What water heater setup for jetted shower?

[Kodidavis29]

Hi guys new here but am torn about a decision to upgrade to a tankless water heater 11gpm Westinghouse model sold at the box stores and online. Or just add another 40galon water heater in series to my exsisting 40galon.

My setup is a custom jetted shower just built with 4 jets 2.5gpm each a rainfall shower head at 2.5gpm a standard shower head at 2.0gpm and a handheld shower at 2.5gpm.

They all have separate valves so they typically won’t all be running but in the event they all do id be pulling 17gpm.

Running it now with just my 40 gallon I get about 6-8 min shower.

Every where I look online they talk about the water heater having enough gpm to power your setup but they seem to forget that the thermostatic valve in the shower pulls cold water into it as well I would assume you need to know the ratio to figure out exactly what the gpm of hot water you need actually is.

My biggest question is will 11gpm work if I go tankless also I’m in Michigan so my rise is high about 40degrees incoming so specs on this claim to only be 5gpm at that high of a rise. My thought was to keep the old tank and use it as a point for the water to atleast get to room temp prior to going through the tankless. (But what’s the point of tankless then)

Energy usage isn’t a huge concern but always something that can help change a decision.

So what do you guys think add another tank or go tankless all together?

 

[FullySprinklered]

Another tank. Think latitude, cost, maintenance, etc.

 

[Sponsor]

 

[Reach4]

also I’m in Michigan so my rise is high about 40degrees

I suspect that 120-50=70 could be closer to your needed rise.

 

[Terry]

With a water heater you can use the high setting and then a tempering valve to bring that down to 120.
A tankless putting out 5 gallons at 120 won't do much for you. You would need two of them, and an upgrade to the gas piping and the gas meter.

 

[Jadnashua]

A hot water recovery system might be very worthwhile for you. It essentially takes heat from the drain water and preheats the water going into the WH, meaning that the rise isn't as great. While some situations make a tankless a good choice...IMHO, not in Michigan where it gets quite cold a good portion of the year and if you're on a deep well, maybe all year! There is a huge difference in performance on tankless between temperate water coming in verses the frigid stuff people up north get, or those with a deep well.

 

[Kodidavis29]

Thanks guys I think I’m going to go double tank!

I know it will be a easier setup and just not be a unlimited supply how long do you think a shower will last adding another 40gal tank?

 

[Reach4]

how long do you think a shower will last adding another 40gal tank?

At least twice as long as now. You will be adding recovery heat from 2 WHs. Depending on things, it is possible it could keep up.

 

[Dana]

For energy-pig showers like that a drainwater heat recovery heat exchanger pays for itself pretty quickly by shrinking the size of the water heater needed to sustain the load, and by dramatically cutting the amount of energy used (by not letting it literally run down the drain.)

The tallest and fattest that fits is the "right" one, since the increased performance more than offsets the increased cost. A 4" x 72" unit would more than double the showering time of the existing 40 gallon water heater.

Even when the tank is depleted, (output temp < 100F) the recovery time is faster, since the water that entered the bottom of the tank from the output of the heat exchanger is typically north of 70F even when the incoming water from the street is 35F.

To get the most out of it, the output of the heat exchanger feeds both the cold side of the shower (or the cold distribution to the bathroom, or even the whole house is fine), not just the cold feed to the water heater.

 

[hj]

I was observing in a courtroom one day when the defendant was a woman who had a pistol in her purse. It was a .25 automatic. He asked her WHY she had it and she said for protection. He told her that the only thing that gun would do is make the assailant angry. Your 40 gallon tank is like that gun, completely useless for MOST applications, other than a studio apartment with a single occupant. I think people put too MUCH faith in a drain line recovery system.

 

[Dana]

I was observing in a courtroom one day when the defendant was a woman who had a pistol in her purse. It was a .25 automatic. He asked her WHY she had it and she said for protection. He told her that the only thing that gun would do is make the assailant angry. Your 40 gallon tank is like that gun, completely useless for MOST applications, other than a studio apartment with a single occupant. I think people put too MUCH faith in a drain line recovery system.

Who asked her- the assailant? Or the prosecutor, or judge, mayhaps?

I'd be taking cold showers sometimes without the 4" x 48" drainwater heat recovery unit, but with it the system is capable of delivering a 4 gpm gusher all day & night throughout the winter with the boiler never modulating up to more than ~60,000 BTU/hr.

A 2 gpm shower at a temperature rise from 35F to 105F is 70,000 BTU/hr. If it's a faith-based solution, it's still working!

 

[Dana]

Any chance this house is heated with a hydronic boiler?

If yes, even a 40 gallon indirect water heater operated as a priority zone off the boiler can deliver twice the amount of hot water (or more, depending on the boiler size and the heat exchanger inside the indirect) of a typical 40 gallon standalone.

Regarding the tankless option:

17gpm at a 70F rise (35F in, 105F at the shower head) is almost 6oo,ooo BTU/hr. Most tankless units top out at 199,000 BTU/hr- you'd need three of them for this to work during your peak flow requirements, but a condensing 199K tankless would cover 5.5 gpm at that rise.

A 60-80 gallon condensing tank with a 76K burner would probably work just fine, unless you're looking for the "endless shower" experience.

