Smart Circulators

Brad White_141

Of course you are correct

and I should have qualified my response, Josh. On a ModCon I would use VS if I could. No problem using a DP bypass on a conventional boiler.

If I just had to use a DP bypass on a ModCon, I would be very scrupulous with balancing and holding the pump head to the minimum to do the job.

My just-completed project, (the Vitodens at my Susan's house- photos to come!) has a 15-58 running at low speed and requires just under 2 feet of head across the system. Granted I piped this as a loop so the pressure shift (point of no flow) moves as TRV's modulate. But it shows how little pressure is required.

I will admit that the bathrooms, with recessed Burnham CI radiant radiators and which have no TRV possibility, so are manually balanced to their net flow requirements of 0.25 GPM. Pretty piddling! This flow increases to about 0.50 when the other radiators are satisfied and closed, so the 15-58 is riding it's curve pretty well.

Mark Hunt

No


Just standard three speed.

The folks at Wilo told me about the new circs that will be heading our way in the future.

Looking forward to that.

Mark H

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Mark Chaffee

Unknown

Minimizing return temps is well and good, but if you're only pushing 1 GPM through your heating system because the pump has slowed down, and you've got a regular size boiler pump on a primary circuit as required by all mod/con manufacturers, then your return to the boiler is not going to be your radiant return water temperature... it will return a portion of its own supply water to itself through the Tees or LLH..

That's what I'm saying, I don't see any benefit here; if you are not dissapating the BTUs, you don't get to "fake it" simply by reducing flow through the distribution system. OR do I misunderstand your point?

Mark Chaffee

Real Appliations of Smart Pumps

I have attached some good reading that will hopefully help all of those looking for a simple solution for increased comfort, energy efficiency and control of any hydronic system utilizing products which have been available for years.

A few posts have accurately detailed the cost and involved wiring for a delta P system. We have been doing these types of systems for years utilizing our standard 00 circulators (00-VV) which can accept a control signal to infinitely vary the circulators speed. Most of the installations have been in commercial systems or commercial LoadMatch systems where there is a building management system which provides the signal to control the circs. Why mostly commercial installations? Cost.

For residential applications we have found that controlling the system on a differential temperature provides fantastic results and at a much more palatable cost.

Most installers design a system based on a 20 delta T. So why not have a circulator that maintains that 20 degree design no matter how many zones are calling or what time of year it happens to be (changes in heat loss). We do this by using a Taco 00-VS circulator. All you have to do is hook up two 10k sensors (included) and then dial in the temperature differential (5-50 degrees) that you would like to maintain.

I have attached a link to one of our technical articles called "Maintaining a Difference - Delta T" which I wrote back in 2004 showing all sorts of interesting applications for the Taco circulators which run on Delta T.

I have also attached a related article that talks about the effect of zone valves and changes in differential pressure on a system and the operating curves of circulators called “When Zone Valves Close.”

These plus many other technical articles, piping diagrams, and application information pieces can be found in the Taco Radiant Made Easy Application Guide at:
http://www.taco-hvac.com/en/products/Radiant+Made+Easy+Application+Guide/products.html?current_category=170

Please feel free to contact me for any additional information or with any questions.

Sincerely,
Mark Chaffee
Taco, Inc.

Mark Hunt

I see your point


and it is a good one Rob. I was thinking about this the other day as I watched my latest GB modulate input according to OD temp.

What if we could modulate the boiler pump according to fuel input? Do I need X gpm when the boiler is in low fire?

At least with the AM10 control on the GB, the boiler's target temp is adjusted as well as it's firing rate. While I may not get those cool return temps from the plate radiant directly to the boiler, the boiler is still well within the condensing range.

I believe that the Quantum boiler does not require P/S piping due to it's higher mass. I may have to look at that boiler again.

Mark H

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Unknown

Yeah, that would be the piece of the puzzle needed to ensure proper dT operation with the mod/cons; now, variable speed pump on primary AND secondary circuits, that could do some good things for sure. I'm not familiar with the Quantum myself, if you do find it doesn't require P/S please post about it!

Constantin

No, I think we agree...

... without question, unless the boiler can modulate its pump too, then the benefits of lower return temps is quickly lost... the whole system has to be able to take advantage of the variable-speed circulators, not just bits of it. Said advantage may be so infinitesmall that it's not worth the extra expense in most, if not all applications.

The small Vitodens has a variable-speed circulator in it, IIRC. Perhaps other mod-cons do also. The variable-speed circulator may explain why the Vitodens has a 8x lower measured electrical consumption than competing boilers (as per ACEEE).

My observations stem purely from observing the return temps coming out of a RFH system header where the floor temps were below 70°F but the return temp coming out of the header was 80°F. Evidently, the return water temps were being tempered somewhat, something that I could observe whenever I closed the ball valve on the PBV.

