Replies

1. 
   Scott | Jul 16, 2008 04:47am | #1

   Hi. Welcome.

   Do a search for "tankless". You'll find lots of introductory stuff.

   Scott.

   Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”

2. 
   Clewless1 | Jul 22, 2008 03:40pm | #2

   I've read a lot of talk about tankless WH, now and done a lot of analysis over the years about water heaters. My experience is in energy efficiency. For most/many applications, IMO, the tankless is NOT the way to go ... that is if you occupy your house w/ a normal/typical lifestyle

   Tankless equipment is much more expensive due to larger capacities and other requirements (someone mentioned spending a small fortune on 7 ft of stainless flue for his gas fired unit).

   The efficiencies are no different, really. The combustion or heating efficiency ... you can buy the same efficiency in a tank style (90+).

   Tankless buys you not having to maintain temp in the tank ... that is ... you save the heat loss of the tank ... which is very small (assuming the tank is well insulated as most are these days). If you use your own fair share of hot water ... this becomes a small issue. Tankless equipment IMO is being WAY oversold these days ... claims of huge energy savings, etc. ... You run a tankless side by side w/ a tank style in a normal home and the tankless will use less energy ... about 1/10 of 1% less. Big woo. Tank style survives a power outage longer than tankless.

   That's a tankless point of view. Unless you have a good reason for needing it for other reasons, I wouldn't necessarily do it. There are other discussions as well that address tankless.

   I just did a radiant slab using a combined domestic water heater w/ a [built in] HX for the radiant slab ... so far, so good, but I've not had large hot water demands put on it. It's like only an 80 gallon tank (although I left room for a second tank just in case I needed to ad capacity) ... the application was house/apartment combo.

    

3. 
   NRTRob | Jul 22, 2008 05:29pm | #3

   it's pretty uncommon for tankless heaters to be a good heating source, and they aren't that much better for most people for DHW either.

   generally, a typical family in a typical house in a heating climate would be better served with a mod/con boiler and an indirect tank heated by the boiler.

   -------------------------------------
   -=Northeast Radiant Technology=-
   Radiant Design, Consultation, Parts Supply
   http://www.NRTradiant.com
4. 
   BillHoover | Jul 22, 2008 08:41pm | #4

   Before you consider a tankless for hydronic heating, consider what the return temperature will be and see if the tankless can tolerate that temperature.  If the return temperature is too high, the tankless will not be able to turn down the burner enough to keep it from over heating. 

   There are better alternatives.  AOSmith makes a 96% efficient, power direct vented 50 gal water heater which has side taps for hydronic heating.  This unit will cost about what a tankless unit will cost (installed) and it will be much higher in efficiency.

    

   Bill