Automatic feed value obsolete?

Live/Learn

My question concerns the use of a automatic boiler feed value on a hot water syatem that is protected with a LWC control. I feel I would rather keep the feeder shut off and allow the LWC to shut-down the system in case of a major leak. I feel that if the value is left on the boiler would probably be saved but the home would suffer a major flood. The automatic value's only use , I feel , is for initial boiler fill-ups. Am I thinking right on this subject?
Thanks in advance , Live/Learn

Constantin

Good Question

I presume that you're referring to an automatic feeder valve, whose main purpose I gather is to prevent a boiler from dry firing.

On our hot water system, I intend to disable the valve for the very reason you're raising: leak detection. Naturally, this can only be done safely on a system which has a LWCO that also gets cleaned, etc. to ensure its proper operation when an unsafe condition arises.

Some systems like the single-pipe steam we have in our current rental apartment lose mass all the time and hence need a feeder if the owner/renter doesn't want to keep an eye on the water levels within the boiler. Here too though, a LWCO will hopefully provide the shutdown protection that is needed.

Our neighbors LWCO was filled with crud and hence did not shut her boiler down when it ran out of water.... oh what a mess that was.

Neil_5

What would maintain the pressure at say 15 PSI in the pipe system, this pressure would only be maintained if there are no leaks, correct? If you have a slight leak say at the radiator/convectors valves, then the pressure would drop?

When I turn off my cold water valve before the automatic feeder, over time my pressure drops, but water content is there. I plan after the heating season to redo all my leaky valves at the convectors.

Neil

Weezbo

You can operate a boiler as a closed system...

however it is encubant upon you to have a maint. schedule. then your safety will rely on human intervention rather than say the valve feeding the boiler. Pressure differences are normal as the boiler ramps up and down.... as for leaky valves on the convectors ..thats sorta got me wondering why they have valves on them.What kind of valves? jomar?

Neil_5

The valves on the convectors are for turning off that individual unit water flow thru the convector. Some of them leak around the stem, very little, dont want to start fussing with them now in the middle of the heating season and risk a shut down.

Ron Schroeder_2

I have been thinking of adding a low pressure cut off switch set at about 10psi in addition to the LWCO if the automatic fill valve is closed.

Ron

Neil_5

Is there any harm having say 5 PSI in the system? The water is there and police by the LWCO, but the pressure is now at 0, how does this affect the boiler operation?

Weezbo

Oh so you turned the auto feed off and the pressure droped

Well, now there could indeed be a problem with that,especially if the boiler wasnt piped for steam .or doesnt have a low water cut off on the burner. pressure swings from o to 30 psi are not particularily "Good" things.

Neil_5

This is not steam, HW system, with a LWCO in. I turned the feed off and overnight the pressure went from 15 to 0, when I turn the feed back on the pressure went back to 15 with a quick less than a second hiss.

Uni R

**Neil**

"Is there any harm having say 5 PSI in the system? The water is there and police by the LWCO, but the pressure is now at 0, how does this affect the boiler operation?"


To a degree there is. 12# is the norm to get water up two stories and still have it under some pressure upstairs. If the water was hot enough (212+) and the pressure was low, it could flash to steam upstairs with nasty results. Also, unless there is a bit of pressure up there you can't vent air from the upstairs branches. That's the rationale behind the base pressure.

Neil_5

LPCO

Should be standard along with LWCO valves dont you agree?

Uni R

Not sure...

Some would argue that a flow sensor is enough and not even bother with a LWCO. I'm not sure.

Live/Learn

need for auto feed valve

Thanks Weezbo for your responce. Yes I have it serviced yearly and I keep an eye on it often. I installed the system myself last year and so understand my system pretty well. I have no leaks and my pressure is steady @ 12lbs cold & 20 lbs hot. I don't worry about the possibilty of a flood ,if I have a leak ,with the valve on as long as I'm home but if I go away for awhile I'd be concerned. That's why I have the valve shut off and am relying on the lwco control. I would think if the lwco failed it would fail to ignite the burner as the crud on the probe would insulate it from the boiler water and interrupt the circuit. What do you think? Live/Learn

Ruthe Jubinville

Feed valves

I was told at a heating course in 1969 to forget using them. I did for many years. Jerry

Weezbo

well, the nature of all component things is decay.

should we not have a feed water then we need to maintain and monitor .a parked aeroplane doesnt crash too often,however you will have certain maint that will need to be done if you want it to fly. low water cut offs and auto fill have been replaced a plenty if my experience with service is indicative of general the general scope of things.many people isolate the fastfill and backflow preventor with two valves one up stream and one down,it makes it easier for maint. maint . is alot of work and yet is so often neglected .an isolated system is allowed even in a residence it may be even argued that by it being isolated, it at least has some greater likelihood of being monitored for possible problems...so, with one you are perhaps giving your self and family a greater degree of comfort and safety.

Jack, CVMS

Auto fill valve - yes or no?

Here in this part of Alaska virtually all of our hydronic systems are filled with at least 35% PG. If water were to be added without the knowledge of the HO the percentage could become so low as to offer no freeze protection. For that reason we never install makeup water connections unless the HO demands it.
If there is pressure loss, that usually indicates a leak. If there is a leak, fix it.
We may have to pump a quart or so of fluid into a system in the fall, but that is a good time to add inhibitors if needed.
We also use larger expansion tanks than most installers I've worked behind, and pre-pressurize them to 15 psi. That way the pressure stays between 15 and 20# regardless of system temperature. Makes the pumps work more efficiently as well.

Christian Egli

Aeroplanes can't be parked on December 17

Thank you Weezbo for the mention. You got me going.

Today, December 17, was the day when the Wright brothers successfully lifted the plane off the earth. That was in 1903. They didn't crash either.

Year 101.

The Air Force and the Wright family members lay a wreath to their exploit here in town, where it all happened. There are airplane flyovers and the Air Force Band plays a tune.

No day to be parked on the runway.

This just has nothing to do with hot water boilers does it? Lots of hot air? Maybe.

All these questions about expansion tanks and fill valves makes you long for the time when hot water systems were installed with a bathtub-like tank up in the attic. The level could be visually inspected and corrected by any home owner with a bucket. It was so intuitive any one could understand it. There were no boiler and altitude gauges necessary. Trapped air just bubbled up in the tub. Then someone invented the bubble bath.

If the fill valve closed is no good and if the fill valve open is no good either, how about having the valve barely cracked open? so that pressure may be transmitted but so that in case there is a major system leak, no huge gushing flow of water will result.

jerry scharf_2

you could kill your pumps

If there is not enough pressure for the supply water temperature, you can get cavitation on the inlet of the pump. This will destroy the impeller in no time. It depends on a bunch of things, but there should be information on just about every pump on what manufacturer specifies for minimum inlet pressure.

jerry

Weezbo

Wright right brothers:)

ok *~/:) Way ta go ....those two had a clue as to what did and did nt fly i bet they would be happy to have had you working on the fuel supply lines:)