Fill valve open or closed

Unknown

http://www.heatinghelp.com/newsletter.cfm?Id=48

Here's a part of it....


This boiler ran, but it was losing water up the chimney. The rate of loss was such that the system pressure never got low enough to cause the automatic feeder to feed. The steam that was forming inside the boiler kept the pressure up. But the pressure never went high enough to pop the relief valve either. To make things worse, the temperature the aquastat was seeing was not accurate because the aquastat’s probe was in a well, and no one put heat transfer grease into that well, so the burner kept running. It was a very bizarre hydraulic balancing act, but what you need to know is that the water left the boiler, but not the system. The pressure inside the boiler pushed with equal force against the supply and return mains. The boiler was filled with nothing but fire and red-hot iron and the water was all out in the system piping.



And then the lady of the house told the man of the house that she was chilly, and she asked him to turn up the thermostat. Which he did. And when the water in the pipes hit that hot metal, the water exploded into steam, causing the back section of the boiler to rupture with obscene violence. That back section became the engine that drove the other three cast-iron boiler sections across the basement. It ripped itself away from the piping and nearly knocked the house off its foundation.

This picture represents what happens when a feed valve keeps up with a leak, or with a dripping relief valve, as is also described in the article.

Noel

Gary F.

Fill valve open or closed

I have been having on going discussions with different techs as to whether or not the fill valve on a residential hot water boiler should be kept open or closed any input would be greatly appreciated

Rob T

I'm just learning but,

from what I have seen here at the Wall and read in Dan's books a properly setup hot water heating system does not need the feed valve left open. Also depending on where your pump is it can cause an over pressure situation.

Rob

Guy_5

Feed Valve

Feel free to correct me, but I believe the idea behind the feed valve on a hot water system was to hopefully prevent the system from dry-firing in the event of a leak, thus saving the boiler, and perhaps the building.
I say hopefully, because my experience has been that the feed valves either sieze, or get filled with debris and have a hard time passing water after a few years. Still, I would rather not take the chance of operating without one.
If the feed valve was shut off and a leak dveloped you would probably notice the lack of heat, or the sound of your boiler hopping about in the basement, but if you weren't home.....

Dale

On the box

The instructions on the MM brand valve say to close feed to it after the purging. To prevent dry fire the hot water low water cut off is installed.

Rob T

As Dale said,

the instructions say to close it.

From my understanding the feed valve is for the initial fill and to purge the system.

A LWCO is needed to prevent dry firing.

Having said this I know for a fact that my home system and the ones here at work were run for years with the feed valve wide open.

When I first got involved with hot water heat I was told by a pro that they did this as an "insurance" policy.

I have since shut all the feed valves and only use them to purge.

Rob

Alan(CaliforniaRadiant)Forbes

It's hard to argue

with a picture like that, Noel; but I think it was an anomoly, i.e. it doesn't happen very often; it was an unusual circumstance.

I prefer to leave the fill valve in the open position; for the most part, it gets rid of nuisance calls since most systems will give up a few drops from somewhere, be it a leaking pipe, a faulty air vent or some other errant opening.


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Unknown

I agree

That this one was bad enough to photograph as an example.

I can't begin to stress how many cracked ones have a layer of SOME sedement above the crack. Notice the blue color in the iron where the fire hit dry iron.

We cut them all open when returned for warranty. The blue color usually gives it away. Boilers with a defect usually come back clean.

Noel

Terry St.James_2

Feed Vlaves

I live in Canada(Montreal) and most places here usually keep the feed valve open. Not completely open ,mind you, but open nonetheless. Biloers here run quite often from October to March,sometimes April. I find it more of a security thing myself....also helps me sleep at night with no worries.

Mike T., Swampeast MO

If left open

Most jurisdictions will require a double backflow (usually RPZ principle) prevention device that must be inspected annually.

Something as simple as shutting off and draining the domestic system for service will result in a backflow from the hydronic system if the fill valve is left open.

I believe that many areas require the backflow prevention device on ALL hydronic heating systems.

Bob_19

I Would Think

it depends on a few factors.
How well is the system maintained?
Is it watched? Is it attended to 24/7
And how large is the system in question.

Me, myself, I would keep the valve open, and keep the prv clean and set, even with flow protection/LWCO, things stick, bind, or just don't operate when you need them.

But I have seen the fast flow lever kept up by many people, the world is not a perfect place.

john_22

feeders

I could be wrong but if the manufacturer says to close the valve and you leave it open going against their recommendations any liabilty for damages like noels picture above fall on you.( I believe i got that from mr firedragon if not sorry george)id rather close the valve and not pay the legal fees.

Jerry Boulanger_2

If left open...

You cannot tell if or how much water the system is taking.

You risk a potential flood if the system springs a big leak.

You risk a backflow from the boiler system into the potable water supply. The motto of our local municipal cross connection control program is 'If you don't want to drink it, don't connect your water system to it.'

These are the main reasons why most manufacturers of fill valves recommend that they be valved off unless it is necessary to add water to the system. It's also why it is code in some jurisdictions.

If you want to avoid all of the above, an alternative is to use a small packaged automatic system feeder.

Glenn Harrison

Check out this file.

This is B&G's install instructions and warnings for PRV's. You will need Adobe Acrobat reader to view it.

http://fhaspapp.ittind.com/literature/files/610.pdf

Bob_19

Good Job

> This is B&G's install instructions and warnings

> for PRV's. You will need Adobe Acrobat reader to

> view

> it.

>

> http://fhaspapp.ittind.com/literature/files

> /610.pdf

Bob_19

Good Job

I've never seen that before, it does make a whole lot of sense.
The things we do will always be improved upon by others.

Rob T

Good Read.

I notice that B&G does not show a back flow preventer either. Kind of adds weight to the "shut the valve" theory.

Going to leave mine closed and just monitor the pressure monthly.

Rob