Hot Water Recirculation

Injector?

Similar principle with the tee injector but somehow looks like this...

Somehow this does not gel. Whenever there is a flow to a branch and a return, there will be an accompanying pressure drop. This means that the return stream is at a lower pressure than the mains. No venturi can put this stream back into a higher pressure main as the second law of thermodynamics will be violated.

The only option is to feed it into the mains down stream where the mains pressure had droppped because of other branches along the way.

Bioramani

Just use trace heating: simple to install and change later.

This is probably NOT what you are looking for, but it is the only thing I have seen that resembles your description.

http://www.nibco.com/cms.do?id=2&pId=345

http://www.hotwaterlobster.com/

Saves water, but can raise fuel cost.

I think you are talking about this one, it's called a MonoFlow Tee

http://www.bellgossett.com/Press/BG-monoflo.asp

I don't know about using the "venturi" principle, but I have seen single-pipe loops with a similar fitting that does induce flow based on a scoop inside the fitting causing a pressure differential between the inlet and outlet.
If you are looking for extending hydronic heating water to new additional heating units, and have a one-pipe system, I would suggest the following for future:

1) cut into supply line and groove ends for mechanical coupling.

2) Install "Twin-Tee" fitting like the ones from TACO.

3) Install tiny wet-cartridge circulator pump sized for the capacity to match the load you are serving.

That has worked in every application I've had for several years now. In fact, it is the basis for my new designs using single-loop main lines for all WSHP and geothermal projects. Simple, works, easy to maintain, no balancing, cheaper than 2-pipe reverse-return, smaller main circulator pumps.

Aside: Spoke with some Germans once who use fittings like what you describe - big on saying "it's the delta-P, not brute force!" and they thought we all waste a lot of pump energy - but they also thought we all still do "direct return" loops. They did perimeter heating-only loops to reverse flow on a timed basis with a 3-way valve, so on those I don't think they use that same fitting - but it avoids having to up-size radiators and slab loops on the 'end' of a single-pipe loop, as the last will be first to see hot water on the next cycle.

my sincerest gratitude to you guys who given time to reply on this matter. I'm planning to use this on domestic hot water services for hotel. Also might see the benefit of using it in domestic hot and cold water circulation to minimize stagnation on the distribution system.

More power to all CR4 members.

I do not know about the fitting you are looking for or a gravity circulation system, but I have helped a commercial hotel achieve a hot water circulation system utilizing a small electric pump (Autocirc is the brand with which I am familiar- there are others). There are two possible styles, one installed at the hot water source, the other at the furthest point to which hot water is delivered. Since the hotel in question used electric hot water heaters (due to logistics issues, this proved the most economic), savings in water consumption more than compensated for the small additional cost of intermittent operation of the pump.

Hi ericpolc,

You mention this application in terms of a commercial venture ie hotel.

Watch out for 'Legionella' problems with the low DHW temperatures you are liable to get with what will become a ''gravity circulation'' sub-loop system. be especially aware of the possible proliferation of the LP bacillus in systems where the temperature remains below 60C at all times especially if you are supplying shower heads.

You will need to consider how to sterilise the system regularly either by water treatment dosing or pasteurisation to 60C+ for a minimum of 2 hours per 24!.

I would strongly recommend that you instal a return main and pump the whole thing it is really the only way to avoid dead legs with the possibility of a build up of the LP bugs.

The last thing you want is a case of that being set at your door, it won't do either your reputation or bank book any good!

Good luck.

Massey.