Mixing Valve

michael_34

I am looking for a commercial tempering valve. The hot and cold supply and the DHW out are all 3" copper.



Thanks

Henry

Watts

Conbraco, Watts, Leonard Valve all make tempering valves. Most are reduced to 2 inch Here is an example:

http://www.wattscanada.ca/pages/_products_details.asp?pid=6718

hot_rod

size the valve

to the amount of GPM you plan on flowing thru it. On larger applications sometimes you see a Hi-low system. A small size valve to handle very small flows, piped with a larger valve.



Here is an example of a Leonards hi-low.



hr

icesailor

Sizing thermostatic mixers:

The question is, are you trying to extend the amount of hot water you will be delivering or are you trying to control the temperature in the system. There is a difference. If you are trying to control the temperature in the system, you MUST size the valve to the system. You may have 3" supplies into the system but you only need a 1 1/4" valve. Because it depends on flow through the valve.

The whole subject is much more complicated than you may realize. What are you trying to do? I've been down this road before.

gennady

tempering valve

Size of the line has little to do with size of mixing valve. Mixing valve is picked up by amount of tempered water needed and pressure drop trough the system. Each brand has its own charts. Also, there is an issue of high and low loads. most of the valves have to compromise on temperature control at the opposite sides of load. Lets say same mixing valve picked up for 50 apartment load, might have a problem to control water temperature when only one faucet is used. It is best to contact manufacturer rep for application help.

michael_34

Much more harder than I realized

I am tying in a solar thermal to an existing 9 story 127 unit residential building. Mostly elderly.



I am worried about loss of flow in the building installing a smaller mixing valve. I'll attach a drawing to help clear my mud.



If I can put in a smaller diameter mixing valve, say 2" with minimal flow loss that is great!



Thank for the help

Mark Eatherton

Tough call...

Extended care facilites, and nursing homes don't have any "normal" hot water usage patterns, so the engineers who design these systems typically cover their butts, meaning the system is grossly over sized. ASHRAE doesn't even attempt to generate a usage profile chart like they do for other facilities.



In reality, you need to do due diligence, and talk to the people who are using the system (administrators and their assistants) to gage exactly what the largest hot water load would be. Laundry facility? Full service commercial grade kitchen? These loads will be much greater than the DHW loads, and the chances of having parallel loads is slim to none. Old folks don't shower as often as younger folk do, unless there is a schedule bus trip to a bingo parlor or casino, then EVERYONE wants to smell good ;-)



Over sizing an anti scald tempering valve can actually cause more problems. Valves are designed for certain "minimum" flow standards. If flow drops below this minimum, and they will, then the system starves for hot water because the cold water pressure will always be greater than the hot water pressure due to inherent pressure drops through tanks, etc.



Conversely, undersizing a tempering valve is also problematic, hence the 2 stage systems that HR told you about.



It is up to you to choose a "Happy Medium" to design around. I'd also recommend two valves so that hot water service can be maintained at all times, especially when rebuilding the valves.



Just because the mains are 3" is not necessarily an indication of the required mixing valve size. Those pipes sizes were based on flow potential, which in reality, is a moving target and is usually no where near the rate the designers used in their design.



In regards to your solar design, you should have a tempering valve between the solar preheat and the aux system, otherwise, during peak insolation it is possible to send too hot of water into the boilers, thereby causing their on board manual reset high limit to pop, and you will not know it until its out of hot water.



Also, regarding your SPH tanks, they will all be the same temperature because they are all seeing the same flows on discharge and recharge. They are in parallel.



If you wanted three different tank temperatures, then the tanks would have to be in series, not parallel. I see no advantage to that in my minds eye, but its also Monday, and I'm only on my first cup of Joe...



ME

michael_34

Mark E

My Comments are below your paragraphs:

Extended care facilites, and nursing homes don't have any "normal" hot water usage patterns, so the engineers who design these systems typically cover their butts, meaning the system is grossly over sized. ASHRAE doesn't even attempt to generate a usage profile chart like they do for other facilities.



Yes, this I know!; ) I tried desperately to get them to put a meter on the DHW to help size this system. It never happened.



In reality, you need to do due diligence, and talk to the people who are using the system (administrators and their assistants) to gage exactly what the largest hot water load would be. Laundry facility? Full service commercial grade kitchen? These loads will be much greater than the DHW loads, and the chances of having parallel loads is slim to none. Old folks don't shower as often as younger folk do, unless there is a schedule bus trip to a bingo parlor or casino, then EVERYONE wants to smell good ;-)



To clairify, this is a Co-op living center. The residents have their own laundries and cooking facilities.



Over sizing an anti scald tempering valve can actually cause more problems. Valves are designed for certain "minimum" flow standards. If flow drops below this minimum, and they will, then the system starves for hot water because the cold water pressure will always be greater than the hot water pressure due to inherent pressure drops through tanks, etc.



That is my worry. Old people hate cold water (at least most). My worry is choking off the hot water supply.



Conversely, undersizing a tempering valve is also problematic, hence the 2 stage systems that HR told you about.



It is up to you to choose a "Happy Medium" to design around. I'd also recommend two valves so that hot water service can be maintained at all times, especially when rebuilding the valves.



Just because the mains are 3" is not necessarily an indication of the required mixing valve size. Those pipes sizes were based on flow potential, which in reality, is a moving target and is usually no where near the rate the designers used in their design.



Good to hear.



In regards to your solar design, you should have a tempering valve between the solar preheat and the aux system, otherwise, during peak insolation it is possible to send too hot of water into the boilers, thereby causing their on board manual reset high limit to pop, and you will not know it until its out of hot water.



Yes, I agree. I am fighting with a couple of engineers on that point.



