Two Faucets in Shower? Still Legal?

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On Wed, 8 Jul 2015 20:11:02 -0700 (PDT), snipped-for-privacy@gmail.com wrote:

Don't know about the USA but in Canada they are legal if you have a "tempering valve" on the water heater, which mixes hot and cold to limit the output temperature.
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It sounds like your tankless water heater is undersized for your situation.
Tankless heaters are generally rated for a given temperature rise at a given flow rate. If you draw water faster than it can heat it, you'll get cooler water.
Likewise, if the water coming into your home is colder, the outgoing water will be colder too. The heater can only raise the temperature so much.
It would be like trying to heat an entire house with a small space heater. If you close the doors you might be able to heat one room. Open the doors and you'll lose heat faster than the heater can warm it.
When you bought your heater you should have checked the temperature of your water supply, what flow rate you would need (how many fixtures you would be running at once), and selected a heater that could meet those requirements.
At this point, you really only have a few options.
1. Return the tankless heater and go back to a tank heater.
2. Replace the tankless heater with a more powerful model.
3. Add a valve to the water line to reduce the flow rate (giving the heater more time to heat up the water).
Of course, putting low flow aerators on all of your fixtures would help too.
One way you can test if your water heater is the culprit is to open a hot water valve at a sink or washing machine outlet. Basically someplace with the "two handle" operation you are describing. If the water cools down as you open the faucet further, you know the heater isn't able to keep up.

As far as I know, single handle pressure balanced shower faucets are now required for new construction (or remodels when you upgrade the plumbing).
You might try replacing the balancing valve in the faucet, it might just be defective. Sometimes they get plugged up with grit and stop moving correctly.

Odds are the pressure balancer is crusty/rusted too. Time to do some maintenance.
Good luck,
Anthony Watson www.mountainsoftware.com www.watsondiy.com
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On Thursday, July 9, 2015 at 12:31:55 AM UTC-4, HerHusband wrote:

Agree. Sounds like another satisfied tankless customer. I see what's going on and how it's annoying, but I'd say the root cause are the properties of the tankless. It would be solved by having a tankless sized to maintain constant water temp up to whatever the max usage rate of the whole house is. But that will likely take a much larger model, because you have to support the max reasonable load of the whole house. And if he's having this problem with just one point of use, it would likely require a much bigger unit to support two or three simultaneous draws. Alternative, as you say, is to restrict the hot water flow rate so that the tankless can keep up. Even then though, I wonder how variable their burn rate is and if they can actually maintain a perfectly constant outgoing temp rate? IDK, because I don't and won't have one, for a variety of reasons, starting with cost.
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There's nothing wrong with tankless as long as they are sized for the application.
As with most things, people buy the wrong thing then complain about the item as a whole. "Those things don't work" instead of "I got the wrong model".
A tankless heater designed for a single faucet isn't going to perform well for an entire house.

I looked at tankless models when we built our house. We didn't have gas available and electric models would have required major electrical supply upgrades. We have relatively cold well water so we would have needed a large model. And, as you say, they're kind of expensive.
However, I have used tankless heaters at many cabins and cottages and they perform very well when sized correctly. Best part is the hot water never runs out.
Anthony Watson www.mountainsoftware.com www.watsondiy.com
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On Thursday, July 9, 2015 at 10:57:03 AM UTC-4, HerHusband wrote:

I'd say even if they're sized right, the fact that in most cases you'll never recover the increased upfront costs of the unit and installation are something that's wrong with them. That cost can include running a larger gas service. The OP might run into that if he tries to put in a larger one. And the alleged savings in operating costs, I think in many cases are overstated.

There you go.

