I haven't personally switched to tankless but have been involved with hundreds and have feedback from dozens. Most all of them are one unit supplying the entire house. Some have a second unit and others have tankless for the master and tank for the rest of the house.
They seem to work best if it is centrally located. Singles and couples seem to have better cost savings. Families with teenagers or overgrown kids that like long, endless showers drive the cost savings out of the house! A poor location with long runs will decimate savings. It is not a one fits all scenario.
I have a gas fired tankless hot water heater installed in my basement for the past 8 years. Air supply and exhaust is a double wall direct vent system. Great system as you can run more than one shower and washing machine and dishwasher at the same time and still not run out of hot water. In the summer when we do not run the gas fired hot air furnace our gas bills are in a range of $13.50 to $20.00 which includes a monthly meter charge of $8.55 per month. The higher bills are the past several years since we installed a gas clothes dryer and we do a lot of laundry. You do need to service the unit periodically (flush the water lines with an acidic vinegar solution to remove lime scale build up in the heating coils). New homes with piping runs designed for a tankless avoid running a lot of cold water down the drain waiting on hot water.
www.tanklesswaterheater-reviews.comCan someone tell me which one I should buy for the whole house 6 people. 2 adults and 4 kids all over 12 years old.
I have a Rinnai unit, rated at 199k input. Other brands work fine. Size by selecting units that will make at least 5 or 6 gallon flow rate at 125 degrees outlet based on the local inlet water temps. Select yours from a dealer that has installed lots of tankless units and talk to some clients from several years ago.. If he cannot give references, try another company. These units cost more than tank type units, unless you are looking at heat pump type water heaters (another choice if you do not have natural gas and in some local areas there are rebates available to help pay for the cost difference of a heat pump type versus a standard electric tank type). Be aware you will need a larger gas line than if you were using a standard tank type gas water heater. This adds to install cost. I have a 3/4" gas line to the Rinnai and only a 1/2" line to the Lennox hot air furnace.
The only actual experience I have with electric point of use hot water heaters is in the UK where they often have a unit installed into the water pipe right above the shower head. With the visible wires to the unit, I always wonder about running electricity and water together just before the water hits my body. So far, so good.
It isn't only the number of adults and the kids in the house. Your usage patterns are also important. Put a note pad by each sink, shower/tub and have family members keep track of when and for how long they've used HOT water. Then you can go back and estimate the flow rate of the water used. Flow rate determines the size of the tankless. The hot water system pipe design, long trunks or end runs, size 1/2 or 3/4 for trunks, will then give you an idea if you'd be seen a little water sandwich (cold plug of water), or a big sandwich.
You need to look at the fixtures, are they low flow fixtures, or higher flow. low flow fixtures may not trigger some of the less expensive tankless heaters to turn on.
Look at when you do laundry and use the dishwasher, keep track of the time. Record it in the note book.
Check your water for hardness and minerals.
Then once you've got all this down, estimate for how long the water would be running (hot water), and the flow rates (you can measure flow rates by capturing one minutes worth of shower water in a bucket and measuring the volume).
Calculate what you think you need for sizes, put it on a piece of paper that you can hand out to plumbing contractors that you'd buy and install the tankless unit. Let them ask questions and estimate ,sizing. then ask them to explain.
If you do the work up front, it will be far easier to choose the unit AND you will be happier with your choice of units.
Right size for a tankless water heater basically depends on how many gallons water will be coming out of the taps at the peak hour i.e. when everyone likes to shower in the day. Simply add 2 gallons for each faucet and shower head that will be in use to find out your maximum hot water usage. You then estimate how many BTUs are needed to heat so many gallons and that needs you to know the tap water temperatures in your city. Naturally, you are going to need more power if the water that enters the water heater is very cold. Here is an article on tankless water heaters. Sizing and some other features are explained under the title: What Features to Look for in a Good Tankless Water Heater. To get good results, I suggest you do some research first and then seek professional advice and installation.
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