 

[Kodidavis29]

This house is unfortunately heated with forced air. I haven't bought the second tank yet I was a little distraught with the guy at the home center.

he kept pushing me on tank-less and I explained to him all the research I have been doing and he just kept telling me I was wrong that Tank-less are designed to run everything in the home and that if I want to use all my jets just don't run laundry or dishes.

I am worried I am wasting my money buying another tank and that even with two tanks I will only tops get a 15 minute shower.

what about tank-less and my old tank. so my old tank would be pulling from the tank-less unit. would this be something that would work with my setup.

I am assuming most people who do these setups just go boiler should I look into that?

Thank you guys for all the help!

 

[Kodidavis29]

Any chance this house is heated with a hydronic boiler?

If yes, even a 40 gallon indirect water heater operated as a priority zone off the boiler can deliver twice the amount of hot water (or more, depending on the boiler size and the heat exchanger inside the indirect) of a typical 40 gallon standalone.

Regarding the tankless option:

17gpm at a 70F rise (35F in, 105F at the shower head) is almost 6oo,ooo BTU/hr. Most tankless units top out at 199,000 BTU/hr- you'd need three of them for this to work during your peak flow requirements, but a condensing 199K tankless would cover 5.5 gpm at that rise.

A 60-80 gallon condensing tank with a 76K burner would probably work just fine, unless you're looking for the "endless shower" experience.

Would you thing this would be the best option just ditch everything and go for one of these?

 

[Kodidavis29]

Thoughts About this??

https://www.homedepot.com/p/Westing...rable-Stainless-Steel-WGRGH20NG100F/302480437

 

[Kodidavis29]

Alright guys I have a decision to make now. also need help.

I have found 2 models and have been dealing with a plumbing supply house to see what is available.


let me know what you think.

Option 1 - 40 Gallon in series with my original 40 gallon. $500 Cost

https://www.hotwater.com/water-heat...igh-efficiency-gas-tank-water-heater-gahh-40/

Option 2 - switch to a 75 gallon powervent $2800 Cost

https://www.hotwater.com/water-heat...sl-power-vent-gas-tank-water-heater-gpvx-75l/

Option 3 - Switch to a high output hot water heater $2800 + Cost
https://www.homedepot.com/p/Westing...le-Stainless-Steel-Tank-WGR060NG076/205625747

https://www.homedepot.com/p/Westing...le-Stainless-Steel-Tank-WGR080NG076/205625761


I need to know best bang for buck because I am stuck lol.

 

[Dana]

The stainless 60 gallon condensing Westinghouse puts out more hot water than the power vented 75 gallon unit with the same 76K burner size, (due to 95% combustion efficiency compared to 80%).

The $375 cost-adder for the 80 gallon version may be "worth it", but probably not.

A stainless tank is going to outlast the glass lined AO Smith by 3x, and probably WAY beyond the warranty period in a residential application.

The Westinghouse water heaters are re-badged HTP Phoenix Light Duty water heaters ("light duty" only in comparison to bigger-burner commercial water heaters). Depending on the amount of local support you may be able to get a better installed price quote for the HTP branded units (or not).

 

[Dana]

Would you thing this would be the best option just ditch everything and go for one of these?

If "one of these", refers to an indirect fired water heater running off the boiler, it's a definite "maybe". The size of the boiler and the size of the indirect matter on making that decision. Most boilers are ridiculously oversized for the space heating load, with more burner than a typical standalone tank. The additional load of an indirect usually yields a much higher as-used AFUE. Whether the boiler is right sized or oversized, sizing the indirect for the domestic hot water load is usually the right approach. A 200KBTU boiler with a 40 gallon indirect can serve up a LOT more hot water than any 40 gallon standalone, but you'd still want a 60-80 gallon indirect, in anticipation of the day when a right-sized boiler was installed.

 

[Kodidavis29]

If "one of these", refers to an indirect fired water heater running off the boiler, it's a definite "maybe". The size of the boiler and the size of the indirect matter on making that decision. Most boilers are ridiculously oversized for the space heating load, with more burner than a typical standalone tank. The additional load of an indirect usually yields a much higher as-used AFUE. Whether the boiler is right sized or oversized, sizing the indirect for the domestic hot water load is usually the right approach. A 200KBTU boiler with a 40 gallon indirect can serve up a LOT more hot water than any 40 gallon standalone, but you'd still want a 60-80 gallon indirect, in anticipation of the day when a right-sized boiler was installed.

I don’t have a boiler I must of missread what he was saying.

 

[Kodidavis29]

I think I’m going to stick with my regular thought and go two 40s wife and I talked and this will limit us from abusing our resources and keep us in a limitation state. However in the future if we decide we need more it’s only a small out we will be. Now the fun part hooking it up.

Plumbing them together gas water all easy but big debate now is the expansion tank necissary I have seen 100s of water heaters and never seen them on them until recently. Home center guys says it’s code and I have to do it but don’t really trust him. Also if I do what size and should I do two or one?

 

[Reach4]

Also if I do what size and should I do two or one?

I presume city water. Sized the thermal expansion tank as if you had an 80 gallon WH.
http://www.amtrol.com/wp-content/uploads/2017/11/MC10230-09_17-TXT-Handout-Brochure.pdf would point to using the Well-X-Trol ST8 or bigger. There are calculators and charts for other brands too.