Also, regarding your SPH tanks, they will all be the same temperature because they are all seeing the same flows on discharge and recharge. They are in parallel.



Originally I had them is series. My concern once again was the flow rate. Me and my engineer friends decided to change to parallel for that reason. I usually always put them in series, but I was eagerly swayed. What is your opinion on this Mark?



If you wanted three different tank temperatures, then the tanks would have to be in series, not parallel. I see no advantage to that in my minds eye, but its also Monday, and I'm only on my first cup of Joe...



I couldn't sleep because I am letting all this bother me. I didn't need coffee today! lol

michael_34

Thanks HR

Leonard seems to be the answer. They were very helpful.



Thanks,

Michael

michael_34

Yikes!

Sticker shock on the leonard valve.



HR,



Doesn't Caleffi make a similar valve?



This is a 127 unit residential bldg. There is no commercial facilities for cooking. Each unit has a kitchenette with no dishwasher. Most people are over 60 that live there.



Let me know,



Thanks,

Michael

Mark Eatherton

Series versus parallel on tanks...

michael,



Other than HR's recent comment in regards to series DHW heaters, no one has been able to convince me that series is a better option than parallel.



If I had a situation whereby I had drain waste heat recovery, or any other low temperature differential potential with a significant potential contribution, I MIGHT have pre heat tanks in series. Drain waste heat recovery in series with solar DHW pre heat, in series with aux. tank. On my own house, I piped the incoming potable cold water in series through the GFX heat exchanger because it is designed for simultaneous draw/recovery, and then from there to the solar PH tank, and from there to the aux. tank. If the waste heat recovery potential is not simultaneous to the availability of the waste heat (i.e. refrigerant waste heat recovery) then it makes sense to keep that tank first in line (coldest possible water) in series with the other tanks.



If you have more than one tank connected to any single heat source (solar, aux, waste etc) then parallel insures that all tanks will see even flows, even temperatures, and minimal pressure drops on draw as well as circulation.



I also prefer to pipe them in reverse return, versus the pyramidic piping that you show. Less fittings, cleaner design, easier to work on with proper isolation and unions.



ME

icesailor

Assisted Living/Nursing Homes:

Trust me. I'm the voice of experience.

If you put your cheap pants on, you will loose your shirt and pants over this.

Whatever the management tells you their needs are, double it at a minimum and tripling it would be better. The Leonard valve may seem pricey but there is a lot of liability insurance built into the price. Some buildings like Nursing Homes require a maximum of 116 degrees. You can't feed a pressure balance shower valve with 116 degree hot water and get enough hot water out of the valve. Especially if the valve is thermostatic.

You may luck out with your cheap pants on, and get away with things. If the AHJ follows the letter of the regs, you could be seriously hurt. If someone else comes along saying they can do it cheaper, and they don't need to do what I am suggesting may need to be done, let them have at it. You can end up looking like a real fool.

Just My Experience.

SWEI

tempering valves

Those dual path setups don't come cheap. What would it take to "roll your own" using two appropriately sized ASSE 1017 valves?  I haven't studied them in depth - perhaps there's more there than meets the eye.



FWIW, Symmons quotes a 0.5 GPM minimum flow on their 6-900 and 6-1000 "when valve is installed at or near the hot water source with re-circulated tempered water and continuously operating circulating pump."

michael_34

Caleffi Cheap?

Are you calling Caleffi Cheap? Do you hear that Hot Rod? I'm just kidding of course.



I hear you Icesailor. I think I was a little sticker shocked. This is my first commercial install and $xx00. for a mixing valve blew my pants off (believe me, not worth photographing).



I was expecting around $xx00. As long as it functions properly and everyone is happy then it is well worth it. Amen to that!



Thank you for your bluntness. That I really do appreciate.

Michael

Mark Eatherton

Wanna get REAL naked???

I was on a project the other day, and was told by a reliable source that the tempering valve that was installed in a 150 unit senior housing complex was $8,000 dineros. It is a solid state electronic control, and included the circulation return pump and a diverter valve on the return, and a remote alarm in case of failure, but really, $8K? How much of THAT price do you think is a liability insurance policy... It was the first one they'd ever produced with the electronics package.



The manufacturer is well know, and shall remain nameless. Not so much to protect the innocent, as to respect Dans rule of not talking pricing, which is more directed towards labor costs, and not necessarily material costs...



ME

michael_34

parallel vs series

Mark,



I agree 100%. If I thought I could get away with the pre heat tanks plumbed in series it would be a done deal. I'm a little leery though. So is the engineer I am working with. Shoot, he is specifying 3" copper even on the tanks.



I would love to see a drawing of the reverse return on 3 pre heat tanks. The pyramid style that I have in the drawing did not excite me. I know I can make it look good, but man that is a lot of copper.



Can you post the reverse return or email me direct.



Thanks for all your help Mark

Michael

michael_34

did know the non pricing rule!

I will edit my post.



8k! Wow we!

michael_34

I will check out the Symmons

As long as the components are quality items, that is all that does matter.



Big building, bigger price.



Thanks,

Michael

SWEI

electronics

I recently added them to a hotel project, metering the output temp of a large ASSE 1017 valve. At this point it's only trending and alarming , but it's cheaper than any kind of mechanically redundant system.  Total installed cost delta (thermowell, sensor, control input channel, plumbing labor plus software changes) came to about half the cost of the valve.  I figured it was cheap insurance, and (based on previous experience instrumenting seemingly mundane parameters) we'll probably learn something important once we have a couple years of data collection.

michael_34

Leonard or powers

I am down to two different valves. A leonard: TM-2020B-DT or Powers: SH 1434-14.



Cost are similar. Does anyone have any opinions on which valve is more reliable? Or is there a better valve?

Thanks,

Michael