Tankless HW and an angry wife!

[kungfuthug]

Hi,

I bought a new house a in 2012. It was a spec built home and we never had any input towards the appliances and fixtures. It came with a natural gas tankless hot water system.

We immediately were disappointed. To get hot water to the upstairs shower and sinks it can take 2 minutes. We can handle that, but when we are running water in the kitchen it takes well over a minute to get hot. When we do finally get it hot, as soon as we turn the tap off intermittently or slightly adjust the temp to increase the cold we have to wait for the hot water to arrive again. This is a real pain in the ass while doing dishes, and my wife has had enough. It is either leave the water running continuosly or wait for it to heat up again. We are wasting so much water. I need a solution... fast!


I thought of a couple ideas.

1. I have a granite countertop with the single hole for the plumbing lines and thought maybe if I had a faucet with separate hot and cold taps I could at least keep the hot running and adjust the cold water. This would eliminate the issue of losing the hot water while the tap is running when I turn the lever towards the cold a bit.

2. A separate small hot water tank just for the kitchen sink.


Any recommendations?

 

[havasu]

You could always go back to a tanked water heater and install a Grundfos recirc pump. I had your same problem and now I get hot water in about 4-6 seconds from all my faucets, and I have about a 100' run to the water heater.

 

[jim603]

Hi,

I bought a new house a in 2012. It was a spec built home and we never had any input towards the appliances and fixtures. It came with a natural gas tankless hot water system.

We immediately were disappointed. To get hot water to the upstairs shower and sinks it can take 2 minutes. We can handle that, but when we are running water in the kitchen it takes well over a minute to get hot. When we do finally get it hot, as soon as we turn the tap off intermittently or slightly adjust the temp to increase the cold we have to wait for the hot water to arrive again. This is a real pain in the ass while doing dishes, and my wife has had enough. It is either leave the water running continuosly or wait for it to heat up again. We are wasting so much water. I need a solution... fast!


I thought of a couple ideas.

1. I have a granite countertop with the single hole for the plumbing lines and thought maybe if I had a faucet with separate hot and cold taps I could at least keep the hot running and adjust the cold water. This would eliminate the issue of losing the hot water while the tap is running when I turn the lever towards the cold a bit.

2. A separate small hot water tank just for the kitchen sink.


Any recommendations?

I install quite a few "on demand" water heaters and have found that anyone who does not install a Navien NPE water heater, which depending on the model you choose (A or S series), has a "buffer tank" to help with those cold water sandwiches and allows for more instant hot water. By the time you utilized the water in the buffer tank, the tankless unit is heated up and bringing you the water you desire.

When a customer chooses not to buy a Navien, I usually sell them on a State (A.O. Smith) tankless water heater and those do have about a 45-60 second lead time before they are heated up to the desired temp for a shower.

So, your options really are to switch over to a Navien with a buffer tank, switch over to a regular tank water heater or settle with what you currently have.

Best of luck!

 

[kungfuthug]

What if I took just the kitchen hot water line (after my tankless heater) and routed it into a 10 gallon electric tank or smaller if they make them. This would give me instant hot water but what would happen when I started using it? The tankless heater would start to discharge immediately into the input of the electric water tank and then mix with the hot creating only warm water?

 

[KnarlyCarl]

How does this sound?
Install a recirc pump at the tankless water heater and a relay to operate it on low voltage, maybe install a separate water line loop if you can, put two push buttons at each sink in the house. One push button turns the pump on, making the water heater do its job, it also would activate a latch relay. The other push button would deactivate the latch relay, turning off the pump when you're done with hot water, this way, you could turn it on or off at any sink in the house, as long as the deactivate push button is wired in series with the others in the house.
Where did I come up with this? I have it in my house with my Navien, which has a built in circulator, and I also installed a separate hot water line throughout the house so I have about a wait of only one second or so before I get hot water. I also put in a led (it's actually part of the deactivate push button) to indicate when the pump was running.
I had the parts available, I knew how to wire it in, so it wasn't too difficult for me.
Does this sound like something you would like to tackle with my help?

 

[kungfuthug]

Thanks for the reply.

I am a master electrician so relays and pushbuttons are commonplace in my brain...

I would like to understand this further and at this point I am very interested in your setup. Do you have a picture of your setup?

 

[KnarlyCarl]

Yes I'm excited to know you're an electrician, it makes explaining things easier.
This picture is in our master bathroom, and on hindsight, I now think the labels look out of place and a little ugly, but you do as you like. The low voltage wires in with the high voltage may not be kosher, you tell me, but we're in a ridiculousy loose code county and I don't need permits/inspection for ANYTHING, not even for the addition I put on my house.
Anyways, the top button is NO momentary on, the bottom is NC momentary off. The top is for turning pump on, and also the latch relay to keep the pump on, the bottom is to break the latch relay, wired in series to the other NC buttons in the house.
Pump is built in to my water heater like I said, but you could get a bronze or stainless pump, being as its domestic water, plumb it in with a separate loop (and if you could run this loop in your house would be best). This recirc loop of pipe would just have to be at the tankless water heater only if you can't get to the rest of the house, and put a swing check valve to prevent pulling cold water past the water heater.
My end result? I feel like royalty man, it's totally worth doing, my favorite feature of my house.
If you want a plumbing diagram of sorts just let me know, all I ask is if you do it, let us know how it works out.

 

[KULTULZ]

Would some thing like this be feasible- http://www.fasterhotwater.com/Tankless circulation pump.shtml

I was ciphering on point-of-use tank water heaters and they may present problems such as TPRV discharge and anode rods.

 

[KnarlyCarl]

That pump is a quick fix and I looked into it but misses a few very important things I wanted.
Running water continuously through the tankless will not void the warranty at least on my heater because that's the design of the built in circulator, it's meant to do that.
That pump will push hot water to your faucet like a recirc loop but uses the cold water line as the recirc loop, and if you need cold water, it wont be cold, so you have to wait for cold water instead, maybe not a big deal, just an inconvenience. It also requires you to turn a faucet on then off to activate the pump, a simple method for sure, not a real downside, I just went to a little extra work to not have to do that. I have friends over, I can just hit my button and they don't have to cycle the faucet. I also know when my pump is running, although it wouldn't be too hard to put an indicator of sorts for this pump.
Nice little setup for anyone looking for a quick way to add recirc capabilities to their tankless

 

[frodo]

I prefer a simple on/off switch wired to the sink area from the pump at the water heater

on a seperate circ line. turn your pump on when in the kitchen, off when not in the kitchen.

or, wire the pump to the light switch.



simply, run a #12-2 w/ ground and a pex from the kitchen to the water heater

 

[KnarlyCarl]

There you go, I just wanted a method at all four of my sinks and maybe went a little overachiever mode on it

 

[KULTULZ]

That pump is a quick fix and I looked into it but misses a few very important things I wanted.

Running water continuously through the tankless will not void the warranty at least on my heater because that's the design of the built in circulator, it's meant to do that.

That pump will push hot water to your faucet like a recirc loop but uses the cold water line as the recirc loop, and if you need cold water, it wont be cold, so you have to wait for cold water instead, maybe not a big deal, just an inconvenience. It also requires you to turn a faucet on then off to activate the pump, a simple method for sure, not a real downside, I just went to a little extra work to not have to do that.

How about a valve design such as this- http://www.redytemp.com/hotwatercirculatorproblems.htm

I personally like the idea of just hitting the tap and all the magic starts there...