Constant Circulation Piping Layout

Amovida

Hello. Thanks to everyone in advance for anyone willing to take a look at this. I have been working on my layout for my CU3A boiler and 79g Viessmann indirect using Runtal radiators (roughly 20) of them for our retrofit for our 1880's home in Boulder, CO.

I think I have it figured out and I have spent time thinking about the location of the check valves? I wondered if the Quicksetters on each manifold branch are a good/helpful idea or should I scrap them?

Certainly would appreciate any input regarding the layout and any mistakes I may have made. Thank you

HydronicMike

I only see the need for a check valve with the indirect. The other 2 aren’t needed.

Seems like you are splitting to only two manifolds. If properly sized you can ditch the 2 main circuit setters and put balancing/flow valves on each circuit in the manifolds.

Amovida

Thanks Mike…appreciate your response…I will have balancing/flow valves on the manifolds…I had thought it might make sense to have the quicksetters if you needed to balance the individual branches (to each manifold)…but it sounds like that is not the case and the manifolds flow valves are sufficient.

My current system has a lot of ghost flow from a poorly designed layout so I am particularly not wanting to repeat that ****storm (hint: it's not snowstorm ;)

I was planning on using Viega check valves….I probably need to look up their head/pressure drop. Here is my updated layout if anyone else would be kind enough to comment.

Screen Shot 2025-04-25 at 3.06.30 PM.png

hot_rod

a check after each circ should be adequate. Caleffi has a union style serviceable check, high Cv. Delete the Quicksetters and use a nice check😀

It is common to run a wide 30-35 delta in panel rads, you want low return to get in condensing mode. Running outdoor reset I suspect?

No need for a delta T circ on the indirect, give it all the gpm you can for fast recovery

Amovida

@hot_rod Just to make sure I have it right…delete the extra check valves…then put one after each circ…maybe the 3047 you have above or a Viega….and then delete the quicksetters and done….or replace the quicksetters with a check valve also?

Also: High GPM…no Delta T circ necessary on the DHW. Copy.

Yes on outdoor reset.

hot_rod

I prefer to see the checks about 6-12” downstream from the circs.

You could check the return side of the indirect, if you are concerned.

The pumps with internal checks are an option, but the checks take a beating in that turbulent flow right at the pump discharge.

I’m thinking this is that low pressure drop Viessmann? If so the expansion on the return is fine.

Amovida

Thanks @hot_rod The Viessmann manual shows the expansion tank coming off the dedicated fitting on the back of the boiler located near the fitting for the return. I'm guessing that is sufficient?

Is there any harm in throwing in a couple extra checks (other than cost)….I'd really like to pipe it just the once and eliminate ghosting.

hot_rod

I think the TRVs will prevent ghosts in the heating loop also, should the checks not work

On the dhw, two checks S&R should do it