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Tankless water heater is just that, tankless. It doesn't hold any water nor keep it at a hot temp 24 hours a day even when you are not using any hot water. Instead they heat water as it runs through the unit at the time you actually turn on the taps in your shower or bath. It uses a heat exchanger to rapidly bring it up to temperature. They run on electricity, natural gas, or propane but only when the water heating is required at the time of your shower or bath, not 24 hours a day like a tank heater. Basically you will never run out of hot water with these except that you might have a problem with output if two showers are being used at the same time or laundry is being done at the same time as someone is showering. Tankless heaters last twice as long as conventional and do not have to be replaced as often.
Google says they are 24% to 34% more energy efficient than conventional storage tank water heaters. So it really depends on how energy efficient your want your footprint to be. You will only save about $10/mo on electricity. Based on this not being a lot of monetary savings, I would buy a natural gas or propane standard tank heater. If you want to be prepared in case of outages, propane would be the fuel I would use because it is kept in a large tank installed on your land and does not need the grid.
I am revamping the water heating solution of an old house. It currently has a boiler that runs on propane. I would like to have an alternative option (electric) in case propane runs out or the unit has issue.
Surveying the market place, it seems there are "tankless" electric water heaters, and there are units that have a very small tank, ranging from 2-6. My questions:
1. If tankless works, why a tank?
2. What's the point of a 2 gallon tank?? Can hardly take a shower with it....
3. Some sites say tankless has a higher upfront setup cost. Is this comparing to the gas/propane tank boiler, or comparing to electric water heater with a tank? Where does this higher upfront cost come from? It seems some units are VERY inexpensive, much more so than the other 2 categories. Here is one example:
4. Is there any "standard" minimum requirement for tankless water heater? (in terms of power watts, voltage, etc)
1) For gas, I would consider Tankless.. Not so much on electric. From what i've heard, reliability on the electrics is.. Not as good as gas.. plus, you'll likely have to have new electric service run to the location of the tankless heater. Which.. May or may not be a problem. But, it does raise the initial cost.
I looked into this about 5 years ago when I had to replace mine.. Things were just not there at that time. Perhaps things have changed.
2) 2 gallon tanks are generally used for a sink or something like that. If you had a workshop or something with a sink in it and needed hot water. Might put in a small 2 gallon tank. An office building that just has bathroom sinks and a kitchen sink might have a small HWH around 2 gallons. Because they don't need a 40 gallon tank for showers or something like that.
Also, some people have a dedicated hot water faucet at their kitchen sink for coffee/drinks/etc. Another place where a small tanked heater might be used. So they don't sit there running water waiting for it to get hot. Though, there are other solutions for this problem.
3) See #1. Electrical service that you'll have to get run for the tankless heater. Your standard water heater is probably on a 20A 240V circuit. Tankless is going to need multiple 80A breakers as I recall. Which also means, higher gauge wire. For example, a 'standard' house where it needs to support 2 showers and 2 faucets at the same time.. 36kW is recommended, which requires 4 40A breakers. (Pending on other factors)
That also means you need a 300A panel in your house. Many people won't have that. Most people will have between 100 and 200A panels.
Changing all that.. We'd have to get an electrician for the quote, but.. I'm betting you're looking at a couple thousand all told in updating your electrical service.
4) Again, depends on what you have in your home. if you just have a single bathroom, one shower at a time and a couple of faucets, you can get away with a 24kW (Approx 3 Gallons/minute).. But that will require a 200A main panel and 3x 40A breakers.
Also.. This sucker is going to DRINK power when it's used.. That 24kW model, and these are rough numbers, are going to pull about 100A max. So.. yeah, about 24kW. At around 14 cents per kWh. If my math is right here.. That thing would cost about $3.36 an hour to run? If you take a 10 minute shower each day.. That's 5 hours per month.. So, about $17 a month in energy usage. In general, this is still less than a tank model, but.. Not much. Maybe $28/mo? Someone can double check my math here. The advantage is that it only uses power when you're using hot water. Tanked hot water heaters insulate really well nowadays, so, there's not much heat lost when it's just sitting.
