is it ok to reduce

Mark J Strawcutter

I was looking at the wrong page of the catalog. Thanks for clarifying Art.

But now we're back to the original question - if a ball valve is a bad choice for balancing, what makes the smaller sized B&G circuit setters different?

Mark

Jon S.

is it ok to reduce

I want to replace a piece of baseboard with Runtal BB in my masterbath. The loop just covers the bedroom and bath and it's 3/4. The Runtal is 1/2 supply and return. Is it Ok to reduce this?

Tom Meyer

First find out why it was 3/4

There could be several reasons why it was originally 3/4". Heat loss, pressure drops, etc. Before you change it to 1/2", try to figure out what the installer was thinking. If you put in 1/2" without doing your homework, you could set up a situation where the water will flow past the bathroom loop instead of going through it. After you get the "why" figured out, then recompute using 1/2" and see if it will still work.

Good luck.

Senior Designer/Trainer
Precision Hydronics Corporation
www.precisionhydronics.com

Jon S.

Its a single loop

Its a single loop. First supplies the bath then the bedroom and then returns. Is this OK to reduce?

hot_rod

You could

pipe in a bypass with a ball valve to balance a bit if it could be made acessable. Hard to answer your question without more info. Actual zone load (btus), loop length, pump size, etc.

It sounds like a restriction to 1/2" would work IF the load on the entire loop can still be satisified. 1/2" should easily carry 15,000 btu/hr. Again depends on total loop length, fittings, etc. Siggys baseboard series loop calculator would be the perfect tool to calc all this out and assure trouble free performance.

hot rod

Tom Meyer

3/4 to 1/2 inch

Jon:

From what you just said, I'm assuming a couple of things. The supply side for that loop comes from somewhere, and it returns to somewhere. Also, the loop is sized for 3/4 inch flow and pressure drop. What you want to do is cut out a portion of the loop, and install a section with half the diameter. In my mind's eye I see a 3/4 branch coming off the main supply (also assuming the rest of the house is heated by the same hydronic system), bringing it up to your bathroom at 3/4 inch, then reducing it down to 1/2 inch for the length of the baseboard, then increasing it to 3/4 to go to the bedroom, which is expecting a full 3/4 flow. 1/2" copper has a recommended maximum flow rate of 1.5 gpm. 3/4" pipe has a recommended maximum flow rate of 4 gpm. Also, when you introduce 1/2 pipe in the middle of a 3/4 loop, you're essentially introducing a flow restriction of sorts. This could cause issues depending upon how the rest of your system is piped.

I don't think the question is as simple as "Can I do it?" with the information you've given. You have to sit down and do the math, look at the rest of the system, and, as Dan says "Think like the water."

Senior Designer/Trainer
Precision Hydronics Corporation
www.precisionhydronics.com

Steamhead

I've run into this with toe-kick units

and here's how I got around it:

Instead of piping the entire flow of the 3/4" loop thru that 1/2" baseboard, get a pair of 3/4 x 1/2 x 1/2 tees and pipe a 1/2" bypass around the 1/2" baseboard. This way, the flow that won't go thru the baseboard will go around it, and there will be enough flow for the rest of the loop.

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hydronicsmike

Why..

use Ball Valves for balancing purposes? Price?

Mike

Mark J Strawcutter

What do you like for balancing? (nm)

hydronicsmike

personally,

I like to use a Balancing or Globe Valve which are both designed for balancing purposes. A Ball Valve is a Shut Off Valve.

At least this is what I have been taught.

It was explained to me that the flow characteristics do not change very much through a Ball Valve, unless it is at least 2/3 closed. That gives me 1/3 or 33% balancing opportunity. (Full Port)

With a Balancing or Globe Valve, I can adjust the flow as soon as I turn the spindle. That would give me 100% balancing opportunity. Am I wrong?

Mike

Mark J Strawcutter

my dilemma

My understanding is pretty much the same as yours with respect to ball valves.

I don't like globe valves because of longevity problems with packing and washers. Others have commented that plug valves become unmovable over time. Legend makes "butterfly" balance and purge/balance valves that look interesting but others have commented that they suffer from leaking around the stem.

I guess the correct solution (albeit a rather expensive one) is to use B&G circuit-setters.

Mark

hydronicsmike

I agree

and like the circuit setter idea. A while back, someone told me about full port circuit setters. I wish I'd remember who makes them and who sells them. Cost is an issue as well, but I put pride into workmanship and if a few extra bucks can eliminate problems, I spend it.

If you have any info on full port circuit setters, I'd be very greatful if you could email me a link or any info regarding those.

Thanks.

Mike

Steve Levine

Most toe Kick heaters

have significant pressure drop as the coil circuit is one loop with many 180° return bends (not Slant/Fin's Kicker - It's coil is headered to reduce pressure drop). A piece of 1/2" baseboard for the bathroom will have little effect on the loops flow. Pressure drop in pipes and ducts is expressed as a loss per 100 feet. A relatively short restriction to 1/2", say 5 feet has only 5% of the pressure drop as 100 feet of 1/2" tubing. Even if it drops the flow 10% (I doubt that much) it will increase the delta T 10%. Therefore if the delta T was 15°it will rise to 16.5°. Figure out how little that will effect the heat output and you will be surprised. Yes the zone may have to operate a few more minutes each day......

