I've had several plumbers check my lowboy heater and say it checks out okay, but it runs out of hot water in 20 (actual 18) minutes. It's a 50 gallon water heater. I've been told that 20 minutes is the minimum time and it is very low.

I would like to be able to take a shower and then soak in the tub. I don't let the shower run while taking a shower. I suds up, then turn on the shower to rinse off. If I try to fill the tub after, it only fills 1/3 of the tub.

One plumber said it needs an adjustment valve to slow down the water coming in. The flow is too strong, thus cooling down the water too quickly. He said it could be the condo's main valve needs to be adjusted by a mechanic. He suggested I bring it up to the association since other owners have complained about it as well.

Does this sound like a problem with the plumbing?

Ok, you have a problem on your hands. I would need bit more info to be exact in my calucations, but: let's do the math together to see where the problem is:

Shower:
You have 50 gln hot water heater...
You have a shower head that uses 4 gallons of water per minute...
You mix hot and cold water in ratio of 3:1...
So...
You are using about 3 gln of hot water per minute...
Result: you will get about 17 minutes of hot water out of your heater.

Now, you don't get evenly hot water all 17 minutes. As your heater depletes hot water, it is refiling with cold water. After few minutes of use, your hot water inside your heater will not be as hot as what you started with. You will be adjusting hot water knob cutting into your precious showering time even more. This is especially true in winter and / or cold climates.

Tub:
If your tub holds 80 gallons of water, as most of them do, you will barely fill it up with hot water out of your 50 gln heater. But most likely you will fill it up with hot water only half way. By the time it fills up, water will be already warm - and not as hot as you wanted. If you have cast iron tub water will cool down even faster. In other words, your heater doesn't hold enough hot water for required demand. That's why jacuzzi tubs have built-in heaters so temperature drop is kept to minimum.

You have 3 ways of solving your hot water problem:

1. The most economical approach to your problem is to install low flow shower head. Most low flow heads have flow of 2.2 gln per minute these days. You will double your shower time. Disadvantage: noticeably low volume. You will have to get used to it...
2. Install tankless hot water heater. It will give you endless hot water. Disadvantage: high start up cost
3. Install 50 gallon hot water storage tank with hot water circulating pump. You will double up your shower time as well. Disadvantage: High start up cost ( But, since you are in condo, this option is probably not possible ).

You may also install thermal blanket around your heater. It will raise the R-Value of your water heater insulation by about 3 Thermal Points. You will probably not notice this at your shower head, but your heater will be better insulated holding heated water at more stable temperature.

Wow, your time was so accurate! The plumber timed it at 18 minutes!

Will the hot water tank with circulating pump fit into a limited closet space? If you can imagine, I have a lowboy, with the A/C unit above. What would the start up cost be?

Also, one plumber said the adjustment could be to the condo water pressure. Is this an option?

Also, I considered an electric tankless. Have seen some disadvantages such as if the power goes out, totally cold, noisy, power surges, etc. Thank you for your response so far, I am impressed!

CarlieT:

1. You are in condo, the extra hot water storage tank and hot water circulating pump is probably out of question. Since you have "low-boy" unit now, it tells me, that you have very limited space since low-boys are made for tight spaces. In addition, this option requires some wall cutting to install hot water loop. This option works well in houses.

2. If you want to invest few bucks, and have endless supply of hot water, than tankless would be best way to go. They are clean, very small (about 18"H x 14"W x 8"deep) and give unsurpassed service. There are several models on market: Bosh, Takagi, Noritz, Rheem, BradfordWhite and Rinnai, just to name few. Overall, the Rinnai is the best, at least in my opinion. We have never had any negative feedback with Rinnai's and our customers just love them. The heater itself costs about $1,100.00. You will need your plumber to do some pipe modification inside your w/h closet to connect the heater, but nothing major. All would be only superficial work.

Tankless heater would be the best solution to your hot water problem. Also, it doesn't reheat full tank of water 24/7 as conventional water heaters do, wasting energy , and your money, in the process. It is a good investment.

Here is link on Rinnai: www.foreverhotwater.com. Rinnai even lists approved installers in your area.

3. The water pressure to your building has nothing to do with your inadequate hot water production in your condominium.

For the record, Milo's clocking my water heater at 17 minutes was even more accurate than the plumber's -- I clocked it as well and thought it was 17 minutes. I am simply amazed.

Glad to be of help ! Let us know how you did ! Milo

Nice job Milo:

FWIW: Automatic mixing valves for the shower definatele help with time, but it would not give nearly the performace your asking for. Primarily the auto mixing valve and a low flow shower head are ways to REDUCE water consumption, not make it larger.

Tankless has disadvantages as well. One is that you may not get hot water at low flow fixtures. So if your used to turning on the faucet to a small trickle and expecting the water to be warm, it probably won't be.

The combination of a tank and tankless or even point of use tankless designed for the application (hand washing) can offset that. But with space considerations. It's not going to be viable in your case.

Oh, interesting.

Milo,

In reference to your post #2 you have done a great job and good calculation, every one is amassed with your knowledge, keep up the good job, Thanks.

John

Correction, to my post #9 every one is amazed, Thanks

The tank will heat water then stop. At times the water is very hot and other times it does not make hot wter at all. I checked the circuit breaker and it was not tripped. What can I do next.

Hello Samn,

You responded to a 4 1/2 years old thread always check the date on the left upper corner of the post 1, this thread may be dead by now please staret a new one for yourself this way it will visible to all the experts and will respond you quickly, Thanks.

John