Confusion about mixing valve in boiler return line

[sgschwend]

OK, I have read about the use of a mixing valve. There is often one in the boiler return line to keep the boiler coils from having cold water introduced to them. I just don't see how a mixing valve would work in either the cold start mode or in the up to temperature mode.

Does the mixing valve produce an over temperature output when both inputs are above the set point?

If both inputs are below the set point does it do nothing? Or does it act like a closed valve (not likely)?

Thanks for the help!

 

[jebatty]

The boiler return mixing valve (Termovar, for example) returns full boiler output to boiler until boiler reaches "operating temperature," typically about 160F. It then opens to allow hot water to enter the system, but only enough to insure system return plus boiler output maintains about 160F return to boiler. When system return reaches 160F, little mixing occurs, and nearly full boiler output goes to system.

 

[Jeff S]

OK, I have read about the use of a mixing valve. There is often one in the boiler return line to keep the boiler coils from having cold water introduced to them. I just don't see how a mixing valve would work in either the cold start mode or in the up to temperature mode.

Does the mixing valve produce an over temperature output when both inputs are above the set point?

If both inputs are below the set point does it do nothing? Or does it act like a closed valve (not likely)?

Thanks for the help!

I was wondering this my self.Since I'm in the plumbing stages of my EKO 25 using NoFo's Simple Storage System

In my case I can understand two lower temps because the controller on the EKO will not turn on the the wood circulator until it reaches a boiler setpoint.

In NoFo's simplest storage it seems very possible for both inputs of the mixing valve to be higher than the set point,how does the valve react to that ?,Does it allow the lower of the two(probably the return) to flow only ?

 

[stee6043]

OK, I have read about the use of a mixing valve. There is often one in the boiler return line to keep the boiler coils from having cold water introduced to them. I just don't see how a mixing valve would work in either the cold start mode or in the up to temperature mode.

Does the mixing valve produce an over temperature output when both inputs are above the set point?

If both inputs are below the set point does it do nothing? Or does it act like a closed valve (not likely)?

Thanks for the help!

I was wondering this my self.Since I'm in the plumbing stages of my EKO 25 using NoFo's Simple Storage System

In my case I can understand two lower temps because the controller on the EKO will not turn on the the wood circulator until it reaches a boiler setpoint.

In NoFo's simplest storage it seems very possible for both inputs of the mixing valve to be higher than the set point,how does the valve react to that ?,Does it allow the lower of the two(probably the return) to flow only ?

Once all of the return water in the system is above the mixing valves setpoint (140 in my case, Danfoss) it's wide open to the system and you won't get any re-circ through the bypass loop. You don't need any mixing once your system is up to temp. These things are not "smart". They are exactly the same as the thermostat on your car. As the spring loaded valve opens it basically switches from 100% bypass to 100% system return....

 

[Jeff S]

Thanks for the response,that helps a lot.

 

[muncybob]

On a related note: Without using any type of heat storage would I be better off with a Danfoss ESBE valve or the Laddomat? Seems the Laddomat is used more when a storage tank is utilized?
Appears the ESBE would be cheaper initially but should I go this route if I do ever install storage?