What Do I Need To Know About Circulator Pumps?

[OverkillYJ]

Hi everyone. I have a circulator pump that is going bad. It is probably at 10%-20% of the expected flow rate at best. I think it may be undersized since a medium sized zone was added making a 2 zone system a 3 zone system. The failing pump is a Taco 1/25HP Model 007-F5.

So I am going to replace it this week, but I wanted to figure out if I should upgrade it. Since its an oil furnace I figure maybe if I get a better pump it will cost me more in electricity but save me more than that in fuel costs. Im not sure, thats why I created this post to ask people who know more about these than I do.

I would have pulled it to see if I could clean it out and get it to work for now, but I only have a shutoff valve on the return side, not the furnace side. I may add a ball valve when I pull this since I have to drain part of the system anyway.

Thanks for the help.

 

[Sumboodie]

You have a water circulator on a furnace?

 

[OverkillYJ]

Boiler, furnace, blah blah blah. That's your contribution? I have gas forced air furnaces too. Obviously this would be a boiler.

 

[American Locomotive]

What makes you think the circulator is going bad? Usually these cartridge circulators will make an absolutely terrible racket if they're going bad or just not work at all. Never really heard of one working 20%.

You can just replace the cartridge instead of the whole housing, by the way.

 

[dhally]

Really the only way a centrifugal pump like this can have reduced flow, is if the impeller gets smaller. That would be caused by erosion, corrosion, or a combination. Which means the fluid has grit or chemicals in it.

 

[jmiller_2308]

Unfortunately I don't know enough about fluid dynamics and thermal transmissions to quantify if your pump when in normal working condition is sufficient for however big your 3 zones are. However, I can tell you that my house uses the same version of taco pump as you have and it sufficiently runs 8 loops configured over 2 zones for about 2100 sqft of in floor heat so I suspect the pump is big enough if it is working well.

I also have another taco pump that hangs off the boiler that pumps to the air exchanger for forced air heating as well as to my indirect water heater.

In addition to looking at servicing your pump you should also look at any mixer valves you my have in your system. I have a honeywell mixer on my floor heat that I recently replaced the guts to because it no longer mixed well. After servicing it my in floor heating is now a lot better.

 

[Innovate1]

They make flanges that have ball valves built in. That's an option when adding a valve. Sounds like pulling the pump and looking things over would be a good first step. Since the system looks fairly old the issue might be other places. They publish performance curves for these pumps so if you decide to bump up the power you would need to estimate the flow and back pressure and then pick a pump that has a bit more flow and a little higher pressure. Measuring would be better but that involves more work and cost. Might be able to test the pump by itself with a bucket of water, a restriction on the output, a pressure gauge and a stopwatch to get flow per minute. I haven't had to mess with mine yet so I can't give more help. Just did a quick google search and there are a bunch of youtube videos on circulation pump testing. There are also forums more focused on these systems such as here:
https://forum.heatinghelp.com/discussion/83464/how-to-check-taco-007

 

[fitter30]

For a few dollars more pick up a Taco e series pump their more efficient. Pumps are not picked by flow rate alone. There is head pressure all so that has to be addressed.

 

[Jaguar Fan]

For a few dollars more ....

That's a classic Clint Eastwood Spaghetti Western from 1965. The trio of movies directed by Sergio Leone staring Clint Eastwood were "A Fistful of Dollars," "For a Few Dollars More," and "The Good, The Bad, & The Ugly."

 

[PoorUB]

A Taco 007 should be able to handle three zones in atypical home. Perhaps your pumps is going bad. Impellers will wear out and fail.

Unless you have some unusual situation I would put another 007 on it, but perhaps the 007e-ECM.

 

[rlitman]

Really the only way a centrifugal pump like this can have reduced flow, is if the impeller gets smaller. That would be caused by erosion, corrosion, or a combination. Which means the fluid has grit or chemicals in it.

Cavitation will erode impellers much faster than grit.

 

[kaymccampbell]

Pick out a nice Grundfos 3 speed pump. They fit exactly where the Taco is. Then you can adjust your pump speed to better match its environment.

 

[Innovate1]

Really the only way a centrifugal pump like this can have reduced flow, is if the impeller gets smaller. That would be caused by erosion, corrosion, or a combination. Which means the fluid has grit or chemicals in it.

Maybe that's the most likely - not sure that's even true. Could have bearing issues or motor issues that cause it to run at less than design speed.

 

[PoorUB]

Pick out a nice Grundfos 3 speed pump. They fit exactly where the Taco is. Then you can adjust your pump speed to better match its environment.

If he has zone valves that is the wrong answer. Most three speed Grundfos pumps have a steep pump curve. as the flow drops in the system, the pump pushes more pressure. The Taco 007 has a very flat pump curve. As flow decreases the pump doesn't produce much more pressure.

If there are no zone valves and all zones are pen all the time, then most any pump with a proper flow numbers will work.


And then on this link, a typical Grundfos curve,
https://hydrosolar.ca/products/copy-of-grundfos-pump-ups-15-58-fc-115v-3-speed

Pump curves, 007 is #5.

 

[Sumboodie]

Boiler, furnace, blah blah blah. That's your contribution? I have gas forced air furnaces too. Obviously this would be a boiler.

If it was "obviously" I wouldn't have asked.

I'm not an HVAC expert. Was not sure if you were wrong or it was some unique setup.

 

[ipgenie]

I've got a similar circulator on my boiler system. A few years ago it started making some noise so I popped a new cartridge in and it was good to go. I got a leak in the copper line and my BIL was helping me replace the tubing and he overheated the pump housing, melting the impeller a bit,so another new cartridge and its been working great since.

I'd do like suggested above and try a new cartridge first. Cheapest and easiest option and unless the added zone is just adding too much head pressure, you'll be good to go.

 

[fitter30]

Btu output rating of boiler and what are your heat emitters ( fin tube, radiator). 007 pump at 8' of head 10 gpm. Boiler water in and out should be 20° difference like the each zone. 20° is a normal design temp.