return system, with the aquastat performing the function of a thermostat.  It's a Chicago thing--I don't understand.