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Old 02-13-2010, 05:09 PM   #31
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DIY gas tankless water heater


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Originally Posted by dawktah View Post
however with the units I installed they will restrict their output to match gas supply, but I am sure that is within reason.

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All units will do that.
They can't input anymore gas then they are supplied with.

Of course, they tend to burn dirty, and not supply you with the water capacity they are rated for either.

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Old 02-13-2010, 08:20 PM   #32
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All units will do that.
They can't input anymore gas then they are supplied with.

Of course, they tend to burn dirty, and not supply you with the water capacity they are rated for either.
This is something different. Trying not to say brand , Beings with an R ends with an I, but if it doesn't get enough gas to heat water let's say at 4 gpm, it will constrict the water flow to let's say 3 gpm where the gas its getting will allow it to heat to set temp. Don't ask how I found this out...
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Old 02-13-2010, 09:49 PM   #33
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LOL...

But you still end up with the same problem. Not enough hot water.
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Old 02-24-2010, 09:52 PM   #34
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DIY gas tankless water heater


I have two friends who have installed begins with "R" and ends with "I" tankless hot water heaters and have spring, summer, fall, and this winter under their belt. One guy used the big one as he has a 5-bedroom, 3 full bath, 2 powder rooms and four kids. Never runs out of hot water. The second guy has a smaller 4-bedroom home with 3 kids and 2 full baths, 2 powder rooms. Again, no problems with hot water and I mention kids because their laundry load is probably double ours. My kids are out of the house and we have a 4-bedroom 3 full baths plus a powder room. We currently have a 50 gallon gas HWH [14 years old] and its definitely on its way out, so I'll probably decide within the next month. I would do the conventional one myself, but the tankless I'm a little hesitant with.

I should also note the tax credit FWIW, and both these guys are actually claiming their gas bills have gone down noticeably since the install.

Whats the deal with the exhaust stack anyway? Looks like you can't use ordinary galvanized pipe, have to use SS special stuff. Fortunately, I think the gas service pipe will be adequate, but I'll have that checked to make sure... gas is not something I like messing with.
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Old 02-24-2010, 10:49 PM   #35
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Ask them about sandwhiching.

people get use to it. But it s PITA at first.
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Old 02-25-2010, 05:37 PM   #36
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Ask them about sandwhiching.

people get use to it. But it s PITA at first.
Oooh, the dreaded cold water sandwich. My wife and I had issues with it initially but now have changed our habits to prevent it. Since we have the heat running off of the R___i we don't experience it all all. I guess it will come back in the Spring. As long as you leave faucet off less than 60 seconds it seems to avoid it. Honestly it's only an issue when showering, no other use will it be an issue. On a scale advantages far outweigh cold water sandwich as it can be avoided by habit. Also, distance to units.
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Old 04-14-2010, 06:20 PM   #37
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Resureccting this thread. Wanted to know if you've installed the tankless and if so, how it went?

I'm in the same boat. I also live in Socal. I am currently remodeling my master bathroom and have purchased a R______I tankless and plan on installing it myself. The tankless will only be supplying our two bathrooms upstairs. The rest of the house... kitchen, laundry, bathrooms downstairs will be serviced by an existing 50g tanked heater. The reason I am installing the tankless is because I the 50g won't be able to supply enough hot water for my new multi-head shower for longer than 8 min. No use in going through all the trouble of designing a nice spa like shower if I can't stay in there longer than 8 min.

I did have a question about the gas line. The unit I have is 199K BTU's. I will be placing it in the attic directly above the two bathrooms. The closest gas line is the one supplying my furnance (80K BTUs). The gas line to the furnace is a 1" line for the first 25' from the meter and then reduces to a 3/4" for another 15'.

The tankless will be a total of 60' feet from the meter. If my calcs are correct, a 60' run @ 1" would be enough to supply the tankless. Could I place a tee on the 1" line supplying my furnance, continueing the 1" to the tankless and branch off the 3/4" to the runance?

Hope that question makes sense.
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Old 04-14-2010, 07:58 PM   #38
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No. The gas line must be sized for the longest total run. And include all appliances between the furtherest one and the meter.

So you need to add your existing water heater, and furnace to the tankless.
So if your water heater is 36,000BTUs. furnace 80,000 BTUs, and tankless 199,000 BTUs.
The line starting at the meter must be 1" until one of the appliances are feed.
Then you subtract that and have your new line length. Say its your water heater at 20'.

