I’m looking into tankless water heaters, but what do I need to know about the wiring of my condo first and how do I find that out? Amps? Volts? What? :smack: People said they were expensive but for a tiny condo (470 sq ft) there’s some small ones that seem perfect. Maybe even one tiny one for the kitchen sink/dish washer and another for the shower/laundary?
Do you have natural gas in your condo?
I have several in my condo. They do take some getting used to, especially in DC where the ground water temperature can drop into the 40’s during the coldest days of the year. But the benefit (recovered closet space) more than makes up for the short learning curve.
IMO you need at least 150 amp service mains and two available spots in your service panel.
My largest one (feeding the shower) draws 70 amps when it’s cooking.
You need to study some temperature rise charts to determine how much heating power you require. I’m posting from my phone so I can’t really do much linking, but I’ll return tomorrow if others haven’t supplied much info.
Could you expound on this?
I’m currently in the process of getting one. And by “process”, I mean that my general contractor and plumber are trying to figure out what the hell they’re doing.
We know that we need a new gas pipe run (because the one to the hot water tank is too small) and electrical but they’re coming back out later this week to measure my water flow to make sure I get one big enough.
They wanted to put in two big ones because they reasoned that there are three shower heads (in one shower stall), two sinks, a tub and an entire kitchen being serviced by that tank. Because once I get it, I’m going to turn on all those things at the same time. :rolleyes: I just want to be able to fill up my tub without running out of hot water halfway through.
I’m thinking of getting one for my house as well. The temperature of the water coming out of a given tap will depend on how much hot water you are using at that instant (gallons per minute) as well as how cold the water coming into your house is.
Since there’s no tank to store hot water at some given temperature, you can get very hot water at a lower flow rate (i.e. open one tap) or a lot of water at a lower temperature (run both showers, the dishwasher and the clotheswasher at once). The system can only produce so many units of heat energy for all the water flowing through it. Obviously if you have very cold water coming into your house (from the local water supply) that can make a difference to the final output of hot water that you get.
From the research I did when considering this for my condo I discovered that had I had a gas hookup it would have been a wonderful idea. With just electric it was mediocre at best, not to mention the nightmare of trying to expand my electrical box when you share walls with a neighbor. Too little benefit for too much effort.
A bit of “FWIW” here:
In my previous house, I had a gas-fired tankless heater to serve the whole house’s hot water needs - bath, bathroom sink, kitchen sink, utility room sink. It was superb, kicking out as much water as you needed at ~70C.
Only two disadvantages:
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You need to turn the tap on pretty much all the way before the heat exchange kicked in. We had to warn guests about that.
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Once the hot water started coming through, the flow is significantly reduced, so it takes longer to, say, fill a bath than a normal arrangement.
But once you’re aware of these points, it’s a very neat system, and cheap to run on UK gas prices.
Not sure if this helps the OP in any way …
From your second paragraph I can’t tell if you’re going for a gas or electric heater.
The good thing is that they can heat water for as long as you want to draw it, but the problem is they can only deliver the heat to the water so fast. Meaning if you draw water at too high a rate, you’ll end up with a lukewarm shower. Mine works just find except when it gets really cold out, and then I have to turn down the rate of flow from my hot water tap in order to get really hot water. I don’t expect a massage from my shower head so I’m OK with this. I’ve gotten used to this and now it’s second nature, but it can be a pain trying to explain it to a guest. “OK listen carefully, here’s how to use the shower…”
This is the brand I use. I think it’s the Tempra 29 (two heating elements) and it serves only the shower because I wanted to eliminate the possibility of being in the shower and have somebody turn on a hot tap elsewhere in the house. Each internal heating element draws 35 amps at full load. The kitchen and laundry areas are served by their own smaller point of use heaters.
Here’s their sizing chart. Based on my experience, I disagree with it somewhat. I would not share a shower’s point of use water heater with any other tap or appliance, except possibly the washing machine.
Here’s the temperature rise chart (scroll down). You can see that water temperature at the tap depends on the temperature of the groundwater and the rate at which you draw it through the heater. So if the groundwater is 40° and you’re feeding a 2GPM shower head, you’ll only get an increase of about 50° using the Tempra 15 (a 14.4 KW heater at 240V). That would be a lukewwarm shower at best. Another point to consider - I have 208 volt service in my unit rather than 240v, meaning less power to the heating elements.
