Tankless water heater review

[desimulacra]

 I searched and found nothing on this in the forum. Anyone aware of Krystal Planet?
http://www.krystal-planet.com/docs/pdfs/Tankless%20Hot%20Water%20Heater%20Brochure.pdf

What do you think?

[MountainDon]

Their specs are missing one important piece of data. That is the temperature rise. Any tankless heater has a limit on temperature rise and flow rate. Have a look at the specs on a name brand like Bosch or Rinnai and you will see what I mean.


The temperature of the incoming water in winter is what should be used for determining capacity. Around here the winter water is very cold compared to summer as our cities storage tanks are above ground.

The flow rate they give, 2.5 gpm, would be enough for one shower, or washing machine, etc. at a time, in my opinion.

[davidj]

From following tankless water heaters for a while, my take on it is that around 130K BTU/hr is good for a single point of use and moderate temperatures and 200K BTU/hr is really the best bet with cold intake or two fixtures at once or if you want a luxurious shower.  We've had two cheapo Eccotemp outdoor propane units - the 30K BTU/hr device struggled to do a light shower except in Summer (but it was only $130) and the 60K unit ($200) produced a reasonable shower Spring/Summer/Fall but still had a low-flow feel to it.  The Krstal Planet unit is about 12KW, around 40K BTU/hr.  I.e. you're gonna be pushing it to just get a light shower anytime but Summer.

[rwanders]

I have a 199k btu Rennai at my cabin which has 38 degree input water----it does quite well for a hot shower and kitchen faucet at the same time. I believe a 40k btu unit would be next to useless unless you've tapped into a hot spring for your water supply. Unfortunately, you can have cheap or hot but not both in the same package. 

[devildog]

It didnt make this top ten
http://reviewguider.com/tankless+water+heaters/guide/top+tankless+water+brands
Darrell

[glenn kangiser]

Looks like it needs a 60 amp 220v breaker.  It may increase the size of electric service you need.

[davidj]

I think the temperature rise for this unit at 2.5GPM is:

12000 [joules/second] * 60/(2.5*3.5) [seconds/liter]  / 4200 [joules/L/C] * 9/5 [F/C] = 35F

This assumes perfect efficiency, but it's probably more like 80-90%, so say 30F temp rise.  So if you want a 105F shower, you need a 75F water supply at 2.5GPM!  Or, more realistically, you have a 40F water supply and more like a 1GPM shower, which is better than nothing, but only just.  It does have the advantage that it might remind you of a holiday in Southern Europe 30 years ago when you were staying in $5/night rooms - basically you're copying how they did it then!

[MountainDon]

remind you of a holiday in Southern Europe 30 years ago when you were staying in $5/night rooms - basically you're copying how they did it then!

That reminds me of campgrounds in Europe back in the early 70's. Some had free showers.  That was with cold water only.  Try that in November.    Hot water was obtained via a coin operated meter and a rush to finish before the meter went "ka-chunk" and the hot water ceased flowing.  

[desimulacra]

Thanks again. Intrigued by the price but I understand much more now. I think I might go with propane to keep service size down and heat up.

[builderboy]

I've got a German made Steibel Eltron electric tankless heating my 360 sq ft floor just fine. My plumber had trouble with the temp rise in winter for domestic so I went much cheaper with a 25 gal elec. tank. Works fine for 2 persons.