Cold water fill valve - open or close ?


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Old 11-28-09, 05:22 AM
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Cold water fill valve - open or close ?

I have old 1957 Bryant forced hot water boiler with steel pipes and natural gas with real castiron baseboards.

Do not think I have any lowwater cutoff or other saftey cutoffs for this boiler - except PRV and standard overpress relief valve.
---
A plumber last week replaced the B&G 100 red circ pump with green Taco 007 pump
And he "says" the cold water fill valve should be left/stay OPEN all the time
It had been closed for very long many years maybe 20-30+ years Closed (since I can now see bright clean brass stem inside fawcett now showing with it in open position)

The heat and this boiler has worked great all those years with this cw fill valve Closed and not had a problem.

So how should it be OPEN or CLOSED ?
Why should I change it to OPEN now ?
(I'm not too confident in the plumbers who put in the circ pump - not have much experience with gas/hot water boilers - young been doing about 10 yrs only)

--flowdirection -->>
---a----b---c-d--------CircPump---Boiler---> To Radiators
!
!

a = cw fill valve/fawcett shutoff
b = checkvalve
c = PRV press reduce valve (c&d are dual combo)
d = press relief valve

The coldwater fill (a) line supplies the hot water heater (right next to the boiler) too, besides connected in to Boiler like mapped out above

Also my piping and heating looks like below from old B&G 100 pump manual : (maybe easier to see this )

http://www.bellgossett.com/homeown/manuals/1.1.htm
---

If the cw fill valve is left open -
Doesn it possibly keep letting water/air/bublbles to get into system ?
If there is a leak/crack somewhere someday - wont it maybe flood basement ?

If left Closed -
Can the boiler blow up or crack if water does evaporate/leak and it gets dry and burners keep going ?

Really confused - what is best thing t o do ?

Does it come down to what is best of the worst thing could happen -
either flooding water OR a blown up boiler/(maybe house fire) ?

Is it something to really worry/lose sleep over ?

Guess a flood is better to deal with

I dont know ? rookie... pls advise
Thanks
 
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Old 11-28-09, 05:48 AM
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Leave the valve open if you think you have entrained air in the system. As the air is vented, the pressure may drop and until the water is replaced by the device.
Other than that, there is no reason to leave it open once the system is full.
 
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Old 11-28-09, 08:21 AM
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Other than the 'look' of the stem, do you have reason to believe the valve actually was closed? It's possible that a few opening/closing cycles on the valve polished up the brass stem by rubbing/twisting against the valve packing... maybe/maybe not, just a thought.

Something else to worry about (not really)... back in the day, most boilers had the 'combo' regulator/relief valve that it seems you have on your system. Most building codes have gone away from that setup to an ASME (American Society of Mechanical Engineers) approved relief valve. These approved valves are different in that they are rated to relieve a certain amount of pressure at a certain flow rate. You should know that your relief valve probably doesn't meet current codes... there's probably nothing in the codes to make you have it changed, but if you did have a new system installed, it would have to have an ASME valve on it.

I would always opt in favor of water damage versus 'dry firing' the boiler and the resultant chance of house

Google "Water Cop" if you are concerned about basement flooding. (though, if the leak is upstairs, it may/may not help)
 
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Old 11-28-09, 10:25 AM
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B&G states that fill valves are to be closed once the system is filled. If worried about dry firing then a LWCO should be installed.

The reason to keep the fill closed is to prevent the boiler from exploding (I did some research on this to figure out the reason). If the fill is left open the boiler can flash to steam and destroy the building. Here is why:

Say a leak occurs and the water leaks out faster then the pressure reducing valve can re-fill the system. Remember that the pressure reducing valve is a slow fill device.

Now the boiler fires and the water level in the boiler is low. With no water at the aquastat well it won't see the high temperature and turn off the burner. Now the water starts to boil. The pressure relief valve opens and starts to dump steam/water.

And as such the boiler pressure is above the pressure fill point. So no new water is coming in.

Finally the boiler goes dry and the pressure starts to fall off. And what happens? The pressure fill valve starts to add water to a red-hot boiler.

This water flashes to steam in an instant and the boiler explodes.

If the fill valve is closed, no additional water will go into the boiler. So even though the boiler is being dry fired, it won't explode destroying the building. Although there is still the chance of fire.

Which brings us back to a LWCO. They seem to be the way to go. Install one and leave the fill valve closed.

Al.
 
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Old 11-28-09, 10:43 AM
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So probably go back to closing it ?

