Can someone please explain the the VR1816s constant pressure curve

keyote

http://s3.supplyhouse.com/product_files/Taco-VR1816-HY1-FC2A00-Product-Overview.pdf
http://s3.supplyhouse.com/product_files/Taco-VT2218-HY1-FC1A01-Product-Overview.pdf
http://s3.supplyhouse.com/manuals/1281025495227/35863_PROD_FILE.pdf

When i look at the VT2218s variable curve it clearly states in that setting it will operate anywhere within the clearly defined green shaded upper and lower bands, similarly the alphas use orange to do the same thing for their pump. The VR1816 however does not clearly state it has a fluid operating range and its graphic seems to indicate that, you could lock in a head at 5' 10' or 15', its not clear thats the maximum head or a fixed head. and perhaps more mysteriously it has no clearly defined lower band like its cousin the VT2218 or fellow DP pump the alpha , its graphic implies it might be able to go as low as 0 gpm and 0' head creating a no flow situation through a boiler. Im sure this must be an incredibly naive question but please help

If anyone knows Im curious if these smaller viridians pumps can be programmed from a laptop like the bigger viridians

Jamie Hall

Amazing what these computers can do... what the the controller is doing is varying the speed of the pump -- the rpm -- to maintain some specific condition. The options appear to be fixed speed -- when the pump will behave like a plain vanilla pump, and the flow will vary more or less inversely with rpm. That's your first set of curves. The second option is to maintain a fixed pressure change -- head change -- across the pump; clearly there is a pressure differential sensor in there somewhere. The controller will do this by varying the speed of the pump in response to a pressure change to hold the pressure change constant. The third option adds flow into the mix, and adjusts the pump speed to provide an increasing pressure when the flow increases. Or conversely an increasing flow when the pressure increases.

It looks as though in variable speed mode you can dial it up and down as you like, and it will hold that speed. The other two modes each have three setting only.

The only way you could get zero flow out of the thing is to face it with a pressure greater than its shutoff head (17.7 feet more or less in maximum speed setting; 5, 10, or 15 feet in the constant head setting; about 3.7, 6 and 8 in proportional) -- and the only way to do that is to either try to pump against a static head greater than that, such as out of a standpipe, or close a valve.

That help?

keyote

Thanks jamie
I sort of understand how the pump is able to sense a valve opening or closing and adjust its pumping, the first part of my question is if i say select 10' head on the constant pressure mode is the pump going to produce 10' head no matter how many valves are open or is it going to give me my design heads for each valve or combination of valves or is it going to give me 10' head regardless the combination of valves open. I dont know if that even possible but all the similar pumps very clearly say the pump will infinitely adjust within the variable band and this conspicuously does not. I suspect it does not adjust like the alpha but is only offering a constant pressure of 5 10 15 lbs that will be maintained as valves open and cloase even though you may want 6' feet for valve 1 and 9 feet for valve 4, Perhaps its proportional pressure mode is supposed to be the alphas autoadapt equivalent but that still leaves the issue below.

So im even more concerned with my second part of the question is what the hell is the lower confine of its operating range. Again all the other pumps for the variable mode of operation very clear show a curved upper and lower band, essentially two separate curves shaded between and clearly state the pump will self adjust anywhere needed within this band. But this chart does not show two curves the top "curve" is three flat lines and there is no bottom curve at all. You really have to look at the three pumps variable curves to see what i mean.If you notice on the VT2218 and alpha there is a point below which the pump does not operate in other words it has a minimum head and flow curve that would garuntee a certain flow through the boiler.

Gordy

You need to be looking at the curves more than the functions.

A delta t pump can give delta p results. Think about it. If all zones slam shut but 1 and the pump is screaming the delta will narrow. When the delta narrows outside its setting the pump will slow down.

If one zone is open, and others follow the delta will widen beyond the setting, and the pump will speed up.

In your case you would want constant pressure if zoning with zone valves. Stick to that chart.

keyote

Thanks Gordy
I think you just said that a delta T pump will effectively do the same thing as a delta P pump.
Now yesterday i said that to someone here myself, I said isn't it true that although the DT pump is only responding to DT it will inadvertently do the same thing as a DP pump when a valve opens or closes, but it also does something more by maintaining DT.which i would think gives another level of control.

Now I wont pretend I quite understood the refutation but it was I think about the fact that DT is not so important, that pursuit of it might actually cause an inability to transfer heat or attain equilibrium. They thought the better control is with water temp determined by the tstat and ODR although i dont understand how they are mutually exclusive I know theres this huge chunk of missing info i have about flow not totally but chunks missing.
Bottom line was vote in favor of DP pump

So I was talking to them to get an opinion on DP vs DT pump because its seems since taking your advice on adjusting my loops and adjusting my DT down to DT 12, Im am now within the VS1816 as well as the VT2218 curve, I think. But since I dont understand the VS1816 data sheet Im not sure.No one whos responded to my questions about the VS1816 addresses the exact questions I ask so I guess they dont see where Im confused probably because its so basic but I think if I am answered i will understand.

