Running out of hot water dilemma

[Juni]

Greetings:
I will try to be short & succinct ;-0
Our 22 year old AO Smith 50 gallon gas hot water heater failed 2 days ago.
We have a whirlpool tub in the house that has not seen much use since aforementioned tank could not adequately fill it.
Since we are needing a new tank we want to it to finally accommodate the tub, which uses approx. 53 gallons.
I found several makers (Smith, Rheem & Bradford-White) who make a 55 gallon tank.
My plumber's supply house has none of these. He's not sure why. An odd duck?
I did locate a Bradford-White (RG255H6N) in NJ--about 1 1/2 hrs. away. Apparently the plumbing supply in that state sells to the public.
Space is a problem--so anything bigger than this won't work.
It appears that all of these companies have lots of negative reviews....so who?
Also, if I buy it myself, rather than the plumber would that present any issues?
Accepting all opinions, ideas, and thoughts!
Signed-Just a gal weary of those cold showers!!!!!!!!!!!!!

 

[Plumber69]

Greetings:
I will try to be short & succinct ;-0
Our 22 year old AO Smith 50 gallon gas hot water heater failed 2 days ago.
We have a whirlpool tub in the house that has not seen much use since aforementioned tank could not adequately fill it.
Since we are needing a new tank we want to it to finally accommodate the tub, which uses approx. 53 gallons.
I found several makers (Smith, Rheem & Bradford-White) who make a 55 gallon tank.
My plumber's supply house has none of these. He's not sure why. An odd duck?
I did locate a Bradford-White (RG255H6N) in NJ--about 1 1/2 hrs. away. Apparently the plumbing supply in that state sells to the public.
Space is a problem--so anything bigger than this won't work.
It appears that all of these companies have lots of negative reviews....so who?
Also, if I buy it myself, rather than the plumber would that present any issues?
Accepting all opinions, ideas, and thoughts!
Signed-Just a gal weary of those cold showers!!!!!!!!!!!!!

When you fill a tub, I believe you're mixing 80% hot to 20% cold. If the 50 didnt quite make it, turn the tank up hotter. Maybe then you would get a 70/30 mixture

 

[Sponsor]

 

[Terry]

An easy fix is to add a tempering valve on the water heater and turn up the heat on it. You can blend it down to 120 degrees even if you're running the tank at 175.

 

[JerryR]

I did what a Terry recommended above to solve the same issue. My big whirlpool tub would run out of hot water before it was filled even with a 50 gallon tank.

I have since been using a. Simple to install Honeywell mixing valve, turned up the water heater to 145 degrees and adjusted the valve to supply 120 degree hot water. No more problem. Tub fills and doesn’t run out of hot water. It’s like I put in an 80 gallon tank.

here’s a brochure. https://www.alpinehomeair.com/related/amx300tlf.pdf

 

[MACPLUMB]

if you are buying new be aware that all new heaters have more insulation so they are taller and wider,
to get more hot water get a high recovery heater

 

[Tuttles Revenge]

We often do as Terry suggested above. Installing a tempering valve allows you to turn the heat up inside the tank thus storing more BTU's/Energy in roughly the same volume. The tempering valve also protects against scalding when its outgoing temperature is set to a safe level of 110-120 depending on what your locality considers safe. My rough understanding is that you are creating about 20% more energy with this method.. Would love to hear from one of the math nerds to either verify, debunk or update that amount.

As Masterplumb mentions too.. read and understand the physical measurements of the tank itself. Sometimes you end up with a taller tank which requires the water supply pipes to be raised up.. Vent height may need to move as well.

 

[Sylvan]

I have been buying Rapid recovery hot water tanks with great success

http://aerco.com/sites/default/files/document/document/AMR Series TDS.pdf

 

[ImOld]

It boggles my ancient mind! Is it people have an aversion to big box stores? You can check every detail of anything on-line or visit a store as I do most of the time. 55 gal gas water heaters, tempering valves, whatever. You can touch it, measure it, take pictures with your iPhone!

