Bad mixing valve

Snowmelt

https://s3.amazonaws.com/s3.supplyhouse.com/product_files/CashAcme-24514-ProductOverview.pdf
Ever have this mixing valve go bad on you?

hot_rod

Bad as in? They tend to lime or scale up easily, all brands do. You need a 20 or more ∆ between hot in and mixed out for them to be accurate. A min. 1 gpm also.

That 20 gpm is BS! try shoving 20 gpm thru an opening the size of a pea. Sure it's possible but look at the pressure drop, what pump would you use for 45 pressure drop?

Snowmelt

It’s only been a month I have the mix at factory setting which was about 120 , the boiler is set at 180, it was nearly Luke warm temperature. I turned it all the way up and still it’s just above Luke warm but not even close to hot.

hot_rod

did it work when you first installed it, or not ever?

Snowmelt

Had to work, it was hot to touch where I could only hold it for 5 secounds, now it’s Luke warm.

hot_rod

Snowmelt said:

Had to work, it was hot to touch where I could only hold it for 5 secounds, now it’s Luke warm.

Did you try turning the knob all the way open and close to see if it frees up a stuck spool?

You are sure you have flow going thru, no air lock that could be causing little or no flow?

Circulator is pumping away from the "H" port?

Solid_Fuel_Man

Are you pumping away from the Mixed port?

Snowmelt

its defiantly stuck closed. I felt the pipe this morning, it may be air bound I will try bleeding the air today. it was working just last week were my wife could feel the floor was warm. the floor didn't feel warm Friday night so Saturday I looked at the valve, it wasn't getting warm.
of course im pumping away from the mix valve, im not a rookie.
im leaning towards air or bad mix

hot_rod

very simple innards, but it doesn't take much to gum them up.

This spool was in a domestic water valve that the water flowing thru started to dissolve the peroxide cured EPDM o-rings that Caleffi uses, a very chemical resistant o-ring design.

Chemicals added to the public water must have been fairly aggressive. Wonder what those chemicals do to human innards

kcopp

I have seen grit get in there and mess all kinds of things up.
Pull it out and flush the lines as best you can.
May be best to install new valve instead of fixing what you have.

hot_rod

In a bind you can actually remove the guts from a thermostatic valve and move some heat. If there are valves around it you can manually balance it, but it will not change as S&R changes, it's now a dumb valve

You might be amazed how much more flow you move when the guts are taken out. Thermostatic are very flow restrictive devices.

3- 5 GPM reasonably without throwing some serious pump energy at 'em.

Zman

I can't believe they advertise that valve for hydronic heating. Have you seen the pressure drop chart? ~4 PSI at 5 GPM

hot_rod

Not understanding how Cv works in a valve like that is probably why so many radiant systems slip behind as you approach design conditions.

You will often see 2 or 3 circulators connected to 3 Cv thermostatic valve!

If this attaches it is a handy spreadsheet to help understand the effect of CV. Used for design or troubleshooting.

It applies to ANY valve, zone, ball, balance.

Snowmelt

Hot rod, it was air in the line. I came home from work, I bleed it out, ( 3 five gallon buckets, then the line became hot.

hot_rod

Snowmelt said:

Hot rod, it was air in the line. I came home from work, I bleed it out, ( 3 five gallon buckets, then the line became hot.

It can take a lot longer than one would think to get a good clean purge, you can spend 5 minutes or more on a single loop getting then to run clear. Good that you got it going.

Snowmelt

yea my wife was complaining her feet were cold. lol
hey, were you in NJ a few weeks ago? did a class on your material. john serlerno was the rep?

Le John

Hey @Snowmelt should you need to change it I’d recommend the caleffi version. Has a temperature gauge to see what the outlet temp is. Pretty nice valve.

hot_rod

Le John said:

Hey @Snowmelt should you need to change it I’d recommend the caleffi version. Has a temperature gauge to see what the outlet temp is. Pretty nice valve.

Nice solder joints!