Help me choose a new-fangled circulator pump (or tell me to stick with my 007)

[avc8130]

Since I'm such a tinker-er, my next thought is to attack my circulator pump setup.

Here is what I have:

My supply is 1.5" from the boiler. There is a Tee that has 2 ports: 1 1/4" and 3/4".
3/4": Indirect Hot Water. This has a dedicated circulator pump and Tees off BEFORE the heating zones to make a "priority loop" for DHW demand.
1 1/4": Has a TACO 007 circulator and feeds 5 heating zones through 5 zone valves.

My return is 1.5" into the boiler. The 3/4" DHW return feeds into the return first, then the 5 heating zones come in.

I am thinking one of the more modern circulators to feed the zones might make the system as a whole more efficient.

The question is: "which one?"

Grundfos Alpha:
ECM motor (supposedly much cheaper to run)
Delta P
~$160
I think this would adjust pump speed to maintain a consistent flow through the zones as the valves open/close based on pressure drop.

Taco Delta T:
Not ECM motor
Delta T control
~$160
I think this would adjust pump speed to maintain a consistent temperature drop from supply to return, adjusting speed as the zones open/close and the heating demand changes. One of my concerns is that I can't get an accurate "return" temp without influence from the DHW return. Would that be a problem? Will this pump cost more than the Alpha to run since it isn't ECM?

Taco Viridian:
ECM Motor
Delta P
Price: Unknown

Does swapping the circulator to a modern one sound like a good idea? If so, which one?

ac

 

[Clarkbug]

From those two choices I would say the Alpha. The ECM motor is nice, and the Delta P would be useful given that you are set up with zone valves.

 

[mikefrommaine]

I would say the alpha is a good choice for the 5 zones. It will vary its speed depending on how many zone valves are open. And the taco delta t for the dhw it will slow down to give you the desired delta t across your dhw coil.

That being said I've got a bunch of standard 007's in my system which I the tinkerer in me would like to change but it would take 20 years to save enough in opereating costs to pay for the upgrade.

Your payback may be quicker, ecspecially for the heating zone loops. I have 6 zone pumps that only run ~6 hours a day during the winter.

 

[avc8130]

I would say the alpha is a good choice for the 5 zones. It will vary its speed depending on how many zone valves are open. And the taco delta t for the dhw it will slow down to give you the desired delta t across your dhw coil.

That being said I've got a bunch of standard 007's in my system which I the tinkerer in me would like to change but it would take 20 years to save enough in opereating costs to pay for the upgrade.

Your payback may be quicker, ecspecially for the heating zone loops. I have 6 zone pumps that only run ~6 hours a day during the winter.

I wasn't planning on changing the DHW circulator for now. It is a little tiny thing and should have been easy to size for the proper flow.

The 5 zones are my main focus. My 007 runs quite a bit. I have never logged it, but it is not uncommon for there to be at least 1 zone calling for heat. During the evening/night I know that goes up to 2-3 and possibly 4 often.

ac

 

[mikefrommaine]

That's where an alpha shines. Right now when only 1 or 2 zones are calling for heat your 007 is probably moving more water than is needed. The alpha would modulate its speed and use less electricity. If you find only 1 or 2 zones are calling at a time for most of the day than the savings could quickly pay for the pump.

 

[Jeff S]

A 007 uses approx 85 watts per hour(120v x .72amps ==86.4 watts) and in my area I pay approx 12 cents a kilowatt so even if the circulator ran constantly it would cost about $7.50 a month.(86.4 watts x 24 hrs x 30 days =62.2 kilowatts) - (62.2kw X $0.12 = $7.46). realistically it does not run all the time so maybe $3 - $5 a month and this is only during the winter.Perhaps if I needed a new circulator I would consider a more efficient one but I don't believe I would replace one to save a few cents per month.Not trying to discourage you from being more efficient just my take on it

 

[heaterman]

The zone valve side of the system is ideal for a VS circ like the Alpha or the Wilo Stratos.

