Alright, I'll admit..................hb

heatboy

I can't figure this out. I hope one of you know how to apply a re-circulation pump/loop to a water heater (indirect, direct fired) that is utilizing a mixing valve on the domestic hot water outlet. I don't think it can be done and I would like to be proved wrong. The re-circ pump must use the mixed side of the mixing valve, but without any hot water be drawn, there is no way to mix cold water with the hot to attain the needed mixed temp for the re-circ.

hb

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Unknown

Would this work for you?

put a check valve in the cold before everything to keep it from becoming warm.

Noel

Jamie_6

we have used these in the past!

I like them because it's made for this application! I hope it helps.
Go all the way to the bottom of the page. THE SPARCOMATIC. You can get them to come with one temp. presets also.


http://www.sparco-inc.com/html/mixingvalves.htm

Jerry Boulanger

Here's a piping schematic that..

may help you. It is from the install instructions for Symmons thermostatic mixing valves.

Jerry Boulanger

This piping schematic might help.

It comes from the install instructions for Symmons thermostatic tempering valves.

It also helps if you leave some of the recirc piping uninsulated - that way the valve will always have to be letting ina bit of hot water. It keeps the valve working and the temperature more stable.

Mike Kraft

heatboy......

I've installed these with great success.No pumps no power easy install and it works.

cheese

http://www.nibco.com/newproducts/justright/

Daniel Paul_2

Mixing valve

Depending on what brand mixing valve your using and what size. The best valve, I think, is the Honeywell/Sparco. There bigger valves have a special port for the recirc line. On most valves though, tieing in the recirc to the cold side of the valve works fine. We set up the circ to run constantly. What ever you do dont tie in to the tank. The mixing valve can't temper the water down because there isn't any draw of water, and cant mix with cold water. I beleive installing a check valve will stop thermal expansion and you will probably need an expansion tnak for potable water. We don't usually use the check valve and everything works fine. When hot water is used the cold water over comes the hot backing up into the cold

Danny

heatboy

How would ...............

the loop stay warm, Noel? Would some of the water go through the tank, via the cold inlet and some go back through the valve allowing the valve to react?

hb

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[Deleted User]

Close...

but I wouldn't put the check valve into the cold water inlet. It wouldn't do any good. It needs to be on the circ return. Also incorporate a ball valve and a purge cock to make sure the pump is completely wetted prior to starting it up. The three way valve will work fine. As its' sensor senses maximum temperature is reached, it will close down its hot port and open its cold port which still allows circulation to occur. As its sensor detects the need for more hot water, it will close the cold port, and open the hot port, therby diverting flow back to the heat source to wash more hot water out into the loop.

It will be somewhat herky jerky at first, but will eventually even out. Don't forget to incorporate a timer and an aqua stat on the return to shut the system down once hot water has made it back to the source.

Here's Noels picture modified.

It's essentially the same thing as a closed loop staple up system except that the pump is a LONG way away from the 3 way valve. All the same principles apply as for mixing operation is concerned.

ME

[Deleted User]

The just right works great....

provided that the mains and distribution are above the storage tank. If not, the movement of hot water is limited to what the venturi tee can pull during a draw.

In situations where the tank is higher or on the same floor as the distribution mains and return, little to no gravity flow will occur. You need good height to make these sytems work right. But you are correct, where porperly installed, they work great. Smile and say CHEESE!!

ME

Al Letellier

Recirc with mixer

Use the right tanks and they give you a tapping directly into the tank for the returning recirc water. Saves a lot of work and fittings. (Phase III and Weil Plus tanks amongst others)

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Steve Eayrs

I think the guys are talking about...

when you are using a 3-way mixing vlv. You can't run it straight back through the tank w/ a mixing vlv. If you do, you will be getting 100% from the tank. The whole idea of a mixing vlv is to be able to run the tank hotter than what you want coming out of the tap.
Steve

opps! this should be down below the next message.

Chris Maderia

Here's a piping diagrham

Just had a customer having the same problem this is what we did.