So to bring you up to speed Im going to risk the no buffer and no P/S but go with the lochinvar KHN 085 and start with two zones valves ganged and see If perhaps i can get down to one floor per zone in real life.But I dont know which pump to try and so feel free to give me your take. From your above comment Id say youre leaning DT but PLease go on.

Gordy

I think a delta t pump will give YOU more tangible results. Either it is holding the delta, or it's not.

With delta p pump you need to know more in depth about heads, and flow rates. I think for you it would be more tinkering.

I could be wrong. They would not make both if there was not specific apps for them. However I see delta p more useful in a trv system.

Gordy

There was a day when zoned systems had a single speed pump with a differential bypass, and they worked.

Jamie Hall

Try again here a little bit. In constant pressure mode -- I think what you are referring to as delta P -- the pump senses the pressure gain across the pump, and will adjust its speed to make that gain. For example if you have selected 10 feet head gain, the flow can vary from 0 to 8.2 gpm. The pump isn't looking at what valves may or may not be open -- just at the head gain. If there were less resistance in the network which the pump is pumping through, then the flow would increase beyond 8.2 gpm, but the head across the pump would drop, in accordance with the pump's maximum curve. The maximum flow that pump can make is about 15.8 gpm, but that is at zero head gain. if something changes in the network to increase the resistance to flow, the pump will slow to maintain a constant head gain. If there is enough resistance, it will slow to essentially zero flow; this is true of all centrifugals, variable speed or not.

Any centrifugal pump -- and these all are -- has a flow curve, or set of flow characteristics, which relate the flow (gpm) to the head gain (psi or feet) and to the pump speed -- rpm. Back in the day of constant speed pumps, you had a single curve. Now, however, with variable speed pumps -- which these all are -- you can adjust the speed of the pump to get various combinations of head gain and flow, within the limits set by the maximum speed of the pump and its physical characteristics. How you choose to control that variable speed -- and hence flow and pressure -- is wide open. You can set constant pressure -- one mode of this pump. You can set a rising pressure with flow -- another mode. With other sensors, you can adjust the pump speed to try to maintain a constant temperature difference (although that is very very difficult, since there are big lags in that parameter),

Now in your situation where you are wondering about delta P pumping vs. delta T pumping, that has nothing to do with the pump itself, but with the control. Constant pressure will give you constant flow through each zone, regardless of how many zones are calling -- and thus constant heat from each zone, assuming that the boiler has the capacity to hold a constant temperature input. This, combined with an outdoor reset to adjust that input temperature should give you very good control.

hot_rod

Gordy said:

There was a day when zoned systems had a single speed pump with a differential bypass, and they worked.

So a ∆P circ is an electronic version of a PAB with a single speed circ all in one energy saving tidy package.

So with a zoned system the ∆P function with indoor and outdoor reset, already included with that boiler, and the ramp functions so give you more adjustability that you can handle. Enough to make your head spin

Gordy

I can remember when there was about four different bar soaps on the shelf. Now look at it.......

Gordy

Oh my lava for the working hands. Then came Irish spring. Remember the Irishman. With the knife slicing the bar of soap to let us know the different colors were all the way through. Sold......

Gordy

So Bob you feel there is not a cross over where delta t can mimic delta p?

hot_rod

Gordy said:

So Bob you feel there is not a cross over where delta t can mimic delta p?

No, I would agree that could be possible.

What I do question, with a multi zoned system and a properly sized circ that the ∆T is more efficient or provides additional comfort, savings or control vs the ∆P.

As we have heard numerous times matching a ∆T circ in a one pump, multi zoned system with a boiler minimum flow and no accurate communication between the boiler and pump, may not provide desirable results.

Jamie Hall

Gordy said:

Oh my lava for the working hands. Then came Irish spring. Remember the Irishman. With the knife slicing the bar of soap to let us know the different colors were all the way through. Sold......

Boraxo. Works for me...

And I totally agree with @hot rod . Plenty of control.

The biggest problem that I see with a delta T control is, as I say, the lag inherent in the controls. Seems to me that unless you have flow sensing as well, and some serious computing power, you would be chasing the set point... maybe I'm missing something.

Oh heck. Steam RULES!