 

[avc8130]

A 007 uses approx 85 watts per hour(120v x .72amps ==86.4 watts) and in my area I pay approx 12 cents a kilowatt so even if the circulator ran constantly it would cost about $7.50 a month.(86.4 watts x 24 hrs x 30 days =62.2 kilowatts) - (62.2kw X $0.12 = $7.46). realistically it does not run all the time so maybe $3 - $5 a month and this is only during the winter.Perhaps if I needed a new circulator I would consider a more efficient one but I don't believe I would replace one to save a few cents per month.Not trying to discourage you from being more efficient just my take on it

Yeah, this is exactly my concern. I plan to monitor my circ pump for a month to see just how much it is running and then make a decision from there.

ac

 

[BoilerMan]

I'm going to side with Jeff on this one. I'm an electrician, and my wife has been known to call me the energy Nazi.......... (trust me the Kill-A-Watt meter, and my calculator are always figureing, and my electric bill is never over $35 even with $.14/Kw)

A plain old 007 is cheap-off-the-shelf and there are a bunch of places that stock them, even Lowes has them, so you can get one on a Sunday if needed. The Alpha or Stratos, do save electricity, and don't get me wrong I have LED lights in places in my house, but the cost of the unit vs electricity saved on a residential system may not be worth it. Now if you had a zone by circulator setup, just be going with ZV and a single circ would be the way to go (VS circ or not) Also, Taco makes more energy efficient ZVs electronic motorized ball valve, but again, if it were a new install, and not replacing something that is perfectly good........... If you were off-grid and wanted a boiler system, then it would be a whole different story.

TS

 

[Jeff S]

That sounds like a great experiment,I may hook up a kill-a-watt to mine and do the same so I can get some more hard numbers

 

[BoilerMan]

A kill-a-watt and a 120Vac hour meter are useful and dangerous tools for we tinker-ers.

TS

 

[Jeff S]

It was one of the best $20 I ever spent.

 

[Pat53]

That's where an alpha shines. Right now when only 1 or 2 zones are calling for heat your 007 is probably moving more water than is needed. The alpha would modulate its speed and use less electricity. If you find only 1 or 2 zones are calling at a time for most of the day than the savings could quickly pay for the pump.

Ditto for the Alpha. I run my Alpha for 3 zones and even when 2 are calling for heat its using a grand total of 8 watts and moving about 3 GPM. I pay almost 20 cents / Kwh so it really makes a difference as opposed to 3 Taco 007's going. I paid about $200 for it 2 years ago and I figure it has just about paid for itself by now.

 

[BoilerMan]

Wow, 20cents/Kwh.......Ouch! ours was 16.8cents, but has dropped to 14cents. I also think of the heat gererated by the pump itself as not a loss, but heat that is delivered to the house due to it being in the beulding envelope.

TS

 

[heaterman]

There is a factor that is often overlooked with delta P circs and that is the ability to dial in a decent temp drop by circulating less fluid. From a hydronic point of view this to me is at least as important as the reduction in KW used. Any boiler, gas, oil, pellet, wood, nuclear or whatever you are running, will deliver higher efficiency with a nice fat Delta T as opposed to generating maybe a 3,5 or even 10 degree drop. I have seen this happen on every installation we have used a VS pump.
Any system will "work" better with a 20* drop compared to a normal situation which will usually be in the 5-10*F range. I am constantly shocked by the amount of heat that can be transferred with a higher temp differential and lower flow rates and have come to the conclusion that most systems are drastically over pumped.

 

[maple1]

heaterman, not sure exactly what you mean - are you recommending a delta T pump over a delta P?

 

[avc8130]

heaterman, not sure exactly what you mean - are you recommending a delta T pump over a delta P?

I second this question.

ac

 

[Mike Hippert]

I think what heaterman is saying is because delta P circulators will run at a lower flow rate then a standard circulator does due to its ability to adjust for load based on pressure you end up with a higher delta T. Take my house for example, with the Taco 007 pushing against 5 feet of head on the first floor it is pushing about 16 gallons a minute! The return temp into the boiler is only slightly lower then the temp going out. But my Grundfos Alpha on the same zone will only push 2 gallons a minute giving me more then 20 degree of delta T and with a greater delta T everything runs more efficiently.

 

[maple1]

I think that's also what delta T pumps do? Except maybe more directly as they measure temps, rather than sense pressure differentials.

Personally, I had been wondering if I should have sprung for a delta P pump this fall rather than the regular 15-58 I did get for my zones, but that was before I learned of delta T pumps - so now I'm wondering if a delta T pump would be the better choice yet again for zoning with one pump & multiple zone valves.

