Runnning out of hot water. Help please.

[Dogwell]

UPDATE:

We swapped out both elements of our 50 gallon State water heater and installed a CSV valve. Temp on the heater is maxed out at the recommended level. Showers still run out of hot water before we've finished. Would a tankless electric unit at each of the 3 showers solve our issue and allow unlimited hot water? Thank you.

 

[WorthFlorida]

UPDATE:

We swapped out both elements of our 50 gallon State water heater and installed a CSV valve. Temp on the heater is maxed out at the recommended level. Showers still run out of hot water before we've finished. Would a tankless electric unit at each of the 3 showers solve our issue and allow unlimited hot water? Thank you.

What does that mean "recommended level"? Most tanks will have separate thermostats for each of the heating elements. You should be able to set them to at least 140 degrees. These read 150 and others might read low, medium and high. When set to the 140 degree level you use a thermostatic mixing valve to bring the temperature down to below 120 degrees. You'll not run out of hot water. Never leave the temp above 120 degrees without using a mixing valve.

If you're not sure how to setup and install a thermostatic mixing valve you'll need a plumber.

 

[Sponsor]

 

[Dogwell]

What does that mean "recommended level"? Most tanks will have separate thermostats for each of the heating elements. You should be able to set them to at least 140 degrees. These read 150 and others might read low, medium and high. When set to the 140 degree level you use a thermostatic mixing valve to bring the temperature down to below 120 degrees. You'll not run out of hot water. Never leave the temp above 120 degrees without using a mixing valve.

If you're not sure how to setup and install a thermostatic mixing valve you'll need a plumber.

Hi WorthFlorida. The max recommended temp on the water heater is 120° so that's what the temp is set at. I came across this at Home Depot. Is it similar to what you described above?

https://www.homedepot.com/p/Heatguard-Water-Heater-Tank-Booster-24409/203721329

And I found this online with an added temperature gauge.

https://www.homedepot.com/p/Cash-Ac...er-Pro-with-Temperature-Gauge-24644/206945096

Thanks!

 

[Dana]

In most areas codes for new installations now require:

1> A minimum storage temp of 140F or higher (high enough to kill off legionella colonies.)

2> A tempering valve or thermostatic mixing valve to mix down the water to <120F for hot water distribution plumbing that goes to sinks, tubs, & showers (but not required to temper dish or clothes washing appliances), which is what that "Water Heater Booster" product is.

 

[Dogwell]

Hi Dana, thanks for your response. So the thermostatic mixing valve WorthFlorida mentioned is different to what I linked to above, right? Can I set my heater to higher than 140 with the mixing valve? Can you please give me your advice on the point of use tankless units? Many thanks!

 

[Dana]

For a lot more money you could also install a drainwater heat recovery heat exchanger, which can add a substantial amount of "apparent capacity" in showering mode (does nothing for tub fills though), returning a large fraction of the heat that was going down the drain back into the incoming water stream (to both the shower, and the water heater.) At US average electricity pricing a DIY install will usually pay for itself in under 5 years for showering families. The biggest & fattest one that fits will pay off sooner than a smaller-cheaper one, due to the higher return efficiency. To be worthwhile you need at least 5' of vertical drain downstream of the main shower(s). They must be mounted vertically to work at full efficiency, and have extremely low return efficiency in horizontal applications (though there are a few that are designed for horizontal drain plumbing.)

 

[Dana]

Hi Dana, thanks for your response. So the thermostatic mixing valve WorthFlorida mentioned is different to what I linked to above, right? Can I set my heater to higher than 140 with the mixing valve? Can you please give me your advice on the point of use tankless units? Many thanks!

No, it's the same thing. The only difference is that the one you linked to has a handy pre-plumbed bit for the cold water feed to the thermostatic mixing valve. You can usually beat that price if you plumb in the cold feed yourself with pipe & fitting rather than that flex connection. But they are functionally identical. Either way, you can crank the storage temp to whatever works, and adjust the temperature of what's entering your hot water distribution plumbing with the knob on the valve.

 

[Dogwell]

For a lot more money you could also install a drainwater heat recovery heat exchanger, which can add a substantial amount of "apparent capacity" in showering mode (does nothing for tub fills though), returning a large fraction of the heat that was going down the drain back into the incoming water stream (to both the shower, and the water heater.) At US average electricity pricing a DIY install will usually pay for itself in under 5 years for showering families. The biggest & fattest one that fits will pay off sooner than a smaller-cheaper one, due to the higher return efficiency. To be worthwhile you need at least 5' of vertical drain downstream of the main shower(s). They must be mounted vertically to work at full efficiency, and have extremely low return efficiency in horizontal applications (though there are a few that are designed for horizontal drain plumbing.)

