What's The Difference

Owen

What's the difference between a condensate pump return and a boiler-feed pump return on two pipe dry return?

Jamie Hall

It's in the control.

The condensate pump system is controlled by the level of the condensate in the receiver; when there is enough of it, it switches on and pumps into the boiler.  Whether the boiler needs it or not.  The boiler feed pump, on the other hand, is controlled by the level of the water in the boiler, and switches on to feed from the receiver -- whether there is any water in the receiver or not.



Both of them work, after a fashion.  In a perfect world, with no leaks etc. etc.  In either case you must have both a separate LWCO -- at least one -- and either a conscientous operator who checks the boiler water level regularly or an automatic feeder.  The condensate pump is more likely to flood the boiler than the boiler feed pump system; if you have to have either one, I'd take the boiler feed pump.



Neither one goes on a dry return, for obvious reasons, although the dry return may  feed into the receiver.  The receiver is, by definition, wet.



The real question, on a two pipe residential steam system, is why have one at all?  Unless there is something seriously wonky with the rest of the piping, it shouldn't be needed.

Owen

The Question...

was ill-timed. I'm studying Dan's "Lost Art" book and had my question answered in the book not long after I posted it.

I work at a school dist. and there are five steam systems of seven that have more than one receiver. The biggest has six. Some of them could be eliminated by re-piping. Dan's concise explanations make it possible for me to get somewhat of a handle on this crazy stuff. And it's fun. I love the obscurity (exclusivity even) of the knowledge to be gained.

This receiver/feed pump stuff is excellent because I've got al kinds of funky stuff going on with all these tanks. Real head scratchers. The books can provide a real "AHA" experience.

Jamie Hall

Steam heat is fun, isn't it?

and as you say, it's also kind of neat to be in possession of somewhat out of the way knowledge!



On the other hand, working for most school districts is no fun at all these days...



It's not uncommon to need receivers and either boiler feed pumps or condensate return pumps in bigger systems; the problem being that gravity, while very reliable, can sometimes be very slow also.  On the whole, I prefer boiler feed pumps, as there is much less possibility of messing up the water level in the boiler.  If the receiver tanks are nice and large, and any makeup water which may be required is fed into them, it's mostly a matter of making sure that all the controls and pumps are running properly!



One thing which I can't remember whether Dan mentions or not is that one does want to make sure that the water in the receiver isn't too hot, or that if it is hot that the pump(s) is (are) correct for the application.

nicholas bonham-carter

some systems needing both types

i think if there was only 1 boiler which fed an out-building as well as its own building, that both types would be needed. the out-building would have the condensate tank and pump, which when full, would pump the condensate back to the boiler-feed tank in the boiler room. that could be a chore to diagnose in the event of pump failure!--nbc

Owen

Ask And You Shall Receiver Tank

At the High School, there are, (i'll have to make sure of the types) six receivers.

Five are (I think) condensate tanks and one is a boiler feed pump, the last one in the boiler room which I, proudly, installed. Four of the six pump daisy-chain style to the feed pump, one, in the boiler room, directly into the feed pump tank.

Right now it all works ok, except for lots of weird "What the heck is that sound?" moments.

Or "Why's it doing that?"