Forced Hot Water Heating System Valves Question


Hi,
Live in the typical two story Colonial.
Have gas fired, forced hot water heating system. About 30 years old.
Has two zones, and an electric circulator for upstairs, and one for downstairs.
On each of these lines, there is a valve that operates sort of as a check-valve.
When the circulators are Not going, these check valves apparently prohibit any hot water from circulating by gravity. Think they have a spring loaded ball in them.
If there is a power outage, and you back the stem out, about a dozen turns, the spring, I guess, then puts no force on the ball, and the hot water heat can then circulate by gravity
(the furnace just cycles between the high and low set points without any external power required, as it has the older millivolt thermocouple controls)
Questions:
a. are these things (these check-valves)"really" needed ?
b. are they still used today in forced hot water systems, or...?
c. If they need replacement, what brands and model number are used commonly for this sort of thing now ?
Any thoughts on this would be most appreciated.
Thanks, Bob
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It's called a flow check. It prevents the circulator from one zone pulling water through another. They are used today, however most/many cartridge circulators now have the check valve built into the pump
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In multiple circulator systems you need a check valve in each leg otherwise when one circulator is running, water will circulate backwards in the non-operating legs (if you draw a picture of the system you will see why this is so).
I'm not familiar with the adjustable ones you describe. Mostly I just see standard soft seat check valves. Soft seat are used because the noise hard seat valves make telegraphs through the piping and you hear clicking as the zones operate.
The check valves shouldn't stop gravity circulation unless they have excessive opening force. The hot water will still rise up through the check valve and cool water will fall down through the return. But gravity circulation is slow and weak compared to power circulation.
HTH,
Paul F.
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How can it circulate by itself without power, with pump impellers blocking flow, 30yrs old I dont think it was designed for gravity feed . AC has to power the relays and controls, or is this different.
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ransley wrote:

I don't believe those pumps will block the flow. They may slow it.
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ransley wrote:

In my old system, with valve adjusted open there was enough from the temperature differential to give modest flow. It would prevent freezing, but surley is nothing like it moves with the pump going. The OP is able to keep his gas boiler burner going with no power. My oil burner would be dead.
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I have a few boilers, I cant run any without 120v and a few amps. Running without a pump sounds risky with full Btus going in, I think it would be an experiment to see if the boiler may overheat, you just are not circulating the same amount of water to keep the boiler at the temp it was designed for today, We used to have gravity feed its been converted to pump, It would make me worry trying it without a pump.
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wrote:

I have a few boilers, I cant run any without 120v and a few amps. Running without a pump sounds risky with full Btus going in, I think it would be an experiment to see if the boiler may overheat, you just are not circulating the same amount of water to keep the boiler at the temp it was designed for today, We used to have gravity feed its been converted to pump, It would make me worry trying it without a pump.
An old boiler doesn't care what the temperature of the water in the pipes is. It shuts down when it's aquastat reaches high limit. Gravity and convection aren't going to do much for a modern system with 3/4" pipes, but should work OK for a system that was designed to work without circulators, with larger pipes, despite the obstruction of the pump impeller
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Bob wrote:

Yes.
Yes
Probably whatever the plumbing/heating supply stocks.
You are very lucky to have a system that will work at all with no electric. About 10 years ago I played with the check valves on my brand new oil hot water heat and found that if opened, the water would circulate all the time, although much slower. Still it was enough to heat the different zones to above what the thermostat was set at.
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I don't know what you have but I believe what you have is zone valves. this valves are needed because they control your furnace to go on and off when both thermostat from both zones do no longer require heat furnace will shut off and stay off, the furnace control system is interphase with these valves. valve most open for pump to go on and at same time bring furnace on and yes this valves are still in use. Of hand Honeywell is one and Taco which works on different principals of Honeywell, there maybe others that I do not know about. Both of this valves will work but you need some one who is well familiar with controls and plumbing to replace or change if that is the case.

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