Yes I remember talking about this when I posted initially, but the price was very high and it would do nothing for our basement bath which is used just as regularly as the two upstairs.

I have seen tankless electric heaters for around $300. I could get three and still be cheaper than the heat exchange unit. I'm not sure if they can be used along with our existing tank (plus the booster / mixing valve we've just discussed) or what else I need to consider.

 

[WorthFlorida]

You asked about a tankless system. Sure they're good but very expensive to install. Keep away from the low price units. There is a tankless forum on this site. Here is an example of a good tankless unit. I found it online but I would not buy it online. You want a local dealer for any problems or parts needed in the future to service it. But look at the power requirements of this unit. Sure it is a high end high demand unit so you'll need to search from here down but a tankless can still not provide the hot water needed for your demands. For most homes, unless you have 200 amp service, could not be installed so there is research and education if you want to go this route.
https://www.ecosmartus.com/product/ecosmart-ECO-27-27-kW-Electric-Tankless-Water-Heater
Tankless have GPM ratings and it need to exceed slightly your estimated water usage during high demand

 

[Reach4]

Adding 3 tankless water heaters is cheaper? You may have not priced in the new electrical work. They might each require a 60 amp 240 volt circuit, although you could get a smaller capacity unit. At least the periodic maintenance of tankless water heaters is something you can do yourself. And you could use the same deliming equipment on each unit in turn.

You can put another water heater in series with your current WH. If your needs drop in the future, you could turn off the power to the first one. No tankless drama. One more 30 amp 240 volt circuit typically.

 

[hj]

The only way to tell if your heater is working properly is to test it, but, I am not sure that you, or he, has the necessary tools and experience to test it correctly. In other words, the ONLY test I would believe, is one I did myself or observed someone else doing.

 

[Dogwell]

Hello. Thank you all. We bought the Sharkbite booster and noticed on the installation sheet that there is a massive pressure loss with this product. Is there any way to combat this? We actually suffered from pressure loss before and installed a CSV valve. We held back on installing the tempering valve because unless we've misunderstood, it'll just create pressure problems again that we had resolved.

 

[Dana]

There is no "massive pressure loss" with a thermostatic mixing valve. What verbiage on the sheet led you to that conclusion? Or was it just the little graphic?

 

[Dogwell]

The bell curve shows a loss of about 8psi at a flow rate of 4gpm and 15psi at flow rate of 6gpm. Did we interpret something wrong?

 

[Dana]

A typical shower flow is ~2 gpm, and only 3/4- 4/5 of that flow is coming from the water heater. How much pressure drop do you really care about?

100' (equivalent length, with the equivalent lengths of all ells & tees factored in) of half inch copper has a pressure drop of about 10psi @ 6gpm too. Is that "massive"?

 

[Dogwell]

Our pressure was quite low to start with. We are on a well and after adding the CSV it improved drastically. We set it to 60psi. Our showers have dual heads which we weren't able to use prior to the CSV but have enjoyed after the CSV. Won't a drop of 15psi be very noticeable? Sorry if I sound ignorant. This is a genuine question. We would like to be able to use two showers simultaneously and all three the times we have guests over.

 

[Dana]

Even with the larger capacity of the increased storage temperature it's going to be pretty marginal to serve up three showers at a time, just on showering time. But if you're static pressure is 60 psi, you'll have no problems with serving up three showers at a pressure drop of 15psi at the tank, 45 psi.

At standard (formerly "low flow") showerhead delivers 2.5gpm @ 80psi, and about 2 gpm @ 60psi (your setting), and about 1.3-1.4 gpm @ 40psi- it's fairly linear within those ranges, but it's still a curve. If your showerheads deliver ~2 gpm @ the full 60 psi, it'll still deliver about 1.5 gpm at 45 psi, which is clearly noticeable, but not a disaster. With only 2 showerheads running the drop at the mixer will be less than 10 psi, with still more than 50 psi out of 60, for less than a 15% drop in flow. It would be measurable, maybe even noticeable, but not a big deal.

 

[Reach4]

pressure loss

http://media.wattswater.com/pressuredrop_valvesizing.pdf talks about drops... I did not draw a conclusion.

There are other mixing valves if you wanted extra assurance, including from Cash Acme.

Sizing larger than needed is not like oversizing a well pump or a boiler; it's OK. In this case, overkill would not hurt.

If you feed the dishwasher and washing machine with pure hot, you will reduce the amount going through the mixer when those are in use.

 

[Dana]

I suspect there will be as much or more pressure drop from the distribution plumbing when running three showers than from the smaller sized mixing valve, but sure, it doesn't hurt to oversize the mixing valve (within limits- it still needs to work, after all.)

 

[Jadnashua]

Many thermostatically controlled shower valves will flow more with less drop than their pressure-balanced only sisters.