Gordy

I think it depends on the emitter. Mass rules of course. As far as lag. The delta t circulators logic is very responsive. It's the boiler logic that becomes sloppy, and unhappy. However much goes on in the boilers cauldron verses out in the emitter. That is where the extra control comes in. It comes into play no matter the circ logic no?

keyote

So Bob you feel there is not a cross over where delta t can mimic delta p?

No, I would agree that could be possible.

What I do question, with a multi zoned system and a properly sized circ that the ∆T is more efficient or provides additional comfort, savings or control vs the ∆P.

As we have heard numerous times matching a ∆T circ in a one pump, multi zoned system with a boiler minimum flow and no accurate communication between the boiler and pump, may not provide desirable results.

Yeah but since no one has yet explained the vs1816 curve i dont know if its going to be even worse reagrding the low flow situation because .... well I cant keep typing out my question guess ill just flip a coin.
Its like asking what time it is at a philosophy convention

Gordy

It was answered.

keyote

Im going to buy both damn pumps and pipe them parallel with a diversion valve and settle this

Canucker

Gordy said:

It was answered.

Numerous times

Gordy

Why not pick one, and take a chance it will work to your expectations. If not then buy the other.

However if you want to set up a lab that is up to you. I don't really think it will be one with many constants to compare.

Gordy

I will say with the undesirable results of a delta t pump. Mass was the Achilles heel. The lack of it.

keyote

jamie
maybe Im missing something.
The boiler is set to give say 127 degree water on design day. zone 1 calls for heat, DT pumps and boiler starts, water begins to heat. DT pump doesnt know or care it only knows and cares about the dt, it doesnt care or know if its approaching or moving away 127- 117 or 110-100 or 85-75 couldnt careless if the boilers shut down and the waters cooling [if its allowed to continue to run] or if the boiler just started and the waters warming or if another zone just opened and the waters being mixed hotter or colder. it only cares about slowing or speeding to get the DT10 degrees. its not chasing the setpoint its chasing the DT 10 regardless of temperature.The boiler will continue to send 127 degree water until tstat is satisfied.
If it turned out the water temp and ODr ratio from design were off say cycling or boiler never shuts off they could be tweaked until optimized. If it were only a temporary condition like an open window or morning sunlight the call would be longer or shorter.

because the loops are different lengths and the rooms have different loads the flow valves will have to be balanced which frankly i haven't a clue if what i just said is true but thats my guess that some initial conditioning will have to take place. The design has room btu loads that can be converted to flow valve settings i think?

keyote

Is there a way to buy those european micro ecms i just saw 2.5 watt pumps they say theyre 120 volts dont think the cycles matter in a permanent magnet dc

hot_rod

From what I read there are more hypothetical answers to your questions than answers from practical experience, and documented operation over a period of time. I don't think a 15 minute observation at start up; give you enough info to declare victory.
The only data we have seen here is from Hatt observing HIS system under ∆T pumping conditions, over a long period of time. He identified issues, worked some out with the various manufactures but is still not 100% satisfied with the system operation. Maybe he will never be

So exactly what are you goals and what are the indications that they are met? Comfort, efficiency, fuel savings, bling factor?

I feel if the system is designed accurately as possible to the load, boiler, emitters, piping and components sized and balanced correctly, including loop balance at the manifolds, you will have an efficient, comfortable system that you should call a win.
With a multi zoned system, results from over 10 years of experience and several million ∆P circulators in operation indicate they work as promised.

I don't care if my ∆T varies a bit, why should I? Can you say or prove that a system designed for a 17∆T, but occasionally runs at 20 or 14∆T will be noticed as far as your comfort, efficiency, cost of operation or bling is concerned? If so , show me the money.

Now certainly if you replace a grossly oversized circ, on an oversized boiler or mismatched distribution, an ECM, may show some increase savings, lessen cycling, eliminate zone hammering, reduce flow velocity noise, etc. That is a good result.

So understanding WHY you are choosing one over another type of ECM, and what exactly you expect to see is more the question.

I like the idea of two different types and report back your finding.

You can by Euro pumps online, I've used a UK site, just beware of shipping cost and import issues.

keyote

Hot rod Gordy

I must be really dense because to me only Jamie seems to have addressed the questions I posted at the top, and i dont understand him. first I need to know if the VS1816 is even suitable, as i said it seems to be a completely different than the alpha not really variable at all, the data makes no sense and may not provide minimum flow like i was told the VT2218 does. Theres no point getting into the relative merits if only one pump will work. I just want to get it a heating system installed before fall.

keyote

hot rod i have no opinion or preference just want it to work, you guys have raised concerns i thought were resolved when i changed boilers just want to get it ordered.
The only preference i have is because i dont understand the VS data sheet and so am not sure it works, not because its a DP pump the alpha if it had a wider top and bottom operating range would work, the VS seems either completely different or retarded documentation. So because of the uncertainty of that i favored the VT2218, I also think I understand better how the DT would work in the system but that goes back to that data sheet i dont understand.at this point I dont even care if i understand how a DP pump works if you and gordy say to use one then im using it. I just want to make sure it will guarantee flow like the VT and that its going to adjust like the alpha

keyote

thanks hat so it has a minimum flow rate as well?

