Feed valve

Tom G

According to the Bell & Gossett website
(http://fhaspapp.ittind.com/homeowners/PressureReducingValve.htm)
it's so while you're filling you can keep the pressure low. Fair enough, since once the rads fill and you close the bleed valves the pressure rockets unless someone is right there. But that's a really simple task -- I still see no reason for one for each boiler. If anyone knows better please share..

Tom G

feed valve question again

I originally posted the question:
I have three HW boilers heating three apartments. Can I feed them from a single feed valve? What if I install a one-way valve at each boiler, to isolate each of them?
------
... Al Letellier replied (thanks!) with this:
Unless the boilers are tied together in some way, you need a separate feeder for each boiler. A single feeder would add pressure to all the boilers if one lost pressure for any reason, and you would over-pressurize the others, blowing the safeties. If the boilers are on a common header and are stage fired, one is enough.
-----
sounds reasonable to me, but then I read from the Bell & Gossett website:
"A feed valve’s job is to set the initial system pressure. That’s it. For safety’s sake, you should close the supply valve to the feeder once the system pressure is established. This is important because a feed valve that’s left open can mask a system leak. Systems leaks that go undetected can lead to air problems and boiler corrosion problems."
------
this would mean I wouldn't have to worry about over-pressurizing my system. I hadn't heard of closing your supply valve, is this recommended practice? ... I don't have low water cutoff. But if I did close the supply valve, then I could use one feed valve for three boilers?

DanHolohan

I think

the feed valve should be kept closed, and the boiler MUST have a low-water cutoff.

Andy Morgan_2

"Unless the boilers are tied together in some way, you need a separate feeder for each boiler. A single feeder would add pressure to all the boilers if one lost pressure for any reason, and you would over-pressurize the others, blowing the safeties"

I don't get this. If you have three boilers with the headers together, one feeder is fine.OK. If you have one feeder supplying three seperate boilers off of one water line, one looses pressure, how are the other two going to over-pressurize?

Did I miss-read something? I'll be the first one to second- guess myself!





Andy Morgan

R. Morgan Mechanical, LLC

John_33

Yes, most definately must have one. And further, SHOULD have two....cheap insurance, I think - everything fails sooner or later.

Dave T

why install one at all

If you intend to shut the feeder off why bother having one, just fill it with the shut off valve. What am I missing here. Does everyone shut the 'automatic' water feeders off except me?

bill clinton_3

feed valves

If you're going to make this a manual feed system by closing the shut-off valve, either one or none will serve.
There is no chance of a single fill valve increasing the pressure in any boiler higher than in any other boiler, no matter how many boilers or how many times the valve operates.

Personally, I leave the valve open: The reason is that ALL systems leak to some degree even if the leak is only a molecule or two at a time. Sooner or later, a closed valve guarantees a low water condition and potential dryfire. On low mass systems, think: "sooner," and "dead boiler". Sure, a low water cut-off will give protection against dry-fire, but only so long as its operative. Get a bunch of nuisance shut-downs (which WILL happen with a manual feed low mass boiler) and you got a customer jumping out the LWCO as a "temporary" fix. Now you have guaranteed destruction.

My experience and judgement come down on the side of leaving the shut-off valve open.

By the way, given the rate at which B&G feed valves stick closed, I would recommend installing another brand (Conbraco works good for me) and, if feeding multiple boilers or a particularly critical installation, installing two in parallel for redundant protection against low water conditions.

Go ahead and install that LWCO, however, if this is a low mass boiler, I would recommend instead a flow switch. This gives you protection against both low water and no-flow due to dead pump.

Bill

Einsiedler

checks

What about 1 feed valve feeding 3 separate fill lines to 3 separate systems. (assuming all 3 require same static fill pressure).
put a check valve on each of the 3 feed lines after the fill valve..

When a system pressure is lower than fill valve setting, wouldn't the fill valve only send water to the line that is lower pressure then fill setting? (the other two checks would remain closed since the pressure is higher on the system side of the check).

any thoughts?

Einsiedler

Andy Morgan_2

That's what I Thought ...NM

Andy Morgan

R. Morgan Mechanical, LLC

Andy Morgan_2

That's what I thought... NM

Andy Morgan

R. Morgan Mechanical, LLC

RELY

Three seperate systems one feed valve? Why risk three boilers if one fails and all water is lost.Use three auto feeders and one watts 9 D backflow preventer.Install lwco on each boiler and protect your investment

Tom G

that's what my original message was asking

Tom G

> Three seperate systems one feed valve? Why risk...


Because feed valves cost $30 vs $2 for check valve. If it makes no difference, I've got plenty other places to spend the extra $56. Like maybe on a couple LWCOs...