Check valves & flow control valves on hot water heating systems:

This article explains types of check valves used on hot water heating systems.

This article series answers most questions about Heating System Boiler Controls on central heating systems to aid in troubleshooting, inspection, diagnosis, and repairs.

Q&A on Check Valves on Hot Water Hydronic Heating Systems

These questions & answers about heating boiler check valves, also referred to as flow control valves, flo-control valves, and similar valves used on hot water heating systems were posted originally

at CHECK VALVES, HEATING SYSTEM - be sure you review that article.

How are Manual Flow Control Valves Adjusted?

How are the manual floor zone valves with screw driver slots in 1/4" shaft adjusted? I'm guessing they might turn a percentage of a full turn.

Are valves open with slot vertical and closed at 90 degrees? It's tricky to test and notice a change in a warm floor.

Thanks for any help you can offer, n 2016-12-22 Gil Corey

Reply by InspectApedia Publisher (mod)

@Gil Corey,

The open position of the manual lever on a zone valve depends on the model. E.g. on many Honeywell valves the OPEN position is marked on the valve body and there's a latch into which the lever is slid horizontally while on a Taco 500 series zone valve like the Taco 571, the manual OPEN lever is pushed fully "DOWN" to open the valve.

If the flow control valve you are describing is one with a simple flat bladed screwdriver slot, turning the slot to be parallel to the direction of the pipe is fully open, turning the slot across the pipe is fully closed, and turning it 45 degrees is about 50% open.

The TacoSetter balancing valve shown below is a sophistication of those older simple slotted balancing valves and allows you to set a specified flow rate in gpm.

Other products such as the Honeywell / Resideo MZV525E-T/U Motorized Zone Valve w/aux switch included a balancing valve to moderate flow.

Other hot water heating valves that use a simple ball valve may be adjusted to part-way open where again if the handle is in line with the pipe it's fully open. But take care that some of these valves are intended to be used only as fully-open or fully closed. Check your valve manufacturer's specs.

See details at

HOT WATER HEAT FLOW BALANCING VALVES i

Post a photo of your balancing valve and I can comment further

Daniel Friedman

Sketch of my B&G Flo ControL Valve Installation

Here is my water heater have B&G flo control valve:

1. bottom connector connect to boiler,

2 left connector connect to expansion tank,

3 right connector connect to pipe to radiator.

Is expansion tank at the right place?

My boiler is only for heat. On 2019-11-20 by nguyen

by (mod) -

At the bottom of CHECK VALVES, HEATING SYSTEM you will see installation instructions for several models of flow control or check valves.

There you will see that when the valve is used in the position shown in your photo the end that we think is connected to your expansion tank supposed to have been plugged.

The result of that may be that the expansion tank is simply out of wrong location where it's not effective

that in turn would cause water to spill at the relief and it would cause the heating system to use water.

I think our expansion tank is not in the right place

Shown just above is a photo of how connections are made at the B&G flo control valve.

We hired a contractor to convert oil water heater and tankless hot water to a gas water heater and tank hot water 4 years ago.

I suspect that the expansion tank is at wrong location On 2019-11-25 by nguyen

Reply by (mod)

At FIND the EXPANSION TANK  we show the acceptable locations for heating boiler expansion tanks.

For an overhead expansion tank:

For free-standing expansion tanks sitting on the floor, at the article I just cited you'll see

For stand-type expansion tanks Amtrol warns:

Do not install the EXTROL on a dead-end pipe or wherever air can collect. This can cause corrosion and possible leakage.(Amtrol atReferences or Citations )

 

Can a Bell and Gossett valves be adjusted by stretching the spring

Can a bell and Gossett valves be adjusted by stretching the spring I want On 2019-11-07 by Bob

by (mod) - Bad Idea

Bob:

For the typical B&G Flo-Control valve like the one shown here, you'll see that there is no internal spring; if your valve has a spring I'd like to know the valve model and to see a photo of it.

There IS a spring inside of some other B&G parts such as the company's pressure-reducing valves.

That spring is adjustable by a locknut & turn-screw.

Watch out: But in any event stretching the spring is in my opinion a bad idea: you're modifying the manufacturer's part in a way that risks any of several failures including leaks or failure to operate as a check valve as it should

Can I regulate hot water temperature so that it stays constant ?

My wife has a business with three shampoo stations feeding off one hot water line.

Is there a way to regulate the hot /cold water supply so that it does not cause an outlet being used to change temperature significantly when a second or third is turned on? On 2018-07-22 by Greg

Reply by (mod) -

Yes, Greg,

Install point of use water temperature regulating valves at each shampoo station.

See details at ANTI SCALD VALVES & TEMPERATURE CONTROL / MIXING VALVES

Then assure that the hot water source has sufficient temperature and volume to feed all three.

I like using a properly-sized instant or "demand" type tankless water heater for this application so that not only do we keep temperatures constant but the salon never runs out of hot water.

