Thermostatic Mixing Valves

Docfletcher

I'd like to bump the indirect water heater temp to 140F to aid in the prevention of Legionella. To that end I'd like to install a mix valve. I'd like a versatile temperature range of 120-160 if that's possible.
There is a whole bunch of brands/models out there so I'd appreciate your comments as to which models you pros have found to be worthy of consideration. Thanks.

Bob Bona_4

I was using Honeywell Sparco for the last 15 years plus, with the union connections. They were ok, but really like the Caleffi ones these days with the temp gage on the mix outlet. Nice units. They are union connection as well-great for service.

Docfletcher

Bob, I will check them out for sure. Thanks.

Sparco? I remember when they were a stand alone company. I had the old green zone valves. Using all Taco's now though.

Bob Bona_4

Yeah I do too, they partnered with HW I assume for that anyway. I got sold on the Caleffis when I saw the cool well/removable gage feature. Makes so much sense!

Docfletcher

This one...

http://www.burnerdepot.com/view_cart

Bob Bona_4

The link just goes to an empty cart

Docfletcher

http://www.burnerdepot.com/product_detail/caleffi-521519a-adjustable-thermostatic-and-pressure-balanced-mixing-valve

Bob Bona_4

That thar is the one!

Docfletcher

Cool! Thanks

EzzyT

Caleffi makes the best thermostatic mixing valves out there. There more money then the Honeywell but well worth and a lot more accurate and like bob said the temp gauge that comes with it is a huge plus.

gennady

Honeywell amx and mx series.

buster403

Danfoss also makes a good thermostatic mixing valve.

Docfletcher

I see there is a Caleffi 521519AC model that has built in checks. Where would that be used? I think all I need is the Caleffi 521519A ?

Jean-David Beyer

Why not use 5213 series Caleffi valves with anti-scald feature?

Checks are to prevent accidental cross-overs between hot and cold supply. Depending on application, you might want them. Such as running domestic hot water tank high enough to discourage legionella and not take the skin off your bones when taking a shower.

Docfletcher

Jean-David, The 5213 limits the temp output to 120F. I would prefer more adjustment range than that model gives. The application you told of is exactly my use so based on that I would say AC model will fill the bill. Thanks

Jean-David Beyer

The 5213 series require a minimum flow rate of one gallon per minute. I do not know what the minimum flow rate for the 5215 is, but it is probably about the same.

I have a Lawler valve that holds down to 1/2 gpm, +|- 1F. it goes way off at lower flow rates. Probably the Caleffi ones do too. So do not get one that is too big.

Docfletcher

OK. I'll mull it over for while. As it stands I'm on the fence. Thanks

hot_rod

The 512 has a minimum flow of 1.3 gpm for optimum performance. It will mix below that flow rate but not as consistent. It is adjustable from 85-150F.

Below is the flow graph that shows the pressure drop at various gpm flow rates, for the 512 with a 3 Cv.

If iI'm not mistaken the ASSE 1017 listing requires the checks be installed. Not sure many inspectors are aware of that.

The 5213 has been tested, approved, and re-listed down to .5 gpm flow now. It is limited to 120F, as it carries the ASSE 1070 for point of use installations.

Remember thermostatic mix valves need about 25- 27° temperature difference between hot inlet and mixed temperature outlet. It varies a little from brand to brand. Fall below that and they tend to drift.

Docfletcher

Technical Data 5213
Materials: - Valve body: DZR alloy EN 12165 CW602N
- Regulating spindle: DZR alloy EN 12165 CW602N
- Internal shutter: PPO
- Sealing elements: EPDM
- Cap: ABS
Temperature adjustment range: 30÷50°C (55°C only under supervision and not
within requirements of AS3500 and AS4032.2)
Temperature set: Must be commissioned on site to achieve desired temperature
Temperature control: ±3°C
Minimum cold inlet temperature: 5°C
Maximum cold inlet temperature: 30°C
Minimum hot inlet temperature: 55°C
Maximum hot inlet temperature: 85°C
Maximum working pressure (static): 1400 kPa
Maximum working pressure (dynamic): 500 kPa
Minimum working pressure (dynamic): 20 kPa
Maximum unbalanced dynamic supply (hot/cold or cold/hot): 6:1
Minimum temperature differential between hot water inlet
and mixed water outlet to ensure thermal shutoff function: 10°C
Minimum temperature differential between mixed water outlet
and cold water inlet to ensure stable operation: 5°C
Minimum flow rate for stable operation: 4 l/min