 

[Bob Rohr]

I think that's also what delta T pumps do? Except maybe more directly as they measure temps, rather than sense pressure differentials.

Personally, I had been wondering if I should have sprung for a delta P pump this fall rather than the regular 15-58 I did get for my zones, but that was before I learned of delta T pumps - so now I'm wondering if a delta T pump would be the better choice yet again for zoning with one pump & multiple zone valves.

I'm not sure if all of the delta t pumps on the market are ECM technology? So if energy conservation is part of the goal, look for a circ with an ECM motor.

I don't think Delta P and delta T circs are always interchangeable. They are both intended for different conditions.

 

[Mike Hippert]

I am not 100% sure but most delta T pumps are still not as efficient electrically (I don't think there are any ECM Delta T other then the Taco Bumblebee that may not even be available yet), and they may still push the water to fast for the pipe. I think when they first come on they ramp up to a high flow and then slow down as the delta T approaches it's set point in the pump. Not bad for the boiler but you can still have high flow rates in the pipe or possibly too slow of a flow rate.

I think the Delta T pumps are suited for particular situations, while the Delta P pumps are great whenever you are using one pump for multiple zones or need low power consumption. The Alpha is great, I can tell you how many zones are open in my house based on how many GPM it is pumping. I love it, 1 pump that easily handles the near 200 foot run to the wood boiler and the the 3 different zones (short run to the water heater, and one zone for each floor of the house)

 

[heaterman]

Answers to a couple questions above.........

Delta T vs Delta P; I guess the simplest way to put it is that in nearly all cases Delta P corresponds to Delta T. If you drop the head (P), which usually corresponds to GPM, the temp differential will also change. The less flow, the more temp differential you can generate.
On a commercial job we removed a 3HP Taco 1900 series pump that was rated 70 GPM @ something around 65-70' of head and replaced it with a WIlo ECM pump that would do 40' head maximum. I knew the zone was severely over pumped because with all the heat emitters on we only saw a temp difference of about 5*. We piped up the Wilo and started dialing it in to achieve a 20* temp drop from supply to return. When we finished the process, everything was getting sufficient flow at a head of only 23' and our temp drop was a nice 18-20*. The Wilo used less than 1/10th of the KW the Taco did.

As others have mentioned some of the Delta T pumps on the market are not true ECM motors. The Wilo and Grundfos are. As such, those pumps are not able to "idle down" to the same level that a true ECM will.
Bottom line recommendation for me in almost every multi zone application is going to ECM.

One other factor that should be considered when the topic of per KW costs are "on the radar" is that about 200 coal fired power plants have been or are in the process of being shut down here in the US. Virtually everyone I have spoken with that works in the power production industry has told me that we can expect a 20-30% hike in electric costs on our monthly bills. This is just a fact of life as nothing has as low a cost per MMbtu as coal.
Remember to send a Christmas card and a thank you to our boys and girls at the EPA and in Washington DC for that.

 

[maple1]

Very interesting.

I now find myself kind of regretting the day I picked up the 15-58 at the supplier a few months back - after eyeballing & passing on the Alpha on the next shelf.

Oh well - an upgrade for next year maybe?

 

[BoilerMan]

I'm still curious about the total Kw useage vs. the money saved on electricity and the extra $80 for the pump, assumeing that they both last the same amount of time, which only time will tell.

Now, on a large commercial job, with huge pumps, yes I can see the huge energy savings, but a small residential job with an 80watt pump to begin with vs. 20-60watt I'm not seeing it. AVC let us know when you have run it a good amount of time with the Kill-a-Watt hooked up. This has really got me thinking, as I'm skeptical with small jobs.

Also, my boiler has a min return temp of 149F, so if I used a delta T pump set at 20F, I'd have to keep the boiler at 169F minimum and be right on the ragged edge on the return temp condensing. If I over pump that loop with a 10 degree delta now at a 169F boiler temp I get a 159F return temp. I've wondered about this for awhile actually.

TS

 

[maple1]

BTW, my comments aren't based just on electricity consumption - although that is important to me. They also come from just thinking about proper zone flow from when 1 zone valve is open, to when 5 are open, since I only have the one load circulator. Everything seems to be working OK the way it is (we've never been warmer), and I have yet to wire up my thermometers on the supply & return headers to see what they're actually doing.