Where to put a mixer for radiant

Unknown

And thanks Hot Rod for the links , They explained it all in detail . Hey Scott , thats my new mantra - pump away from the mixer ......ALWAYS !


OK , before I practice my new mantra , heres a hypothetical . Well , this was a real situation . We were installing baseboard in a customers home because the old radiant failed . The boiler was under the stairs , and the customer had a new Weil Mclain under there , internal coil so it maintains temp , with one 007 circ and 3 zone valves above it , on the header . We connected our baseboard to where the radiant was disconnected ( no mixer on the radiant - no wonder it failed ) .

One of the 3 zone valves was a future zone . The customer plans on installing radiant in his den in the near future . He asked me if it would be easy to hook in radiant to this system . I pointed out that I was no expert in radiant heat , but I believe that the circulator has to be pumping away from the mixer first , and since the circ is the first thing off the boiler , it might not work . So then he asks me what would happen if another circ was added after the mixer - meaning ; boiler out , main circ , zone valve , mixer , then the new radiant circulator . Looking at his system , he needs a repipe of the whole header to install the mixer in the right spot . I thought about it a while last night , and was thinking that it should work as long as the main circulator didnt run with the radiant circ . But what would happen if both circs ran at the same time in this scenerio ? Just a hypothetical .

Unknown

I am finally getting around to my little project

I am installing radiant in my front wall using Wirsbo and Quick Trac . I am going to hook it in to the boiler using a simple mixer , a Taco 5000 series . I have a zone set up on the boiler already - supply goes from the top of the boiler through the circ and flowvalve . I have heard that the mixer should be before the circulator though . I mean , the circ should be pumping away from the mixed side of the mixing valve . My question is , what would happen if I pump right into the hot of the mixer ? Will it work at all ? Do I need to pipe a bypass around the mixer to purge it out ? If it won't work , is there a mixer valve made that will work in this situation ? As you can tell I'm trying to avoid a repipe of my boiler - it sits under the stairs and everything is a tight fit . Thanks in advance for any help . Ron

Aidan (UK)

You need...

two pumps, a primary (constant temperature) pump and a secondary (variable temperature) pump. The mixing valve should be upstream of the secondary pump inlet.

Pumping into the hot inlet of the mixer won't work. The inlet port would then be at a higher pressure than the mixed and cold ports, so the hot water would flow out of both the mixed outlet and the cold inlet ports.

Bill NTSG

RON,

If you pump into the mixing valve..........that taco 5000 is going to shut 100% when the water gets above your setting. You will get No Flow through 'yer radiant loop. You need the pump on your return from the zone towards the mixer. That way you can pump back through the zone or back to the boiler.

I would post a picture but I have a new computer and no pictures.

jose

radiant

Usually we put the flow valve at the boiler feed header, and mount the circulator on the mix out side of that taco mixer, so that the pump is pulling thru the mixer instead of pushing.

ScottMP

Allways

Pump away from the mixer.

Allways

Allways

Allways ( thanks HR )

Allways

Allways

Scott

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Bob Bona_4

always pump

away from the mixer, towards the system, or else the mix won't work. You can purge from the manifold..

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

hot_rod

Try this

link. The April 2003 article from PM Mag. A good explanation of the how and whys.

hot rod

http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,96144,00.html

hot_rod

Another link

as this is a common question, for connecting small radiant zones into a current boiler.

Have all these articles at your finger tips with the "Hydronics Know How" disc, from PM Mag

hot rod

http://www.pmmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2379,62497,00.html

Bill NTSG

Yeah But,

... I went to Stadler school long before I attended Wirsbo school. If you look at a Stadler station , or in their catolouge , you will see the pump on the return side of the loop pumping into the valve.

Let me back up a step and say, there is a difference between a mixing valve and a diverter valve. A quick definition; a mix valve has two inlets and one outlet, a diverter has one inlet and two outlets.

Stadler uses a diverter type valve , so that is why the pump is on the return of the loop pumping toward the valve. So I was not completely wrong in above post.

So , next , pumping on the return of the loop is not all that much different than pumping away from the mix valve. It is like pumping away from a boiler or on the return. We know both ways work. My pump is on the return of the loop pumping toward a tee which branches toward the cold inlet of the mixing valve and the run toward the boiler return. It has worked to perfection this way for almost 5 years. I think Sparco showed this method in their literature at one time.