Steve Levine

Jon S.

What if?

What if I put in Two 3/4 x1/2 mono flow tees(one forward at the supply and one reversed on the return)? Would this help prevent alot of the presure loss, or is this over kill.

Art Pittaway

Here's some of the math

Net BTU Load/10,000 = flow rate If the bedroom has 10 ft of residential baseboard (Fins not cover) at 600 btu/ft(+/-)= 6000 btu/hr(load) plus your runtal (load) at 2000(guess?) btu/hr = 8000 btu/hr. 8000/10,000 = .8 gpm The 3/4" loops may have been sized with the "I like working with 3/4" factor". It has nothing to do with flow or pressure drop or system performance. It's the most common size in the truck. Tom has the right idea when he says, "Depending on how the rest of the system is piped". If your pumping through a zone valve and all thats on the circuit is a few feet of baseboard the 1/2" runtal won't matter, but, if your master bedroom is 900 sq/ft with a high heat loss and needs the heat, then you will have to pipe it so the flow is maintained. BTW 1.5 gpm=15,000btu/hr, 4gpm=40,000btu/hr,

Unknown

That's how I'd do it

Monoflow tees are a great way to bypass enough water to keep the flow rate high through the whole zone.

Of course, it may be overkill in some cases, as Steve said.

Art Pittaway

B&G Circuit setters, or any other brand

are designed to work with a meter so a large system can be balanced. The meter will set you back SEVERAL HUNDRED DOLLARS. A B&G Circuit Setter IS a ball valve with ports machined into the up and down stream side. It's a very good ball valve and they are accurate when properly installed, period. But, if you are going to put one valve into a circuit to balance the flow through a branch, use a BV, establish the flow then remove the handle and mark it. BTW BV's have a stem packing and they fail too.

hydronicsmike

You know what else I have seen...

...is someone who manufactures Ball Valves, but instead of having a full port Ball Valve, they designed the ball to look like a triangle. Sounds funny, but I don't know how to better describe it. Look at the picture below.

Those type of 'ball valves' are used and designed for balancing purposes. But those truly really are the only Ball Valves I'd ever consider of using for balancing purposes.

Mike

Mark J Strawcutter

B&G circuit setter - ball or globe

The cross-section of the circuit setter on B&G's site looks more like a globe valve than a ball valve.

I also seem to remember Apollo talking about some of their ball valves with some sort of "blowout proof" stem (whatever that means).

Mark

Art Pittaway_2

Go to www.invensysibs.com

Under "Products", "DuraDrive", "DuraLynx" you will find our Actuated Ball valve line. Your picture is of a "Characterized Ball Valve", it is used with a modulating actuator and tries to give the same curve as a modified globe valve. Very little flow at the start then it smoothly opens up at the end. These valves are not designed for shut-off service as they have a very reduced Cv. But a flow control valve is supposed to be that way so it can control flow to a coil properly. The actuator gets a signal from the control and sensor and rotates the valve a few degrees to a new flow rate. These are for use in commercial buildings with computer programmed controls. Art

Art Pittaway

4\" thru 8\" is globe

B&G Submittal #A-549 Circuit Setter."All valves 1/2" to 3" pipe size to be of bronze body/brass ball construction with glass and carbon filled TFE seat rings." If it looks like a globe you are looking at the large series based on the Trible Duty Valve. Art....11 years with B&G

hydronicsmike

Thanks Art.

Now since you pointed it out, I remember that those were B&G Valves that I've seen. Awesome! Thanks.

Art Pittaway

Port size I believe,

I could not find my chart, but B&G has a chart that shows the flow rates at pressure drops for each size. If you look it up you will probably never want to use a Circuit Setter as a shut off valve. I believe they are very reduced port and when designed they were tested for Cv at each degree from closed to open. This was charted and confirmed by flow meters. When you connect their meter to the CB's ports and read, the chart shows flow. We do the same thing for control valves at Invensys,(aka, Barber-Coleman, Erie) on a closed loop we have valves that are installed with a certain number of pipe diameters into and out of the test valve to meet standards set by ANSI and other organizaitons, and by setting the pressure differential and measuring the stroke of a valve we know exactly what that valve will flow, or Cv. We measure flow through three different size Foxboro flow tubes and record the data. To answer your question, it's not the ball valve, it's it's the testing and assembly that makes the difference. A full port BV off the shelf isn't for balance, but a CB can be used by someone that knows how to, with very good accuracy. Once again...more than you wanted to know! Art

Dougie

Danfoss also makes one

Mark J Strawcutter

never

seen an answer yet that was more than I wanted to know.

Thanks, Art.

Mark