Thanks all - ok so that's:
- 2 votes for Closing ( I tend to vote to go back to Closing it - like it used to be)
- 1 vote for stay Open (NJTrooper)

This boiler is 1957 Bryant and pretty sure I dont have LWCO
How can I tell if do or not ?
Did they have those in '57 ?
---
There was another recent post on here I saw - think NJ Trooper also answered and you listed the pros and cons
posted before - has some good info too:
(But still confused) :

http://forum.doityourself.com/boiler...r-shutoff.html

---
I definitely saw my plumber open this cw fill valve/fawcett with
wrench (was tight - so prob been closed longtime) and then left it open - when they replaced circ pump - after putting on new green Taco pump -
When I think they forgot to prime it/get water back in (they isolated circ pump) (only had min water drainage) (not whole radiator system) and a loud banging for 30 sec happened until I cut off circuit breaker;
due to no water in the pump on starting up, right ?
That's when I saw plumber finally open this valve up to let new water into circ pump/boiler and immed circ pump quieted down to no noise/sound and started working good.

They left and I found it open (w/it shiny brass stem out)
So it has only been turned really once in maybe 10-12+ years or longer.
So I think have some good evidence it was always Closed
in past prior to plumbers getting here.
---
Good to know - if get a new boiler - hope a good installer/plumber will notice the lack of code complying stuff in pipes and update the relief valves etc
--
Side question:
Also I noticed that this cw fill line sometimes gets a lil warm as get closer towards either boiler or the hot water heater (drw?)
Think this happens when house heat/thermo turned up (boiler running more) and when hot water heater is used lot for hot showers.
Does this mean I have hot water migration ?
Do I need a flow control or check valve somewhere in here to stop the heat travelling backwards ?
(think I already have a lil inline check valve - plumber pointed it to me - see my crappy pic)
Does it really matter much or make difference? (it's all same bunch of heat aint it ?)
----
Sooo Im tempted to go back to CLOSING this valve again like MatserPlvber suggests

The B&G manuals I posted and for B&G PRV/relief valves all WARN say alot about keep the cw fill valve closed once after servicing/starting up system. They say to CLOSE it once underway normal operation
BUT they do not explain really why much
Should I go back to CLOSING it ?

Thanks!
 
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Old 11-28-09, 02:03 PM
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It's a tough call... that's interesting what Al discovered about exploshums... I can see the logic in that explanation, and even if the scenario is very unlikely to occur, the fact is that it COULD happen.

My valve is always closed by the way... BUT... I know what the pressure is in my system. The boiler gets walked past several times a day, and there is a gauge in a prominent position that gets a glance every time I walk by... well, almost every time!

I'm willing to bet that 99% of homeowners don't even know their boiler has a gauge, and if they did, probably wouldn't know how to read it, and if they did, wouldn't know what it meant, and if they did, wouldn't know what it should read.

It's a Catch 22 thing... damned if you do, damned if you don't.

It's never too late to become an informed homeowner. Go ahead and close the valve if you feel better about it, but take the time to learn what your gauge should read at various temps, and make it a habit to check the gauge periodically.

I'd also bet that your old boiler does NOT have an LWCO. I don't know if they had them back in the day, but I've never seen an old system that did, unless it was retro-fitted, which is possible with any system, old or new.

If/when you get a new boiler, it will include the proper ASME pressure relief valve as part of the package. It's not something extra that you have to ask for with a new system. Unless your local building codes dictate that you must have an LWCO, you may have to ask for that.
 
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Old 11-28-09, 02:06 PM
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I noticed that this cw fill line sometimes gets a lil warm as get closer towards either boiler or the hot water heater
I'm sure it's nothing to obsess over... it's probably CONDUCTED heat... the pipe getting hot from the heat in the boiler.
 
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Old 12-04-09, 06:18 AM
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LWCO valve and guage readings

Thanks Al and NJtrooper
for excellent thorough answer

Do have idea what a lwco valve part would cost and maybe labor/time for a plumber to put into my old '57 bryant boiler ?
Is the lsco part expensive ?

Sounds like it is a very good saftey thing to have on any boiler in case of leak or water runs out.

I do look at the boiler guages alot - every time I come home at nite - check the boiler. Esp psince it's so old and watch it carefully nowadays.
Also - I have recorded the numbers/position of needles in "normal" running/operating mode - so I have some baseline to compare to just in case for future or to tell a plumber -
It's so easy to forget and trick your mind to think what "might" have remembered to be the usual guage readings.
So I have yellow sticky next to guage showing what standard/normal needles usually look like
--
Is the Altitude labelled needles actually the psi pressure of the boiler ?
So Altitude means Pressure ?

It has red needle always on 30 - really nevers moves
And moving (a very little ) white needle hovers between
12 to 14 when heat is on but lightly in use
And sometimes goes up to 15-17 maybe when running heat/boiler lot more in cold winter
--
Of course below this is the labelled Temp single white needle guage with the *F temps

Thanks
 
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Old 12-04-09, 04:21 PM
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I would figure around 100-200 for the control, maybe more because it will get marked up I'm sure... then several hours labor to install it... so maybe $500 or so? maybe more... hard to tell...

