Proportional NG tankless HW heaters?

[William P.N. Smith]

I'm facing a $320 repair to a (4-year-old?) 70-gallon DHW heater, and
am looking at other options. 8*| My plumber thinks that a tankless
proportional heater will work for us, does anyone have experience with
manufacturers/brands that they could share? Must be proportional, as
we can go from one sink for handwashing to two showers, dishwasher,
and clothes washer simultaneously.

Thanks!

 

[News]

I'm facing a $320 repair to a (4-year-old?) 70-gallon DHW heater, and
am looking at other options. 8*| My plumber thinks that a tankless
proportional heater will work for us, does anyone have experience with
manufacturers/brands that they could share? Must be proportional, as
we can go from one sink for handwashing to two showers, dishwasher,
and clothes washer simultaneously.

Thanks!

You need large rated one. One that can cope with two showers and fill a bath
quickly. Undersize it and you will regret.

 

[m Ransley]

You need a big unit I have a 117000btu Bosch, you will need a 180000
btu unit. You have Takagi, Rinnai and others. Rinnai is rated at 88%
efficient , 5% more than takagi. Also Rinnai heats to temp not temp rise
as my Bosch does. Look at the option of remote thermostat. My Bosch
cost apx 1100 instaled but after seeing its use I will get a 4-5 yr
payback. You will spend allot , maybe 1300 instaled but you will be
happy. Also Tankless don`t loose efficiency over the years as tanks do
and last 3 times longer-no tank to rust out. You will need a major
upgrade in gas line 180000 Btu is more than many furnaces. Im
completely happy going tankless , my summer gas bills inluding cooking
all food and gas dryer are 6-7 $ US @1.00 a therm+. Yes you will pay
upfront, but it is the only way to save all year on Gas.

 

[m Ransley]

Rinnai and others go automaticaly from a low of apx. 20000-180000 btu
depending on water demand- gpm. They are rated in GPM and temp rise,
your most important numbers.

For me my incomming gets to 34f in winter then 73 in summer so your
incomming water temp low Now is inportant in your calculation, if you
live where it is warm in winter and incomming is higher it is less of a
consideration. My 117000 btu is never set to high even with 34F
incomming but I have 1 shower, It is getting warmer so now my incomming
is 40f , Midwest US. Check you incomming temp now and add a few degrees
drop if your local temps are moderating as spring is near.

The 180000 btu , 88% efficient Rinnai will give more HW than a
180000 Btu 83% Takagi.

Don`t guess on the gas line size, a Manometer must be used along
with running ALL gas apliances at testing or you risk undersizing the NG
line and not getting the full potential off your new Tankless.

Another good idea is give the tankless a drain and shutoff and a
shutoff at the output and a second drain valve where in the future you
can pour in CLR to flush the unit. They say it is not necessary but hard
water is hard water.