More efficient alternative to Grundfos 26-99 FC

gmenounos

I have a forced hot water heating system that uses a Burnham Alpine condensing boiler with 2 zones (Amtrol BoilerMate for hot water and radiators for heat) and an outdoor reset. My home electrical usage goes up a lot during the winter heating months and I think it's due to the pumps. Having an outdoor reset may save gas by lowering the water temp, but it seems to use a lot of electricity because the lower temperature water needs to constantly circulate. When the Taco 007 pump on the BoilerMate loop failed, I replaced it with a Taco 007e high efficiency pump so that should help a bit. The other secondary loop pump is a Taco 007 and I plan on replacing it with a 007e before winter. The last pump is a Grundfos 26-99 FC (medium speed) on the primary loop. Does anyone know of an equivalent high efficiency pump? I see that Grundfos makes an ALPHA2 26-99 pump but it has quite a few different modes and I'm not sure which one, if any, matches the 26-99 FC.

Big Ed_4

I believe Taco 0015 3 speed on high is equivalent to the 26-99 on medium ...

Alan (California Radiant) Forbes

Which model Burnham Alpine do you have? You may not need such a powerful pump. The chart at the bottom shows the recommended pump for your boiler.

The Grundfos Alpha series won't help you if you have just 1 zone of heating, but a ΔT pump (Taco) may.

But we're talking apples and oranges here, You need a powerful pump on the primary loop to provide the proper flow through the boiler. The smaller, ΔT pump would go on your secondary piping to your heating system.

Personally, after looking at the data, I think you're stuck with what you have.

EdTheHeaterMan

@hot_rod is the one who will know which Alpha pump will best suite your needs. The primary loop has the expansion tank on it. If the expansion tank is on the boiler loop, then the boiler loop is the primary, If the expansion tank is located on the system loop then the system loop is the primary.

So to be clear I might suggest that you call the pumps by names like System circulator DHW circulator, Boiler circulator and so on. If you are saying that the system circulator is the 26-99, then a temperature differential pump might be your best choice. If there are zone valves on your system loop, then a pressure differential pump might be better.

Can you provide more info about your system? Is it just one sone with one thermostat? Are there different zones? Is it mostly cast iron radiators that were installed before 1950? Is it a one pipe Monoflo® or diverter tee system with convectors on the walls. Is it a series loop baseboard system. Is it a combination of systems?

The type of system will determine the type of ECM pump to purchase.

hot_rod

As @ Ed mentioned you need to know which boiler model and the boiler loop piping.

Either of the new Alphas UPS E or Alpha 15-58, may just make it if you have the smaller boiler.

Big Ed_4

If the flow rate is incorrect , the boiler will drop out on error .

Teemok

If you have a simple primary /secondary setup with two 007e zone pumps. Your boilers pump should meet minimum flow for that model boiler. If economizing electricity you want the boiler pump to closely match or be less then the flow of the zone pump while still meeting min. flow. I assume the indirect DHW tank has priority. So just one pump is one at a time. If fast DHW recovery is wanted over efficiency the boiler/primary pump should flow the same or exceed what the DHW pump does with your tank and piping. If all you have is a 007e for space heating I'm guessing it's a smaller alpine. Piping and any valves CV's should be taken into account estimating flow rates. An 007e might work, a Taco vr1816 or alpha might give you the flexibility to match the zone pump flow closely for the smallest alpines. Sometime you can't match boiler flow and zone flow and you live with that. It's hard to say what's right with no boiler spec. and design info. 26-99 might be over kill but you may have a big boiler that needs that flow.

gmenounos

The boiler is an ALP105 (installed about 14 years ago). The system has 1 zone for heating, controlled by a thermostat, and a second zone for hot water controlled by the BoilerMate (installed about 25 years ago). The hot water has priority so only one zone is active at a time. There are convectors in each room fed via diverter-tees from a single pipe that goes around the perimeter of the house (all installed around 1955). The expansion tank is not on the same loop as the Grundfos/boiler loop; it's on the larger loop just before where the pipe splits between the two Taco pumps.

Joe Mattiello

The 007-F5 has a .7 amp load which is probably not consuming a lot of electricity. You can calculate usage based on cost per KW and run time. DOE is pushing our industry towards higher efficiency products, hence the 007e, and many more ECM alternatives to PSC motors. Don’t just replace a pump for month, go through the exercise of calculating load, and size your pumps accordingly. Have fun with it! You can always call Taco at 401-942-8000 and ask for tech support. 

Teemok

You have three pumps? Two are zone pumps, the third is for a boiler/primary loop only? Piped primary/secondary? The boiler pump is a 26-99fc on an Alp105? If that's the case it's over sized. A Taco vr1816 or alpha (3 speeds) or just a 007e would do well.

Alan (California Radiant) Forbes

Teemok said:

You have three pumps? Two are zone pumps, the third is for a boiler/primary loop only? Piped primary/secondary? The boiler pump is a 26-99fc on an Alp105? If that's the case it's over sized. A Taco vr1816 or alpha (3 speeds) or just a 007e would do well.