That is an advantage. How much it matters, depends on your situation. For me, running out is not a problem with my tank type. On the flip side, when my power goes out, I still have hot water, while with most tankless, you don't.
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On 07/09/2015 10:09 AM, trader_4 wrote:
[snip]

I remember visiting some friends once, during a milti-day power failure (caused by ice on tress). One of the best things about going home was getting a hot shower.
--
Mark Lloyd
http://notstupid.us/
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On 7/9/2015 4:03 PM, Mark Lloyd wrote:

I've had people suggest I go tankless water heater. Of course, the thousand dollars or so is a factor. The hot shower during a power cut is a very good thing.
Will stick with my tank type heater for now.
--
.
Christopher A. Young
learn more about Jesus
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On Thu, 9 Jul 2015 14:55:32 +0000 (UTC), HerHusband

Well, yes there are some things. They are expensive. That's because they have a lot going on in the unit in order to operate properly and safely. And that means a lot can go wrong, and very few qualified technicians to fix it, usually only one source for parts, and that means repairs can cost more than the original installation.
They do have some good selling points, but consumers should know about the good and the bad before making a decision.
--
croy

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+1
--
Web based forums are like subscribing to 10 different newspapers
and having to visit 10 different news stands to pickup each one.
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On 7/8/2015 9:30 PM, HerHusband wrote:

This isn't his problem. The problem is that tankless heater is not heating to a specific temperature regardless of the flow rate so at low flow the water is too hot. Changing the mix at the faucet for more cold and less hot doesn't work because then the hot water, while lower in volume, is much hotter.
Does any tankless hot water heater monitor the flow rate and output temperature and then adjust the flame to keep the temperature constant regardless of the flow? It would not be difficult to do this but a good flow meter that works for hot water is not cheap.
Why would anyone put in a tankless water heater in a residential property? Even for vacation homes it's easy to fit something that turns the hot water heater off when not in use.
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On Thursday, July 9, 2015 at 3:24:23 PM UTC-4, sms wrote:

That would seem to be exactly his problem. At a slower flow rate, it's able to heat the water hotter. If he had a unit with a much higher capacity, then he wouldn't be having the problem.

It can't heat to the same temperature at 5 gal a minute as it can at 1 gal a minute. It's very much an issue of the flow rate.
Changing the mix at the faucet for more cold

That would indeed be the problem he stated.

I would certainly hope so. Otherwise when you were drawing .1 gal a minute, you'd get steam, wouldn't you?

If you had a big family and had experiences of running out of hot water I can see it. Around here, they are putting in two tank type to support large homes, with Jacuzzi type tubs, etc. I can see putting one in there instead of two tank type.

Not so easy unless you have a predictable schedule of when you're going to be there. For vacation rentals it wouldn't work well either.
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If the water is too hot at low flow, there are two likely causes:
1. The water heater is set at too high of a temperature.
2. The pressure balance valve in the shower faucet is defective.
Both are easy fixes.

I have no idea, but a standard tank model doesn't do this either. You set a maximum temperature and the heater heats the water to that level (typically 120 degrees). A tankless heater isn't really all that different. It's just heating the water as it comes in instead of preheating it in a big tank. Either way the water should always be 120 degrees when it leaves the heater.
As I mentioned earlier, the original poster should check the water temperature at a valve near the water heater. If the temperature remains fairly constant at high and low flow, the heater is probably fine. The problem is probably a defective faucet.

Space savings, potential energy savings, endless hot water, gadget wow factor. How important any of these are depends on the situation and the individual.
Anthony Watson www.mountainsoftware.com www.watsondiy.com
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On Friday, July 10, 2015 at 1:38:25 AM UTC-4, HerHusband wrote:

There is a big difference. The tank type has most of a tank of hot water at close to the same temperature. When you start drawing water, you can pull a lot of water at whatever rate you want and the temp is not going to vary much. If you pull enough, eventually the temp will drop as the cold water entering the bottom of the tank starts to effect the hot water leaving the top.
With a tankless, the burn rate of fuel has to be adjusted to the flow rate. Otherwise you'd get steam at .1 gal an hour and the temp would vary wildly based on flow rate. How exactly they do that, IDK, but I'd suspect they use some kind of modulating gas valve.
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On Friday, July 10, 2015 at 1:38:25 AM UTC-4, HerHusband wrote:
Someone other than HerHusband asked:

Yes, per the site linked to below, they do exist. I quote, but offer no exa mples:
"Some types of tankless water heaters are thermostatically controlled; they can vary their output temperature according to the water flow rate and inl et temperature."

