variable speed secondary loop

Jake Timmerman

With variable speed circulators now on the market in the U.S. I have been thinking of applications to use them (besides injection). One thought is to use them on secondary circuits which have zone valves. Vary the speed of the circulator based on the delta P of the circuit. The problem I have is that I can’t find a proportional pressure differential control. Does anyone know who makes one of these with an output signal of 4-20ma? Another thought is to vary the flow into the secondary circuit based on its delta T. The theory is the greater the delta T the more flow the circulator will put out, and once the delta T is closer together the flow will slow until the circuit only gets what it needs. When another zone valve opens, the delta T will raise again and the flow will increase. Will this work? And who makes a proportional differential temperature control? One that puts out a 4-20ma signal.

Dave Stroman

I have thought of doing this with a cast iron radiator job. Rather that cycling the pump on and off to keep the boiler hot, use a veriable speed pump. Slow it down when the boiler drops in temp.

Dave in Denver

jwade55_3

I have used this

one before.

http://www.veris.com/pdf/env/press/wet/pw_d.pdf

J

Jed_2

Take a look at Taco

Newly released series of VS pumps with integrated "on board" direct circulator controls. 00-VR(outdoor Reset), 00-VS(VS Setpoint. think boiler protection), and 00-VV. The VV(variable voltage) includes 4 voltage ranges, 0-10Vdc, 0-20mA, 2-10Vdc, or 4-20mA. Wide variety of applications, including maintaining a pressure differential, or a set point temperature.

Available to ship this Spring, as I understand. Oh! the possibilities.


Jed

chris smith_4

variable speed control

jack,
johnson controls makes a p352p contoler that should work for this, it can be 0-20ma or 0-10vdc, this newer style johnson is very nice, the controls mount on din rail for ease of use, talk to your sales rep to be sure this is the best control for your application,

chris smith
paradise porter maine

Jake Timmerman

Jwade that was just what I was looking for, thank you. Now if I can find out who makes a differential temperature control?

Constantin

I'm of the same mind...

There seems to be no good reason not to use variable-speed circulators, other than teething issues with the PWM drivers or whatever they're using to control the motion.

Correct me if I'm wrong but it seems to me that unless you pressurize the heck out of the system, that you could radically reduce the number of required pumps in warmboard heated homes with less than 1,500 sq ft per floor via VS systems. Something like one pump per floor to keep things simple... Systems with smaller pipe sizes may still require more pumps due to the higher head pressures that small diameter systems develop.

Or am I crazy?

Dave_22

Differential sensors...

Looking at the Taco literature mentioned earlier, I thought there system came with a diff. sensor. I know they have a PDF file that explains this new system- I saw it on a post here within the last few weeks. Other than that, I think the diff. sensors can get a little pricey. Check this out:

http://www.omega.com/ppt/pptsc.asp?ref=DP26&Nav=temp04

jerry scharf

one detail on these

I got some great tech information on these from Taco. They are using triac controls, which make them rugged and simple, but mean that you won't save as much electricity as with a VF drive.

Anyone make a cheap 3 phase circulator pump in the < 1/4 hp range?? OK, stop laughing.

jerry

jerry scharf

Is this a wet unit?

Chris,

I went and read the specs on this, and it didn't say anything about it being a wet/wet differential unit. The pressure ranges (up to 10" WC) sure sounds like it's for air.

thanks,
jerry

Jake Timmerman

Thanks Dave, That is was what I was looking for. You all are great help.

Jed_2

Interesting

Jerry

I was just referencing the tech sheet dropped off by Jim Simas/ES. He didn't have any I/O's, so I don't know how to evaluate cost of operation. I might be getting in over my head regarding controls energy consumption, but can it be that dramatic? You lost me about the 3ph 1/4hp.

Jed

jerry scharf

thoughts on the electricity costs, pump controls

> Jerry

>

> I was just referencing the tech sheet

> dropped off by Jim Simas/ES. He didn't have any

> I/O's, so I don't know how to evaluate cost of

> operation. I might be getting in over my head

> regarding controls energy consumption, but can it

> be that dramatic? You lost me about the 3ph

> 1/4hp.

>

> Jed




Let's you have a couple taco 007 pumps running the system (smaller than any P/S system could realisiticly be) and are running constant circulation for 50% of the year. The 007s use .71A @120V or a total of 746 KWHrs of power (assuming I did my math right.) If you then say your electricity is 11c/KWHr, this comes out to $82/year for the electric bill.