You say you have three shower heads in your shower? You need to know the total demand on a heater in GPM and get the appropriate model.
Most of them kick on at between a third and ½ GPM. Means you can’t get a “trickle” of hot water if you need it. You should also cut the power to the heater if your water supply is cut off for any reason or the heating elements might self destruct when somebody opens a hot tap and the elements have nowhere to dump their output.
I am familiar with the on-demand water heaters in the UK, so when I started thinking about what to do when our 80-gallon water heater (BEHEMOTH ALERT!!!) kicks the bucket I thought about getting a 40-gallon regular water heater and a point-of-use water heater for the large tub upstairs.
I talked to my plumber. He says that unless it’s powered by gas I don’t even want to know. Since we’re on propane here and it would mean running a new line upstairs AND propane is hideously expensive, I guess it won’t happen. He says the electric ones are crap. He also mentioned that by the time the tub was filled it wouldn’t be hot anymore.
I’m thinking of having a passive solar hot water system incorporated into the southeast-facing sunroom we’re planning. Anything that would heat the water without paying for fuel would be a bonus.
There’s a link missing from my 2nd paragraph. This is the brand I use.
No. So electric tankless.
Glad this is of interest to several people.
I put an electric TWH in my girlfriend’s house. It had two heating elements, each of which required its own circuit. She finds it satisfactory, for a person living alone, but I’d suggest a three-element unit for a family house.
I think the unit is pretty noisy, myself. Consider putting it in an easily-soundproofed closet or cabinet.
Huh? What is the noise coming from? There are no moving parts inside.
I’m betting water moves through it, though.
I hate, hate, hate the tankless water heater our landlord put in when the old tank blew. I sure hope it saves him money on heating it, 'cause we’re wasting obscene amounts of water running taps until they get hot. Sometimes, and I’m not exaggerating here, it takes upwards of 15 minutes running the tap on full stream to get hot water. And when the hot water goes, it GOES, no slowly getting cooler to lukewarm. No, if you’re in the shower and the hot water runs out, you go from good to freezing in nanoseconds with no warning that you’d probably rinse off, done or no.
I just put a Tempra 24 in my 2 bedroomr 1 bath condo to serve the whole thing. It draws 100 amps (the 29 is 120 amps). The heater was about $500 and the install $300.
The electrician said the service had a 125 amp disconnect but since it was aluminium wire it was de-rated to 100 amps. I have a KW meter and the water heater, dryer, and AC running at the same time was pulling 130 amps.
He said he could put in copper wire and up the service to an actual 150 amp max because the conduit in the slab wouldn’t allow any bigger. He’d do it for $600 labor, not including materials, which included a new breaker box. The wire ended up being $1120 (the meter is at the other end of the building and copper is expensive), the box and misc was another $250. Plus $60 for inspection.
So, the total was $2800. And I still have to worry about how much stuff I have on at once. I could have gone with a lower amp unit, but this one is just enough for showering when the water is cold. Or with multiple smaller units, with additional plumbing and making sure only one was on at a time.
There is no hope of it paying for itself. It works, but so does a tank. I don’t really regret putting it in, but if I knew then what I know now I wouldn’t have.
Sure but the sound of water moving through pipes is not what I would describe as “pretty noisy”. The shower head and mixing valve itself produces a whole heck of a lot more noise than the water heater in the adjacent closet which, at least in my case, produces no more noise than a public drinking fountain.
Maybe that model has a bad plumbing design resulting in turbulence or something?
The on-demand water heaters I had in England sounded like they were chewing rocks. I don’t pretend to understand what was going on inside them, and I wasn’t about to look.
Gas-fired water tankless waterheaters (“geisers”) are standard in the Netherlands. Few people have “boilers” the kind with tank. I had a canadian visitor last year who was very surprised at the system.
In addition to the (dis)advantages mentioned by Barrington, depending on the capacity of your heater, you might find yourself in the typical Dutch situation of going cold in the shower when someone puts on the hot water in the kitchen.
(the link shows a commercial for the Dutch army on You-Tube. The boy remains in the shower, and earns a “geschikt” meaning “passed the army test” )
It does save on closet space, though, and you’re never out of hot water entirely, and it appears to be quite energy-effective.