Install pump in wrong location, need advice on where to put it

[blackdoglabrador]

So I thought I was good to go. Just finish 600 feet of radiant (loop feed by new green taco zone valve in photo) and went to fire it up, but when I opened the zone valve no flow through that loop (just a momentary flow for a minute), that's when I realized you can not put a pump before the mixing valve (my mixing valves think there is a failure on the cold supply and they close of the hot)..

I am using a primary secondary set up with grundfos alpha on the secondary supply feeding six zones (two only used now). So as you can see in the photo I put the alpha pump first and that feed the header. The header has zones valves (only two installed as of now). After the zone valves I have mixing valves (one taco 5002 and one danfoss esbe valve), which allow me to adjust the temperature as desired. This is all been fed from a tarm innova 30 with 750 gallons of pressurized storage. I decided to mix at each zone because my zones all require varying temperature (i.e. indirect dhw, panel radiators, and under floor radiant). I decided to use the alpha pump because I liked the efficiency.

Well looking back I probably would of just went with circulators for each zone inlieu of zone valves but that ship has sailed. I am committed with what I have and need to make it work. Is it acceptable to move the alpha pump to the return side of the secondary loop? Instead of pushing water through the zones I would pull it? Would this solve my mixing valve shut down problem.

Or is there a easier solution?

Side note, My expansion tank is hooked up at boiler about 8 feet away from this mess.

 

[ewdudley]

Sorry, you can feed multiple zone valves with the same mix temperature with one pump pulling through the mix port of a single mixing valve, but you can't feed multiple mixing valves with one pump.

For now need to add a pump for each installed mix valve, longer term I'm afraid it may come to needing to rip it all out and start over, despite the nice craftsmanship!

 

[maple1]

Would it be any easier, 'for now', to just remove the mixing valve from the DHW circuit, and use just one mixer for your panel rads & in-floor? I'd think they would use about the same temp water. You'd still need to move the Alpha to the return side though. I really like the Alpha & think I would try to find a way to make it all work with just the one pump.

 

[stee6043]

I think the quickest and easiest thing to do would be to put your pump on the return side and a single mixing valve where your pump currently sits. Longer term you might be looking at some significant rework...

 

[blackdoglabrador]

Well a here is the new and improved model. Moved pump to return side, seems to be working okay.

 

[blackdoglabrador]

So that work good for about an hour and then the mixing valves closed. Only to assume that the valve thought there was failure on the hot supply??? So my last idea is to install a alpha pump after the mixing valve for each zone (and remove or unplug the alpha in the picture above). That should work right?

 

[maple1]

If one of those zones is for heating DHW, I would just take the mixer out of that zone. Typically you'd want to prioritize DHW anyway. Then put a tempering valve on the hot-out of the hot water tank so you won't get scalding at the taps. Then only use the one mixer for your heating zones (unless you have both low temp or radiant, and hot water baseboard), which you should be able to accomplish with the one pump you have.

 

[heaterman]

There you go. Always pump away from a mix valve and you'll be good to go.

 

[blackdoglabrador]

Well here is take three on the plumbing redo. Took the advice above and install one central mixing valve after my dhw zone. And everything seems to be working (just need to rip out the individual zone valves when I get a moment, right now have them set to max temp). Thank you for the help.

 

[maple1]

That still looks off. So you put your pump back on the supply side so it's pushing to the mixing valve? Wait now - you don't have your DHW hooked up yet? Is that right? I was thinking your DHW was one of the zone valves that's plumbed in already. If those stubs I see are for DHW, I don't think this will work either.

EDIT: Or are you planning on adding another circ?

 

[blackdoglabrador]

The mixing valve is the just to the right of the pump (pulling water from mixing valve). The mixing valve is the black this with a digital read out on it that read 128 degrees (LK130 Smart Comfort Valve). The dhw is not plumbed yet (it is the two valves to the right of that mixing valve). Only is I have right now is that before the water reaches the mixing valve is cooling, but I think insulation will take care off (only drawing 1 gpm when my 600 feet of radiant is on).