# circulator pump capacity - boiler strugglings to heat house



## joesat78 (Oct 30, 2010)

Hi everyone,

My old circulator pump (TACO 1/8 HP, pic attached) was leaking and the service person replaced it with a TACO 007-f5. The 2 levels on my house that I'm trying to heat is about 1300 sq feet

Now, my house is struggling to get heated. The hot water from the boiler is getting divided into both the sides of the house (same one zone). The right side is getting warmed up with no problem, but the left side is barely getting warm. The service person tried to bleed the water and said that there may be air pockets and when he left he said everything is fine. But, now, 2 days later, my boiler is struggling to warm the house. I very faintly feel the heat when I have my hand near the baseboard. This is happening on only one side of the house.

I'm thinking whether the new circulator has the same capacity of the older one? I'm no expert here, any help on sizing this would be very helpful. The new one says its 0-25 gmp and I'm unable to find the same for the older one (pic attached). Can anyone tell me what the older one's capacity is? Whether the service man replaced the right capacity pump?

Any help would be highly appreciated


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## Donl (Oct 30, 2010)

I'm no expert here, but I would think that replacing a 1/8th hp circulator with a 1/25 hp circulator will significantly reduce the flow. My guess is you need to use circulatror simular to the one just replaced.


Don


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## kabbott (Oct 30, 2010)

That looks like a 110 series taco... If so I believe they pump a much higher flow rate than an 007 but lower max head. You should be 
able to look up the data sheet on taco's web site.

I replaced my 1/8 hp taco with 007's and they pump more than enough volume for my baseboard loops.
What kind of heat emitter's do you have(baseboard, iron radiators, etc)?

It sounds to me like you may have air in one or both loops, that will slow or stop the flow esp on a two story system.


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## joesat78 (Oct 30, 2010)

Yes, I have a baseboard. Thanks for the info. Can someone please explain what the "max head" means? I can understand gpm, but max head goes over my head


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## joesat78 (Oct 30, 2010)

I went to TACO website and collected the specification sheet for both the old (assuming its a 110 series - sure, it looks the same) and the new. They both definitely looks different from the performance capacity perspective. Do the expert eyes here agree?

Even before the old pump was replaced, I did have air pockets in the loop, as I used to hear water rumblings as it flows through the loops, but I never had a problem getting the house heated.

New 007 Cartridge Circulator

Old Pump


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## kabbott (Oct 30, 2010)

Max head = basically the maximum pressure or "head" that the pump will produce. If you look at the spec sheet for the pumps you will see a graph of head vs flow in GPM.
If it is in fact a 110 there is not a huge difference in flow. Some info on what size, how long and if the baseboard is plumbed in series or scoop tee's etc may help 
the experts give you an idea if the 007 will work OK.

If you have air bleeds at the high points I would start there, Also make sure the system pressure is high enough to push the water to the high points.
Some times raising the pressure to 20-25 psi via a hose and boiler drain helps when trying to eliminate the air pockets.

It


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## bigburner (Oct 30, 2010)

sounds like you got AIR. The 007 is a great product. I always pressure bleed the systems we install. garden hose on boiler drain and push the water threw at 30 psi +/- and dump it out the other side [always add valves if they aren't there] I would be surprised if the system has to much head for the 007 & if it did there would be even heat, just cooler because of low flow.


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## joesat78 (Oct 31, 2010)

I'm including the pics of my whole boiler setup. 

Boiler
Domestic Water
Zones (problem in Zone 1)
Zone 1 returns (prob in return 2)
Valves for bleeding

As you can see in the pictures, I have 2 zones. I don't have any problem with Zone 2. 
I have 2 loops in Zone 1. Loop 1 is fine, but loop 2 is where the problem exists. You can see in the picture where the loop 1 and 2 joins and then it goes to the new pump. 
The baseboards in loop 2 barely gets warm. I could only feel the heat very faintly. I was thinking of the very nature of how loop 1 & loop 2 joins, the circulator pump is pulling return water from loop 1. Any theories?

Bleeding: I have 2 valves in Zone 1. The one in the top has a drain and this is what the service person used to drain. The second value (bottom one) doesn't work (so, I was told). He was increasing the pressure to 20 psi before draining them. I don't know how, if the second valve worked, would have helped bleed the system easier/better, but that's what he told me. Any advice on how I could do this myself would be very helpful.

Thank you and waiting for your guidance.


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## bigburner (Oct 31, 2010)

did you check at the base board and see if there are bleeders [called baseboard tees] they are almost always in the pipe coming up or going down at an end cap. use of a screw driver or tee handle will allow to bleed near the high spot. it still sounds like air.


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## benjamin (Oct 31, 2010)

You've got air.

Or maybe a valve stuck partly closed?  That's a gate valve that's labeled "not working" and those have threads inside that can get stripped causing the gate to be stuck closed, that would certainly reduce the flow.  Does that handle turn and can you hear any difference in the pump if it's closed vs open? Does the handle reach a full open position or can you keep turning the handle indefinitely, that is more than twenty turns? It might be possible to find a replacement valve (especially if that's a nibco valve) and swap out the innards  without soldering or draining the system completely.   

Most likely you're just having a hard time bleeding the air because you can't close that valve and flush that zone with a garden hose as others have described, and because there are two loops without seperate valves. The only ideas I have are fixing that valve and power flushing it, or if you're lucky you might find a bleeder valve somewhere in that loop, or install one.  Raising the system pressure also helps by making the air bubbles smaller.  

I wouldn't worry about the capacity of the pump unless the other black Grundfos pump is signifigantly bigger than the 007.  they're probably much better matched than the old taco pump was


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