Should fill valves be left open or closed?

HeatingHelp

Should fill valves be left open or closed?

Read the full story here

solardave

Thanks for this great incite, it demonstrates that nothing is totally simple in this business. I'm used to dealing with a lot of old iron pipe hydronic radiator systems with the adjustable fill valves, with the fast fill option. I have been told in the past that the supply should not be left open. The reason given was in the event of a undetected leak the continuous adding of fresh oxygenated water will cause the iron pipes to rust at an accelerated rate. I'm just curious about the validity of this wisdom. This also begs for the adding of a low-water cutoff.

j a_2

Well I am a closer due to mainly, liability. It's a good policy to walk the owner or his representative thru the periodic steps that the manufacturer requires the owner do...and if in they follow thru as they are supposed to many many disasters would have been prevented...They require weekly check ups, so how does one leave there vacation home vacant all winter with the heat running....

pitman44

We recommend a LWCO on every system we service that doesn't currently have one. I used to feel it was kind of a belt and suspenders type thing until we started testing the relief valve on every system and started finding systems very low on water. Then I started thinking "Since the fill valve or backflow preventer wasn't doing its job, how much further is it before the system water level is too low?"

Skepticelt

Good article. If you leave the valve open and put a bluetooth water meter on the incoming water you will be able to monitor the boilers water usage from whatever device you have paired it with.

Gordy

Closed with lwco.

Jackmartin

In Canada the gas code requires you put a strape on aquastat on the return or supply right off the boiler and set it for 200 degrees
The thinking is if the piping reachs this temperature you want the burner off. We do not put in one with a manual reset as it gets too cold to quickly ;today is -30. The problem being this is a relativey new rule and the vast majority of systems have no lwc or this aquastat. I think in the future I am going to close the valve but given our climate you just have to wonder am I gambling both ways? All the best Jack

Solid_Fuel_Man

I still like the idea of closed fill valve, and a low pressure switch. That low pressure switch would be the first sign of trouble. Have it turn on a light or send a text/email alert to you (the contractor) . LWCO are code here in Maine, and it is rare to see a system without one.

hot_rod

Jackmartin said:

In Canada the gas code requires you put a strape on aquastat on the return or supply right off the boiler and set it for 200 degrees
The thinking is if the piping reachs this temperature you want the burner off. We do not put in one with a manual reset as it gets too cold to quickly ;today is -30. The problem being this is a relativey new rule and the vast majority of systems have no lwc or this aquastat. I think in the future I am going to close the valve but given our climate you just have to wonder am I gambling both ways? All the best Jack

The main issue becomes with today’s highly efficient micro bubble air eliminators air will be purged from systems for several days, maybe weeks on large systems.

With ODR systems it is only when you get to the highest temperatures that you displace all entrained air

Soooo if you have a low pressure cutout switch, as many mod cons do, the loss if a few lbs will cause a lock out.

Only when the pressure is restored will the boiler fire.

I’d highly recommend the fill valve be left open for days or a week.

I’d also drive the system to high limit temperatures when firing it the first time to speed the micro air removal

At the end of the day a fill tank or PIG can solve both concerns. Enough additional fluid to replace purged air, not enough to cause a serious flood concern, also alarm function

AND the pesky bfd issues go away

Harvey Ramer

I always leave the fill valve open. However, I have thought about the different scenarios, and I believe a redesigned fill valve would solve the problem.

A second diaphragm could be added that could shut off the flow completely if there is greater than 3-5 psi difference between the set pressure and the actual system pressure. This would have a manual bypass for initial system fill or service. Once in service, it would function normally and add water as needed while gasses are being vented. In the event of a pipe rupture, it would shut down and prevent flooding.
A set of contacts could even be added to shut down the system or sound an alarm.

Tim Potter

fill valve off, PIG system with a low-pressure trip switch to alarm contact on my t-stat sends me an email. That's how I can leave my home vacant in the winter with the heat running.....
(credit Mark Etherton, hot rod, & others)

Mad Dog_2

Speaking of lwcos. I serviced a gas, steam atmospheric a few weeks ago where the probe lwco not only saved the HO's life & property, but maybe even his neighbors: He said the original installer told him when he converted over from gas, that he "didn't need to do NO maintenance!"
That was 10 years ago. When I took everything apart, the nipple and pigtail were 100% clogged and so was relief valve nipple AND the relief valve! HOLY COW! THANK GOD AND AMAZINGLY THE PROBE NEVER FOULED THAT BAD, The LWCO was the only thing preventing
This BOMB from leveling the house. And, I always leave the fill "live" I've seen lwcos
Fail to work. Mad dog

Solid_Fuel_Man

I should have edited my post to say closed fill valve after a month or so. I make it a point to revisit any job after a month just to look things over.

Also steam is a different animal, of which I'm not well versed in. I'm speaking of water only.

