Isolation Relay for ECM Circulator Pump

dneubauer09

Last winter I had a contractor install a new NTI vmax boiler.
Along with that, he installed a Grundfos Alpha2 CH circulator pump, as our old boiler and plumbing relied on the boilers internal circulator pump. The new pump is wired to the boiler's CH pump circuit, so it gets power only when the system goes on.

I was reading the install manual (page 57 in link below) for the boiler today and it states that if you use an ECM circulator pump, you need to use an isolation relay or you'll burn up the boilers control relay.

I am 99% sure the contractor didn't install a relay, as he didn't even install the pump until I insisted he needed to.

Now I'm at the point where winter is coming and I don't want to wear out my boiler, so this isolation relay needs to happen.

I've done automotive wiring plenty and I know what a relay is and how to wire one, but I haven't done this on an HVAC system before.

What relay will work for this purpose?

Thanks everyone!

Edited for clarity.
Link to manual:
https://ntiboilers.com/wp-content/uploads/2018/12/Vmax-Installation-and-Operation-Manual-pn-85171-1.pdf

GW

Hopefully an NTI guy will chime in, but as a general heating guy, what you describe makes no sense. Maybe you mean additional circs? 

dneubauer09

GW said:

Hopefully an NTI guy will chime in, but as a general heating guy, what you describe makes no sense. Maybe you mean additional circs? 

See here, page 48, the CH pump.
https://ntiboilers.com/wp-content/uploads/2018/12/Vmax-Installation-and-Operation-Manual-pn-85171-1.pdf

Page 57 also has the notice about ECM CH pumps, which I'm pretty sure the Alpha is.

Zman

I am thinking that NTI has a design issue on the board that has issues with ECM's.
One of these, or any relay with a 120volt coil would do the trick.
https://www.supplyhouse.com/Tekmar-004-Relay-120-V-ac-coil-7924000-p?gclid=CjwKCAjwpMOIBhBAEiwAy5M6YFOj2Ix5DzxQQ2rrxVIgHs7TQAKgdGeLVeuUkx19iWLILB4v-481ZhoCn4gQAvD_BwE

Dave H_2

I am not sure of the models of NTI boilers that need this but here is a simple relay that is used most often for circulators.

So I have run into this before (check with NTI for more details) but ECM circulators have a higher in-rush current when starting (go figure since they are so energy efficient) and it has caused a safety relay on-board the controller to trip.

The higher in-rush current is for starting purposes when a circulator is sitting for long periods of time. Their AC cousins have an on-board capacitor to take of it.

I hope this helps, enjoy.

Dave H.

hot_rod

Do you have zone valves? Is so the pump could be placed in auto adapt mode and plugged into a receptacle, powered constantly.

dneubauer09

hot_rod said:

Do you have zone valves? Is so the pump could be placed in auto adapt mode and plugged into a receptacle, powered constantly.

Yes, I have zone valves, so that would probably work just fine.
This is probably the easiest solution, actually.

If I'm not mistaken, couldn't I just rewire the circulator pump from the CH pump circuit to the boiler's 120v line voltage input? That would eliminate needing another outlet and be minimal rewiring, since it is just moving the hot wire 3 terminals down.

dneubauer09

Dave H_2 said:

I am not sure of the models of NTI boilers that need this but here is a simple relay that is used most often for circulators.

This relay seems to have much more going on with it than I am expecting.

I have 2 zones.

Right now my thermostats are wired directly to the zone valves in parallel with the boiler to trigger it to turn on.
Seems like with this, the thermostat would go to the relay, the relay would tell the boiler to turn on.
Then the relay uses the 120v output of the boiler circulator pump circuit to trigger the relay to turn on the 120v to the ecm pump?

Seems rather complicated and perhaps I need 2 zones, not 1?

mattmia2

Just a RIB relay with 120vac coil 120vac contacts would do it for you. RIB is a brand of relays with flying leads designed to mount in a knockout, makes mounting and wiring simple.

Zman

mattmia2 said:

Just a RIB relay with 120vac coil 120vac contacts would do it for you. RIB is a brand of relays with flying leads designed to mount in a knockout, makes mounting and wiring simple.

You probably want a relay with a 120-volt coil so the boiler will maintain control and DHW priority functions will be maintained.
RIBs are great for your application.

Dave H_2

UPDATE - UPDATE - UPDATE

Had a conversation with NTI engineering in regards to connecting ECM circs directly to the boiler controller.

The recommendation (not to connect an ECM pump directly to the boiler) came from the circuit board that was used in our Tx, FTV and Vmax boiler series, which by the way are no longer in production.

All other (including future) NTI product series allow for direct connection of ECM pumps to the boiler.

If you are not sure which model you have, I would get in contact with NTI representatives and/or NTI directly.

Enjoy