Considering tankless water heater

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Old 01-09-20, 08:18 AM
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Considering tankless water heater

I'm sure this has been asked 8 jillion times but I didn't see a thread on the front page.

I'm on a hot water tank and would like to consider going tankless/on demand, for a number of reasons. I know enough to be dangerous but don't feel i have what I need to make a complete decision.

The home is about 3200 squares. 4 bathrooms, all of which get used. 3 showers, also all used regularly. 2 kitchens that are used, 1 dishwasher, one clothes washer (that rarely uses hot/warm water, but should still be factored).

Water has to be pushed up 2 floors to get to my ensuite and the upper main bath. Ive read many warnings about length of time taken to push hot water up that high, but i I have that problem now with the tank so I'm not sure how concerned i really am. If it is a feasible notion i will absolutley consider a secondary on-demand heater installed on the upper floor, if that's a thing. Just thinking out loud on that.

The space my tank currently resides in is tight. I updated my furnace and AC and that is in the same space. I'd like a water softener as well but don't have the room for it. By removing the tank and installing on-demand on the wall, I would then put a softener in line and use the space i gained by removing the tank. This is all my theory i don't know if there are minimum space requirements for either but a new softener won't be anywhere near the size of the tank I'm using today so i don't see how it could be an issue.

I would consider either electric of gas heated but assume that gas would be the best option for my requirements. Either would be easy to fit as the furnace is right there.

I'm happy to hear level opinion but also hope to gain real data for anyone with direct experience installing or using on demand in a home like this.

Cheers,
 
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Old 01-09-20, 11:53 AM
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Tankless are generally better on paper than in real life and tend to work well in locations where the incoming water temperature is mild, as their issue is how much rise they can achieve at a reasonable flow of water. As to electric versus gas, the electric units often take 120 amps (3-40 or 2-60 volt breakers) so a lot of homes simply don't have the necessary service. Gas requirements are also high and sometimes require new supply lines to be run from the street.

You have some research to do to figure out whether this is actually a good idea.
 
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Old 01-09-20, 11:58 AM
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My opinion is to not even consider an electric on-demand water heater. Especially for a larger house like yours, the electricity it requires is significant, and would likely require an electrical service upgrade. Many units also just won't provide the amount of hot water you'd need with multiple bathrooms.

Gas heaters are better and at least usable. They may require a larger gas meter and possibly a larger gas main from the street - but in many cases the gas company will do this for you at no cost, since you'll be buying more gas from them in the long run!

The main issue with them as I've seen and calculated is that there is a much higher initial cost, and the savings that you project over the life of the heater, end up being close to zero after 10 years or so. So all the energy savings over the years, gets swallowed up in the initial device and installation cost. Coupled with the fact that some units have known issues with hard water requiring descaling and issues over time with the heating capacity reducing.

I'm not going to not recommend one... but I would definitely read more and make sure you're making a good decision based on your projected usage.
 
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Old 01-09-20, 01:08 PM
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I have found tankless water heaters to be a love/hate appliance. People either love them or hate them. More in the latter category. They are very flow critical. If one is sized for "normal" flow rates and someone turns on another hot water spigot, everybody's water gets cooler.
 
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Old 01-09-20, 02:28 PM
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My reasoning isn't economics based, and the gas savings wouldn't be very noticeable anyway. I'm fine with paying the upfront to do it right. I have the flow and gas requirements i would need. As mentioned i would install an inline softener if the tank came out so no scaling concerns.
im already considering a programmed circulator for my top floor anyway because of how long it can take at time for hot water from the tank to get up here, I'm not sure if they can be used with tankless.
i did ask about winter months in climate zones like mine and didn't see anything to show that you would see lower performance on water that comes in cold vs. tepid.
 
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Old 01-09-20, 07:34 PM
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didn't see anything to show that you would see lower performance on water that comes in cold vs. tepid.
It's actually a common sense thing. It can be assumed that the colder the incoming water is..... the harder it is to heat. Reputable water heater companies will have a rate of rise chart showing how much hot water it can produce based on the incoming water temperature. Make no mistake.... it is a problem for some.

Some units specifically state they cannot be used with a softener.

An on demand water heater requires a certain amount of water flow to activate the heater.
I don't believe a circulator in the hot water line will work well with it.

If I were to recommend an on demand water heater it would only be for a gas model.
 
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Old 01-09-20, 08:53 PM
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I know Rennai (sp?) has temperature vs flow charts for their tankless heaters. For this area installers usually figure on about 50* incoming water & a temperature rise of 70*.Renai also has water specs in their installation manuals. They also sell some kind of in-line "scale preventer". Some of their heaters are compatible with recirculation.
 
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Old 01-11-20, 06:50 PM
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Do you have gas now there?
 
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Old 01-12-20, 08:32 AM
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I've had different kinds over the years. Got a small ranch last year with a nat gas Rinnai tankless. It's just me and the wife, so it works well, but with your demands, I'm not so sure about it. It also takes a while to heat up and transfer to the faucet, abt 2 mins for my kitchen at the other end of the house... I've seen many install a small temp heater mounted below the cabinet so you get heat fast. I also have town water... I never would have put one one my last house with well water.
 
 

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