I am building a log home in New Brinswick Canada and looking at what to use for a water heater. My plans where to use a tankless water heater but I came across some condensing wall mounted boilers at a home show in Toronto that where suppose to be more effecient.

What is the differance between tankless and condensing and which is better. Could anyone tell me what models of either they have had experience in that are good or I should stay away from.  I have been told that there are problems with some running on propane.

tyr2005;

I have a tankess propane system in my home but, would never use one aqain

Are you talking about domestic HW, or radiant heat?

sc

Please tell us what you are using it for and why you would not use it again!

Thanks

The system would be used for domestic heat only. I was looking at Hydronic Radaint heat, but I am looking at low voltage electric. There is a lot of talk about condensing boilers that are wall mounted and provide on demad hot water. Are these better then tankless and what models look god or should I stay away from.

glen;

is used for domestic water, It is a Ranai unit. It does not work properly at 108 to 110 or 120 degrees, it must stay set @ 115 . At 120 it is always fighting with the anti-scald shower valve and shuts down for a nice cold shower. At lower temps it just goes cold intermitently. Most units will not work at all if you want to just run a small flow (like when shaving) it needs to go full blast. because unit will not come on until it senses a minimum amount of flow.
Dealer and Ranai were not responsive while under warramty , until I embarassed their reps at the IBS show 2 years ago

What is a good tankless system that won't leave you freezing in the shower? I have a Junkers tankless natural gas water heater where I live now and it does that to you in the summer time. When the water from the mains is warm it shuts the water heater off and you're left standing in the shower for 15 minutes with shampoo in your hair if you want a hot shower. Would love to go tankless when I build but I also want a nice long hot shower no matter what the temp is from the mains.

Jelly;
Yours is doing the same thing as mine, the showers anti-scald valve is closing hot off and the tankless flow switch thinks you no longer need hot water
 try setting the temp lower, that way the anti scald won't shut call for hot off

Is anyone having a positive experience with a tankless water heater? If so, what brands work the best?

I have an electric tankless unit with NO problems. The make an model I have is a Seisco Microtherm RA-28. I have had this unit in my house for almost ten years now. I just recently added a solar collector to pre heat incoming water to the unit however. This will boost my temperature rise and available GPM. As a plumbing contractor, I am very comfortable with this electric tankless unit.You do need sufficient power , as draw is high. Remember, it only makes heated water when you open a tap. As for condensing boilers, they are much more efficient at making hot water, but only into a storage tank. I typically use this combination with a radiant floor system . If your making domestic hot water only, it may not be worth the added expenses. Most gas tankless units are about 70% to 80% eff. when running. A condensing boiler , thats condensing are around 95% to 98% eff. A condensing boiler in DHW mode wants to make hot water quickly, this is done by having 190* plus water going into a indirect heat exchanger. At those temperatures, there is not much condensing, so you loose some efficiencies there. an electric unit is about 100%, at the unit. Electrical generation is another topic : ) Also , add a thermostatic mixing valve to the outlet side of the tankless, this may help with those temperature fluctuations.

We used a 6.2g Noritz for DHW in an upscale ICF home, and there has been no issues, else I would have been called on it!

On Propane.

condensing boiler= hot air in chimney transfers its heat to the chimney pipe which transfers heat to the air around the chimney pipe.  If the "hot air" in the chimney transfers too much heat the hot air (in the chimney) will be cooled to the point that ANY moisture vapor in the flue gas will condense.  So-- condensing boilers transfer SO MUCH heat that their combustion gases condense, and because they are so cool the vent gas has trouble leaving the flue. 

tankless hot water heater= a smaller/ less efficient /less volume  "NON condensing" boiler.

I had the same question myself.  Actually had to speak to hydronic technicians.  A "small" boiler is a very big tankless.  If a tankless was condensing and had better heat transfer elements than it would be called a boiler.

**********Go with the boiler.  More efficient and they handle variable load fluctuations better.  One boiler can wash the dishes, wash the clothes, hot shower, and hydronic heat the floor ALL @ the same time.  Tankless are generally one tank=one task.