Does Pressure balanced Fixtures make Mixing valves obsolete?

Discussion in 'Water Heater Forum, Tanks' started by Young_apprentice, Apr 3, 2012.

  1. Young_apprentice

    Young_apprentice New Member

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    Now all valves seem to come pressure balanced showers even faucets. are mixing valves even necessary anymore?

    Is their any application that they are useful or needed. The only example i could think of would be being able to divert super hot water to clothse washer or sanitation devices but they would have to have multiple ports one for Tempered water going to fixtures one for cold, one for hot to mix, and one straight hot from the water heater that is piped directly to sanitizing fixtures. I think watts makes one like that.

    For what reason would you install a tempering valve on a hot water system?
  2. jimbo

    jimbo Plumber

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    Pressure balanced is the "poor man's solution" to anti-scald. It does not allow you to set the WH temp high. If the WH is 140+ you can still jump in and get scalded. You are just protected from "the flush". So I would say NO....tempering or mixing valves are not obsolete.
  3. Hackney plumbing

    Hackney plumbing Homeowner

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    Do the pressure balanced valves you install have a temp limiting stop???? Mine do. I get service calls all the time with people complaining that they cant get much hot water at the shower but it will burn your hand at the lavatory.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    I'm pretty sure all PB shower valves also have some means of setting max temp as do thermostatically controlled valves. That doesn't mean that people realize they are there and adjust them properly.
  5. Hackney plumbing

    Hackney plumbing Homeowner

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    The same could be said about a thermomixer.

    A thermomixer is a more precise appurtenance. Its a higher level of protection compared to pressure balanced with a temp limiting device. The thermomixer actually reacts to the temp of the water.....a pressure balance valve with temp limiter does not actually react to water temp but only changes in pressure. I'm certain you already know this but maybe some others dont.

    I have a discontinued Symmons 5-200 thermomixing 3/4 inlets and a 3/4 outlet for sale cheap. Its new in the opened box and has never been installed.....all the paperwork included. 165.00 with free UPS shipping if you live in a resonable location....LOL. I think it retailed for around 500.00.
    Last edited: Apr 3, 2012
  6. Young_apprentice

    Young_apprentice New Member

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    Once again thanks guys- you all have some much info i have know idea how you all KNOW so much i just bought siggentheilers book on Modern Hydronic heating maybe that will help me out.

    Ok so PB valves do come with Temp limiting stop- i usally just chuck it or set it up so it makes no difference. Do regular LAV faucets have limiting devices that i do not know.... Yeah so the PB Really is just a cheap anti-scald i flush the toilet and saves my skin from the lower volume of cold water thats coming into the shower valve. But the PB valve does little for me IF i have a faulty WH and it creeps up in temperature the PB piston is not going to react to the increase in Water temp. It seems like thermostatic mixing valves do regulate supply temperature which will regulate The temp coming out of say the shower. As they have little thermostats that expand and contract to keep a desired Temperature- Right?

    I guess now im wondering why we don't install thermostatic mixing valeson all WH. they seem to do alot of good stuff kill bad backteria/prevent scalding/ thermal shock/ Yet honestly i only think ive seen them on 2 water heaters in my short short career. IVe seen them all the time feeding Radiant heat which takes cooler water


    But For what reason would you install a thermostatic mixing Valve.
    Last edited: Apr 5, 2012
  7. Terry

    Terry Administrator Staff Member

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    A tempering valve at the water heater is used to prevent scalding.
    The temperature limiting stops on a balanced valve don't do much for you. If someone turns up the water heater settings, then all bets are off.
    For my customers that want plenty of hot water, I install a tempering valve on the water heater, or a tankless water heater.
    Adding a tempering valve is pretty easy, and prevents scalding.
    http://www.terrylove.com/forums/sho...atic-Mixing-Valves-(-water-heater-tempering-)
    Hansgrohe and some others make a thermostatic valve. That's another way to prevent scalding.
  8. Young_apprentice

    Young_apprentice New Member

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    Hmmm ok thanks terry now How exactly does a Thermostatic mixing valve/ or tempering valve increase your hot water capacity, is it because it allows hot water to be stored in the tank at a higher temperature thus lessening heat recovery rate as it keeps it hotter for high HW demand households. Say for example if a family is complaining about not enough hot water could you install a mixing valve and boost the Hot water output? or does it not work that dramtically. It seems like its mostly a pretty good saftey device that protects you from scalding as apparently WH supply tempertaures can vary as much as 10 deg C. thats a pretty big difference Im assuming a Thermostatic mixing valve would be pretty great here as it keep the temperatures constant.

    Lastly if you did toss on a Thermostatic mixing valve because your water heater is now storing so much hotter water would it be smart to put a backflow preventer and then an expansion tank on the cold line to prevent all that hot water from going up and mixing with cold water thus wasting energy?


    Thanks guy's my head is just swimming with questions and now i have an outlet thank you for taking the time to answer. IT means alot to me being a plumbings apprentice
  9. Terry

    Terry Administrator Staff Member

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    You have more usable hot water when the tank is running hot. 140 and above.
    Most homes are running their tanks at 110 to 120. Since you can run the tank hotter, and then mix in cold water to get it back down to 120, there is more to use before it gets cold. Generally you will get about a 1/3 more usable hot water. A 50 gallon tanks feels like a 75 gallon.
    Does it save energy? No, but then that's not really the point if you have high use needs. If you can afford tankless, then you could look at saving energy.
    We're installing expansion tanks on the cold side of the water heater, but nothing for back flow.
  10. Young_apprentice

    Young_apprentice New Member

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    Ok thanks terry that helps, I was just thinking of a backflow(maybe i meant to say check valve i can get them confused often) to assure flow of water in one direction and prevent thermal siphoning that would occur with the water at even hotter temperatures. Plus with the hot side being so hot and the cold side being so well cold their is a potential for differental pressure b/t the hot and cold water supply thus making a check valve is necessary?
  11. Hackney plumbing

    Hackney plumbing Homeowner

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    Pipe the mixer below the top of the water heater. No thermosiphon. Your sporty for a young apprentice.....you ask alot of good questions. :) Thats whats up.
  12. Young_apprentice

    Young_apprentice New Member

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    Location:
    The CAPE
    Thanks hackney. Yeah i saw online most people like to pipe it 12" below the top of the water heater, which is odd because in my experiance although short i've only seen it sitting on top of the WH i dont know why they would do that.
  13. hj

    hj Moderator & Master Plumber Staff Member

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    You heat the water you use, regardless of its temperature, so raising, or lowering, the thermostat setting does not appreciably affect the cost of operating the water heater. You would have to define your term "mixing valve", because many customers do not want a single handle valve in their "retro", or luxurious, bathrooms, in which case a "remote pressure balancer" would be used if the code required it.
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