There are numerous factors to consider, but yes they can be installed for "whole house". I wrote an article that may shed some light on the subject for you http://designsbybsb.com/blog/2011/12/hot-water/
I have wanted one or more in my house for so long, but the cost is outrageous and I really do not have a place to put one
I just put in a Rinnai. Yes, they can definitely supply a whole house and, yes, they are expensive. But my local gas company gives a $600 rebate for installing one.
In short, they are worth it for some people & yes they can be used for the whole house if sized properly as Becky mentions
As for improved energy efficiency, don't expect to see savings as in most cases people buy them for the "endless" hot water.
There are a few caveats - do not buy an electric version & be prepared to have to increase the size of your gas line. There also is the dreaded cold water slug that can occur when the call for heat is stopped and then started back up again (the shorter the plumbing runs the less an issue this is)
Just don't do it, these units are crap, just put $200 in to one, had no how hater for over two weeks, tore it out just yesterday and bought the old norm tank. Do your research, mine was a bosch......
That should have been $2000.....
I thought about years ago for my place but our water main is not buried very deep and the water in the winter hovers just above freezing..and sometimes it actually does freeze. These units can only "boost" the temp up by 40 to 50 degrees at best. so for us that would mean our hot would only be 75 to 85 degrees during the winter.
If you inlet temp is in the 50 to 60 range then it is a viable option. The savings will depend on your personal use habits, Low volume users typically do not see an advantage financially or in supply delivery.
My sister has put two in, one on each floor. She loves hers. She lives on an island and water is expensive. My Aunt @Kay Cass also installed one not too long ago. I tagged her so she can weight in.
We have a tankless water heater now for about 4 years. Love it! It takes care of the whole house! I think it is def worth the money and you get a tax break too.
We got a gas Rinnai and yes it did cost much more (about $5000) but it is worth it!!!!! Most of the money was labor because we have a stone basement and you have to put in an exhaust pipe to the outside which was pretty difficult. The unit itself was about $2000-$2500. We have a very large home and our unit heats the shower and runs the DW at the same time with no problem. We have never had a problem and have saved a significant amount on water because we get hot water in about 45 seconds so we do not need to let the water run full out for 3 minutes before hot water appears.
We are a family of 3 and do a lot of laundry plus 3 showers per day. We have seen significant savings on our energy bill and we never run out of hot water! What's not to like?
I live in Titusville, FL. Our weather would be comparable. I had a Rheem tankless water heater installed about 4 years ago. Works great, I had mine installed on the outside of my garage, therefore I did not have to have it vented. It would have cost a lot more to install inside, because of the expense to vent from inside, when I purchased mine, the plumber charged me $600. to install outside. The materials needed to install inside would have cost more than the heater. Fla. City Gas is our local gas company. I did get a $500. rebate. Bills in summer run about $l6. to $20., winter about $50. to $60, my house is all gas, except for AC and washer.
Yes, we installed a Rennai. We love it. Our gas bill went down. I like the extra space it gives us in the garage, and I like not having a tank of water that we are keeping hot all the time. One is very adequate for a house. Remember, they are "tankless" not "instant". If you are expecting instant hot water you will be disappointed. One thing I don't like about them is you can only turn them up to 140 degrees which isn't hot enough (in my opinion) for washing dishes or for laundry.
I put in a small whole house electric Bosh. It works great and my bill went up about $5-10 per month. The trick is to use efficient fixtures and do not take long showers.
There are two types of tankless systems. And two type of energy sources to operate.
Energy is either all electrical. or electrical and gas.
All electrical types are expensive to operate if your talking about a whole house type system and not a point of use as you would fined under a sink. They often require a 150 to 200 amp panel for a whole house. Gas is much cheaper to operate.
As far as types.
You have an on demand hot water heater that is sort of tankless. And you have a Combi system that provides both your domestic out of the sink, and your hot water to heat your rooms.
These systems run from around $1,500 to seven or eight grand depending upon the size, number of zones and where its mounted.
However, there are some great rebate programs offered to install these systems. In our state there is a $5,000 rebate and 0% loan for 10 years on upgrades that include energy upgrades in insulation as well. So be sure to check your Energy Star Program in your state to find out more about them and what is offered.
Boilers all on demand can be set to deliver as much hot water you want as far as temp. This Combi unit outputs 180 degrees on the heat side and we have the domestic side delivering around 115.
As far as being worth it, Yes every penny. I would suggest you consider this method of heat and domestic water.
Hi @Jeannine M! Still contemplating on whether you should get a tankless water heater? We've got 5 reasons why you'll love it! Hope this helps with your decision making...
We have a Rennai. And love it! It cost about $1800 and is propane fired. We were able to buy it from the gas company for an additional payment added to our gas bill. Plus we got about $1000 back in rebates and energy saving credits. Well worth the expense. Our propane bill has dropped by almost half. And I might add, we cook and use propane fireplace inserts (2) for heat. It will pay for itself much soon than anticipated. I only wish we had one when my son's were teenagers.
My brothers put my Rennai in last year (one is an electrician) and I love it. No more worrying about the water tank leaking or where can I get one small enough to fit in the closet and still give me enough hot water to shower. Yes it takes a bit for the water to get hot at the faucet, but my water, electric and gas bills have not gone up. In fact, the gas bill has gone down. Yes, I did pay over $1,000 for it but it was well worth it. Larger ones for more bathrooms do cost more.
We put one in several years ago and we really love it. The only down side for me is the maximum temperature is only 140 degrees. I think that is a government environmental restriction. I like to have the water in the dishwasher and washing machine hotter than that to disinfect and to get clothes clean. But we keep ours set on 120 for normal use and don't have to add cold to the mix. I turn it up to 140 for the dishwasher and washing machine.
I love my combi-boiler. It runs the heating and the hot water. In the warmer months I switch it to water only. Turn on the tap and you get as much hot water as you want without ever worrying about how much is in a tank. I'd never use anything else!
We love ours!