NY_Rob

No reason homeowners can't be trained to eyeball the boiler water pressure gauge every couple of days. Tie it to another routine task- recyclables go out on Wed... check boiler water pressure after taking out the recyclables.

Gordy

I would believe part of a reputable installers quote would be to go back to check the system to see how much air was removed to affect fill pressure. Yes on new installs fill valve on until air removal has stabilized. I'm thinking more an established system.

Homeowner checking system fill pressure with valve off also alerts them to changes that could indicate leaks. Purely referring to non steam systems.

j a_2

I’d also drive the system to high limit temperatures when firing it the first time to speed the micro air removal
One would hope that’s done as it’s part of the set up for a initial combustion test....

JAdams

If the fill valve manufacturers want you to "shut the valve off" then why don't they build them with shut off s? Granted, I always install a ball valve prior to the back-flow preventer and fill valve, and one after, for service purposes, I also install the LWCO higher than the circulators, for the reason of not burning one out due to being air bound, it works!!!

MCT

Leave it open, install a makeup water meter and check for usage

Bill_Kitsch69

Open.
*Pipe boiler relief & backflow to where discharge won't cause harm or property damage, always.

breeve

For whatever it might be worth:...
1. Each of the "control" / monitoring units is super cheap, especially compared to the cost of an exploded house. Any system involving water and getting water hot should have...
a) a Low Water Cut Off with (at least ) a very plain indicator that it has tripped
b) a measuring device that meters "makeup" / introduced water (usually a half-inch brass "turbine" (approx $5 - creates a pulse per ml - count with an Arduion in a box../.etc. ) is a perfectly good sensor)
c) a high temperature Cut Off (there is no good reason that the part of the boiler wher4e water is involved should exceed 250 or so deg. F.

2. "Callbacks" kinda. BUT there are often people living in the house. Some are idiots. But they aren't all idiots all of the time. Right, they work in offices, shuffle paper, yak on the phone, they don't have plumbing tools, either mentally, nor wrenches, BUT some ( some I say, some) responsibility for paying some (I say some) attention to this thing that is consuming a couple, three, four hundred thousand BTU of nat gas / oil, etc. making steam in their basement / utility room might fairly be incumbent upon them as one of their little jobs in life. True, there are witless people who just wanna be warm. But installers who give their customers a chance somewhat to know and understand their heating system are doing the right thing. Fuel and water bills are "secondary" evidence. Install simple, reliable measuring / monitoring devices that are "primary" evidence and encourage the customer to do a little bit of reasonable looking after.

RayWohlfarth

I used to leave the fill valve open all the time until I read the disclaimer in their instructions, "After the system has been filled, the cold water shutoff valve must be closed."

I still recommend a water meter and a low water cutoff.

schreib

I have plans to reduce my too high concentration of propylene glycol(-100 No Burst, Noble Co) from present 50% down to 35%. While inspecting my system I noticed that my fill valve is open, just a little petcock up stream. So, for the last 4 years since building this home, THAT has been how it is setup. I know my Plumbing contractor put it in at 50% and I know it is still at that now. I bought a refractometer and tested it and another local plumber verified. So, 4 years and no dilution from its original 50%. That makes me feel pretty confident this is safe. In addition it is a Lochinvar WH55 Knight boiler and it has low flow alarm capability.

BUT. Then there is this. I plan to open the system and, over some weeks, drain off 2 gallons or so at a time to let it equilibrate slowly to 35%. I do have a SpiroVent Microbubble eliminator on the system. Is this a good plan or should I consider more remedial measures?

lacro46

It depends on which instructions you read. Different manufacturers have different opinions.

Watts: Operation - To fill the system, open the shutoff valve upstream of the regulator. This valve must always be kept open when the system is in operation. Water will flow into the system until it is full and under pressure.

Taco: Install a shut-off valve on the upstream side of the
Boiler Feed Valve. This valve, provided for isolation purposes during maintenance, must be open at all times
during operation so that the Boiler Feed Valve can
maintain pressure automatically.

Appolo: To fill the system,
open the shutoff valve ahead of the valve.
Raise the lever to its upper-most position for
fast fill. When filled, release the lever to its
normal position. The valve will maintain the
system automatically.

Caleffi: When the system is filled, the shut-off valve can be closed. In order to restore the automatic topping-off condition, merely re-open the valve. The pressure in the system will gradually return to the set pressure.

schreib

For those of us not registered plumbers but skilled DIY'ers it would be helpful to get some clarifications and recommendations.

-- model numbers and details on best Low water Cut off devices-- LWCO's
-- same for water usage meters , blue tooth or otherwise.
thanks.