Now $80/yr isn't that much compared to the fuel bill for the boiler, but you're comparing it to the cost of a more expensive pumping system. It's hard for me to work out the numbers to make the boiler pump make much sense. In a circulator per zone system, it really depends on the cost of scaling the controls and pumps vs the active time on each pump. Having a 0011 or larger pump with zone valves would be where you could begin to see savings.

If you're good at tea leaves, you can estimate the future rise in electricity and see where your numbers go. I'm just on the edge of being able to justify a complex pump system now from my way of cutting things.

I've also been playing with a simpler idea for the controls. First, you put a nice visual diff press guage across the pump. You measure and record the differential pressure across the pump on each zone and compute the hydraulic resistance. Then have the control generate the calls for heat based on sensor input. Once you have this, you should be able to set the pump speed computuationally from the controller without needing real time pressure inputs. Saving $400 or so for a normal wet/wet diff pressure analog transducer makes the other stuff look like it might be worth it. It's not a nice self correcting system like a w/w dp sender, but for the control hacker it's interesting.

The comment about a small 3 phase pump is that it's very easy and efficient to use a VFD to control a 3 phase motors and brushless DC motors. It's not so good with a single phase motor. The GE series 84 ECM motor looks like a nice, efficient choice, but how you could lash that up to a pump is way beyond my ability. It's a tad harder to do a PWM output as compared to 0-10VDC, but it's not that much.

Can you tell I'm a long time controls hacker? I respond to engineer, but I also respond to "hey you."

enjoy,
jerry

Mike T., Swampeast MO

You can also radically reduce the number of circulators...

...if you use proportional flow control devices to regulate the heat instead of digital devices.

With a decent reset curve and constant circulation, the flow rate (and delta-p) through the system isn't going to change much during maintenance conditions.

Remember your "KISS" Constantin.

Danfoss FHV-A w/operator isn't particularly expensive. Should work extremely well with Warmboard.

Mark Chaffee

Taco Variable Speed PDF's

Thought you might like to see those PDF's again. All models and styles of "00" circulators are available in any version of variable speed. They are currently shipping too. Check one out today.

Mark Chaffee

Taco Variable Speed PDF's

Thought you might like to see those PDF's again on the Taco variable speed circs. All models and styles of "00" circulators are available in any version of variable speed. They are currently shipping too. Check one out today.

Constantin

As usual,

You make my day. Thanks Mike!

Now for the next question: Where can I get more info on the unit? The US site seems pretty useless. Can you tell me how much head such a valve adds to the circulation system? Cheers!

Mike T., Swampeast MO

FHV Data

Danfoss FHV Data

Hope the link works for you. Windows 2000 Pro and Internet Explorer 6 have absolutely screwed up the links on my computer and many no longer work. Went to danfoss.com, >products; >floor heat; >FHV (at least I think that was the progression)

Since you've lived in Europe the liters/minute vs. gallons and kwh vs btuh shouldn't bother you too much I hope...

Sorry, but my actual Danfoss catalog is rather old and all I have are the new price sheets listing these as "Radiant Specialties".

It appears to be a very well thought out device with particular attention to ease of installation and service access.

Two versions: one modulates on air temperature, the other on panel temperature. Believe that the panel temp device is quite limited as to square footage of the panel--50 square feet or so seems to be stuck in my head.

Paul Bock_2

Taco has put them together

for me before. They were 3ph, 1/3 or 1/2 hp. used a magnetec drive. works well.might have to trim the impeller in place of a 1/4 hp motor.

Constantin

Thanks again!

I looked up the data, am still scratching my head a bit regarding the chart (not the conversions, trying to figure out the horizontally aligned head pressures the unit develops on different settings). Thanks again!

Kal Row

as does heat-timer

Kal Row

mark - pls tell them to update the web site

it's so far behind your products - just look at how timely B&G's web site is, the new Check-Trol spring-check flange, was anounched, and put on their web site right away!! i have known about these new pumps over a month - yet it's not yet even in the news section of taco-hvac.com!!! like totaly pathetic

for Jake Timmerman - the 00-vs model takes the place of a tekmar 256 does it all except soft cycling control of the boiler
also - heat-timer.com make a digital setpoint control the MCA series that will give you 0-20ma