Hi. I have a 5 zone hot water boiler (4 heat zones, 1 hot water tank) I noticed today my kickspace heater fans kicked on even though t stat wasn't calling for heat. I went into basement and supply/return pipes to that zone were hot even though circulator wasn't running. It seems this is referred to as "ghosting" were another zones circulation causes flow in adjacent zone. I believe a check valve will solve this but what type and where would it be installed? Thanks in advance
heating check valve
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your boiler has a supply pipe that supplies water from the boiler to the zones
and it has a return line from the zones back to the boiler
you need to find where the return line [that is ghosting], is tied into another return line
that is where you would install a check valve
if that is not accessible install a check vale at the kickspace heater, on the return
with the arrow pointing away from the heater
and it has a return line from the zones back to the boiler
you need to find where the return line [that is ghosting], is tied into another return line
that is where you would install a check valve
if that is not accessible install a check vale at the kickspace heater, on the return
with the arrow pointing away from the heater
Diehard
In Remembrance
Do you have a single circulator for the heating zones?
Are the kickspace heaters on are separate loop?
No zone valve?
Are the kickspace heaters on are separate loop?
No zone valve?
Diehard
In Remembrance
Hmmm...would have thought the circulators would already have a built in check valve.
Jeff Handy
Pro Handyman, NOT A Pro Plumber
You can buy circulators with or without checks, and sometimes they are removed anyway.
Why would they be removed?
Diehard
In Remembrance
Apparently some people feel the built-in check valves can impede the flow slightly and/or can just be another potential problem(?) and can be eliminated when using zone valves or flo-check valves.
I guess! I just read that somewhere.
I guess! I just read that somewhere.
Diehard
In Remembrance
Back on the question of possible thermosiphoning.
When adding a check valve, as suggested, I would be inclined to consider a spring loaded check valve. If there is no check valve in the circulator and the direction of thermosiphoning is questionable.
Followed quoted from "A Technical Journal from Caleffi Hydronic Solutions"...
"When both forward thermosiphoning and reverse
thermosiphoning are to be prevented, a check valve with
a slight forward opening pressure is required. Two types of
valves can provide this characteristic: 1) A spring-loaded
check valve, and 2) A weighted plug flow check valve."
When adding a check valve, as suggested, I would be inclined to consider a spring loaded check valve. If there is no check valve in the circulator and the direction of thermosiphoning is questionable.
Followed quoted from "A Technical Journal from Caleffi Hydronic Solutions"...
"When both forward thermosiphoning and reverse
thermosiphoning are to be prevented, a check valve with
a slight forward opening pressure is required. Two types of
valves can provide this characteristic: 1) A spring-loaded
check valve, and 2) A weighted plug flow check valve."
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https://www.pumpsandsystems.com/valves/basics-check-valves
A swing check is the typical check used in the majority of hydronic systems
due to its ability to be a full port and not impede flow
Swing Check Valve
This is probably the most common check valve in use today and is a full port design, meaning the disc, when fully open, is out of the flow stream. This style of check valve is a good choice in applications that have a high percentage of solids and a lower on/off cycle count. Due to the travel distance of the disc, swing check valves close slowly. This causes the last push of reverse flow to slam the disc closed, resulting in a huge pressure spike, causing water hammer. Water hammer is a pressure surge when a fluid in motion is forced to stop or change direction suddenly, causing a pressure wave in the pipe. This pressure wave can cause major problems from noise and vibration to pipe collapse.
Silent Spring-Assisted Axial Flow Check Valve
These full flow valves typically incorporate a center guided stem-disc assembly along with a compression spring. This means the disc stays in the flow stream. The media flows around it and does not require manual or automated assistance to operate. When the pump is running, the valve is open. When the pump shuts off, the valve closes slightly before the reversal of fluid flow, due to the compression spring force acting on the disc, which nearly eliminates water hammer.
