Single Shower Tankless for 3/4" Existing Gas Connection? Small apartment tankless?

[TheOverThinker]

Is there an available low BTU tankless or hybrid tank/tankless unit suitable for retrofit applications in apartments, with existing 3/4" gas service?

These apartments typically have a single bath with a single shower, and then a kitchen sink. Maybe a dishwasher (which could be plumbed to cold). That's it.

Typically the failed existing tank water heater is 20 or 30 gallons, with a single wall vent to the roof, 3/4" gas service, and if there's a drain pan it is just a drain pan. There's no external route to run a TPR, but there's often a kitchen sink nearby that in theory could receive condensate. The typical install location is a closet, with combustion air via a vent in the closet door.

 

[WorthFlorida]

Do you need more hot water or looking for lower energy costs?

 

[Sponsor]

 

[TheOverThinker]

Do you need more hot water or looking for lower energy costs?

Neither. This is for when the old units leak and need to be replaced.

 

[WorthFlorida]

The smallest gas tankless are about 150,000 BTU input. A 30 gallon gas standard WH's are about 30,000 BTU input. Until you get the spec on a tankless unit, it is not a yes or no at this time if the unit will work with a 3/4" gas line. Gas tankless prices have come down quite a lot to almost the cost of a standard tank., however, installation cost can be more. You'll need to look at the spec what the fresh air intake requirements are. Most will have a minimum closet size to pull air from the room. With an input of 5 times more BTU's, the existing exhaust pipe may not be larger enough. Tankless requires maintenance, periodically the heat exchanger needs to be cleaned to reduce the build up of hard water deposits. Tankless units use micro processor controls and it's an another point of a possible failure.

If you are the building maintenance contractor or property manager and a problem arrises, a standard tank is simple, readily available and can be repaired or replaced by any plumber or knowledgeable person.

I like to reference sites that write a good explaination of the basics for tankless.

Water Heater 101: Guide to Tankless Electric Heaters

Ever wondered why your showers are cold? Your water heater might be giving you the cold shoulder. Take the hint and call Fast Water Heater today for a warm solution!

www.fastwaterheater.com

 

[TheOverThinker]

The smallest gas tankless are about 150,000 BTU input[/URL]

That's the rub. That's bigger than needed for a single unit occupancy.
Any small ones out there?

 

[John Gayewski]

There are many point of use water heaters. Emax are the ones we use.

That's the rub. That's bigger than needed for a single unit occupancy.
Any small ones out there?

 

[TheOverThinker]

There are many point of use water heaters. Emax are the ones we use.

I use the point of use heaters for single sinks. And the EEmax tank booster for undersized tank heaters or slow solar thermal or heat pump system.
Here with a shower though, that demands a "real" heater.

 

[John Gayewski]

A shower is 2.5gpm max. They claim way more than that.

 

[TheOverThinker]

The tankless units have a burner range, perhaps 10,000 to 150,000 BTU.
Are there any units that in software can be limited to 100,000 BTU max for example,
thus allowing an existing gas line to work at reduced overall heating capacity?

 

[TheOverThinker]

The RU130iN is 130,000 BTU. The company tells me they may in the future offer a way to (in software) configure it down to lower numbers, in 10,000 BTU steps.​

 

[wwhitney]

Zero experience, but you might be interested in, say this:

Trident on Demand 4.4 GPM 70,000 BTU Natural Gas Condensing Tankless Water Heater AKTRNG - The Home Depot

Ensure your home has hot water with this Trident on Demand 4.4 GPM 70,000 BTU Natural Gas Condensing Tankless Water Heater. It features a stainless-steel design for added durability. It also has a digital

www.homedepot.com

That website has other small options, just go to natural gas tankless water heater and sort by price.

I checked a few larger name brands, and they have 120,000 BTU/hr as their smallest offering.

Cheers, Wayne

 

[Jeff H Young]

The OverThinker,
Late seeing this post, You might want to look very close 3/4 going to single 20 or 30 gal waterheater is not that typical and You might have a 1/2 inch line ? 3/4 would likely be shared with a range . also If the apts are on a single or combined gas system (seperately metered) could effect as most tiny 20 gal w/h wouldnt be supplied with 150,000 or so btu capability or even 100k

 

[TheOverThinker]

The Noritz NR662-OD is 120,000 BTU maximum.
That's 5 gallons per minute, 1/2" gas line, and OK up to maybe 20 feet of 1/2"
or 40 feet of 3/4" per specs.

I'm still seeking a dynamic model that can be tuned to a lower maximum BTU based on examining the flame quality for a given gas pressure.

 

[Fitter30]

Call your gas company they should know what gas flow of meter and regulator. What else is gas? Then can decide if service is capable.

 

[TheOverThinker]

Call your gas company they should know what gas flow of meter and regulator. What else is gas? Then can decide if service is capable.

Calling my gas company has a similar effect to calling Google, or trying to speak to NBC by yelling at my television.

 

[Fitter30]

PG&E? No new gas residential customers in what 2023. Might want to think hybrid wh.