 

[Dana]

If this house is heated with a hydronic (pumped hot water) boiler the better solution might be an indirect fired water heater operated as a priority zone off the heating system. With the (likely) bigger burner of a boiler behind it the recovery times are far quicker.

The all stainless 60 gallon HTP PH76-60 "Light Duty" (light, for a commercial water heater) would usually fit where a 50 gallon standalone had been, as would the 50 gallon PH76-50, with a burner about 2x the output of a typical standalone. (Westinghouse branded versions of these are available at box stores.) They're more money, but more than twice the water heater, of a typical 50-55 gallon atmospheric drafted glass lined water heater, and should pretty much last forever in a residential application.

 

[Juni]

My thanks to all of you for taking the time to offer your sage advice & ideas. A great group here--and I will pay it forward
Note to: ImOld I did all you said. No one in CT has a 55 gallon available. A O Smith actually posted a news article in 2016 stating their "new" 55 gallon model could help out folks with whirlpool dilemmas like mine ;( That began my quest.
Bradford White sales rep told me it's an odd duck size and I could order one for November.

 

[Reach4]

An easy fix is to add a tempering valve on the water heater and turn up the heat on it. You can blend it down to 120 degrees even if you're running the tank at 175.

I made a spreadsheet. You enter the WH temp you are set to, the number of gallons of the WH, the temperature of your cold water coming in, and the desired temperature out of your mixer. Spreadsheet is mixwater.xls inside of the attached Zip file. Here is a sample output...

This says with a 40 gallon WH set to 140, and if your incoming cold is 50 degrees, and with a mixing valve set to deliver 115 degrees, that is about the equivalent of a 55.4 gallon tank set to 115.
If your incoming cold is 50 degrees you have a 50 gallon WH set to 150F, and with a mixing valve set to deliver 110 degrees, that is about the equivalent of an 83.3 gallon tank set to 110.

Use the spreadsheet to put your own number in. If you have warmer incoming water, you get more equivalent gallons.

 

[Dana]

I have been buying Rapid recovery hot water tanks with great success

http://aerco.com/sites/default/files/document/document/AMR Series TDS.pdf

Those water heaters are great and all, but even the smallest burner version would require upgrading the gas plumbing, and may require upsizing the gas meter on many or most single family homes with the typical 3x oversized furnace or boiler.

A 75-100K burner is more likely to cut it as a drop-in replacement with the existing gas plumbing & meter, something like a Vertex (or Vertex 100) or HTP Light Duty.

Without more specs on the spa tub volume it's hard to say with certainty that any of these potential solutions will really cut it. A 10% increase in tank volume going from 50 to 55 isn't likely to make an appreciable difference, but doubling or tripling the burner output might. A 75K condensing burner has about twice the output of a typical 50 gallon atmospheric drafted water heater.

But a 140-150K cast iron boiler or a 120K condensing boiler would have ~3x-4 the output of a typical 50-55 gallon heater, making 3-4 gallons of 110F water per minute once it kicks on. That adds a measurable "apparent capacity" when fill times are longer than 5 minutes, enough to make a real difference for a 10 minute tub fill.

The output of the RG255H6N with the 78K burner is about 62,000 BTU/hr about a 2x improvement from an old 50 gallon. The output of the HTP PH76-50 (or the AO Smith GPHE-50 Vertex) with a 76K condensing burner is about 72K, about 20% more than the RG255H6N. The 50 gallon AO Smith BTX-100 has an output of about 95K.

 

[Juni]

I haven't put any of the above options on the back burner yet, but the plumber stopped by this afternoon and threw another wrench into the decision making. Next to our hot water heater is our Utica boiler, that is approx. 35 years old. He said, in light of it's age, another option could be this: a U.S. Boiler ASPEN High Efficiency,Gas Condensing Boiler Combi. Anyone have experience with this model. Pros/Cons?

