Approx cost of a Gas tankless WH

[Tom3holer]

Hi,
I have a 40 Gal Superstor water tank with a mixing valve heated by my Burnham AL80 gas boiler.
The problem is we often run out of hot water after a couple of showers or a laundry and shower.
The other issue is in the very cold days it has priority so the heat goes off while its running and it takes a long time to get tho house back up to temp.
I have been thinking of having a tankless gas heater installed. What is the approx cost of such an installation?
Thanks for any advice,
Tom

 

[Terry]

Approximate?
$3000 to $4000 maybe. Maybe less, but they would need to be pretty quick or have most of what they need there.
Since they are tankless, sometimes the gas line needs to be bigger. The venting for the exhaust needs to be considered. Most of them are PVC and run outside and you have condensation that needs draining. They are good at running two showers at once 24/7.

 

[Sponsor]

 

[Tom3holer]

Thank you Terry,
That is kinda what I expected.
I do have a generator so had to have a larger capacity meter installed .

 

[Dana]

Naviens with the internal compensation for smaller diameter gas plumbing can be cheaper to install than most of the others. In my area a Navien would usually be well under the typical ~$3K +/- for a condensing 199,000 BTU/hr tankless from other vendors. Right now a lot of plumbers and HVAC folks quailfied to install one are up to their eyeballs in work keeping peoples' heating systems going at sub zero temps, but as outdoor temperatures moderate and before the main construction season gets rolling it'll probably be cheaper than trying to get one installed next week.

Pricing for this type of work on the Cape & Islands is on the gold-plated side, and it always seems to be feast or famine for the local contractors. Don't be surprised if somebody gives you a quote for $5K (especially this week). Just know that you probably don't have to pay that much even on Cape Cod.

 

[Tom3holer]

Good advice and I am not in a rush as have been living with this issue foe several years.

 

[Jadnashua]

What temp do you have your indirect WH set to? I also have to ask what temp does your boiler get to when reheating the indirect? Setting the indirect to be hotter (and with a tempering valve), and having the boiler run at max when reheating the indirect should give you a fair amount of hot water for a shower. FWIW, I've never noticed my place cooling off in between as the result of heating the indirect, and my boiler is smaller. I have a 6' air tub that gets filled almost daily with probably close to 50g, and have not run out of hot water yet. My back loves it! I've been doing laundry at the same time, and again, not run out of hot water. My incoming cold supply is running very close to freezing right now with the cold snap we've been having, and still, no issues with the house or the amount of hot water available.

 

[Tom3holer]

Jim,
The WH is set to 135 with a temping valve and the boiler was set to 180. The boiler will run, in the cold temps we have had lately, just about 25 min when it gets a call for hw. In the warmer temp with no heat needed just the hw we run out after or during the second shower, all with lo flo heads.

 

[Jadnashua]

Set your tank storage temperature higher...you can go up to 160, or even 180. Once you then mix that down to a safe temperature via the tempering valve, you'll have the equivalent of a much larger tank. On some, to change that is easy, on others, it may take a bit more work. I am not up on many, but it should be able to be raised. It is important to have a properly working tempering valve, as you don't want that super hot water circulating in the home, but after being tempered, it will be fine. You'll have a little more standby losses, but in the winter, that's not a big deal, and in the summer, with the incoming water warmer, you may not need it that hot since it won't dilute the hot water as much, and you can use more 'cold' at the shower control valve to achieve the same output temperature. The standby losses will go probably a decade or more before you'd even come close to the cost of installing something else. If that indirect ever dies, consider a larger one.

Make sure that the indirect is set as a priority zone and that the circulator is working properly. It should be able to recover before you notice the house cooling off if all's well there unless the shower is running for hours on end...then, this won't work.

 

[Tom3holer]

Jim,
Thank you I will turn up the temp to maybe 150 and see if that helps.
The hw does have priority and the cir pump is a 5 year old Taco.
My boiler is set to 180 so bringing the water tank up to 180 seems like it might take a long time.

 

[Dana]

Give yourself a 15-20F delta-T between the tank temp setting and the max temp of the boiler or it'll short cycle the burner like crazy finishing the call for heat from the indirect. So if you're at 180F all-out on the boiler, set the indirect to 160F or 165F, and observe it's behavior to verify that it's not short-cycling.

 

[Tom3holer]

Thanks Dana,
That makes sense.

 

[Tom3holer]

I did get a quote for installing a Riannai RCU 98I for $3500 minus the $700 rebate for a total of $2800.
The plumber that came over was very helpful and thought I had a good system with the 45gal Superstor. He said why no up the temp on the WH and see if that helps. The boiler is set to 185 for the HW and set the tank at 155.
So at this point I think I stay with the setup I have and see how it goes.
Again thanks to everyone for the help.
Tom