See TANKLESS WATER HEATERS

If a check valve is stuck closed will that prevent hot water flow?

if a check valve is stuck closed will it prevent the hot water from circulating even though my circulator runs. On 2018-01-0 by mark

Reply by (mod) -

Yes, possibly, but other causes such as an Airbound heating system or problem with the circulator pump are more common

How do I connect a Taco circulator in line check valve for hot water heating?

How to connect a taco in line check valve for hot water heating On 2016-12-01 by Mitch

by (mod) - IO Manusals and contact information for Taco

Mitch:

A Taco Flo-Chek valve is normally installed above the heating boiler on the hot water line exiting the boiler. For other applications or positions I'd check with Taco directly, as in the product literature there is no discussion of position or other installation details.

You can download TACO installation plumbing and wiring manuals and more Taco contact information

at TACO DIAGRAMS, MANUALS, PARTS, CONTACT 

or contact:

Taco Comfort Solutions, Inc., 1160 Cranston St. Cranston, RI 02920 Phone: (401) 942-8000 FAX: (401) 942-2360 E-Mail: Customer Service

Taco (Canada) Ltd. 8450 Lawson Road Unit # 3 Milton, Ontario L9T 0J8 CANADA Phone: (905) 564-9422 FAX: (905) 564-9436

http://www.taco-hvac.com/ the company's Contact page permits emailing a question

Here is how Taco describes their Flow Control Check Valves:

Taco Flo-Cheks prevent “gravity” circulation in forced hot water heating systems during periods when the boiler is hot, but the space heating zone is not wanted.

This makes it possible to use the heating boiler to maintain domestic hot water year-round.

You can also use Flo-Cheks in systems with multiple circulator zones to allow heat to flow only into the zones that are calling for heat.

In addition, the thumb screw can be opened manually for gravity feed applications, if the main circulator stops operating. 125 PSI maximum operating pressure (862 kPa) and 277° F maximum operating temperature (136° C).

Tapping the check valve in my basement makes it close. Can hot water flow "downhill"?

I have three flow check valves off my basement furnace.

Once in a while one of the upstairs zones sticks and the hot water flows and the heat is higher than the set point.

Tap the valve and it closes.If the basement flow check were to stick open the heaters are at a lower level than the boiler. The hot water could not flow downhill and thru the system as it would in the upper zones. Am I correct? My furnace guy tells me it can. Please tell me who is right. Thanks. On 2016-03-03 by Tom -

by (mod) - maybe

Water will flow by natural convection up if it's hot, or possibly down into the boiler if it's cold. It sounds as if your faulty flo-control valve(s) need(s) replacement.

But hot water can "flow" downhill if in fact it's being pushed by a circulator pump. That might be what your furnace guy was thinking. - Daniel Friedman

Tech said I don't need the B&G Flo Control valve and since it's stuck I should just remove it

Have an old b &g control valve on boiler. I believe it's stuck. Have circulating pump (taco) on return side just in front of boiler.

Guy I called took a look and said that you don't really need control valve and to remove not replace.

Said it was put in place before the circulating pump and not needed. Any thoughts. ?On 2015-11-24 by Pedro C

Reply by (mod) - Really?

Pedro:

I'm not sure what control valve you mean - please use the page bottom CONTACT link to send me photos of the valve, its location, and any tags or markings.

If you refer to a flow control valve such as those shown in the article above, it is true that SOME circulator pumps may contain their own built-in check valve.

Most older pumps don't.

You need the valve to prevent hot water circulating by convection when you're not calling for heat.

Just figure: not many installers would go to the trouble and expense to include heating system parts that were not needed.

Can I use a check valve to prevent solar heated hot water rising through heating zones in summer?

I have a hot water boiler that is heated by multifuel and solar. When heated by solar (mainly in warm months) heat rises by convection to the zones through the return pipes.

Can a check valve be used to prevent this and what type would work best? The location would be vertical mounted. (Feb 24, 2014) Lynn Zimmerman

Reply:

Lynn what you suggest sounds right to me.

The check valves discussed in the article above are performing that same function for fossil-fuel heated water, preventing water in the boiler from rising by convection up into the building baseboards or radiators, but opening and permitting water to flow in response to the pressure difference created when the circulator starts.

There are other concerns about solar systems and possible overheating of other system components that mean you'll want to review the design with the solar manufacturer.

 

Could a bad water feed valve causes backflow preventer leak?

Could a defective automatic water feeder valve cause backflow preventer valve to leak at the Vent side of the "T" - (July 8, 2014) Edward Martin

Reply:

Edward,

Some discharge from a backflow preventer is normal, such as if water pressure on the supply side falls to atmospheric pressure.

Other periodic discharge from the backflow preventer, showing up at its vent tube, can be caused by a water hammer problem in the building. To diagnose water hammer troubles see

inspectapedia.com/plumbing/Water_Hammer_Noise.php

If the backflow preventer is dripping constantly there is probably dirt on its moving check valve parts (internally) - a condition that can be corrected by cleaning the valve or by replacing it.

Also check that your backflow preventer is properly installed and located - on the fresh water feed line but *before* the pressure regulator.

