Tankless water heater

I’m considering a tankless water heater system. It will be significantly more expensive upfront but will last longer and be more energy efficient. I know these are common in Europe but usually in a smaller space.

Anyone have one of these systems in a home with an Airbnb who has any opinions about whether to install one or not?

I have some experience. Not in an Airbnb, though.

Gas or Electric?
Whole home or just one room (kitchen or bath)?

Gas. Whole home to replace the tank I currently have.

We really wanted them and I looked into them quite extensively. Our utilites company even offers a great rebate for installing them. However, because of local code and the installation they require it will be quite a project for us - we would have to have new gas lines installed, etc so we haven’t done it but everyone I know that has them, raves about them.

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We have a tankless water heater in the addition I put on the house. It’s where one of the Airbnb bathrooms is. Works great!

Ours uses gas. It was installed as the new addition was built.

From what I learned when I later tried to replace the other traditional water heater in our house, it’s much more expensive to install a tankless gas water heater in the middle of a structure. And it can require an increase in gas service that could be very, very expensive.

Lots to check out with an HVAC contractor and possibly with the gas service before considering whether to switch an existing gas water heater to a gas tankless water heater.

We chose not to replace the original water heater with tankless, as the installation was going to be upwards of $20,000.

No idea about costs in US, but every country where we’ve been involved in property refurbishment, this is the type of water heater we always install if there is a mains gas supply. If it’s the type I’m thinking about, looks a bit like this:

Generally they are more efficient than electricity, and can also be used for heating radiators as well.

They come in different specs, for example our last house in the UK had twenty two radiators and the hot water flow was sufficient for two folks to have showers in different bathrooms without any significant drop off in temp or flow rate.

Our LTR properties all have these fitted. A little bit more expensive to run (as landlords) as we need them certified and serviced each year, but great for the tenants.

Anything specific you want to know?


Exactly. We have a 120 year old house with an enormous basement and all of the (gas) hot water heaters are smack in the middle. These tankless heaters have to be installed on an outside wall (I can’t remember if this a local code or inherent to the tankless heaters). It was just going to be too much!

Just if anyone has had problems. I want to be able to have two guests get a hot shower within minutes of each other is the most critical function. :wink:

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I think they used to require being on an outside wall. They can now be interior (as is our traditional water heater), but installation there can be vastly more expensive.

Of course codes probably differ everywhere.

They need a flue to vent the burnt gases, mounting on an outside wall is the most convenient method. That said, I have seen floor standing versions with longer flues and a quick search suggests they are more common in the US than Europe.



The plumber who wants to sell me one is here now and at initial look at the gas line he said it’s fine and the “vent goes straight out” Mine is in the middle of the house but it’s a one story home with vent straight up out the roof, the main gas line comes in right there where the furnace and water heater is. He quoted me a top of the head $3500-4000 vs $1200 for a new tank. He’s here on another job so I’ll see if I like his work first and foremost.

@KKC, be sure to verify that your house’s gas service is sufficient. A tankless water heater takes a big draw on gas service as it fires up. If the service isn’t adequate, it will rob any other gas-fueled systems (stove, furnace, dryer, etc.) as it works. Increasing the capacity of gas service was what would have made installation here crazy expensive.

If that includes all necessary pipework and electrics, then it’s not dissimilar to a UK quote for a similar sized installation. Maybe a little bit more, but not by a lot.

Now, if only we had mains gas here :disappointed:


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I installed an electric tankless for Gypsy the trailer. It is inside the cabinet under the sink and not dangerous and installed to code. It is a smallish one, seems to work perfectly, but its the trailer electricity available (50amp) (which is a fair amount for a trailer) which likely prohibits shower, dishes by hand and a/c activity all at once. I know 2 guests have had plenty of water, great temps etc. This is what I got: ecosmart-ECO-8-8kW-Electric-Tankless-Water-Heater

I might build an accessory dwelling unit=tiny house that I will put solar panels on and go all electric for our entire property except the small propane tank for trailer stovetop, in which case I would buy one for that new unit and maybe 2 smaller ones for the house, or something like that.
It just seems reasonable not to have the hot water staying warm all the time, and you can really customize size to your exact needs.
Sorry, I do not have experience with gas powered tankless.
One of my friends got a subsidized solar roof set up during her major remodel and stupidly did not go all electric.

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that price sounds awful high

also we do not have any gas, only large propane tank

my friend is in Florida

In all the installations we’ve had, this has never been an issue. Gas fired boiler consume gas at approximately the same rate when starting as they do when running, although we could be talking about different devices here.

In Europe, a 15mm diameter pipe is the standard size to appliances and the supply pipe (from the gas main) is 22mm. No idea what the norm is in US, but I’d have thought that if it’s 22mm or thereabouts then unless you have some serious gas fired kit, it should be sufficient for the majority of domestic boilers.


You think so? To me it’s in the ball park for the UK for a consumer price if it includes all the necessary pipework and electrics, and if it’s a decent quality boiler (i.e. minimum 5yr guarantee).

Got to be honest, I’ve never had to get a quote for full installation as I’ve always done the electrics and pipework myself, only the actual boiler install and sign off being done by the engineer (illegal in UK to do it without being qualified).


For where you are, but in Texas where @KKC is, they practically give away the natural gas for free. It would be stupid to do anything electric that could be gas there.
I’m from Texas originally but now live much more north and am astounded at what they charge for natural gas here. They even charge a hefty ‘natural gas supply fee’ every month even in an occupied space. However they practically give away the water for free, which is super-pricey in Texas. But the water here is crap and should be free. Different places! I’ve also lived near where you are at and understand the different viewpoint.

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The plumber specifically said “gas line is 1 inch.” However, on top of that, I don’t have any other gas supplied systems operational. Dryer and oven are electric. There is gas supply to the fireplace but I wouldn’t be concerned about that in any case.

I’m truly surprised at this. I miss my cheap gas utilities!