 

[Juni]

I haven't put any of the above options on the back burner yet, but the plumber stopped by this afternoon and threw another wrench into the decision making. Next to our hot water heater is our Utica boiler, that is approx. 35 years old. He said, in light of it's age, another option could be this: a U.S. Boiler ASPEN High Efficiency,Gas Condensing Boiler Combi. Anyone have experience with this model. Pros/Cons?
P.S.
Any input on aforementioned system appreciated. Also, Dana mentioned the indirect water heater--but I don't think my furnace is hydronic. Since I may be in the market @ this point for a new one--would that be a better option/combo?

 

[Dana]

I haven't put any of the above options on the back burner yet, but the plumber stopped by this afternoon and threw another wrench into the decision making. Next to our hot water heater is our Utica boiler, that is approx. 35 years old. He said, in light of it's age, another option could be this: a U.S. Boiler ASPEN High Efficiency,Gas Condensing Boiler Combi. Anyone have experience with this model. Pros/Cons?

The only combi-version of the Aspen is the ASPNC-155, with only 155K of burner, which while it would never run out of hot water, the flow rate would be glacially slow for filling a large spa tub. At a temperature rise of 70F (40F in, 110F at the tub) the ~147,000 BTU/hr of output is only good for (147,000 /70F=) 2100 lbs/hr which is (/8.34lbs/gallon=) 252 gallons/hr or (/60=) 4.2 gpm. Filling a 70-80 gallon spa would take 17-19 minutes. (Life is too short for that!)

Low mass combi boilers are only a good fit for homes with low to moderate hot water needs, and high heating loads with the radiation to match. Unless your house is an un-insulated 5000' mansion, it wouldn't be a good fit even without the massive hot water load of filling a spa tub.

The non-combi versions of the Aspen are pretty-good stainless fire-tube boilers, and if right sized for the space heating load and zone radiation could be a good fit, with an indirect water heater tank for the domestic hot water. 95 out of 1000 homes in New England would be just fine with the smallest in series ASPN-085. It's max output at non-condensing temps is about 74,000 BTU/hr. It's likely that your Utica is substantially larger than that, but most cast iron boilers out there are 3x oversized for the actual load (as if we're anticipating another ice age with -100F cold snaps or something.)

To figure out what makes sense for replacement boilers / combi boilers, first run this math to estimate the design heat load, then run the math on the radiation to see if it can run at condensing temperatures without short-cycling itself into low efficiency/high maintenance. Cutting to the chase, the minimum firing rate of the -085 has an output of about 8000 BTU/hr. If your radiation is fin-tube baseboard, the smallest zone that it could run at temps low enough for 95% efficiency would be about 8000/200 = 40 feet of baseboard. Zone radiation smaller than that will result in on/off cycling putting wear & tear on the boiler, and if it's 20' or less it will short-cycle, taking a serious toll on efficiency & longevity.

 

[Juni]

Dana~ Thanks for your reply! I actually posted another question on the forum as our boiler ( a Utica M125AGB Input 125,000--which has served us WELL) started weeping from all it's orifices while turned off. Time is of the essence--family getting crabby with cold showers. Thus have decided to replace the boiler too at this point. My friend has a Turbo max, which I believe is a form of indirect (?) that she likes? Since I'm a female layperson a lot of this is way over my head. But, I'm just not viscerally feeling the Aspen Combi and would prefer "simple" with longer warranty ;-) With the indirect do you need a HE boiler, or can we go with a regular gas boiler (please excuse my simplistic mode-lol). Also, can you give me a ballpark on the indirect set up? The Aspen will be 8K!!!
PS-House is a 7 room 1400 sq ft well insulated Cape with 2.5 baths and radiator/hot water.

 

[Dana]

A TurboMax is a buffer tank for the heating system that has internal coils to heat domestic hot water as it passes through the coil. Some in the HVAC trades refer to it as a "reverse indirect", since most indirects have potable water in the tank, and send heating system water through the internal coils.