You still need 279,000 BTU's for the next 40'. 1" will cover that for the next 40'.

Use the .3" pressure drop. Not the .5" pressure drop. In winter. The gas pressure from your meter can drop by 2". And your gas valves will either sing. Or the burners will go out.

How much hot water will be used as part of the 6 GPM shower head?
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Old 04-15-2010, 11:35 AM   #39
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Beenthere....

Thanks for the reply. I think I get what you're saying. The furthest appliance on this line would be the Tankless, which is 60' from the meter. From the Tankless to the Meter I also have the Furnance which is 80K BTUs. So if I add the two together, I need to supply 280K BTU for 60'. Looking at pipe sizing charts, I need a 1 1/4" line to supply that amount of gas. So for the first 35' or so, I need to run a trunk line of 1 1/4". Then I can branch off to the furnance and tankless. I would then run a line of about 10' to the furnance in 3/4" and another 25' line in 1" to the tankless.

Does that sound correct to you?
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Old 04-15-2010, 01:27 PM   #40
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Quote:
Originally Posted by anonymouscuban View Post
Resureccting this thread. Wanted to know if you've installed the tankless and if so, how it went?

I'm in the same boat. I also live in Socal. I am currently remodeling my master bathroom and have purchased a R______I tankless and plan on installing it myself. The tankless will only be supplying our two bathrooms upstairs. The rest of the house... kitchen, laundry, bathrooms downstairs will be serviced by an existing 50g tanked heater. The reason I am installing the tankless is because I the 50g won't be able to supply enough hot water for my new multi-head shower for longer than 8 min. No use in going through all the trouble of designing a nice spa like shower if I can't stay in there longer than 8 min.

I did have a question about the gas line. The unit I have is 199K BTU's. I will be placing it in the attic directly above the two bathrooms. The closest gas line is the one supplying my furnance (80K BTUs). The gas line to the furnace is a 1" line for the first 25' from the meter and then reduces to a 3/4" for another 15'.

The tankless will be a total of 60' feet from the meter. If my calcs are correct, a 60' run @ 1" would be enough to supply the tankless. Could I place a tee on the 1" line supplying my furnance, continueing the 1" to the tankless and branch off the 3/4" to the runance?

Hope that question makes sense.
Can I ask which spa shower you have chosen? I am planning on the Kohler DTV II, this is very nice since you turn it on and it runs all shower heads until they reach set temp then shuts them off and leaves one running perfect for tankless.
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Old 04-15-2010, 04:28 PM   #41
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Can I ask which spa shower you have chosen? I am planning on the Kohler DTV II, this is very nice since you turn it on and it runs all shower heads until they reach set temp then shuts them off and leaves one running perfect for tankless.
Wow... that thing is pretty cool but much more techy than what I am doing. I am installing Grohe products. 3 body sprays, a large rain shower head and a shower bar. I was going to do steam but my wife opted against it. We don't think we will use it enough to justify the extra expense. Instead, we opted for radiant floor heating and heated towel rack.
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Old 04-15-2010, 05:04 PM   #42
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Beenthere....

Thanks for the reply. I think I get what you're saying. The furthest appliance on this line would be the Tankless, which is 60' from the meter. From the Tankless to the Meter I also have the Furnance which is 80K BTUs. So if I add the two together, I need to supply 280K BTU for 60'. Looking at pipe sizing charts, I need a 1 1/4" line to supply that amount of gas. So for the first 35' or so, I need to run a trunk line of 1 1/4". Then I can branch off to the furnance and tankless. I would then run a line of about 10' to the furnance in 3/4" and another 25' line in 1" to the tankless.

Does that sound correct to you?
Yep, sounds like you on the right track now.
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Old 12-19-2010, 01:01 PM   #43
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Thought I'd update this now that I've got real world experience in my own house. Had the R94LS installed 6 months ago and couldn't be happier. Also got a $700.00 check from my gas company as part of the energy rebate, plus I will get $1500 tax credit when I do the taxes. All that aside, we have not had any issues with two or three showers going and laundry at the same time. Most people turn on the water, stick their hand in to check temp... and get in when they feel its comfortable. I have never had a cold water burst or "sandwich" in the 6 months that I've been using it and I don't wait that long to get into the shower.

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