Tempering valves driving me nuts!

Ken C.

Most of the new houses my company plumbs have boilers with tankless coils for domestic hot water. We use a 1/2" Watts tempering valve (model 70-A?). Often, I am called upon to set the water temp at 120 degrees at the faucets, using a thermometer. However, I usually have to adjust the tempering valve about five or six times. Has anyone else found these to be difficult to adjust precisely? Sometimes, you turn the knob a tiny bit, and the temperature jumps way up. Other times, you turn the knob a lot, but the temperature doesn't change. It drives me nuts! On houses with indirect water heaters, we ususally use a 3/4" Taco tempering valve (model 5000???), and these, too, don't respond consistently to adjustments. Does anyone have any tips to reduce my frustration with these things?

Ken_8

I too have tried a few brands,

and find none of them work well on tankless coils. I know Watts was one brand - I don't recall the other two.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Firedragon_4

You may be using the right company, wrong valve.

Try a Watts MMV or the 1170. The Honeywell/Sparco products are also very good for these applications.

bob young

HOLBY

TRY A HOLBY. A little pricey but they have been around a long time and they work well. as long as you are getting the correct price for the job this is the cadilac of mixing valves. don't forget---pipe to specs.

EJW

Mixing valves

Go with the Sparco, I have 2 in my house, one for the domestic and one on my outside faucet for washing the truck in the winter. They are the best IMHO. They dont need to be trapped like the 70a, in fact one of mine is upside down or handle down, however you want to look at it. I install alot of them both on indirects and coils. No troubles. EJW

Weezbo

sparky mixers are good.:) Honeywell products.

next radiant garage slab try one of the Low temps out. you will be plesantly suprised.

Steve Miller

mixin' valves

One problem I used to see with the Watt's 70A's was variations in pressure can cause fluctuation in temp, especially on well systems or undersized water piping. One way we solved the problem on tankless coils was to use an electric water heater as a storage tank. We ran 120 volts to the bottom thermostat to energize a bronze pump to circulate water out of the bottom of the tank thru the coil and back to the tank. This does 2 things, it takes the mixing valve out of the picture. You can even wire in the upper thermostat and use the high limit snap switch to break volts to the pump to provide high limit protection. Secondly, you always have 40 - 50 gals of hot water on hand, also you can over come problems like mineral build up on coils and poor heat transfer.

Another problem I've seen with the Watts valves that are trapped,,,,like they recommend in the instructions. If the valve is trapped, it's not seeing the high temps from thermosiphoning. When someone draws hot water, the trapped valve has to react to the rapid change in temp and that's where you can see some fluctuation until the temps stablize. If you don't trap the Watts valve, it will see the high temps from thermosiphoning and not have to react so much to dial to find a constant mix. I think the only reason Watts wants you to trap the valve is to increase the longevity of the valve. I've seen Watts valves last a long time not trapped. It's also a good idea to exercise the dial when you're running some hot water about once a month, just remember the setting when you're done. This will help flush out debris and mineral buildup on the thermomstat and keep the dial from getting froze in one position.

Steve M

Weezbo

With steve on that ...

water heater and recirc controlled of the water heater thermostat,with st-12,check,(on cold) in a garage you need to elavate the water heater and keep an eye on heigth of pump(above 18" to sparking devise.considered any electric even low voltage around here.) next step up to water maker:)

ScottMP

Sparco

Sparco , sparco

Sort of like badger badger badger.

scott

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Scott Denny

Valve size

Scott Denny

Valve size

I've used a number of these tempering valves. My 2 gripes with them are:
1) They are only available up to 1". I have jobs where I need 1-1/4" to 1-1/2" forcing me to install 2 parallel valves to get adequate flow.
2) These valve have a tendency to lime up and malfunction in certain water conditions.

eric_2

Has anyone

tried the Taco mixing valves for this application? I have a few guys who love them on radiant jobs. Was wondering how they would handle tankless jobs.

EJW

Overcoming minerals?

How can you overcome mineral build up if you are still using the coil?

clammy

tempering valves

i am sort of forced to use watts 70'a at where i work and it seems most if not all of the installs i see the tempering valve is not correctly installed as instruction .I usally istall them on a thermal leg 10 t0 14 inches below the tankless or indirect and rarely have any complaints about fluxacations in water temp .I've also used sparco and found them to be a vastly better product and a few more bucks but well worth it .I,ve used the taco tempering valves on domestics water and for radaint mixing and they performed great as for domestics water they seemed to be simalar to the sparcos ,it's hard to get the bosses to make the switch to sparco or taco instead of watts but i,m trying i,ll wear them down sooner or later and they,ll make the leap hopefully the rest of the service guys will join in instead of just popping in replacement guts for a watts peace

J.C.A._3

Over 1\"

I've used a multitude of products. My favorite....Symmonds. They seem to be a bit more stable than many of the other offerings.

I've used and rebuilt some Watts and Powers mixers, but find the Symmonds to be a little easier to control.

We just finished a rather large job using a Leonard high/low flow mixing station, and I'm quite impressed with it.(3 119 gal storage tanks being supplied by a tankless coil w/ about 90 units being serviced) Easy to install and once set, it stayed rock steady on the set temps. Chris

Joe Mattiello

Taco 5000 series

Mixing valve is a good candidate for this application. The piping is the key, for domestic hot water recirculation. Attached is a drawing that should help you. Please advise, is you require additional assistance.

Joe Mattiello
Technical Service Technician

Steve Miller

overcoming mineral buildup

Of course relacing the coil is what you'd wanna do if the coil is really bad but in answer to your question: Is by circulating water thru the coil to a tank is that you don't have to rely on perfect heat transfer as you would directly going thru the coil one time for a call for DHW.

Steve M

Steve Miller

overcoming mineral buildup

Of course relacing the coil is what you'd wanna do if the coil is really bad but in answer to your question: Is by circulating water thru the coil to a tank is that you don't have to rely on perfect heat transfer as you would directly going thru the coil one time for a call for DHW.

Steve M

hr

They all require maintenance

the harder the water they see and the more volume the more frequent the maintenance.

They all operate with closely machined tolerances and after a while the spool will stick.

Under 1" size I have had good luck with the updated Honeywell/ Sparco's. Since they teflon, or whatever, coated the bore, and switched to a high tech spool material the build up issues have been minimized, but they will never go away when an o-ring seal is in the mix

hot rod

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Mr. Bill

Tempering valve

There are lots of variables that go into the mix. Pressure fluctuation is a common one that most thermostatic valves can not react fast enough to.

Danfoss now markets an ASSE 1016 tempering valve that is approved for temperature and pressure.

Might be worth a look.

Robert O'Connor_6

can

you give us a link?

Thanks

Robert

ME

Mr. Bill

Link

http://www.danfoss.ca/products/pdf/Series 30 HR & HV_datasheet.pdf