The justification for a ΔP-enabled pump should be based on the electrical savings vs. the incremental cost of going with a fixed-speed pump and buying and installing a PBV. Then there is the issue of having replacement parts available in the supply-chain... Yet, if the trends in the electronics business pesist, it may even become cheaper to use a ΔP pump rather than a fixed-speed pump with a PBV in the future.

Josh_10

Mark you have given me some great food for thought. So basically the idea is to keep putting differential pressure regs in our secondary circuits and a delta T pump on the primary or tertiary (depending on which one has the boiler).. Hmm I am going to try it TODAY. Just so happens I have 00VS in my van and the perfect job to try it on.

Paul Pollets

PBD sizing

An 11/4 pressure bypass differential valve may be vastly oversized. I use 3/4" PBD's. Usually Oventrop or Danfoss...sometimes Caleffi. It will save $$ over the 11/4" size.

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ALH_4

Agreed

With a UP26-64 and larger, a 3/4" (Caleffi and Danfoss at least) is a little undersized. The 1" Danfoss is a nice size, but due to a change in the product lines we carried we got away from using them much. For the most part, I try to stay away from system circulators larger than a 15-58 in a residential application even if it takes two. Some customers would mention faint noise with the larger circulators. Once a Vitodens 44/60 was in the mix, there were already 26-64's or 26-99's on the boiler so it made less of a difference what was chosen for the system pump.

-Andrew

Mark Chaffee

00VS instead of a differential By-Pass

The 00VS on the main loop would actually eliminate the need for a differential by-pass valve.

Also, if you are looking for a great by-pass valve at the right price check out the Taco 3196 at http://www.taco-hvac.com/en/products/Differential+Bypass+Valve/products.html?current_category=204

- Mark Chaffee
Taco, Inc.

Mark Chaffee

By-pass & Pumps

Most likely the issue you have here is the high head pumps referenced are not matched to the type of systems you’re installing, so the need for a differential by-pass valve (and a large one at that) is a must. Check out Taco’s differential valve at
http://www.taco-hvac.com/en/products/Differential+Bypass+Valve/products.html?current_category=204

I think you will like the performance and price point. Now about those pumps. I have attached one of our tech articles which covers differential valve sizing as well as a good explanation on choosing the correct style pump (flat curve vs. high head) for your job.

If you need more detailed information there are many other technical articles, piping diagrams, and application information pieces which can be found in the Taco Radiant made Easy Application Guide at:
http://www.taco-hvac.com/en/products/Radiant+Made+Easy+Application+Guide/products.html?current_category=170

Please feel free to contact me for any additional information or with any questions.

Sincerely,
Mark Chaffee
Taco, Inc.

Unknown

Smart Circulators (WILO Stratos)

Folks, it is coming, it does work, and we will have application/energy saving seminars throughout the States and Canada. If you would like specific information feel free to contact myself (or any of our local WILO reps) any time...

Josh_10

I know the one and I use them exclusivly. There are three of them on the job I am doing right now.

ALH_4

pumps

Yes, perhaps instead of reaching exclusively for Grundfos circulators, I should have used 0010's and 0012's. My former employer's circulator of coice was Grundfos which of course does not have an equivalent for the 0010/12. I have rarely needed more than 10ft of head. Nearly every system I have designed has used a properly sized differential pressure valve.

The noise seemed to be coming from the pump itself. It was very quiet and could barely be heard even near the pump, but the pump was mounted solidly to unistrut on an interior wall and the floor above seemed to amplify the noise. It was still very difficult to hear unless everything was completely still and quiet.

Is a pump with a flat curve quieter than a high head pump?

-Andrew

Mark Chaffee

High Head and Noise

The pump itself should not be any more noisy if has high head vs. a flat curve. Only when combined with a system could a high head or high flow circ create noise in the piping. i.e. Short loop, small diameter piping with a high flow pump = velocity noise and possible fitting errosion.

- Mark Chaffee
Taco, Inc.

Josh_10

Mark here is one scenerio that I could see going wrong with installing a delta t pump on a secondary or zone valve circuit. Let's say on a cold start one zone of many calls for heat. Well until that zone heats up significantly that pump will run full out. And that will cause velocity noise. Right?

Mark Hunt

Q95M-200


Modulates between 80k and 200k. Too big for most residential applications but P/S is not required.