Gordy

You can review someone else's data, and draw conclusions to its lack of performance, and dissatisfaction..........

keyote

Thanks Hat that was pretty clear. either pump will work. Difference negligible is consensus, while some think DP and others DT slightly safer choice.
what shall we talk about now?

keyote

I have been wondering about what where gauges and what else i might want to install to study it

hot_rod

We see a lot of the 132 Quicksetters getting installed at the pump discharge side. It allows you to see and adjust flow.

The low lead version has a temperature gauge for DHW recirc balance, as well as a spring check.

It serves as an isolation for one side of the circ also as it is 100% shutoff.

It is a lot more accurate that that digital GPM readout found on some ECM circs, don't trust that display.

Shut off, balance, flow and temperature indication, also with an insulation shell. Now in press versions also.

A creative guy might remove that gauge dry well and add a rear connection pressure gauge, if he wanted to observe ∆P increase.

Just a suggestion

Gordy

The low end gpm on those quick setters for the pipe size involved in most near boiler piping really is not low enough for what we seek here..

hot_rod

The low lead version is made for DHW branch balance, so it has a lower and tighter range. We can build them with most any range if we get requests to change the range we will certainly look at that.

3/4 pipe at 1 fps velocity is a 1.7 gpm flow, at 4 fps, 6.6 gpm so the scale should be in the typical 2-4fps hydronic range that you would expect to see in a 3/4 pipe..

Although I don't like to see any balance valve chocked down to the low end, better to drop a size. Or adjust the pump speed

This valve, any valve relay, especially check valves should be selected by Cv or flow rate, not the pipe size necessarily.

SWEI

hot rod said:

This valve, any valve really, especially check valves should be selected by Cv or flow rate, not the pipe size

Strongly agreed.

I'd add proportional control valves (which includes TMV's and TRV's BTW) to that list.

Jamie Hall

SWEI said:

hot rod said:

This valve, any valve really, especially check valves should be selected by Cv or flow rate, not the pipe size

Strongly agreed.

I'd add proportional control valves (which includes TMV's and TRV's BTW) to that list.

I'll second (or third that). There is one, and only one, exception to that of which I am aware: valves on saturated steam mains much be full port, or odd things happen. But operating a valve, especially for control, outside its rated range will lead to poor control at best, and early failure at worst.

Paul48

Oh Boy!........Keep this up and he'll be into next spring.

Gordy

Hold on now. Keyote asked about gauges to study the system not control it.

hot_rod

Paul48 said:

Oh Boy!........Keep this up and he'll be into next spring.

Or hire one of the wallies to come out and get er done

Gordy

He already has flow gauges on his manifolds.

keyote

I think the KHN boiler and other controls will be pretty robust, but to make use of them [and keep this insanity going] we need more information.
Hot rod that things looks really cool. but I have webstone iso drain flanges and theirflanged check, for pumps.
A flow meter seems a great idea but i would think a balancing valve would not be good doesnt my pump need to go anywhere from 1-8 gpm depending on calls, if the balancing port were wide open is that full port?
My install is going to be quite tight, near boiler piping 42"between indirect and boiler. The boiler if i recall has a SWT guage to be installed on supply nipple that will be mere feet from the pump but i was wondering if i should install a PT instead or elsewhere they do fail a lot though , and a flow meter would be great but the one i saw were insanely expensive that ones not too bad if it wont choke the flow, be nice to have a flow meter after every zone valve if they were not expensive. Yes the flow meters on manifolds but they are on every floor so not observable at boiler.
But wait aren't they more like flow valves that will allow me to balance between loops relatively rather than meters? no youre right its both a meter and a valve and if it add the meters i get the manifold total. since im only doing one floor at a time [and adding the cellar baseboard with this first zone i would splurge on a flow meter after the zone if ts not restricting
So it seemed the consensus was that the 1.25 header was sufficient at 1.98 fps, this boiler has a 1'' supply return port im wondering weather to stay at 1'' including the pump, dirt airmag discal etc then jump 1.25 just before the zone valves. saves a little on parts and i think it drop pressure where i want too.
The only thing is the indirect is already all in 1.25 so I'd have to put a reducing tee on boiler that was 1'' for the Ch and 1.25" for the indirect

keyote

Dont suppose there a way to get the back issues of idronics i know i can read them online