Good on ya for keeping an eye on the boiler! You're a rare breed Phil... not many homeowners can be bothered.

s the Altitude labelled needles actually the psi pressure of the boiler ?
So Altitude means Pressure ?
Sort of... indirectly.

I believe if you look at your gauge closely, you will see that there are TWO scales. One ALTITUDE, and one PSI.

There is physics involved in the explanation. I'm just going to say that there is a mathematical relationship between the two.

It takes 0.432 PSI to push water UP a pipe 1 foot. To push up TEN feet then would take 4.32 PSI, etc...

So, if you MULTIPLY the ALTITUDE by 0.432 you will get PSI.

OR, if you DIVIDE the PSI by 0.432 you will get ALTITUDE.

This is based on sea level atmospheric pressure of 14.7 PSI. Your mileage will vary if you are on the top of a mountain.

It has red needle always on 30 - really nevers moves
And moving (a very little ) white needle hovers between
12 to 14 when heat is on but lightly in use
And sometimes goes up to 15-17 maybe when running heat/boiler lot more in cold winter
The red needle will never move. It's only a MARKER. The white needle is showing your pressure. The numbers you gave sound fine, as long as you are reading the PSI scale. If you are reading the ALTITUDE scale, the readings are low. Look closely at the gauge...
 
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Old 12-04-09, 04:40 PM
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The "altitude" needle can be changed manually, and will stay there.

In my experience, the altitude needle was usually set at the pressure required to fill the system. For my 2-storey house with boiler in the basement, the altitude needle was originally set at about 11 psi. And there it stays.

Historically, it seems that the altitude needle was red in color. Maybe that has led some to set theirs at the relief valve setting, typically 30 psi.

I sense that modern boiler trindicator gauges, e.g., Winners, don't include a separate altitude needle. I think they are a bit of a anachronism. But they still tend to confuse people.
 
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Old 12-05-09, 02:21 AM
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old debate

A never ending debate. My thoughts:

I agree w Trooper. That boiler bomb scenerio is very unlikey. Why? Well, first, I have not seen it happen in 36 years of pipefitting.

The other reason is that there is a good chance that the leak is away from the boiler so the boiler does not go dry even when filling slowly and leaking remotely.
Next reason, as mentioned the sensible practice of using a low water cutoff.

I have seen plenty of heat outages caused by low pressure that were caused by venting air or leaky vents or slow leaks on relief valves while the fill is closed.

Why would your pipes leak anyway?
1- Rotten? I hope not!
2- Frozen because of foolishly no glycol. Would you leave your car with out glycol?
With very little glycol you cannot freeze and break a pipe, even with slushing.

Nobody seems scared to leave their domestic hot water on and under pressure all the time, and at much higher pressure normally than heating systems.

If you are in an extreme cold area, a heat outage can be more damaging than a small leak. In frozen climates the danger of freezing your plumbing due to low pressure, especially in a zone above the boiler is much higher than the chance of a dry boiler.

Your choice is to shut it and keep a frequent look at the pressure or...
Keep it on like you do the rest of your plumbing, and keep an eye out for leaky vents and relief valve.
 
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Old 12-10-09, 03:10 PM
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Originally Posted by OldBoiler View Post
B&G states that fill valves are to be closed once the system is filled. If worried about dry firing then a LWCO should be installed.

The reason to keep the fill closed is to prevent the boiler from exploding (I did some research on this to figure out the reason). If the fill is left open the boiler can flash to steam and destroy the building. Here is why:

Say a leak occurs and the water leaks out faster then the pressure reducing valve can re-fill the system. Remember that the pressure reducing valve is a slow fill device.

Now the boiler fires and the water level in the boiler is low. With no water at the aquastat well it won't see the high temperature and turn off the burner. Now the water starts to boil. The pressure relief valve opens and starts to dump steam/water.

And as such the boiler pressure is above the pressure fill point. So no new water is coming in.

Finally the boiler goes dry and the pressure starts to fall off. And what happens? The pressure fill valve starts to add water to a red-hot boiler.

This water flashes to steam in an instant and the boiler explodes.

If the fill valve is closed, no additional water will go into the boiler. So even though the boiler is being dry fired, it won't explode destroying the building. Although there is still the chance of fire.

Which brings us back to a LWCO. They seem to be the way to go. Install one and leave the fill valve closed.

Al.
I was thinking about this in the last few days. If you put the LWCO above the boiler, then this situation will be avoided. I also looked in my manual and it specifies the the LWCO be installed in that manner. Unfortunately mine was not installed that way. I think I may be moving it when I install my boiler bypass.
 
 

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