rinnai & tagaki

bob young

any comments on these inst. heaters for domestic hot water for residential use. multiple showers ,etc. as opposed to convential 50 gal. gas water heaters.

Bob_9

I've got a TKD-20 Takagi. I put it in place of my std. 50 gallon water tank. It works great with my 1.5 bath house.
If my tub is filling though, it takes all of the flow this unit will provide and using anything else at that time doesn't work well.
We've learned to adapt to the limits of this type of heater.
Also, I don't see the energy savings as touted by ths type of unit.
The best part is that it just keeps giving hot water. We can take 2 showers in a row and my wife can immediately fill the tub.
I don't know about Rinnai.

Alan(CaliforniaRadiant)Forbes

Both

are good products. If you're running out of hot water with the TKD, the TM-1 (Mobius) will provide more. The energy savings is from no standby heat loss; in a typical storage-type water heater no matter how well it's insulated, the water will give up some of its heat to the space; this does not happen with "flash" heaters.

I go to the Rinnai on jobs when there's space to tuck it in its cabinet.

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Brian (Tankless)

Depends where you live, Bob.

Groundwater temp is everything.

I live in the VERY deep south, and haven't needed to sell/ install anything bigger than the T-K1 (165mbtu) except for commercial use.

We very rarely get lower than 70*F cold water, right now, it's at 85*F )the gulf is at 86, check out IVAN.

So I can get 6.9 gpm out of a T-K1, and 9.6 gpm out of a T-M1 Mobius. All happy customers so far.

I'll attach a chart or two.

You'll like them, but choose the right one.

Tankless in "West of IVAN territory".

Bob_9

Yah, I've got all of the technical details about flow and incoming temps. I guess what is deceiving about the claims these MFGs make is in the GPM delivery. If you're down south in a warmer climate then your temp rise is less and you realize full capacity. Up here in northern Illinois capacity drops off quickly when incoming H2O is 40-45degrees.
They also claim energy savings from no standby loss but, from my experience I don't see it.
Before, I kept my 50 gal std. heater hot all the time, my 50,000 btu burner always keeping the tank hot even when no one was home. Now I've got a burner that modulates from 20,000 to 185,000 btu. It seems to me that the thing is always firing at the high end of that rating. I haven't seen a energy savings. I see much the same costs but now I don't run out of hot water.
I like the units but they do have their limitations.

Dave Faust

Takagi Flue Blues

Takagi wants the flue for the TKD-20 to be 25' max. -5' for every 90. They also insist on a class three, single wall stainless steel flue w/ no leaks. The litaturature I saw befor I bought one said that the unit "can be" side wall vented. It takes a lot of figuring to put it out the roof. Also condensation dripping onto the heat exchanger is a no no. With all of the disadvantages of side wall installations, seems like they would be trying to maximize the maximum effective flue length.