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Not so. Flow Rate is known drawback of tankless WH. Well, maybe not a drawb ack, per se, but a key factor in sizing a unit. It's a drawback in the sens e that you may need to purchase a bigger/more expensive unit based of your flow rate/temperature rise requirements.
The more flow you demand, the lower the water temp at the output because th e water is not in "contact" with the burners for as long a time.
Granted, flow rate will impact a tank heater also in that you will run out of 120 degree water sooner with a higher flow rate, but the difference is t hat regardless of how many showers you turn on, you *will* get 120 degree w ater out of the tank for some period of time. With a tankless heater, you m ay never get 120 degree water if the flow rate outpaces the heater's abilit y to impart the required temperature rise.
From: http://energy.gov/energysaver/articles/sizing-new-water-heater
SIZING TANKLESS OR DEMAND-TYPE WATER HEATERS Tankless or demand-type water heaters are rated by the maximum temperature rise possible at a given flow rate. Therefore, to size a demand water heate r, you need to determine the flow rate and the temperature rise you'll need for its application (whole house or a remote application, such as just a b athroom) in your home.
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On Fri, 10 Jul 2015 05:36:55 +0000 (UTC), HerHusband

A better answer is more money than brains. In normal use a tankless will NEVER pay for itself in energy savings - not even close.
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On Friday, July 10, 2015 at 1:24:11 PM UTC-4, snipped-for-privacy@snyder.on.ca wrote:

Probably true.
But it might pay for itself in energy savings plus water savings. Water is cheap in the US but that isn't true everywhere. We had a tankless in Germany for the kitchen, based on not wasting water (kitchen was a long way from the boiler).
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On Friday, July 10, 2015 at 2:01:11 PM UTC-4, TimR wrote:

It would cost me more. I can just about guarantee that we would use more water if we never ran out of hot. Even with a 50 gallon tank, SWMBO and I can empty the tank when taking a shower, either separate or shared.
Heck, on a lazy, winter Sunday morning, we'd probably stay in the shower until noon. ;-)
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On 7/10/2015 2:31 PM, DerbyDad03 wrote:

There are other ways to get there aside from tankless. My old oil fired boiler would keep up forever but it was not very efficient. Most electric water heaters have a first hour rating of 50 or 60 gallons. My indirect fired tank has a rating of about 250 gallons. It is 40% better on oil than my old setup.
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wrote:

Water isn't cheap here either - but unless it is a big house and the heater is at the wrong end, unless it is a very high quality unit it will still not last long enought to pay for itself - and even then, a unit of high enough quality to last that long will cost so much it STILL won't pay for itself.
It's just about the APPEARANCE of being "green"
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On Friday, July 10, 2015 at 1:24:11 PM UTC-4, snipped-for-privacy@snyder.on.ca wrote:

et

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While you may very well be right in regards to your second comment, your fi rst comment doesn't hold water. (pun intended)
"More money than brains"
The fact that someone can afford to pay for the pleasure of "endless hot wa ter" doesn't mean they suffer from diminished brain capacity.
If someone offered you free endless hot water, would you pass it up? I know I wouldn't. So, if my resources were such that I could absorb the initial and incremental cost differences of tanked vs. tankless hot water without f eeling any pain, I'd do it in a second.
We all do things like that quite often. We could sit on wooden boxes instea d of couches. We could cook over an open fire instead of on a gas range. Th e fact that we spend more than we actually *need* to on things that make ou r lives more enjoyable doesn't (always) make us idiots.
Granted, when we make decisions based on unsubstantiated data and/or spend more than we can comfortably afford, then the "brain power" argument is val id.
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