Now.. Having said all that and given all the reasons NOT to do tankless. Why WOULD you?
Well, on Gas, all that electrical consideration is pretty much out the window. You might need to have power run to it, but just standard power, no other upgrades would be required, and likely, you probably have power near it already, because.. Even on my house which has no gas service, when it was built, they put in venting for a gas HWH. Of course, you did mention this was an old house.. So, it may or may not be there, but I'd kinda suspect it is.
Being "Green".. Yes,these do save some power. But, the economics don't really work out on electric because of the upgrades you'd need to put in. But, you know.. Some people don't care about that.
Resale value. You will be adding value to the house with one, most likely. I can't say that for certain, but.. If you're 'flipping' a house or something, having a tankless HWH will benefit the next person, so.. I could see upping the resale value. I don't know if it would up it enough to recoup the install costs, tho.
This one is.. I don't know if this is an advantage or not. Could go either way. These things mount on the wall. Imagine it springing a leak. but, of course, if you have a HWH and someone didn't put a drain pan below it (As the a-holes who built my place didn't).. That thing springs a leak you could be looking at a couple thousand in floor repairs. You only get burned by that once, tho and have them put a damn pan in after the first leak.
Again, i'll boil this down to the following.. Gas, pretty much would be worth it. Electric.. Not so much.
Last edited by Labonte18; 11-02-2022 at 10:23 AM..
I am revamping the water heating solution of an old house. It currently has a boiler that runs on propane. I would like to have an alternative option (electric) in case propane runs out or the unit has issue.
Surveying the market place, it seems there are "tankless" electric water heaters, and there are units that have a very small tank, ranging from 2-6. My questions:
1. If tankless works, why a tank?
2. What's the point of a 2 gallon tank?? Can hardly take a shower with it....
3. Some sites say tankless has a higher upfront setup cost. Is this comparing to the gas/propane tank boiler, or comparing to electric water heater with a tank? Where does this higher upfront cost come from? It seems some units are VERY inexpensive, much more so than the other 2 categories. Here is one example:
4. Is there any "standard" minimum requirement for tankless water heater? (in terms of power watts, voltage, etc)
1. Tankless works, and the 'instant' thing goes both ways: the 'instant' you are out of fuel/or electric is out, you get a COLD shower!
2. One issue with 'instant' water-heaters is that they need a 'minimum' flow rate to make the 'heat' come on; instants w/the 2-gallon tank are supposed to 'help' with this issue, but often add to the cost.
3. Instants require HUGE power-lines ran to breaker panel (electric), or might require upgraded gas/fuel service & lines as well for gas/propane ones. The one you linked to is just for a sink - with a tiny flow rate; no way it could support a shower, or multiple users using hot-water at once.
4. This depends on how many uses will occur simultaneously (more than one shower? clothes-washer/dishwasher/ multiple sinks.) If you go 'minimal' here, you may get a cold shower if someone decides to run a load of whites/hot in washer, or 'do dishes' while you're showering!
5. Another option is to consider an Electric Heat-Pump WaterHeater; they have a tank and are very-efficient with electricity, and use standard inexpensive electric-waterheater wiring, and give a bonus 'de-humidification' to the space they are located in.
They are 'expensive' up front, but will pay you back over time with energy savings - something that no other option will!
Might even be cheaper than having to 'retrofit' in a tankless unit, depending on your situation.
Many areas you can get rebates from local utility and/or on taxes.
Plus, even if power goes off, you still have a tank of hot water, and the heat-pump is so efficient (400 watts!), it can also be reasonably run on solar or backup-power!
5. Another option is to consider an Electric Heat-Pump WaterHeater; they have a tank and are very-efficient with electricity, and use standard inexpensive electric-waterheater wiring, and give a bonus 'de-humidification' to the space they are located in.
