tankless water heater questions
#21
I think tax rebates ended in '16?
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#22
Gas line sizing isn't done by any form of pressure test.  Its a series of calculations applied to the job and then used with a set of tables.  If you can supply a sketch with distance measurements from meter to appliances and the appliance gas consumption numbers, I'll do a sizing for you.  As you've noticed there's a myriad of venting systems used and each appliance has its limitations on the lengths to the venting permitted.  That info can normally be found in an online copy of the install manual for a unit you're interested in.
Blackhat

Bad experiences come from poor decisions. So do good stories. 


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#23
Much higher repair factor as opposed to a standard WH. Cost and time, The coils need to be flushed on a regular schedule.


Al
I turn, therefore I am!
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#24
Thanks blackhat! Out for a couple of days but will get that once I'm home. I assume there will be a label on the furnace telling me about it's requirement?
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#25
There should be a manufacturer's data tag with it.
Blackhat

Bad experiences come from poor decisions. So do good stories. 


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#26
I could never make the $'s work for a tankless system as a retrofit.  Maybe it makes sense for new construction if you have needs for unlimited hot water, but I don't see it as an economic option for the average household, and definitely not mine.  Gas is pretty cheap were I live; my average gas bill for hot water is less than $20/month.  I'd never pay for any savings a tankless system might yield over it's life.  Why is it you want one?  

John
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#27
(02-02-2018, 04:25 PM)JosephP Wrote: It probably won't pay for itself.  But it will make a lot more room in the utility room...  And it would give endless hot water.  Not a frequent problem... actually changing that may cost us more in water and using more hot water than we otherwise would.  Not a math problem - a fee hundred over 10-15 years for a lot of convenience isn't much $.

My initial interest was for money savings and environmental footprint.  Once I was wrapping my head around the total setup, I realized I could store two bikes in the space a tank heater stood.  It made me really want to make it work.

I have been looking at putting a recirculation pump on my plumbing system.  The return line is already installed.  Instead of installing one with a set timer I was contemplating some sort of smart switch or outlet on the pump.  That way I can program it from my computer or phone or use a voice controlled app with Alexa or Google Home.

The tap water is so cold here and it takes a long time to reach most of the faucets in my home.  I just end up washing my hands in cold water.
A carpenter's house is never done.
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#28
(02-02-2018, 10:54 PM)blackhat Wrote: Gas line sizing isn't done by any form of pressure test.  Its a series of calculations applied to the job and then used with a set of tables.  If you can supply a sketch with distance measurements from meter to appliances and the appliance gas consumption numbers, I'll do a sizing for you.  As you've noticed there's a myriad of venting systems used and each appliance has its limitations on the lengths to the venting permitted.  That info can normally be found in an online copy of the install manual for a unit you're interested in.

So here is what I found:
Meter says "175 CFH @ 1/2 Diff."  and "5 PSI W.P."

Line coming out of meter into house is 1.35" OD (assuming that is 1"...)

I didn't go into the crawl space, but can if need be to confirm sizing or where it decreases size down there.  Measuring across the floor, there is right at 50' of pipe by the time it goes down into the crawl space; over; across; then back up through the utility room floor.

That should require four 90o turns (I can't imagine they'd have used any more).  There would be another three 90s to get to where I'd hang the heater.

It is 3/4" pipe where it comes out of the floor.  There is a 3/4 x 1/2 x 1/2 Tee that takes gas from that pipe to the furnace and current heater.  Would be no problem if I need to change that to a 3/4 x 3/4 x 1/2 Tee.

The furnace (Rheem model RGLG-10EBRJR - installed 1993) says it is 100,000 BTU/hr.  (Of note...1993.  I'm assuming that furnace will not outlast our next water heater.  It heats the house well, so we'd go with whatever is an "equal" replacement today.  With higher efficiency is that the same or lower BTU???)

No other gas appliances.

Appreciate any advice you can offer!!!
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#29
Have the gas company or a plumber do the piping.

Do not do this yourself.

BTW, I'm with John got several estimates the numbers just didn't work.
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#30
If I need new gas pipes it is probably off of the table. I'm trying to figure out if it is an option given what I have now...
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