"Dunkirk's Q95M-200 gas-fired modulating condensing boiler was the first 95% AFUE gas boiler available and the first boiler to qualify for the U.S. Federal Government's $150 Homeowner High Efficiency Tax Credit. Ideal for high efficiency replacement jobs, new homes, radiant heating, and domestic hot water applications, Q95M cost saving features include infinitely modulating capacity from 80 to 200 MBH, outdoor temperature reset, and domestic hot water priority. The Q95's electrical operating costs are lower than other high efficiency boilers because no primary/secondary dedicated piping arrangement is required. One circulator can service the boiler and all zones. Intake and flue gasses can be piped with readily available 3" PVC to 60' and the contractor has the option of left, right or rear exit for return plumbing and gas piping. Piping connections on the rear and top of the units facilitate multiple boiler installations with boilers in close quarters and the integral condensate trap requires no field assembly. The unit features a standard 115v convenience outlet as well."

Mark H

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Unknown

Interesting! I'll have to check that out. Thanks mark!

rumn8r

Pressure Trransducers...

Don't connect directly to the pump. They have to be interfaced with a VS controller.

If it were THAT easy, EVERYONE would be doing it:-)

ME

rumn8r

Another problem with the delta T prophecy...

If the system is piped parallel direct return, as most systems are, and numerous zones are on line, including a short zone and an extremely long zone, the long zone is going to be starved for flow because my ex-brother in law principle has kicked in (wet, lazy and stupid).

Right?

If the VSP is controlled based on delta P, then there are no issues.

ME

Brad White_141

But the circulators we are talking about

have built-in VS controllers, do they not? The Grundfos series does and takes a 0-10VDC or 4-20 mA switchable signal if I am not mistaken.

Harold

I tried to use a variable speed pump as the only pump in my secondary loop with solenoids for each of the zones. I had to use an external pressure control. I really do think that pressure control via a variable speed pump is the way it should be done.

The pump was too noisy, in my opinion, for a residential application. I tried two of the same pumps, and finally had to remove them and install a pressure bypass.

I really think one of the specs provided on pumps should be some characterization of noise levels.

New pumps are, I believe, using different types of motors and controls which should help. But beware of pumps that are really thought of by the manufacturer as a commercial device in residential uses.

WaterHeaterGuy

Solar application

Here in WI I am installing one of Grundfos TPE pumps on a 24 panel solar application. I am reveling at the thought of my pump slowing down as a big fat cloud casts a shadow over my array for a few minutes. Then as the cloud passes my pumps speeds back up to normal operation.

This will assure me the best performance of my heat exchanger, while the ability to save me a bunch of money in operating costs. (Remember running a pump at 80% capacity saves 50% in energy.)

I have worked with the engineers and they estimate a 4 year payback on the pump. Rough numbers - normal pump $1500 - Variable speed pump $2500.

I was also told that the residential versions in the Grundfos lines should be out within the next year or two. I am enclosing the energy comparrison done by the Grundfos engineer. Enjoy

Tim_33

I think

the 20 deg DT is/was used for sizing equipment only, not as a control point, and I also believe that is the wrong number to use. Sticking to the old 20degDT is the same as sticking with 180 supply temps, designing every system to be piped primary/secondary, using three way unit control valves and constant flow based on maximum demand, and wasting a great deal of money and energy on things like circuit setters and oversized pumps. It is done "because that's the way it has always been done". Not good enough reasoning. It is an arbitrary number and not appropriate for modern control systems.

Current best practices for hydronic design (at least in the commercial side of the industry) include sizing coils and other terminal units with delta T's of 30 or 40 degrees. Primary, variable flow pumping systems, controlled by means of a representative dP, with modulating/condensing boilers and outdoor reset are now common where this was not possible in the past.

With local, proportional control, modulating a two-way valve based on discharge air temperature or room temperature would be compromised if the control scheme was to include the antiquated 20 deg DT criteria. Let/make the local controls meet the demand of the space and let/make the pump controls be flexible enough to accomodate the varying demand. Delta T in this type of system will only approach the design/sizing crietria at worst case conditions.

Tim_33

Coordination & design

The biggest hurdle to overcome in the dilema of variable speed pumping is the reluctance to make the break from primary/secondary systems when using mod/con boilers. As long as the manufacturers of the boilers refuse to establish and provide realistic variable flow data for their equipment and default to the tried and true "must have boiler ciruclator sized at xx gpm", the true potential savings available through low temperature, high DT, variable pumping design, will continue to be negated by the waste and duplication of the constant flow boiler circulator. This is a much greater portion of the energy consumed in a small residential system than in a large commercial system. The cost of operating a 1/4 hp blr circ on a small system that has a single 1 hp system circulator, is a much more significant energy cost than a 3/4 hp blr circ running constantly with a couple of 15 hp system circulators. Simple pump controllers can easily be set to maintain minimum flow rates required for boiler protection, yet most manufactures require or at least recommend at the cost of voiding the warranty, that a dedicated boiler circulator be provided.

PJO_5

Why not use...

a couple of solar powered pumps for the application? Same benefit and much less cost - including free electric from the sun as needed?

PJO