Mix Valves

Aidan (UK)

that the 3-port mixing valve is a long established technology in commercial heating here. There were very few houses with any mixing systems until underfloor radiant heating appeared. The VSI pump is a recent arrival, which has only become practical with cheaper micro-electronics in the past 10 years. It has to overcome the industry inertia of 'the usual way' of doing things.

However, I did send an enquiry to Grundfos(UK) about variable speed injection pumps. I don't think that their Sales Engineer knew what I was on about. There's only the usual domestic circulators available, none of the small dedicated injection pumps that seem to be available in the US.

Dana Zaichkin

Favorite motorized mix valves

I was wondering what some of the favorite (ie: responsive,reliable) motorized mix valves and actuator combos are being used - particularly when used in two-temp systems and w/ a Tekmar and reset? I'm aware of the ESBE and those marketed by Wirsbo, but few others.

Thanks

DZ

heatboy

Dana, I have used many different.............

makes and my favorite is the Belimo. I have 3/4", 1", 1 1/4" and 1 1/2" in the field and all have been flawless. They are so quiet, you have to watch the handle to know it's moving. Wirsbo is now offering the Belimo valves with the pro SERIES line.

hb

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Dana Zaichkin

Beautiful!

Always nice to see your work hb. Thanks for the Belimo info. I must have old info - thought Wirsbo used Erie valves with their control/valve combos.

Best Regards

DZ

hot_rod

The biggest concern with motorized valves

or pumps for that matter :)is the sticking issue. Regardless of the brand, either the link, motor, or gears will fail if they stick.

For this reason, maintain good fluid quality, be it water or glycol. Also I feel the exercise feature prevents premature failures. To rotate the valve through it's entire range weekly or at least monthly, will keep them happy and free. Look for a valve or controller that has this option.

The brand hb mentioned is often seen on HVAC zone controls and dampers, also.


hot rod

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Dana Zaichkin_9

Similarly...

Thanks HR. Has your experience shown any difference in "sticking, seeking or control quality" depending on how the valve is sized? Particularly, might a 3/4 mixer be preferable over a 1" assuming the 3/4 could accept the flow.

Best Regards

DZ

heatboy

Every Manufacturer...........

has literature to aid in valve selection. RB wrote a great paper on sizing mixing valves a few years ago. I would share it, but it was on my old computer that,...... well, lost it's smoke, so I don't have it any more :-(

I have never had a mixing valve seize in all the years I have been doing this. It can hapen though with a grossly over-sized valve, for sure. Most of the time, a line sized valve will be too large to work properly. Everyone rambles on about how great VSI is, and it works well if done correctly, but just like mixing valves, they have to be sized correctly to work correctly. I have seen some injection systems that are no better than the worse kind of mixing valve system.

hb

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hot_rod

Had trouble with

the early iron body tekmar valves. They had some sort of hard plastic "vanes" in them that would break. Then again, used to be I wasn't so religous about system cleaning. So the problems were partially my fault I suppose

Also seems the very early ones didn't have a tapered pipe thread (hard to seal) and often the port tappings were not square to one another making for some crooked piping.

I suspect over sizing the valve would limit the travel of the mixing spool. I think it would be best if the valve operated across it's entire movement range, both from a wear and a temperature control point of view. Which is why an exercise feature would help.

Mix valve or vs pumping will give you the same end result. All in all I have had much less hassle with injection mixing. My current pump "favorite" seems to have the early low torque, limited sizing range, and sticking problems addressed. It's fun, for me anyways, to listen to the pumps rev up and down and watch the temperature gauges respond. I think we will be seeing more and more VS controls in the near future be they delta T or delta P controlled.

As hb mentioned, proper sizing is always important, be it valve pump, pipe, boiler, etc etc. A little "front end" math can save hours of head scratching and call backs, generally :0

Defective 4 ways make for good 3D stick figures, however.

hot rod

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[Deleted User]

I'm thinking...

this guys got WAY too much time on his hands. Ya know, I'd bet we could sell them, to wet heads if no one else.

Leave it to HB to be the first to come out with hydronic yard art. From a true artiste!

I'd have expected something like that from HR!


What RB said is that the control device should account for 1/3 of the pressure drop of the controlled curcuit. Kinda tough to do with a 4 way and multi zone systems. Thats why I like variable speed injection pump controls. Its like having a clutch on an automatic transmission, with OVERDRIVE!

Precise control when done right, with a pump that uses its full potential...


ME

heatboy

Why is it.............

that in Europe, where they know this stuff cold, motorized mixing valves are the preferred way of mixing? Could it be that they use boiler reset on every piece of equipment and when running on reset, your VSI pump will be ramped almost all of the time if your system is laid out correctly? Also, I never understood the concept of "rapid reaction" i.e., the injection pump reacts quicker than a mixing valve. There must be something I am not seeing clearly. All the systems we install have boiler reset (mostly full) so there is no hunting of the mixing valve as it does trying to mix with 180° supply temps. So with all of the new modulating, condensing boilers coming to market, where is that going to leave VSI. In this scenerio, I believe, electrical consumption will be much greater long term that it is with mixing valves. Or, again, what am I missing?

hb

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Steve Eayrs

Some of us still live an oil fired world.

We cannot always do a full reset. Also I don't see the electrical consumption as an issue with injection pump, since a small (15-42) pump can handle quite a system, and doesn't take much to operate. Some motorized mixing valves consume about as much power.
I would say the biggest reason to go with VSI is the cost. By the time you put a motorized control on a 3 or 4-way, you have more cost in parts, than a simpler tekmar injection pump control and pump.
I find the labor to pipe also less. Also when it comes to repairs a pump is a lot easier and cheaper to replace than most 4-ways. I feel the sizing to also be more forgiving, than a 4-way, where 100% of the system flow has to run through.
Just why does Europe use mainly mixing valves? Have anything to do with a lot of constant circulating systems, over there? Or is it that between Veissmann and others they have the mixing vlv concepts down so well that they see no need for change?


Steve

Boilerpro_3

Some maybe answers to your questions HB

In Europe I imagine they can run full reset on most of thier boilers, so the injection pump will run at nearly full speed most of the time. The issue of quick response is related to this and the predominant use of cast iron boilers this side of the big puddle. Sudden drops in system temps due to setback zones cycling require the mixing device to react quickly to prevent cold thermal load shock...VSI reacts almost instantly and very quickly, where, I understand, mix valves take a while to work thier way around. With the use of condensing boilers and full reset at the boiler, I agree there will probably be less need VSI injection and mixing valves. However, the potential issue of cold or hot thermal shock in condensing boilers seems to be continued to be glossed over, so VSI may still need to be used. If all these issues are adressed in newer boiler designs, mixing valves and VSI will probabluy become vary rare, except on multitemp systems. JMT

Boilerpro

DAN AMBROSE

MIXING VALVES

TRY VIESSMAN VALVES,ACTUATORS,CONTROLLERS AND BOILERS. www.viessmann-us.com