That may or may not be appropriate for your system. For the smaller versions to work well requires higher water temperatures than would be suitable for efficient use of a condensing boiler. I have a similar 48 gallon Ergomax (same type, different brand) that does just fine with 130F heating system water (cool enough for some condensing efficiency, but it's being helped out by a drainwater heat exchanger. It's a bit marginal for filling tubs in winter if kept at condensing temps.

Any boiler can run a standard indirect, which are cheaper than a TurboMax or Ergomax. But it's not necessarily cheaper to install another cast iron boiler than a high efficiency boiler these days.

The Utica M125AGB is RIDICULOUSLY over sized for a 1400' cape in CT, assuming there's glass in the windows and some fluff in the walls and attic. For reference, I live in a sub-code 2x4 framed 2400' bungalow with clear glass storms over circa 1923 single panes, with another 1600' of insulated but not directly heated basement. At 0F outdoors, 70F indoors my heat load is about 40,000 BTU/hr. Even if your house were substantially leakier than mine ( it could be) and you have 1000' of UN-insulated basement it's unlikely that your design heat load is higher than mine.

The description "...well insulated Cape..." means the load is more likely to be in the 20-25,000 BTU/hr range. That would make the Utica 4x oversized for your load. There are very few cast iron boilers that wouldn't be more than 2x oversized for the load. Which is why modulating condensing boilers that can throttle back to well under your design load numbers are a better choice for comfort. But if you have sufficient radiation you might do just as well using a condensing water heater as a combi-heater. If you're willing to share your ZIP code and exact meter reading dates & amounts from last winter I can run the fuel-use based load numbers for you. If you're going for another cast iron boiler + indirect it'll almost always need to be the smallest in the series, and even then it will be oversized.

Measure up the radiators (take some pics too) and we can figure out about what water temp it takes. If it can still heat the place with 140F water an HTP Light Duty Phoenix sized for your tub fills might be the right approach. The PH76-80 is the 80 gallon version which is big enough to fill most residential spa tubs, and may have a floor footprint about the same size as (or smaller than) the Utica. You might be able to get a recommendation from HTP home office (only a few hours drive from any location in CT) for a contractor who is competent to design and set up combi systems with that series. It's designed to be easily adapted for hydronic heat, but many heating & plumbing contractors wouldn't know where to begin.

 

[Juni]

Wow Dana~such a wealth of info! Sorry to say I don't have the gas bills from last year. My radiators are as follows (all tubular):
Upstairs BR 19" x 4.5"
Upstairs BR 19" x 6.5"
Master BR 22" x 5.5" & 25" x 4.5"
LR 22" x 5.5"
DR 22" x 5.5"
Sunroom 22" x 5.5" CORRECTION
Kitchen has an electric toe kick heater under the sink
Both bathrooms have electric wall heaters, although plan for main one is to add a radiant heat floor.
Unable to load any pics.
After digesting your info we are gravitating towards the regular cast iron boiler since I assume, correct me if I'm wrong, we can reuse the same chimney vent and the warranties are better?? From what I have read the condensing ones utilize a different vent? Also, the indirect looks like we can position it in a better spot as opposed to where the current water heater is crammed. As an aside, if power is ever lost, we could still utilize whatever hot water is in the tank as opposed to the combi which would have nothing to offer in that event, is that correct?

 

[Jadnashua]

Regarding the costs of storing hotter water in your tank would be the same if it wasn't for storage losses...the insulation on today's tanks is better than those of old, but the bigger the temperature difference of the surrounding area and the water stored in the tank, the more heat will escape into the room. In the winter, that might be a benefit, but in the summer where you're cooling, it's not (unless you're using a heat pump WH). Indirect tanks tend to have quite good insulation. Electric ones do, but usually not quite as good. Gas fired ones have the flue going up the middle, and are the least efficient (but may be the cheapest to operate depending on your local utility rates).

 

[Juni]

Addendum to house info for the calculation:
Must be brain freeze from no hot water ;(
Left out the sun room!
Cape has & 7 rooms!