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Recirc pump ~replace - do I need an unpowered relay?

A recirculator pump died - (I think condensation - it was circulating cold water when A/C was on - I think I have that under control).

Be gentle on me - I am not an HVAC installer, but I have worked with a lot of instruments, tools, etc. (experimental physics + fix everything at the house)

So I bought a replacement circulator, but when I got it home I realized that the one that I bought has no provision for a 24 control line like the one that died has. I bought a Grundfos to replace the Taco that died.

I am not sure but I don't think that I can even get a small Grundfos that has a relay built in? I have a ups15 35, a 1/25th hp pump.

So presently there is a 24v ac control line, that gets live when the system is calling for water to be circulated. So I need a relay. I looked at the Grundfos single zone UPZC-1, but it includes a 24v transformer.

I'm ok with buying it if it will work, but I think all I need is an unpowered relay? Is such a thing common? I don't want anything looking jury rigged. If the grundfos will work, I am fine using it? Is there some other part I could buy?

Any tips would be appreciated.



  • JStar
    JStar Member Posts: 2,752

    Aquastat, switching relay, dry relay...all just switches. You must have had a 120 volt line going to the old pump, right? What was the model of the old pump? You should have an aquastat of some sort on the water heater now, which will close a 24 volt circuit supplied by a transformer. That 24 volt circuit should close a relay to supply 120 to the pump.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,216
    what was the taco model #?

    Is this on a chilled water system?
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Tom_Andersen
    Tom_Andersen Member Posts: 2
    It was a taco 005 zf2 - cast iron

    First - thanks for the replies. I found some diagrams which show how to wire what I need. Them and a meter and a bit of head scratching and I will be good.

    It was the 'wrong' pump I think. The cold water that ran through it for only a few hundred hours per year, plus sitting in cool water for 3 months led to condensation ( I think) in the pump motor, and it froze. The impeller spun fine, but the motor had rust around the cartridge.

    There was another one sitting in a place that gets used about 2 min/year (my emergency propane heating). So I took it out and got the AC back up running quick. That second taco died after only 8 weeks on the job. It was identical to the first one.

    So the plan is to put a $100 cast iron Grundfoss in the emergency heat side, and put a more $ bronze one in the cooling loop. But it looks like I need to by zone relays too.

    I had a Taco wax based powered valve die on me last year, on inspection I found what IMHO was a glaring obvious problem. So no more Taco.

    My system is a 3 ton water to water ground source heat pump that heats the floors for 8 months of the year and runs 3 multiaqua chiller coils that are installed at the highest points in the house.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,216
    Sorry to hear your loss of faith in Taco

    I find them to be good products and I am happy to use them where they fit. Is this a closed system? 8 months says to me something is wrong aside from the pump.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • Joe Mattiello
    Joe Mattiello Member Posts: 639
    zone pump, and zone valve

    Sorry to hear about the products that failed; I’m not sure how long the pump was in service but the pump is covered under a generous 3 year warranty.  Taco products are certainly robust enough to last the 3 years, and in most cases under favorable conditions will last much longer.  An important attribute of the Taco pump to remember is the replacement cartridge assembly available.  Apparently, the cartridge was fine but the motor failed so that wouldn't have resolved your problem.   However, if the relay failed you could replace the relay board, or purchase a standard 005 pump and use a SR501 single zone switching relay.             


    The taco Heat Motor zonevalve is also covered under a 3 year warranty on the heat motor, and a whopping 5 years on the valve seat assembly.  That’s about as good as the warranty on my new caddy!!  Love that car!!  Anyway, I would reconsider condemning the taco products simply because you have a problem.  As you may know, you can purchase products for your application from anyone, but when you have a problem it’s an opportunity for the manufacturer to shine and help out with your issues. 
    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions
This discussion has been closed.