Tankless Water Heater?

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Old 03-22-15, 07:50 PM
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Tankless Water Heater?

Hello, Guys! Sorry I haven't been on in awhile, my life has been pretty hectic. Anyway, my dad is talking about getting a tankless electric water heater for in the house during the summer, as our hot water is currently derived from the oil-fired boiler that runs our heating. What I need help on is sizing the unit, in addition, I need to know if the oil burner can be shut off in the spring, summer, and fall, or if it needs to run year-round. It hogs oil.

We have a 1/2'' feed coming from the street coming in at 125psi, with our pressure regulator set at 75 psi. We have 2 bathrooms, washer, kitchen sink, and a hot water spigot outside. Is there anything I'm missing?

As always, thanks guys!
 
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Old 03-22-15, 11:00 PM
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Good to see you checking in.

I'm guessing you mean a 1/2" water line in from the street.
These things draw large amounts of electricity on demand. Many times a 100A service is not large enough to run the house and the water heater. A 27k tankless heater needs 112A at 240v.
Rheem Tankless Electric RTE 27 Series


Personally, myself, I'd go with a standard electric storage type hot water heater. If you had natural gas it would be a different story.
 
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Old 03-23-15, 10:05 PM
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I'm guessing you mean a 1/2" water line in from the street.
These things draw large amounts of electricity on demand. Many times a 100A service is not large enough to run the house and the water heater. A 27k tankless heater needs 112A at 240v.
Rheem Tankless Electric RTE 27 Series
Yes, a 1/2'' line from the street. All of the piping in the house for water is 1/2'' as well. (Heating lines are much larger but that's irrelevant I think) And I know the heater will draw massive amounts of power. We have a 200A service which is very lightly loaded except at Christmas time. In fact, I was looking at that exact unit, as well as one from EcoSmart.


Personally, myself, I'd go with a standard electric storage type hot water heater. If you had natural gas it would be a different story.
Unfortunately, we have a family of 6. At our last house we had a tank style electric and after 2 of us got done the rest of us had cold showers. And no natural gas or room for a propane tank, that's the first thing I thought of considering we are getting a new stove and dryer once the house is done being gutted and refinished. (We had a small fire on our coffee table caused by an unattended candle. Very little fire damage, just a lot of smoke and soot.)
 
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Old 03-23-15, 10:46 PM
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Sorry to hear about your misfortune at the house.
 
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Old 03-24-15, 12:19 AM
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I don't know what size tank the previous house had but I never recommend anything but an 80 gallon electric water heater. Set it to 140 degrees and have a tempering valve to limit the outgoing water to 125 for safety and you will probably get six showers in a row unless you are like me and run it for 30 minutes with a high volume head.

My parent's house had a 1/2 inch galvanized water service and the pipes were so clogged with rust and other corruption it could barely serve the shower alone. Any other water usage would cause scalding in the shower. This was in spite of having about 104 psi static pressure. I re-piped the incoming from the meter to one inch galvanized and then ran one inch PVC inside to the other end of the house. Made the hot 3/4 copper anywhere it served multiple taps and 1/2 for single tap runs. Made all the difference in the world.
 
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Old 03-25-15, 04:41 PM
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I think Furd is right, an 80 gallon tank type heater would be the best all around bet. I think if I were you, Justin, I'd Google Rheem Tankless Water Heater Complaints and/or Reviews.

My further suggestion is that you go the 80 gallon route and get an Energy Star unit. I don't think that over the long term the tankless will make your family happy. Remember, it will also have to have annual maintenance. I wish Lawrosa were around and you could get his opinion too. Keep in mind, if you decide to go with a tank type unit, there are new mandated energy requirements going into effect on April 16 and 75 gallon and larger electric water heaters will have heat pumps and a lot of added insulation making them wider and taller. They will also cost quite a bit more.
 
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Old 04-08-15, 10:10 PM
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Thanks for all the replies guys, sorry for taking so long to respond I've been pretty busy.
I don't know what size tank the previous house had but I never recommend anything but an 80 gallon electric water heater. Set it to 140 degrees and have a tempering valve to limit the outgoing water to 125 for safety and you will probably get six showers in a row unless you are like me and run it for 30 minutes with a high volume head.
I believe the previous house had a 50 gallon tank, and my dad drained the silt off the bottom once a year. I don't know if an 80 gallon tank would physically fit in the basement due to how low the ceilings are (1890s house), plus everyone in my family except my dad takes a 20 minute-1 hour shower. We have a head that's attached as well as a detachable sprayer. I know for a fact both of them are run at the same time.