hot_rod

521 have a 3 Cv, 5213 a 2 Cv

Docfletcher

I was/am a bit confused by their terminology...
5213 Minimum flow rate for stable operation: 4 l/min etc.
But now that I understand Cv a bit better I think I get it. Thanks

uge

Symmons, Powers & Leonard all make great valves. Your valve selection must be based on min/max flows. All valves have a minimum flow rating. Make sure the valve you select will meet that minimum flow and still operate correctly. Operating one lavatory will be your minimum flow. The only valve I know that will go down to 1/2 gpm/minute without a recirc system is Symmons. Check with the manufacturer to make sure they can do that and meet ASSE standards.

Docfletcher

Thank you, I will consider all the info you guys have taken the time to share.

icesailor

It is my understanding, and from personal experience, that it is far worse to oversize a thermostatic mixing valve than to undersize it. That most valves are designed, spec'd and installed as WAY oversized. An valve sitting idle with no flow is 100% oversized. If you have problems with controlling mixed water temperatures through a thermostatic mixer, it is probably way oversized.

hot_rod

most of the basic residential 3 way thermostatic mixers, up to 1" size will be around the 3 Cv range. Next step up to a high flow would be a Cv 4 or 5 to 1-1/4 size. Typically around an 8 Cv for 1-1/2 to 2".

Cv being the gpm through the valve or device with a 1 psi drop.

For a typical home a mix valve with a 3- 5 Cv should be plenty, and still provide accurate low flow mixing. If you have a critical application a point of use ASSE 1070 valve could be installed at the fixture. This valve has a 120F max setting and a quicker response and lower flow rate accuracy.

Understand that a valve with a 3 Cv is not limited to 3 gpm, but note the pressure drop as you run higher flow rates.

Here is an example of a pressure drop chart for a 3 Cv valve. Note the pressure drop if you intend to run higher flow rates.

Run across the bottom to your intended max flow, straight up with a ruler, then read to the left to see the pressure drop at that flow rate.

Really you would not typically run much more than 5-6 GPM through 3/4 copper tube, keeping you under 4 fps flow velocity, or you may experience high velocity noise, and potential corrosion erosion.

Here is an old sizing wheel the PHCC supplied it members many many years ago, probably find an electronic version online, not unlike the B&G Syzer for hydronics.

Docfletcher

How close does the 5213 need to be to the fixture?

hot_rod

POU valves, "point of use"

Generally right at the final fixture. Under the sink, behind a tub or shower.. It will mix anywhere in the system but the closer to the fixture, the less water down the drain before it mixes to the desired output temperature.

Docfletcher

I can get under the shower 3' or 4' from fixture. I noticed the 5213 can be set as high as 131F that makes it better for me than I previously thought.

hot_rod

Nope, the 5213 cannot be set above 120F. That is what the ASSE 1070 listing dictates. That strict requirement it what allows it to be a POU valve.

If you want a valve to adjust beyond 120F, it will be an ASSE 1017 listed valve.

85-120F is the adjustable range, .5 gpm minimum flow, and of course Low-Lead compliant for the 5213.

hot_rod

Listing explanations

4Johnpipe

I use Taco 5000 series...high flow if needed.

Steve_210

I was don't check valves on the hot and cold maybe I am being overkill but I did have problems years ago. once bitten twice shy

Steve_210

I meant to say I always use check valves.
Sorry

Docfletcher

In the 5213 specs it says you can squeak 55c (131f) out of it. Am I misconstruing something?

Thanks John I'll be sure to look at the Taco.

hot_rod

Are you looking at min. hot inlet?

ASSE is very strict, 120F limit on POU listed valves.

