What is a balancing valve

[Jonathan Cartwright]

I saw this valve today on a residential water heater circulation system. This was not for home heating just for hot water circulation.
Per the Nibco web site this is a balancing valve. Can be adjusted and the valve position is displayed in the window on top of the knob.
My question is: What does a balancing valve do and why is it on this system? Are there things I should be telling/reporting to a client about these?

Thanks

Jonathan M Cartwright

[Jerry Peck]

I can't answer that question, but ...

I've never seen an orange cord and plug set - all of the orange ones I've ever seen are extension cords, and cutting off the end of an extension cord and using it for the purpose shown is not allowed.

I also like those stored paint cans next to the gas water heater. :eek:

[Michael Thomas]

It maintains the required static fill pressure. AFAIK all a HI can do is look for leaks

[Michael Larson]

It is controlling the temp of the hot water loop. It would tend to reduce or increase the flow in the loop.

Never seen this setup. I wonder how effective it is.

[Jonathan Cartwright]

It is controlling the temp of the hot water loop. It would tend to reduce or increase the flow in the loop.

Never seen this setup. I wonder how effective it is.

How would this affect the temperature of the loop? If you change the flow rate would'nt the water temperature remain the same?

Jonathan

[Jerry Peck]

How would this affect the temperature of the loop? If you change the flow rate would'nt the water temperature remain the same?

Jonathan

Jonathan,

My thoughts of its operation (I couldn't really tell from the description on that link) was the same as Michael's.

I've never seen that type either. It is also not designed for that use so much (if at all) as for heating system use, but, it is installed there.

However, the way it would work would be like this (as best I can envision it):

The hot water going out into the hot water system piping loses heat the further the hot water travels (i.e., the greater the length of heat sink piping transferring heat from the water to the air, the greater the temperature loss there will be in the water) the more heat it loses. Increase the flow and the cooling water is replaced more quickly with heated water.

Slow the flow down and the hot water will lose heat faster than it is replaced by the circulating hot water.

Of course, though, that means the water heater will be operating more ofter than it would otherwise operate, using more energy to keep the water the same temperature (probably overall reducing the energy in a heating system by maintaining a more constant water temperature, but wasting energy in a hot water circulation system for domestic hot water use only.

[James Duffin]

It may be called a balancing valve but it looks like here it is being used more for flow control. Most heating coils are rated for a certain flow and this valve can be used to help maintain the rated flow.

[Steven Turetsky]

I have designed and installed a number of instant hot water systems, the most recent was to supply hot water to 7 scrub rooms serving 14 operatiing rooms in Richmond University Hospital in Staten Island, New York.

First off, let me say that I am not familiar with the exact ones that you have in your photograghs, so much of what I contribute regarding this subject is based upon previous experience on similar projects.

I. There are two separate items in your photos, not one two piece item. There is a mixing valve, and there is a circulating pump.

The mixing valve. The mixing valve mixes the hot and cold water together. Lets say your hot water maker makes water that is 160 degrees. That is too hot and could burn someone, so you mix cold water into the hot to cool it down.

I'm sure right now you are saying... " why not simply turn down the temp on the hot water maker?". OK, so lets take it a step further. You have a 50 gallon water heater and every morning 5 people all want to take a shower right after each other. If the water heater was turned down to a safe level, I'm sure it would run out of water faster than it could recover, but if you had 50 gals of very hot water, and mixed the cold in, to bring it to a safe temp after it leaves the heater, you would have more usable hot water.

The mixing valve is acting like a safety valve.



Now, an instant hot water loop.

As I said, the last one I installed was for scrub sinks on operating rooms. The doctors did not want to wait for the hot water for the boiler to reach the sink. It was a long run and took a long time to get hot water.

I've installed them in high end houses where the folks wanted the hot water to be hot when they turned it on and not have to wait for it to pass through the system.

Lets say you have a sink on the 3rd floor of a house, far away from the hot water maker. When the system cools down (in the middle of the night), and the first one up in the morning wants to shower or wash up, he (or she) has to wait a long time to get hot water. Some folks find this annoying.

If you return the end of the line back to the hot water maker, creating a ... "LOOP", and if you install a pump on the line that is controlled by an "aquastat", well, everytime the temp in the loop drops below a preset temp., the pump come on and circulates the water in the loop.

Some folks use a timer instead of an aquastat, but I think that is senseless. If you insulate the line, it is suprising how little the pump will have to work to give you 24/7 instant hot water.

[James Duffin]

I do not see a mixing valve in the pictures. Only a pump and the thing with the blue handle. Also I think this is a space heating only system.

[Steven Turetsky]

The "thing" with the blue handle is a balancing valve. But I too only see an in and and out, I don't see how it is doing much of any regulating... unless there is more than the pictures reveal.

[James Duffin]

This appears to be a one zone heating system with a balancing valve regulating the flow on the one zone. It looks like an appropriate setup to me.

[Steven Turetsky]

What purpose do you think the b valve serves?

[Jerry Peck]

Steven,

I understand balancing valves with a hot and cold in and a tempered out, but that balancing valve ... ??????

