DHW recirculation

vr608

So, I'm looking at possibly investing in a hot water recirculation loop since we have problems waiting for hot water and tend to waste more than we should. I have a 1920s era house with the traditional trunk and branch system of hot water distribution, and I recently started looking into the Watts and Grundfos recirc systems. What I don't like is the tie-in to the cold water line, and I'm wondering if I could modify the setup somewhat by adding a dedicated return line off my longest branch back to my indirect.

Attached is a schematic of what I'm thinking about doing. Any reason why this wouldn't work?

Abracadabra

Don't see why not. add a check valve to the return line and make sure the piping is all insulated.

wcs5050

Dedicated return is the traditional way if you have good access in basement. Use a strap on surface mount close-on-fall aquastat L6006C1018 on return piping before tank to cycle the pump so it doesn't run 24/7. Smaller size stainless or bronze pump.

vr608

Thanks, I definitely plan on insulating. Is there a rule of thumb for pipe size? I was planning on using 1/2 pex.

JUGHNE

If you search this site for "Hot Water Faster" there is some discussion about what you want. Even a simple solution that may work in your case.

vr608

wcs5050 said:

Dedicated return is the traditional way if you have good access in basement. Use a strap on surface mount close-on-fall aquastat L6006C1018 on return piping before tank to cycle the pump so it doesn't run 24/7. Smaller size stainless or bronze pump.

Thanks, I am definitely concerned about how often the pump is going to run, so I'm definitely going to go the aquastat and timer route.

JUGHNE said:

If you search this site for "Hot Water Faster" there is some discussion about what you want. Even a simple solution that may work in your case.

Thanks for the search terms, I had difficulty finding the most useful articles, was using less efficient search strings I suppose.

JUGHNE

Hot Water Faster was the title of a posting here not very long ago.

vr608

I actually did read that thread, it was pretty helpful. I was actually looking for more info on whether this could really work in my configuration, since the I'm that thread didn't indicate whether he had a trunk/branch system as well (or I missed it).

I suppose as long as there is a secondary route for the water to flow back to the tank via the pump I guess all should be well, I'm just worried about parts of the system not getting as circulated as the section closest to the loop. Having trouble understanding the fluid dynamics of it all.

SWEI

Code here requires 3/4" insulation on recirculating hot water lines. It's not that much more expensive than the 1/2" wall stuff.

vr608

Thanks, I'll keep that in mind regarding the insulation. I think 3/4 is definitely the way to go at this point. Problem now is sourcing a pump that doesn't cost an arm/leg.

wcs5050

I've had trouble on jobs with timer when power goes out... you then must reset it. Aquastat alone works pretty well. If your a tinkerer then resetting timer probably not an issue.

Dave H_2

If you are concerned with the timer and power outages, daylight savings, and keeping the run time down to a minimum. Take a look at the SmartPlus. All of that is built into the circ and is designed for return line applications with a trunk and branch.
SmartPlus

Dave H.

vr608

Yea, not as concerned with the timer, will probably go along with aquastat for the time being, cheap and pretty reliable without all the fuss.

My main concern now is choosing the correct pump, and where to mount it (before or after tank). Most of the off-the-shelf solutions like the Smartplus have the pump mounted atop the tank, and its not clear which option is the preferred solution.