Image 3. Silent spring-assisted axial flow check valve
Most requests for check valves take into consideration the line size and pressure class alone, as media pressure and flow can vary dramatically where pipe designs are oversized for future concerns or undersized due to lack of or incorrect information. This is not always the best way when deciding which style of valve to use in a system. Other things to consider are working pressure, flow rate, the specific gravity of the media and temperature. An analysis of the system design is highly recommended. It is necessary to understand why valves fail and the root causes. The most common failure is due to excessive wear of the internal parts of the valve. Springs, discs and stems wear prematurely by not being held steady during operation. When the disc is not stable due to insufficient flow to hold it in the full open position, chattering can occur.
What is Meant by Check Valve Sizing?
Sizing a center guided valve is not difficult. Along with the pipe size, pressure class and type of valve required (flanged, wafer, etc.), users need the actual working pressure, flow rate, media type, temperature and the specific gravity of the media. It may be as simple as building the valve with a lighter spring to allow the valve to fully open. In order for the valve to reach the full open position, it may need a lift limiter to reduce how far the disc travels. When the valve is 100 percent open, it will be stable in the flow and will result in reduced premature wear and failure by eliminating the effects of chatter. It is very important to remember that these valves are designed to the actual flow values and not to the line size. A properly sized valve will be in either the full open or closed positions.
A swing check is the typical check used in the majority of hydronic systems
due to its ability to be a full port and not impede flow
Swing Check Valve
This is probably the most common check valve in use today and is a full port design, meaning the disc, when fully open, is out of the flow stream. This style of check valve is a good choice in applications that have a high percentage of solids and a lower on/off cycle count. Due to the travel distance of the disc, swing check valves close slowly. This causes the last push of reverse flow to slam the disc closed, resulting in a huge pressure spike, causing water hammer. Water hammer is a pressure surge when a fluid in motion is forced to stop or change direction suddenly, causing a pressure wave in the pipe. This pressure wave can cause major problems from noise and vibration to pipe collapse.
Silent Spring-Assisted Axial Flow Check Valve
These full flow valves typically incorporate a center guided stem-disc assembly along with a compression spring. This means the disc stays in the flow stream. The media flows around it and does not require manual or automated assistance to operate. When the pump is running, the valve is open. When the pump shuts off, the valve closes slightly before the reversal of fluid flow, due to the compression spring force acting on the disc, which nearly eliminates water hammer.
Most requests for check valves take into consideration the line size and pressure class alone, as media pressure and flow can vary dramatically where pipe designs are oversized for future concerns or undersized due to lack of or incorrect information. This is not always the best way when deciding which style of valve to use in a system. Other things to consider are working pressure, flow rate, the specific gravity of the media and temperature. An analysis of the system design is highly recommended. It is necessary to understand why valves fail and the root causes. The most common failure is due to excessive wear of the internal parts of the valve. Springs, discs and stems wear prematurely by not being held steady during operation. When the disc is not stable due to insufficient flow to hold it in the full open position, chattering can occur.
What is Meant by Check Valve Sizing?
Sizing a center guided valve is not difficult. Along with the pipe size, pressure class and type of valve required (flanged, wafer, etc.), users need the actual working pressure, flow rate, media type, temperature and the specific gravity of the media. It may be as simple as building the valve with a lighter spring to allow the valve to fully open. In order for the valve to reach the full open position, it may need a lift limiter to reduce how far the disc travels. When the valve is 100 percent open, it will be stable in the flow and will result in reduced premature wear and failure by eliminating the effects of chatter. It is very important to remember that these valves are designed to the actual flow values and not to the line size. A properly sized valve will be in either the full open or closed positions.
Diehard
In Remembrance
I also prefer the swing check for applications where it can be used. However, as with the traditional Flo-check that has been used for the purpose of protecting gravity flows there are other considerations.
https://www.pmengineer.com/articles/84208-the-dos-donts-of-hydronic-system-design
https://www.pmengineer.com/articles/84208-the-dos-donts-of-hydronic-system-design
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Diehard
In Remembrance
A lot of good information in that collection of articles on hydronics.
I found it interesting that the circulators check valve helps in the forward direction, as well.
I found it interesting that the circulators check valve helps in the forward direction, as well.
