Taco VDT Pump

CMadatMe

Has anyone used this pump as their system pump in mod/con application where you were zoning with zone valves? I had a couple of my top notch contractors install them in the last month and both pumps were making so much noise. Both jobs were in their houses. They were testing them out prior to making a decision on putting them in their customers homes.



Both were installed on Vitodens 200's using Low Loss Headers not primary secondary. Once we changed them out and used Grundfos Alpha, noise gone and running smooth. I'm thinking the Delta P pump is more reactive to the consistent flow and water temp changes in the system vs the Delta-T pump. Anyone have a theory or some thought?

Unknown

Disappointed too,,,,

after some MAJOR probe moving,,,, the ONLY way I could get this unit to respond with any degree of accuracy was to strap the probes directly on the HX inlet & outlet,, within the cabinet,,,,, I have a Solo 60.



This is my first & LAST VDT Taco circ,,,,   next time I`ll try Wilo. 

bill_105

I'll second that!

Make it 3 for the day

Last month I added some baseboard to a poorly designed house. I did the Calc. and showed the customer the numbers and they were sold.

But I had trouble getting the house Temp. up. I overdid the element too. While in a panic mode I turned the 008-VDT (8 months old) down to a 10 degree delta T. Don't ask why, I havn't a clue. I left for 1 hour, came back and that house was cooking. Fine!

 About a week later I turned it back to setting 4 or 20 DT. The thermostat is now less responsive to the house Temp, and at a  moderate outside Temp. (30)

I wish Taco would weigh in. Somethings not right. A couple weeks ago some guy here was complining about noise, and not water speed noise. Funny how it was in the same town of Anc. AK

 The logic and sales pitch are great. Spock would be impressed. I just dunno!

Acid test tonight - forecast is 18 below.

CMadatMe

Dave and Bill

The first pump already went back to Taco. The second will get back to them this week. They are very interested to in trying to find the cause. I will let you guys know what I find out.

Terry Larsell

I tried one

I tried one, set up the system without a bypass using actuators. I was going to use the Grunfos Alpha but didn't think it would have enough gpm to run this large house. The Taco could be heard throughout the house and I couldn't figure out why. I swapped with the alpha and all the noise was gone. I left the alpha on and it is working great , I love the digital readout. I'm learning that it doesn't take much flow to get the heat out in a high mass system.

CMadatMe

Terry

Did you send the pump back. I recevied an e-mail from John Barba and I'm sure he would like to hear the application. You should give him a call at Taco or send him an e-mail via Taco's site. He is interested in what the problem is.

KBP&H_3

Also.

Same thing. I recently installed a VDT on my own system , changing from four circs to zone valves and the VDT. Noise!!!  especially on start,  and it changes every step the program runs based on the return water temp, the circ noise can change every 5 or 10 seconds, and can  be heard through out the house, longest run 220'. Also. I have a Burnham Revolution and the internal 007 circ creates more pressure than the 008  with one zone ( or 2) calliing on the feed. When this happens the hot water feeds up the return and shuts the VDT down in error mode, since the return is hotter  ( 210*) than the feed. They should install a switched bypass control in these to bypass the sensors if one goes bad and any other problem that might come up.  Tried Flo Pro site e mail but also ended up with script error message.

CMadatMe

Terry, KBH

Try this to get a hold of John johbar@taco-hvac.com I recevied an e-mail from his this morning concerning this issue. They are aware of a problem and believe they have it fixed. I'm sure he would like to know the application and would want the pump back

KBP&H_3

VDT

Also. it seems after watching the pump, that the pump responds by the return temp instead of the supply temp, , With the boiler at high limit 175 0r so, if the return temp drops, the pump speed drops also, instead of the pump taking the higher available water temp and using it to keep the diff temp at  the setting , thus raising the return temp.. It seems to work backwards,, I changed dip 3 to direct acting mode, but it didn't seem to make any difference in operation.

KBP&H_3

VDT and Taco

I contacted John Barba at Taco ( I should have contacted them first) and he informed this is a limited problem which I believe is true due to the circumstances I have. John and Taco are working on this and will have a solution shortly ( days). It;s nice to see a company stand behind their product with so many different applications in use, The matter is being resolved and I would like to thank Taco amd John to their quick response. Thank You,

Unknown

Never second-guess JB or JW,,,

@ Taco,,,, I talked to JB too,,, he acknowledged a problem so I await his rectification on the matter,,, I have the  utmost faith in Taco products.

Anchorage

Anchorage 0013 VDT noise and response problem, feedback to Taco/Proctor

All,

Some feedback on the Taco 0013VDT that I have been testing for the last month, installed in my house in Anchorage, Alaska.



