Siegenthaler's info is flawed and the honeywell sparco info is flawed and you're the bigger idiot for relying on it.
So your contention is that;
the low-loss header arrangement I suggested won’t work
AND that I am wrong,
AND John Siegenthaler PE ( a very highly respected Engineer, author and heating lecturer) is wrong
AND Spirax Sarco (a multi-national manufacturer of steam, gas and water valves and fittings) are wrong about their own TMVs.
That is an amazing theory although slightly disturbing; I really did not know that people were made that stupid.
My contention is that;
it works
AND that you are wrong
ANDyou cannot understand how it works because you are stupid.
This is a much simpler and more likely explanation.
The UFH mixing valve has a minimum
working pressure of 0.2 BAR which is 2 metres in terms of static head. Therefore
the hot port of the mixing valve will require this minimum amount to blend and perform correctly.
Onetap wrote
The static pressure on the hot port is of no relevance
He was referring to "working pressure". Pay attention at the back.
You should have Googled for the meaning of the phrase “working pressure”.
http://tinyurl.com/278bf5d
A piped system has a working pressure. Pressure vessels, storage vessels or heat exchangers will have an fixed brass data plate giving both the ‘working pressure’ and the ‘test pressure’. If anyone had used the phrase ‘working pressure’ to me in the context of the flow through a valve, then I would have questioned it to confirm what he meant. It would have caused me to suspect that he may not know what he was talking about.
It seems the term was misused but you, having no knowledge, experience or qualifications in this area, did not question it and have copied and pasted it all over the internet.
You need a differential pressure across a valve, system, orifice, etc to generate a flow. With control valves the flow at a given pressure differential is expressed as a Cv (imperial units) or Kv (metric); Kv is typically the flow in cubic metres per hour at a dP of 1 bar. Knowing Kv you can calculate the required dP for any other flow rate from dP = k Q^2, where k is a constant.
Your TMV with “unequal design geometry on the inlet ports” would require two different values of Kv for hot and cold ports.
How many times have you installed such an arrangement with a tmv having unequal design geometry on the inlet ports?
And since you sound like a desk jockey, how many times have you specified it on a low loss arrangement and had positive feedback that the ufh system performed satisfactorily?
See above; I do not use TMVs, except as blending valves on DHW supply systems.
I have installed dozens of motorized mixing valves. I have specified hundreds, as a “desk jockey” design engineer, motorized and pneumatic valves, mostly in diverting mode, a standard control technique for heating and chilled water coils in constant volume systems. There are flow measuring devices in commercial systems ( orifice meters close-coupled to DRVs). The system operation and flow rate is measured, adjusted, verified and witnessed by independent commissioning engineers. Every one of those valves, without exception, has worked as intended.
I have never seen a 3-port valve like yours, that had two different values for Kv. They were/are not made. Only a fool would buy one. If you have such a valve, then go and get the two Kv values and report back.
I have seen a 3-port (plug & seat) mixing valve on a site where I worked, installed as you proposed. At the limits of its travel, the valve plug became locked against the seat by the pump pressure and the actuator was unable to move it. Manually opening the valve would release it, until it next went to 0 or 100%.
Onetap wrote
I didn't ask for an apology
What's this then?
Onetap wrote
It isn’t a request for an apology, is it? It is a statement.
You’d only apologise if you had sufficient intelligence to understand that you were wrong, the integrity to admit you were mistaken and the courage to apologise to the people you’ve been libelling. You have none of those qualities and so there is no point in asking you to apologise.
So I didn’t.