Take another look at what the manufacturer recommends:

Alan (California Radiant) Forbes

I'm even wondering how the existing 007 works for your indirect. From the chart below, it should be at least a Taco 0010 or a Grundfos 15-58 at top speed. The 007 might work, but how long does it take to recharge the indirect? And without adequate flow, the boiler will short-cycle.

hot_rod

One pump manufacturer claims pumps consume up to 30% of the energy, worldwide.
Changing all of them to drives or ECM would be a huge change on the grid. That is a pretty big deal in my mind.


Enough power savings to provide for HPs and EV chargers as a trade out

In a heating climate a circ could run 5000 hours.
I see ECM circs running as low as 17W replacing 70W circs, do the math!

Ever been in a mechanical room with a dozen or more PSC circulators? Moving 100K load

Teemok

This is what I was looking at bellow. The 75' of associated piping equivalence is a lot added 15.1Ft? His CH zone loop is a 007e he doesn't need the the full 105k firing rate. A small Alpha is 11ft@7.5gpm That will work just fine as long as there's no weird valves or small or long pipe sizes. Gianonni's hidden cost.

hot_rod

I think the confusion is always about which loop is the primary. It is not always the loop with the boiler in it

The loop or circuit with the expansion tank “becomes” the primary loop

That 105 boiler, according to the manufacturer needs the 26-99 or equivalent 

Doesn’t matter if it is a primary or secondary loop

I think that is Alan’s point. I agree😎

Teemok

I was not debating or claiming that the manufactures recommendation wasn't a 26-99 ON MED. or equivalent. It's not that far off if you're looking to optimize electrical efficiency over peak output. The only negative would be not being able to get the full fire capacity out of it with the lower flow. It will just modulate down correct? It is an assumption he doesn't need 80kBTU

hot_rod

Most of the better mod cons allow  you to lock them to a specific firing right in the control. Basically you limit the fan speed
So it could be possible to use a lower pump gpm, I suppose?

If you have an indirect I think you would want full output, and the correct pump to allow full output.

Not all boiler brands give you a head loss chart to make the derate pump decision. And some brands vary the pump speed. So different options are out there.

Teemok

Of course hot-rod is correct. Most mod/cons step fire up and modulate to the load presented via the delta T. they see. Some do vary their pump speed, not this one. I don't think limiting fan speed speed would be needed but that my opinion. The flow reduction makes for a higher delta. In this case he has a 007 on the indirect. It's too small and limits the load from the tank and that load gets lighter as the tank nears it's set point. Full capacity would be missed maybe for the first part of a cold start DHW call. It's been 14 years. If a gpm reduction means a 30% loss in peak capacity that he almost never uses, who cares? I have seen mod/cons that fire at over 50% for 60 or so seconds until they modulate down and short cycling is the result. If the boiler loop (not the primary ) is low mass more flow doesn't change the short cycle condition much. On DHW call near set-point the load gets small enough that more flow changes little there as well. Luckily DHW is not usually a high % of time. It satisfies and is over.

hot_rod

Mod cons have negative pressure gas valves. So if you reduce the inducer fan speed youreduce the firing rate, super simple. I think you would reduce short cycling boilers by reducing the burner firing rate? My Knight boiler allows me to set step firing also to eliminate on/ off cycling. I have it run 20% for 15 minutes, then it steps up to 30, 40, etc until it reaches 100%.

It also has a boost function. If for example it is at step 1 firing 20% and after a period of time the SWT has not gone up, it will bump to the next step, even if the time period has not expired.

I have a 55K boiler and have it locked down to around 30,000 btu/hr my design load.

So in a perfect world, my boiler starts firing in October and just modulates all season, never going off completely. I'm getting close. Once mod cons can fire down to 5% that will be possible for any system.

You also just touched on my argument against delta T pumps on hydronic distribution.

The system delta T wants to, will, prefers, and left to its own devices will</ move around a bit.

The selling point of ∆T circs is they keep the boiler running longer. A fix for oversized boilers perhaps? But the longer cycles are at the expense of a constrained output. Do you want the heat output now or a few hours later?

Your indirect is a classic example. When the tank is cold expect to see a large delta through the coil with a fixed speed, fixed flow rate circ. . That's good lots of BTU being delivered, maybe seeing 30- 40 delta or more.

As the tank temperature increases that delta will close, maybe running 5° just before it satisfies. This, due to the delta between the tank water and boiler water is closing, less heat being delivered.

IF you install a delta T pump, set it at say 15∆, you are limited to that heat exchange rate only, math below

If you have a big dhw dump load, want to recover the tank quickly that constrained delta pump is working against you. It has the brakes being applied by a randomly installed delta t number.

Let the delta T move around. The measurement of the delta T tells you how much energy is being transfered into or out of a fluid stream.

All systems strive for and will find thermal equilibrium. Unless you get in the way with some control. Obviously we want and need some control, high limits for example. We don't need boilers running 240 degrees!

The universal BTU formula, it cannot be denied

500 (f) ∆T

500 X 4 gpm X 40∆ = 80,000 btu/ hr transfer

Now at 15 delta

500 X 4 gpm X 15∆ = 30,000 btu/ hr transfer

Which ∆ will recover the tank faster, or you home, or any load?