I would concur based on some of the recent reports in this particular thread that that TACO 0013 VDT pump I have been testing is not entirely "commercial" yet in my opinion (an engineers euphemism) and its noise issue and the thermal response characteristics require some manufacturer investigation and re work. I must say though Taco/Proctor have been very good and proactive in helping solve the problem and I give them top marks. Although it appears not to be a one off case, I will now test the smaller 008 version and see what happens. My expectations are pretty simple........silent and efficient operation, stable output that that really does match the thermal loads of my system and boiler, and great zone temp response. I have not seen the poor DT temp response on my system once the loads (supple and return) temps have stabilized, I have seen counter intuitive startup response which impacts the boiler cycles.I would also point out that the dip 3 on (direct) mode does not work for DT applications, at least on my system as it simply spins up the pump inversely to DT. This is not documented but I do not see it helping any...I can be reached on 907 748 1140 if anyone needs more information.



Email sent to Proctor sales/ Local TACO agent for AK on Jan 5th 2010

*******************************************************************************

I have been running a test for a couple of weeks on a noise reduction coupling (acoustic isolation joint) I made. This is fabricated from a short section of 1 ½” silicon rubber multiply hose mounted on the upper mating flange of the pump. This really works well and has reduced the noise generated by the pump to “almost” background levels. There are still some discernable “peaks” in noise at certain rotational RPM’s depending on what the controller is doing at the time, i.e ramping up/down etc. The pump does not wake us up at night now, but if you are awake you can clearly hear what it is up to. I doubt the isolation joint meets code so will have to remove it at some stage. My conclusion is this 0013VDT circulator generates a far amount of electromechanical based noise when modulating it’s RPM’s under most circumstances. The source of the noise is most likely a combination of the power switching electronics and the motor windings. At full speed the pump is quiet, and emits mostly just a white (background) noise. If the controller dip switch 2 is set at default, the pump speed falls too low and it emits a “cogging” sound that is clearly audible even with the acoustic isolation joint. I now run it only with DIP-2 up. I have not installed the 0008VDT yet for comparison. I will give it a try though when I get a few hours later this week and advise on the results. If this does not work I may elect to return the pumps and simply go with either a bigger fixed speed again (and diff bypass) or try a Wilo Stratus.



Putting the noise issue aside for a moment, it is apparent that the pump control software is also best suited to a system that has reached thermal equilibrium conditions in the zones that it is driving. An example of this is when multiple zones are on demand and the boiler has run at least a few cycles (at least 3-5 minutes), and the return water is no longer rapidly changing in temp with time. I.e slugs of water with different temperatures caused by the lag in the system, and the boiler cycling up for the first time. More zones are better than less as the boiler rise rate is slower. The pump control response does not work that well in the period before thermal equilibrium in the demand zones is attained. i.e in the first 3-5 minutes of operation, particularly for on/off non modulating boilers. Obviously managing the DT (and pump output response) in this period is going to be a compromise in any event, but I think the present settings for residential systems could be improved. The 30 second startup run is to short, and allows the pump rpm to become unstable for a few minutes until the system catches up and is thermally equilibrated. This is visible by the pump rpm swinging from low rpm to max rpm a few times as the boiler hits it’s first firing cycle cut off. The rapidly changing pump response triggers the boiler to fire again very soon as the temp is drawn down quickly…….which could be simply prevented by having a longer, more controlled pump circ fixed RPM startup cycle. It works pretty well after 3-5 minutes in DT mode as the boiler temp cycling rate is then stable, supply and returns are changing in temp more slowly. I would suggest allowing the end users to change the default start up period for RPM control to at least cover the first 1-2 boiler firing cycles of non modulating boilers. In my case this would be 3-5 minutes, and during this time the pump RPM should target a fixed speed close or slightly above the future DT mode control set point. Full RPM is not really necessary on a zone valve system for startup if the duration is longer…I should probably have a diff bypass valve installed! Some value between 25-75% would probably be better during this period. Likewise the controller could also monitor the actual supply and return temp values over a small time period (not just the DT), and determine whether startup mode, or DT mode was more appropriate, and increase or decrease the rpm slew response rate appropriately. Allowing the end user to fine tune all the default/setup parameters (max and min speeds, slew rates versus temps and DT’s etc) similar to the TEKMAR version would be a big plus and make the pump much more versatile. Just a thought…



rgds Ryan

mor

$$ cost

Do you find the vdt cost effective against using a separate controller to a standard pump?

mor

$$ cost

Do you find the vdt cost effective against using a separate controller to a standard pump?