Docfletcher

Technical Data 5213
Materials: - Valve body: DZR alloy EN 12165 CW602N
- Regulating spindle: DZR alloy EN 12165 CW602N
- Internal shutter: PPO
- Sealing elements: EPDM
- Cap: ABS
Temperature adjustment range: 30÷50°C (55°C only under supervision and not
within requirements of AS3500 and AS4032.2)
Temperature set: Must be commissioned on site to achieve desired temperature

hot_rod

I'll check on that C listing.

I'm not following exactly what you are trying to accomplish.

If it is scald protection at the point of use, code requires and liability potential would indicate a ASSE 1070 valve LIMITED to 120F, or even 110F in my opinion, is what you should install.

If you want hotter at the fixture, highly discouraged, and a potential soft tissue lawsuit, then just set a point of distribution ASSE 1017 valve at tank.

Docfletcher

At first I wanted 140f at the water heater but of course not at the shower. It was my hope to control water supply temp to the system with the 521. Then Jean-David Beyer informed me that I would not have scald protection with a 521. So now it appears I need both the 521 (at the heater) and the 5213 (at the shower). I would run a line from below the 5213 to the dishwasher so it would get the 140F water. As for the set point on the 521 I would initially set it at 120f and see how it works out.

This way the water heater will act more like a larger heater and prevent bacteria. Protecting the household, especially my son.
Everyone gets a safe shower.

2 showers here so I guess i'll need two 5213's.

Does this sound like a good plan?

hot_rod

Run the tank at 140, just for the dishwasher? Then mix to 120 for the rest of the home. Still a bit too warm for household use IMO.

Or just mix to 120 at the tank and use the temperature boost feature on the dishwasher, save running another line just for the DW.

OR buy shower valves with the pressure and temperature function. Most of the nicer Grohe and other top end shower valves are ASSE 1069 (I think that is the listing #) both temperature and pressure balance "scald guard". Temperature mix alone does not always mean scald protection.

I do like to run the 140- 150F at the tank for potential bacteria issues, but that is too hot for the DHW.

So elevated tank, with 120F mix, then any of the above options for shower protection, POU mixers or shower valves with that function built in.

Remember any mixing valve will need cleaning and de-liming, some times every 6 months if you have hard or high mineral content water. So plan for that ongoing maintenance when you install them, add isolating valves. The more valves you install, the more you will need to maintain.

Also the hot water going to a mix valve needs to be 25- 27° warmer than the mixed temperature for the valve to regulate accurately.

I suspect in the near future buildings, especially commercial health care, etc will be required to run, or elevate the entire DHW system to 140F or higher, daily, for at least 1 hour. Caleffi and others already have products for this function.

This will require a mixer valve at EVERY dhw connection or faucet, a big expense and maintenance concern.

Protection for legionella potential and protecting for scald potential is not easily accomplished., they are at odds with each other, temperature-wise.

Docfletcher

Yes, 140 for the dishwasher was my thought. There is a heating element in the dishwasher to raise temp but it increases washing time waiting for water to heat, and is expensive.

For one bath I already have fixtures bought, so POU valves are the way to go for me.

Of course I could set 5213's to 110F and see how it works out for us. Slightly higher is always an option if needed.

Jean-David Beyer

I wish I could send 140F water to my diswasher (that will take up to 149F) and my washing machine (that I read somewhere could take only 120F, but has a sanitize cycle that runs at 152F, but I cannot find the maximum supply temperature anymore, not even in the installation manual). But it does not matter because the hot and cold water to the house is embedded in the concrete slab of the house (along with the radiant heating tubes). It would be a serious expense to run a separate hot water line to the clothes washer hot input (if it will take the higher temperature), and the dishwasher. So I will let that alone.

I decided to get a 5213 valve for the output of my indirect and set it to 120F. and set the indirect to 150F (so it will probably run at 140F +|- 10F. I set it up from where 120F comes out of my closest hot water tap, to the white arrow that I suppose means 140F. When I did that, it just barely would turn on, ran for a few minutes, and then I could get 140F out. That is why I assume the aquastat is +|- 10F, or close enough. That should make it miserable for most bacteria in the tank. Now if I could put in a recirculation system, I could run 140F or so through all the hot water pipes, but I do not have a return line for them, and the pipes are not, and cannot be, insulated, so that would waste a lot of heat while the circulator is running.