Variable Speed Circulators

salisboss

I have a Taco circular pump on the return side of my three zone hydronic system. Do Taco pumps have adjustable speed (not sure of the right term) to try and minimize the head pressure issues caused by pumping into the boiler?

Jamie Hall

Not quite sure what you mean by "head pressure issues …". The total head loss seen by the circulator is determined by the piping and the flow rate, and it doesn't matter one bit where the pump is on the circuit. It could be anywhere. What does matter is where the pump is located with respect to the expansion tank -- not the boiler -- and that the tank be close to the pump inlet and that the flow be away from the tank.

Any other arrangement runs the very real risk of the pressure out in the system or at the pump inlet dropping too much -- quite possibly even low enough to cause cavitation in the pump, which will destroy it remarkably rapidly, or sucking air into the system particularly at higher points.

In direct answer to your question, yes, most newer Taco pumps are variable speed.

salisboss

Thanks. My pump is on the wrong side of the tank and I don't have enough pipe into my air scoop so I am getting air every few weeks this year (usually one purge a year is good). I was hoping to slow the water down through the scoop to hopefully get it to actually remove air because it isn't. My auto air vents keep filling with water and not doing anything

SuperTech

> @salisboss said:
> Thanks. My pump is on the wrong side of the tank and I don't have enough pipe into my air scoop so I am getting air every few weeks this year (usually one purge a year is good). I was hoping to slow the water down through the scoop to hopefully get it to actually remove air because it isn't. My auto air vents keep filling with water and not doing anything

I would definitely correct the expansion tank location. Buy a microbubble resorber and use that instead of the cheap air vents that are prone to failure. Install it on the supply with the circulator pumping away from the expansion tank.

hot_rod

Most all of the circulators on the market now have multiple speed settings or variable speed functions. We have the widest selection of circulators available since the beginning of mankind.

Ideally you would want to know 3 things to size properly
Fluid type and temperature
Required flow rte in GPM
Feet of head

Head is maybe the most confusing, I think of it as the resistance to flow that the piping, heat emitters, boiler, everything in the circuit presents to the flow.

The more flow GPM you try to push thru a system the higher the resistance, head.

You would first define the heat load of the system, then the type of heat emitters, then size the circulator to that requirement.

You could gauge up you current system and determine what flow you actually have, Idronics 16 will show you how to do that also.

I agree your best approach would be to change the relationship between the expansion tank and circulator. Add a more efficient air separator while you are at it.

https://www.caleffi.com/sites/default/files/coll_attach_file/idronics_16_na_0.pdf

salisboss

> @SuperTech said:
> > @salisboss said:
> > Thanks. My pump is on the wrong side of the tank and I don't have enough pipe into my air scoop so I am getting air every few weeks this year (usually one purge a year is good). I was hoping to slow the water down through the scoop to hopefully get it to actually remove air because it isn't. My auto air vents keep filling with water and not doing anything
>
> I would definitely correct the expansion tank location. Buy a microbubble resorber and use that instead of the cheap air vents that are prone to failure. Install it on the supply with the circulator pumping away from the expansion tank.

Setting my system up to pump away is my summer project for when I can turn the heat off. Just trying to get by until then.

mattmia2

You should still eventually get rid of the air. Something is leaking if you keep getting more air(and that will corrode other things with the oxygen that new air and water bring)

Dave H_2

If you have a current 007, there is no way to change the speed.
The newer 007e does have that capability, but it does it automatically, you don't have to adjust it.
The 0015 has a selector switch on the outside with three settings; low, medium, and high. Same with the newer 0015e3.

Dave H.

salisboss

> @mattmia2 said:
> You should still eventually get rid of the air. Something is leaking if you keep getting more air(and that will corrode other things with the oxygen that new air and water bring)

I have been looking for leaks constantly with no success. It's so frustrating.

hot_rod

In some cases when you are pumping at the PONPC you can pull a sub atmospheric condition in the piping circuit. Any auto vents, loose valve packing or seals can allow small amounts of air into the system.
With an inefficient air eliminator, you may not get and maintain a completely air free system. The old scoop vents struggle with micro bubbles to begin with.
With improper piping, the deck is stacked against good air removal.

Increasing the fill pressure a few pounds can sometimes help with a chronic air problem, expansion tank pre-charge would need to be adjusted also.