Unknown

Yes & No,,,,,

Yes IF it performs as stated by Taco,,,,, No if you have to put-up with the racket it makes because I had to run-on constant high speed to get heat!



I`m told my name is added to a "waiting list" of updated control boards to be sent to me,, believe-me, my patience is growing very thin!!!



As Ryan states above,,, I am having the same probs with it.

bill_105

The list!

What do you do, e-mail them to get the new and improved part?

Of the two 008 VDT I've put in, they're working just fine. But one guy says when he's on his computer he hears this humming high and low, high and low. He says he just hums along. The pump is on the other side of a wall and six feet away. Then again he is hard of hearing!

I'm Sure glad this is going on now. I was pitching  a 0012 VDT to a real important person to us. But it didn't happen. 

Funny- that one is in Bootleggers Cove.

Proctor, in Anc. didn't even know what a VDT was a year or so ago.

Unknown

I hear ya bill,,,,

or maybe it`s the circ :-).



This is for my-own boiler, and man I`m disappointed at the response I have gotten!

Squealing, rattling and short cycling(I have a 42 gallon buffer),,,, how can I as a contractor endorse this POS?,,,, and no-one from Taco is readily stepping-up to the plate to remedy my situation,,,,,,, and I`m tired of waiting!

Unknown

Just recieved my replacement,

008-VDT circ(Thanks JB U.S. & JG Can.) from Taco,,, I had already replaced-it with a competitor, but as I`m a firm Taco supporter, I will change-it back to see if the "bugs" are resolved,,,,,,, will keep you posted! :-)

bill_105

That's Great news

A few days ago JB at Taco e-mailed me. He provided his cell number and the local guys cell number. I have yet to call.

I'm only reluctant to install this 0012 VDT for the fear of noise.

What his world needs is more willing labrotory rats!

Nonetheless, Taco, as I always thought, is a wonderful company.

Unknown

My conclusion is,, ITS NOT POSSIBLE W/008-VDT,,,

My "new & improved" Taco 008-VDT sent to me is NO better.

I have 2400 sq.ft. on a Solo 60,,,, M/F, 3 zones with a 42 gallon buffer,,,CIBB in all, still no proper Delta control,,, lucky if I see 8F. I have moved the sensors(& dip switches) everywhere I can imagine,,,, NO-GO,,,, I was actually trying for 16F,,, nothing doing!



The noise factor is STILL THERE,,, (a slight moaning) that varies with pump RPM,,, but accomplishes nothing except annoyance.



I purchased a Wilo ECO before, and changed-back as I love Taco products,, but this should be brought-back to their drawing-board as there ARE STILL problems!



As a contractor/installer I will avoid this product,,,, and changing-back to my Wilo as we speak!  

Unknown

Sorry to harp-on Taco VDT-008,,,,

but I see nothing happening,,,, these really are "crapola",,, so far behind the times,, the noise factor is excruciating for a  wet-rotor circ. and other than a replacement for what you had,, don`t waste your time,, Taco seems to have no interest!



I have 2 of them,,,, anyone want them for scrap?

Anchorage

Taco 008VDT pump feedback...

Here is a copy of the email I sent to Proctor Sales/Taco distributor in Anchorage, Ak on Jan 18th 2010 after testing both the 0013VDT and 008 VDT for approx 1 month as part of my homes Hydronic heating efficiency upgrade project. In conclusion I would have to agree with Dave's comments, confirmed by my testing that these new wet rotor Circs are really not worth looking at until TACO resolve numerous basic engineering issues.





Feedback on the Taco 0008 VDT

************************************



I installed this pump on Friday and have been running it for three days observing the heating system and pump controller response. My initial thoughts have been confirmed but I also have determined there are a few other issues with this particular pump model as described below.





DT and thermal/flow response



The 0008 VDT Circ that I have been testing is unable to maintain a reasonable flow through my system at a set DT, whether it be 10 or 20 DEGF. During operation the pump continues to slow down it’s RPM output and the flow rates drops off to almost minimum (in most cases) which is insufficient to drive heat through my system. The result is insufficient heading in all zones, and large DT’s across all the convectors. I suspect there is a DT control issue (firmware program) with this particular pump, but did not see it on the 0013 VDT. The logic error allows the pump flow rate to gradually taper off over time, and sit at a flow rate that really does not provide much energy transfer to the zones. I monitored the DT across the supply and the return for various settings with a k type thermo couple hooked up to my Fluke meter on one side, and the TAC0 702 readout on the supply side. The readings confirmed my suspicion that the pump did not hold the DT setting on the controller potentiometer. I turned the DT setting up to 10, then 5, and it made very little difference to the heating output (pump rpm stayed very low)….house remained cold after 3-4 hrs on a 20 degree day. Left to it’s own devices I doubt I could have warmed the house up from 60-70 DEGF at all so I went to plan B.