I think Furd is right, an 80 gallon tank type heater would be the best all around bet. I think if I were you, Justin, I'd Google Rheem Tankless Water Heater Complaints and/or Reviews.
I will Google them as soon as I get done this post.
My further suggestion is that you go the 80 gallon route and get an Energy Star unit. I don't think that over the long term the tankless will make your family happy. Remember, it will also have to have annual maintenance. I wish Lawrosa were around and you could get his opinion too. Keep in mind, if you decide to go with a tank type unit, there are new mandated energy requirements going into effect on April 16 and 75 gallon and larger electric water heaters will have heat pumps and a lot of added insulation making them wider and taller. They will also cost quite a bit more.
What will have to be done maintenance wise? I've always assumed they were plug and play...
 
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Old 04-08-15, 11:03 PM
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I guess you have a choice.

IMO

2- 40 gallon electrics
electric tankless
LP tankless

LP would be the way to go over electric IMO...

But whats your electric rate?

Tell us more and we can guide you better.
 
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Old 04-08-15, 11:16 PM
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Eltrons are better because 3-40amp or 3-50 amp in the 36 model.

http://s3.supplyhouse.com/manuals/12..._PROD_FILE.pdf

The only electric tankless I saw work well had 3-40 amp elements.
 
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Old 04-09-15, 01:14 AM
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Tankless heaters need to be "descaled" on a regular schedule based upon the amount of minerals (hardness) in the water. This might be every six months in an extreme condition or maybe only once every two or three years. It will require a pump, hoses, service valves on the heater (an extra often not installed) and a bucket to hold the descaling chemicals. The operation takes from one to maybe three hours during which time the heater is not available for its intended purpose.

Electric instantaneous (tankless) heaters have to use very high watt-density elements to keep their size down and these are particularly sensitive to changes in the water flow. The flow switch "hanging up" for even a couple of seconds after the flow has stopped can cause the elements to burn out I personally would not have a "whole house" instantaneous electric water heater if you gave it to me AND the electricity to operate it. I've seen too many on the scrap heap with melted cases.
 
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Old 04-09-15, 08:54 AM
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What will have to be done maintenance wise? I've always assumed they were plug and play...
What Furd said! In fact, he said it all better than I believe I would have.
 
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Old 04-14-15, 09:38 PM
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Thanks for all the input guys! I will let you know how what we decide on!
 
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Old 04-17-15, 10:30 PM
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Originally Posted by Justin Smith
We have a head that's attached as well as a detachable sprayer. I know for a fact both of them are run at the same time.
Easy trick... get a gallon bucket and fill it for up to one minute, or divide the number of seconds into a minute. Knowing your flow rate is valuable information, because it will disambiguate the appropriate WH. Depending on flow rate, a tank WH that can be shoehorned into your basement will not be usable. if the flow rate is lower rather than higher, it is possible that a 40 gal unit could keep up with re-heat breaks in-between those hour-long showers. Hot water "runs out" not at the WH's capacity, but at a point past that, because the WH will be working during your shower.

As Furd did, I will recommend strongly against a whole-house tankless WH. They were originally intended to be small units that were to be installed at point-of-service, such as under the kitchen sink, on the wall in the bathroom... etc. This would cut drastically the cost of a house's plumbing, as only cold water would be piped through the house.

HOT TIP: Get a dedicated 40(?)gal WH for the shower and set the thermostat at the maximum temperature. This will allow you to get the most out of a smaller unit as you will always be mixing cold in the shower, rather than having all the drawn water be 'hot'.

I do not think any of us here fully recognize the difficulty of your situation as it much more of a struggle to do major work when you aren't starting from scratch, as in new construction. It's like trying to build a house inside a closet!
 
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Old 05-13-15, 09:00 PM
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Ok guys, here's an update so far. Progress on the house has been slow, so this was forgotten about until recently. Anyway, we're going to get a 29KW unit after the house is completely finished. We just replaced the service and are waiting on the power company to hang a new transformer and string a new drop. I couldn't talk my dad into installing a LP tank.
 
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Old 05-13-15, 09:59 PM
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I was wondering what you had decided.
We'll be standing by waiting for the low down on the HOT WATER CAPER Name:  yes.gif
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