OldPro69

We used to leave the feeder on and really had no problems. Many of our customers bleed their radiators and without a feeder to replace the pressure, they could have a problem. That was our thought process. Then we had a job where the feeder was left on, the customer decided to save some money and not have us clean and check the boiler for a couple of years. Then they moved out of the house and didn't check on the house for several weeks. She called me up on a cold day in January in a panic. The heat had been off for a long time and water was leaking all over. When I arrived at the house there were two foot diameter stalagtites of ice inside the house. I checked the boiler and found it off on the pilot safety due to a dirty pilot. This was a mansion. We ended up replacing all of the radiators and all of the piping in the walls and ceilings. We had converted this system from steam to hot water many years ago, so the piping was oversized. We obviously resized the new piping and ran all lot of the runs in pex. The total damage to the house was around 1,500,00.00. Since then we always leave the feeder off. We had another freeze up two years later, had to replace all of the radiators, but there was very little water damage. She was also out of town and we believe turning the feeder off saved the house.

EdTheHeaterMan

I always leave them open. Unless I close them for some reason.

RayWohlfarth

Thanks @lacro46 Now I am more confused than ever LOL

sunlight35

A similar question would be should I turn my water main off if I leave for vacation for four months.

Solid_Fuel_Man

In this day and age, vacant houses should all have wi-fi remote thermostats that alert you as the installer or the homeowner or both. 

Just need that C wire ya know!

After initial commissioning, and a checkup a few weeks later, makeup valve is closed. 

george_42

Years ago my neighbor turned his heat down and went to Florida for the winter. When he returned a heat pipe in baseboard had frozen and was leaking water because auto fill was on. Water continued to flow and freeze inside his ranch style home till it was coming our the windows, major damage.

hot_rod

You could also add an electronic water cutoff system, that would prevent flooding and some insurance companies give you a discount on your insurance, so they tell me.
Now you protect the heating and plumbing systems.
Assuming the high tech shutoff system works as promised

Big Ed_4

For safety you can shut it off but you need to check and maintain the pressure in our not perfect world....

scott w.

As a home owner I always leave the fill valve in the off position and check the pressure gage on the boiler weekly. I just think it is safer. I can hear the boiler in the basement when it runs and would know when something is wrong if I am home.
When I leave the frozen north for the sunny south in the winter months I shut the water feed to the house off. Have installed a device called a sensaphone (manufacturer is headquartered in PA.) that monitors the temperature and the electricity. I can program the sensaphone with a high and low temperature limit. It will dial out on the telephone line to my cell phone and announce that an alert condition exists if house goes below the low temp limit. It will announce the current temperature in the house if it is lower than 2 degrees of where I set the thermostat .

You can program for any high low temp you would want. It will call when the electricity goes off. It has a programing function that allows me to set the amount of time before the sensaphone calls when the electricity goes off. Pretty neat device that has many other monitoring functions. You can hook up door entry monitors, water on the basement floor, high sound limit for noise, and just about anything you may want to monitor. I can call my home number and the sensaphone will answer and announce the current temperature in the house and state of the electricity. I get lots of peace of mind with this device especially when a winter storm is raging up north and am watching it on the weather channel.

HomerJSmith

Sensaphone sounds like a product that Radio Shack put out many years ago called a House Monitor. It was connected to your phone jack and monitored the Temperature and any loud noise and would call you if it changed. It would call as many as four numbers and you could listen to what was happening in the house, too. I sold a lot of them to vacation home owners.

It was a great product.

By the way, I turn the water supply to my mod-con off. It doesn't have a low water cutout. It has a pressure sensor that shuts off the boiler if the water level drops below 10 psi. I always installed a conductance LWCO if the radiation was below the boiler. Some jurisdictions require it regardless, so I install one, but it is meaningless if the supply feed is open. Some mineralization is required for the conductance type, I believe.

schreib

To OldPro69:
"We used to leave the feeder on and really had no problems. Many of our customers bleed their radiators and without a feeder to replace the pressure, they could have a problem. That was our thought process. Then we had a job . . .
We had another freeze up two years later, had to replace all of the radiators, but there was very little water damage. She was also out of town and we believe turning the feeder off saved the house."

Can we assume these two instances were in 100% water and no anti-freeze systems?

dgvEP2020

Great article. Thank you. As I understand it the feeder only adds water when pressure drops in the system. Now I have an old gas boiler on a dual zone system (TACO) with an expansion tank. My red zone is 30 psi and I bleed the system at the beginning of the season and I balance at about 25 psi. However after a couple of days the pressure starts to creep up again. My guess is because new water is added overnight when we don't run the heat and the system pressure drops. I hate to keep having to bleed it so my question is: Is it safe to simply turn off the cold water intake valve? My set up on the cold water intake line is shut off valve, back flow prevent, feeder, shut off valve, boiler.
Thoughts?

neilc

dgv, you should start your own thread,
it's afe to turn off that valve if you promise to keep and eye on the system,
start your own thread.