That's what has me stumped ... the "how" it works, other than what I guessed at in my post above.

[Steven Turetsky]

Jerry,

That is what has me scratching my head too. I just don't see the purpose... if there is a purpose... that the valve shown is serving.

It is very possible that it is the right part for a different application!

--Steve

[James Duffin]

The only purpose I see is to regulate the flow of water in the system. A ball valve could be used for the same purpose but it would be missing the test ports and the % gage on the top of the valve. It the pump can pump 10 gallons a minute and the coil is rated for 5 GPM at 140 degrees to get a 60K BTU output then the valve with the blue handle can give you the proper flow rate with the ability to measure your flow.

[Jerry Peck]

Steven,

Maybe we should just call it 'an adjustable line restrictor'? ;)

[Steven Turetsky]

Actually,

I keep going back to the pics... enlarging them... looking... thinking.

I'm really looking forward to someone enlightening me, but to tell you the truth, I have no idea what purpose that set up is trying to accomplish.

1. It could be heat or domestic
2. The way the balancing valve is made up, what is it doing?
3. The pump is on a plug. Does that mean it is turned on/off by hand or does it constantly run and the water in the loop/heater maintains a constant heat?

They say the ends justifies the means. I'm curious what the end is.

[Jerry Peck]

They say the ends justifies the means. I'm curious what the end is.


I'm also curious about the means to that end.

[Steven Turetsky]

Jim,

I just read your post... didn't realize it was there.

So you think that it's just acting like a big regulator?

OK, that's possible, but I still don't see why. If it's a heating loop, once the temp in the loop catches up with the tank... which won't take long, it shouldn't be difficult to keep up the temp. If that was the case, I think they would do more good insulating the tank.

And if they wanted to save money, I'd put that pump on an aquastat.

OH well, folks do strange things.

[Patrick Martinez]

Steve, Jerry,

I agree with both of you on the valve being regulatory. As to it's purpose here, I think it is a poor choice in this application. Looking at the system design, in the event the H/W is well above scalding temp, the regulating valve would likely close. This presents a problem with the recirc pump that it is likely to fail prematurely do to loss of flow over repeated occasions. Steve called it out well with the commercial applications for numerous fixtures requiring hot water immediately. That being the case, it is tempered at the mixing valve having both hot and cold inlet / outlet and serving numerous fixtures, ie, a bank of showers or scrub sinks.

Pat

[Richard Moore]

Puzzling! I went in search of more info. Here are some links and other info, although I'm not sure how much it really helps.



http://www.nibco.com/assets/ST1710L.pdf A onepage PDF "brochure" on the valve. The following is extracted from that and decribes its purpose...somewhat.




• Globe style balancing valve for use in hot water circulation systems
• Provides adequate amounts of water at prescribed temperatures to all fixtures and equipment
• Balancing valves provide desired flow distribution throughout the system
• A properly sized and balanced system will provide an economic and efficient heat source




So I went looking for more info and ran across this paragraph from something that appears to be the plumbing specs for a cancer center in Texas.



Domestic Hot Water Return Circuit Balancing Valves 1/2" through 2" shall be ‘Y or T’ pattern with threaded inlet and outlet connections, equal percentage globe-style and provide precise flow measurement, precision flow balancing and positive drip-tight shut-off. Valves shall provide multi-turn, 360° adjustment with micrometer type indicators located on the valve handwheel. Valves shall have a minimum of five full 360° handwheel turns. 90° ‘circuit-setter’ style ball valves are not acceptable. Valve handle shall have hidden memory feature to provide a means for locking the valve position after the system is balanced. Valves shall be furnished with precision machined venturi built into the valve body to provide highly accurate flow measurement and flow balancing. The venturi shall have two, 1/4" threaded brass metering ports with check valves and gasketed caps located on the inlet side of the valve. Valves shall be furnished with flow smoothing fins downstream of the valve seat and integral to the forged valve body to make the flow more laminar. The valve body, stem and plug shall be brass. The handwheel shall be high-strength resin. Provide valves as scheduled on Contract Drawings manufactured by Armstrong Model CBV-VT or NIBCO T-1710 and F737-A. Furnish each valve complete with optional pre-formed 25/50 fire/smoke rated insulation.

Ok...so maybe the acceptable substitute Armstrong valve has more info?

See http://www.armstrongpumps.com/Data/ioguides/Links/01_02_005/36.89_CBV-V.pdf

Well...hopefully, that's a little more help to some, but I'm really still left scatching my head! It measures, it adjusts, it memorizes, it slices and dices! But, why this would be needed on a particular residential hot water re-circ system is still a mystery to me. :confused:

[Jonathan Cartwright]

I dont know if this helps but there is no hydronic heat anywhere in this house and the circulating pump runs always - if its plugged in.

Jonathan

[Rick Maday]

Jerry mentioned the extension cord which may be a clue to the entire setup here. We can assume that this was a DIY project. And they did it wrong. Whatever "it" is.

Just a guess. :)

[Tom Rees]

The recirculating pump runs always? :D