Plan B: So late on Saturday I switched DIP 3 down (based on experience with the 0013VDT) and forced the pump to run at close to 100% for Sun/Mon. The Pot was set for 75%-85% or so to keep the output up (based on experience only, not documented). With this setting the pump could warm the house from 60-70 in 4-5 hours or so….much slower than the 0013. This is how I limped trough Sun/Mon. The DT across the longest circuit was still unacceptable with multiple zone valves open, the system could certainly be balanced better, but this is an indication that the flow rate still needs to be increased above the pumps max discharge rate at full RPM. No flow noise ether.





Electro-Mechanical Noise



This pump and its solid state controller also generates the same clearly audible electro-mechanical noise that was present on the 0013VDT, possibly a little weaker but it’s still present even with my home made acoustic isolation coupling. This alone makes the siting of the pump in residential homes a problem.



Mechanical Noise



This pump has, I suspect an “Out of balance rotor” or pulsation that transmits a continuous vibration through the pipes when operating at full speed. This is also clearly audible and can also be felt in most of the zones if you touch your finger to the convector HX core. This may be a one off with this pump?







Action plan going forward



Based on one month of documented testing and evaluation of these two new TACO circulators (0013VDT and 0008VDT) I have determined neither is really commercial yet for my residential application. There simply is no benefit at present , either engineering wise or cost wise. I do believe though that the pumps have strong technical merits for Hydronic applications over other existing systems if the engineering and technical issues can be resolved. This is why I went to the expense and time of testing them. So for now I will remove the 0008VDT and return it to your offices asap. I will install a new fixed speed 0010 or similar for the time being, and request a full refund for the original 0013VDT. Will Proctor/Taco supply the fixed speed ? As part of the solution I will also undertake to help TACO engineering test any new or improved products in my home (if they wish) to ensure that any bugs are worked out well before production starts. I remain a bit surprised that the issues I have found are fairly obvious and should have been picked up by TACO product testing and qualification prior to manufacture. I remain very optimistic and think the VDT can be quite easily improved…heres how.





Recommendation to Taco engineering



My recommendation for the pump control response would be to create a 3d map of Head, Flow rate and DT and characterize this for various systems, including multi zone valve, Mod/Con and non mod con boilers. The temp control algorithm will also benefit considerably from incorporate a time dependent Kalman filter (Recursive least squares type control) in order to cope with the startup conditions and supply/return temp lag in various zone combinations. I think having a few different user settings to help fine tune the operating modes will be necessary, such as min. max and boiler target range, flow range etc. This will require a VFD (variable frequency drive), in order to determine the pump RPM and power output on a continuous basis. This will also reduce the electro mechanic noise, as the motor (AC or DC) would be speed modulated with clean sinusoidal waveforms only)



I am also not convinced that through “DT control only” that every system out their has response plateau’s that the VDT controller can find, without any consideration of Head or Flow (how many zones are open). If the DT map for a given set of H and Q has no maxima or minima to find and control around….the response will never be stable. Hence I am also certain that the VDT needs to know it’s RPM and power output in combination with the measured DT (using a kalman feedback/feedforward response filter) to determine the “optimum” operating set point to match the prevailing heat request conditions. Characterizing the pump response, and allowing some basic setup parameters and limits to be entered will then make setup quick and easy for most end-users.







Thanks

daveb149

Waited and waited for the rep to show up, only to have Grundfos save the day

Had a VDT making so much noise in my own house my wife was ready to throw me out! Called the rep several times and got nowhere. VDT made noise, 0010 MS made noise, 0013 made noise. Not to mention my electric bill went up $20 after installing a mod con munchkin (gas did go down)

installed a Grundfos ALPHA on my zone valve loop (auto adapt)  and an ALPHA on my primary (constant pressure to meet head and flow demand of the boiler manufactuer) then placed a UPS26-99 on the DWH as specd by the manufactuer of theboiler.

Happy wife equals happy life! Too cold to sleep in my truck!

Was told my electric bill should come down too-can't wait for the bill to see how much.



Thanks to the local Grundfos rep for stepping up and helping me out with this, beats marraige counseling!

TonyS

I was going to use one

on a wood boiler connection to its thermal storage. After getting cost on both . THE VDT  verses a pump and Tekmar 157. The Tekmar was by far more cost effective.

Unknown

Anything to the contrary???

I`m STILL a Taco kinda-guy,,, but we need breakthroughs,,,,, anything happening?