 

Only one side of heating valve gets hot

Only one side of heating valve gets hot Oct 14, 2015) Joe said:

Reply:

Joe

Then IF your thermostsat is calling for heat AND the circulator is running, the flo-control valve is either stuck closed or has been manually placed in closed position.

 

Is a control valve needed with single zone/circulator to prevent gravity circulation?

Is a control valve needed with single zone/circulator to prevent gravity circulation??

I Had my New Yorker/Beckett Oil furnace with domestic hot water loop, 2 forked zones on single circulator replaced with another New Yorker last month.

Flow between forks/floors is adjusted with a small inline restrictor valve.

The house temp is getting over 85 degrees, but the circulator is not running / thermostat off.

I'm guessing it's "gravity circulation" since the new heater does not have a flow control valve installed.

The old setup did have a valve. Is a flow control valve necessary with just a single circulator pump? Can there be gravity circulation with a circulator pump in line? 2015 10 25 Tom said:

Reply:

Yes, Tom. Though some circulator assemblies may contain their own check valve or flow-control valve. Tell us the brand and model you have and we can help look that up.

 

Use one Flo Control Valve for Two Zones?

Can you use ONE common Flo Control Valve With TWO Circulators? On 2018-10-26 by Fred

Reply by (mod) -

I'm not sure that's a good idea, Fred.

You could install a mater Flo-Control valve and pipe two zones downstream from that feeding two circulators on the return side of the two loops (where they belong), but the problem would be that when just on zone is calling for heat and its circulator running, the pressure drop will open the common FLo-Control valve to both zones.

That means that heat can circulate by convection up through the "off" zone even though it's not calling for heat.

 

B&G Hydro-Trol solved my unwanted gravity flow heat problem but now my circulator pump starts but won't open the Flo-Control check valve

I was in contact with you this spring regarding the check valve problem.

I have since installed a B&G NPT HydroTrol unit and it solved the n"gravity flow" problem. Unfortunately a new issue has arisen.

When my pump (Taco 007-F5) is engaged, it doesn't open the check valve.

If I turn it "manual" the hot water flows easily. I measured the PSI differential across the pump.

When it at rest: (20 PSI), the when the pump is engaged: (20 PSI after the pump and 18 PSI before the pump), so the pressure difference is 2 PSI.

What is the activation pressure needed to open the HydroTrol valve? (The valve is located on the "after pump" side of the system) - On 2017-10-29 by Steve

Reply by (mod) - new flow control valve won't open when it should

I recall, Steve. Welcome back.

Some flow-control valves have a manual lever that might be set to the wrong position, closing the valve.

The B&G control valve about which you ask as well as the older traditional red B&G FLow Control valve are discussed at CHECK VALVES, HEATING SYSTEM

In that article I also mention your valve and give some links to documents for it.

And in the REFERENCES section of that article (at the page bottom) you can click to show references to find I&O manuals and instructions for these valves ( such as inspectapedia.com/heat/BandG_Flo-Control_Valves_Manual.pdf )

From B&G's submittal sheet for the HydroTrol Flow COntrol Valve A-444A it looks to me as if the valve should open at 0.5 psi.

FIRST CHECK: you have the valve installed with flow in the right direction, right? Check the flow arrows on the valve body.

SECOND CHECK: what is the head pressure (or feet of head) against which the circulator has to operate? Is it within range of the circulator's specs?

I might contact the company by phone, ask for technical support, and see if they have a different opinion.
Xylem Inc. (B&G)
8200 N. Austin Avenue
Morton Grove, Illinois 60053
Phone: (847) 966-3700

Followup by Steve

The check valve is installed correctly. From what I can see, determining the head press requires an amp measurement on the pump, which I don't how to do

One thing I've discovered is that when one of the pumps engages, there is water being circulated to the zone, but there is also "back flow" into one of the other zones, (my pumps do not have an anti-back flow valve).

This tells me that the check valve is not opening completely.

Again, when I turn the know to "manual", this back flow stops. Could it be a faulty check valve? Perhaps it's partially stuck?
Steve

Reply by (mod) -

Steve,

If circulator for Zone 1 is pushing hot water into Zone 2 then the valves are not working correctly and it sounds to me as if the problem is that the check valve for a Zone 2 is being left open.

by Steve

It gets complicated...I have 5 pumps and 5 zones...3 on the upper floor (baseboards) and 2 in the concrete basement floor. (designed in 1991...old technology, I assume). I have 1 check valve serving the entire system which is installed after the boiler and all of the pumps.

My current assumption is that the check valve is not being fully opened when the upper pumps are activated, which pushes hot water backwards through the lower floor zones.

Again, my pumps do not have a back-flow check valve. The basement is at 72 degrees, despite the thermostat setting of 68. If I turn the check valve to "manual" I get no back flow, but then I get gravity flow to the upper floor as was the case with my failed check valve from before.

I do have the capability to partially reduce flow through the basement, which should increase the pressure to the upper zones. Would this damage the pumps?
Steve

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Continue reading at CHECK VALVES, HEATING SYSTEM - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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