We have a Bosch/Aqua Star tankless water heater in our home and enjoy it very much. There are a few things for you to consider.
Our unit is 5 years old, works beautifully, and provides endless hot water. 1.How many people will live in your new home? /want to use hot water at the same time. 2.What is the distance from the water heater to faucets? 3.Electric or gas?
We are a design/build firm and have installed several units. Do NOT expect this unit to provide hot water if you are turning it on and off frequently. When my friends come over to do canning with me, they want save water so they turn the water on and off frequently. I'm sure they are saving water but they are not getting any hot water!
Answer to question #1: How many people will live in the house? / use hot water at the same time. You'll need to have either a larger unit or multiple units to accommodate multiple users at the same time. Check the flow. Our unit is small and we don't have a lot of water pressure (we're on a well at 7 gal/minute)so we don't get (hot) water in the kitchen and the bath at the same time.
2.Distance from water heater to faucets. A tankless water heater is not the same a instant hot water. Instant hot water can only be acheived by placing a unit such as HOT TAP under your sink. It has a little tank and it heats water rapidly. Otherwise, you will have cold water until the hot water reaches it's destination. But this would be the case for a traditional water heater. A tankless water heater is ENDLESS hot water, not INSTANT.
3. Electric or gas? We have installed several gas units and one electric unit for our clients. We used the electric only because gas was not available. They both work nicely and they both will need to be tweaked for temperature.
Paulo - We used a demand water heater in rebuilding a 1963 Avion travel trailer. It worked so well we are planning on using this style in our new home as well. In Europe demand water heaters in homes are very common and I loved them. Check online for demand water heaters for the capacity you need. We plan on using 2 - one for upstairs and one for downstairs. In addition, we're putting an in-ground pool in our basement, so we're researching options for heating the pool as well.
Thanks for the reply, but the real question is... Can one get instant hot water AND on demand(endless) at the same time. My in-laws have instant hot water without the use of one of the little pumps currently sold in the market. His house was piped in a loop and his water heater is in the basement. Hot water rises so the pipes are simply an extension of his tank. If i install a tankless in the basement will I get the same result? What if I install a small tank in front of the tankless water heather.
No (and yes) you will not get instant hot water AND be able to use an on demand water heater. Not if you are using the on demand system for what it is designed for....ie. Instant hot water at your folks is designed in a loop off a normal tank type water heater which is designed to keep ALL the water hot ALL the time.(Thus wasting non-renewable fuels I assume) Normally a small pump is put in the loop to keep the water circulating slowly, so in fact the heater comes on more often to keep the water hot. As the water travels throughout the pipes it cools along the way. (another waste of energy)
In an on demand system, the point is NOT to heat the water until it is actually needed, thereby lessening your utilities AND YOUR ECOLOGICAL FOOTPRINT ON THIS EARTH. America uses 5X more fossil fuels per capita then any other nation on this earth.
Yes, you could use the on demand system in a loop setup with a circulating pump, but that would be defeating the whole point. The on demand system would come on more often trying to keep the water hot because it cools on it's journey through the pipes. I am not aware of any energy use studies of combining the 2 systems, but that doesn't mean there isn't one. You could probably get a plumbing & heating design engineer to work up the heat loss vs energy savings for circuling vs noncirculating w/ use of on demand system for you. Regardless of which system you use, I believe insulating hot water pipes throughout our homes DURING construction or refit is too often ignored. That will certainly help somewhat. We did it in our basement which is semi finished but is heated and saw a savings right away. Good luck.
Your question is interesting becuase on-demand hot water heaters only heat water on demand not continuously. Considerations for sizing is total volume needed at peak hours, cut also the length of the run. Most homes are plumbed with copper lines, which if not insulated will allow great loss of heat. Insulating your water lines would be beneficial. Another help might be a type of recirculating pump manufactured by Metlund industries. I have one of these in my home and we love it. Their web site is http://www.gothotwater.com/. When utilizing on-demand water heaters it is a good idea to have one just for the kitchen/laundry room area, and another for each bathroom and another for your hot tub. Hope you find this useful. Doug Wallingford www.wallingfordsales.com
one thing i did for a client was to add a stainless steel holding tank w/ after heaters and circulated water back to heater.a 110v thermostate on tank regulated temp in tank turning on pump as needed. Don't try this w/ borsch aquastar heaters as they need a delta p of at least 2# to activate gas motor valve.find a takagie or other brand.?s to tboyla21963@peoplepc.com
This message has been edited. Last edited by: trb,
What did you decide to do with your tankless water heater situation? Did you make the switch?
Anthony
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Posts: 2 | Location: California | Registered: 25 May 2007
If you have not made the switch yet I'd suggest you also do a detailed needs analysis of your hot water requirements before purchasing anything. Here are a couple sites that have calculators or list tankless manufacturers:
if the codes are like they are in our home town you will have to have a larger air vent to this heater. Also you might want to consider more than one heater. they come in several sizes and some are small enough to go under the kitchen sink with no problem. one could also be put in the bathroom itself as ours is. They DO save MONEY on your ut bill. this way you have HOT water When and Where!
I am also interested in tankless hot water heating. I have heard differing comments about how much energy it saves.
1. It is more costly to run tankless heaters using gas. I tried to get some way to find an equation that takes gives the equivalent of one killowatt of electricty to the unit of energy measurement for gas to determine the difference. I would also need to find how much gas it uses to heat for a certain time of usage in order to compare it as well as table for gas prices. However, a good independent research paper comparing the two would be good. So I am still looking.
2. How difficult is it to run an electrical line that would be able to power these tankless heaters? I know for the kitchen I may be able to use 120, but for the whole house tankless unit, I would need a 240 connection. I also believe I need to look at changing some things in my fuse box. All of this I got from laypeople chats. Someone also said find out what electrical capacity is available from the electrical lines running to my house. However, it would seem if I have an oven and a clothes dryer that run off of higher voltages, the electrical capacity provided by the electrical lines running into my home is already there and would support a tankless whole house unit.
The way my house is situated, the one bathroom is 10 feet from the place the tankless unit would be from and the other is 20 feet from it. The washer is about 10 feet from it too.
My kitchen though it farther plus I may be using hot water in there while the bath is being used. So I want a seperate one for that for my dishwasher and kitchen sink.
Thanks for any info. I hope my questions and writing were not too tortuous.