They are 'expensive' up front, but will pay you back over time with energy savings - something that no other option will!
Might even be cheaper than having to 'retrofit' in a tankless unit, depending on your situation.
Many areas you can get rebates from local utility and/or on taxes.
Plus, even if power goes off, you still have a tank of hot water, and the heat-pump is so efficient (400 watts!), it can also be reasonably run on solar or backup-power!
I just got an email from my utility, offering a $350 rebate, along with a $300 Federal tax credit if I replace my existing WH with a Hybrid/Heat Pump. I had never heard of these before now, so am interested to learn more. They are saying 2x-3x times more efficient than conventional heaters.
My existing WH is 80 gallon, so from a quick glance at the Home Depot web site, I would be looking at ~$2500 + installation (before the $650 rebate/credit).
I just got an email from my utility, offering a $350 rebate, along with a $300 Federal tax credit if I replace my existing WH with a Hybrid/Heat Pump. I had never heard of these before now, so am interested to learn more. They are saying 2x-3x times more efficient than conventional heaters.
My existing WH is 80 gallon, so from a quick glance at the Home Depot web site, I would be looking at ~$2500 + installation (before the $650 rebate/credit).
80 Gallon? Holy crap. I've actually seen a move away from using water heaters of this size.. My dad's house, in fact, uses two 40 gallon heaters. One for upstairs and one for downstairs.
Where you'd have to be careful here, in my eyes, and I have no reason to doubt any of what CCCyou said regarding their efficiency or what your electric company is saying about it.. How much water do you use?
Now, an 80 gallon water heater is going to use more power keeping that 80 gallons hot than my little 30 gallon heater will.. But, the reason I have a 30 gallon water heater is.. That's all I need. It's plenty of hot water for me to take a shower and wash dishes and do a load of laundry. I'm probably paying $15 a month for hot water.. Buying a system that's 2-3x as efficient.. Well, that could knock my usage to $5-$7.50 a month.
If that goes for 10 years.. That's.. $900 tops in savings.
Is that enough to pay off the added cost?
One of those situations where the verbiage might sound better than the reality once you break the numbers down.
I just got an email from my utility, offering a $350 rebate, along with a $300 Federal tax credit if I replace my existing WH with a Hybrid/Heat Pump. I had never heard of these before now, so am interested to learn more. They are saying 2x-3x times more efficient than conventional heaters.
My existing WH is 80 gallon, so from a quick glance at the Home Depot web site, I would be looking at ~$2500 + installation (before the $650 rebate/credit).
The heat pump water heater could be noisy - make sure to take this into consideration.
I have the 80gal HPWH, as I have 5 people in the house. It uses almost nothing to ‘keep water hot’, as these thing are designed with much more/better insulation than a regular tank water heater. In fact, couple winters ago when Texas had the super deep freeze ( -10 at my house) with power going off, I surprisingly got to take a hot shower the next evening after spending a good part of the day out in the cold tending animals - with power being completely off for 22 hours at the point. If you just have one or two people in the house, the 50gal one will do just fine.
I keep mine in heat-pump only mode most of year round. I only put it into ‘hybrid’ mode if we have guests during the winter.
Actually one consideration to be aware of is that these things are bigger around ( thicker insulation) and taller than a standard WH - be sure you have the room.
The one I have is only slightly ‘noisier’ than a refrigerator. I have mine in the garage , where the added dehumidification is a very welcome bonus.
If you’re not in a huge rush, the HPWH’s often go on sale for $400-$500 off the reg price - shop around!
Also, since you mention revamping an older home W/ propane - is your heating with propane too? Central system? HVAC?
If you update the HVAC you may want to consider upgrading it to a Dual-fuel heat-pump type. These include both a propane furnace AND heat-pump type condenser, and can auto-switch to save $$/ fuel when heating, and make you less dependent on propane refills.
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