Considering tankless hot water

[dheinz]

We're getting information and bids for a tankless hot water system. A local plumber gave us an estimate of $3500 for replacing the existing 40 gallon natural gas tank with a Rheem "professional" model.
The install includes 30 ft of PVC pipe vent to the outside wall. The unit will be installed using the current location and plumbing.

What does the Pelican brain trust say?
All comments and suggestions appreciated...

[masraum]

There are several threads here about tankless water heaters. You may find some of what you're looking for in a search.

[look 171]

Not sure what you are asking. Current location?

I'd buy a Takagi, that's just me

[BK911]

I doubt it will use the same gas line.

[dheinz]

A Pelican thread search reveals a dialogue from 2018. I was hoping to get some more recent information. I'm curious to see if the bid is fair... I feel it is high. I will do my homework and get 2 more estimates.


The "current location " is where the hot water tank presently sits.

The plumber is satisfied with the existing gas line size.

[biosurfer1]

Originally Posted by dheinz

The plumber is satisfied with the existing gas line size.

I would be very skeptical of this.

Conventional gas water heaters need 1/2" gas service, while tankless usually needs 1", or larger if it's not a dedicated line.

Regarding the price, if that includes purchase and install, it's not really out of line.

[908/930]

^^^^ Yes something sounds strange, unless there is larger 1" supply pipe nearby?

So is there a reason you want to change to tankless?

[vash]

I had a Rinnai at my old house for damn near 10 years. it was fantastic and never ever failed us.

when I moved it was the thing I missed the most. so new house, we called a plumber. he quickly suggested a new Noritz. also from Japan. he said they came up with a model that was designed to use the smaller gas line found on most garden variety water heaters. the exhaust pipe is a plastic tube!! he said it is very efficient in utilizing all the heat and that the factory plastic pipe is perfect. he actually ran it inside of a metal flex pipe to add some security.

it has been running 4 years now with zero issue. it sometime hiccups and will shock me with some cool water if someone downstream turns on the hot water, but for the most part no issues. hot ass water. non stop.

I was pretty skeptical, but I read the specs and yes, it uses the typical gas line. but it has its limits. no giant house, no long runs..or so I been told.

my neighbor saw mine and bought it as well to fill her sit up tub. she loves the thing and takes all her elderly friends out to the garage to show it off.

[Evans, Marv]

We have two Rinnai L75rs tankless water heaters that are about eleven+ years old. At the time, I think they cost around $1,100 each and look like they take one inch lines - but propane. It looks like most Rinnai tankless heaters cost $1,100 to $1,800 now, but I don't know that heating capacity. Ours are 6.1 gpm. One does the laundry, garage, and kitchen. The other does the bathrooms. We've never experienced any problems with hot water supply. I think I would expect a similar model to cost in that upper range now. So a bit over $1,500 for the vent pipe (30 ft is a lot), plus labor doesn't seem out of hand.

[Tidybuoy]

Here's a thread I started regarding my tankless and my gas lines. I recommend you do your own calculation just to be sure as the plumber may not know everything.

I have 1" gas line under my house. However, someone pointed out that my meter may not be large enough since tankless use a lot of gas (basically burst firing for rapid heating). My initial thought was that everything was fine but when I added up all my appliances (gas stove top, furnace, and tankless) I came to 356 Cubic Feet per hour consumption (if all running together). My meter's output is 210 cubic feet per hour. That means that my meter is under sized if the tankless is used with any other appliance (i.e., tankless and just one burner on the stove).

Although I have 1" gas lines under the house to each appliance area, my original water heater converts down to 1/2" and I am having to change out that line. Be sure to check your current water heater gas pipe.

I'm going to call PG&E to upgrade my meter, which I have been told is a no cost upgrade.

Question: Gas Line Sizing

[hbueno]

After Hurricane Sandy, I was happy to have hot water from our old fashioned gas water heater. We didn't have electricity for a week, but at least we had civilized hot showers. Our water is suoer hard and I believe that's a bigger problem for tankless vs. old fashioned systems. These may or may not be considerations for you.

[red-beard]

My house, the hot water heaters are getting long in the tooth (17 years). I have done the proper maintenance on them, draining on occasion and replacing the zinc rod.

I expect to replace with similar tank heaters. In the summer, the attic is hot enough that I get solar heated water.

[Evans, Marv]

Originally Posted by hbueno

Our water is suoer hard and I believe that's a bigger problem for tankless vs. old fashioned systems. These may or may not be considerations for you.

Tankless water heaters have valves for flushing the heat exchangers out with water and vinegar. You turn off the circulation valves, then uncap the flushing valves and drain the heat excnanger. Then hook up one intake hose and one exhaust hose (those little six foot hoses at H.D.) and connect them up to a cheap sump pump submersed in a 5 gal. bucket of water & vinegar. Turn the pump on and circulate it for fifteen minutes or so. Do the same with just water to flush, recap the circulation valves, open the feed valves and you're done. That should take care of hard water deposits for a year or two.

[Bill Douglas]

Rheem should be good.

In NZ we all seem to use Rinnai INFINITY califonts. I stayed in a bed and breakfast that had a Bosch one and it was not very nice. Likely to get burnt then cold in the shower.

[dad911]

Tankless need to be sized based on the incoming water temps and the gallons per minute of expected draw. I was able to use a much smaller one in south Florida, as the incoming water was near room temperature. In NJ, with colder incoming water, it is much larger.

Manufacturers have a sizing chart.

[greglepore]

Have had both Rheem and Navient, happy with both. I'd get one that does recirc, and have a recirc pump at your farthest shower, as the only downside is a longish wait for hot water.

[Evans, Marv]

After my post mentioning Rinnai tankless water heaters yesterday, I'm getting advertisements on my news feed page for them this morning.

[IS300]

only way to get hot water.... just installed a Rinnai and hot and cold spigot , great to have hot water outside

[Danimal16]

If you live in Earthquake Country, when you install a tankless, you eliminate 40 to 50 gallons of potable water. For drinking, that is a considerable amount. The worst case scenario is 5 to 7 days without treated water.

Just another thing to consider.

Me, I stay with the full tank system.

[look 171]

Just so you know OP, I have only the old fashion tank heaters in all our rentals. Simple, cheap reliable. I found a to of plumbers do not know tankless enough to sink their teeth into it.