Water Heaters - tankless Qs
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Sip
11-25-08, 05:56 PM
Hi all,
I have a Bosch 2400E-NG. I bought it a while ago during a remodel and am now getting around to installing it.
So I've run into some issues. My gas meter says it's a 5psi unit. The Bosch instructions say the unit requires a 3/4" gas line to supply gas to the unit. From the gas meter, a 3/4" or 1 inch supply line comes out to a connector and bumps up to a 1.25 or a 1.5" pipe. That then feeds to a 1/2" line that fed the current tank water heater. Total distance of the 1/2 line will be about 20 feet.
So my problem is, where the larger pipe reduces to the 1/2" is covered in finished drywall. So i cannot easily replace that T with a larger T.
What i am wondering is: Can I use the existing 1/2" for the 5' length it runs and then come enlarge to a 3/4" pipe for the remainder of the run? and secondly, the unit is designed for 2-3 showers simultaneously and my 2 bathroom house will almost never see 2 showers running at the same time. Given this, do i really need to be able to provide gas for the 175,000 btus the unit kicks out at wide open? I know the 1/2" run for 5' is a pretty big restriction, but by coming out to a less restrictive 3/4" will i minimize pressure loss?
Please don't tell me this is just one of those things i have to install and measure at the units pressure test port.
I have a Bosch 2400E-NG. I bought it a while ago during a remodel and am now getting around to installing it.
So I've run into some issues. My gas meter says it's a 5psi unit. The Bosch instructions say the unit requires a 3/4" gas line to supply gas to the unit. From the gas meter, a 3/4" or 1 inch supply line comes out to a connector and bumps up to a 1.25 or a 1.5" pipe. That then feeds to a 1/2" line that fed the current tank water heater. Total distance of the 1/2 line will be about 20 feet.
So my problem is, where the larger pipe reduces to the 1/2" is covered in finished drywall. So i cannot easily replace that T with a larger T.
What i am wondering is: Can I use the existing 1/2" for the 5' length it runs and then come enlarge to a 3/4" pipe for the remainder of the run? and secondly, the unit is designed for 2-3 showers simultaneously and my 2 bathroom house will almost never see 2 showers running at the same time. Given this, do i really need to be able to provide gas for the 175,000 btus the unit kicks out at wide open? I know the 1/2" run for 5' is a pretty big restriction, but by coming out to a less restrictive 3/4" will i minimize pressure loss?
Please don't tell me this is just one of those things i have to install and measure at the units pressure test port.
Speedwrench
11-25-08, 08:09 PM
follow the manufacturers instructions or you will have problems with the heat output, maybe problems keeping it lit.
life begins when the kids leave home and the dog dies
life begins when the kids leave home and the dog dies
thermofridge
12-05-08, 05:23 PM
These tankless units need to be installed per instructions. The unit will eventually lock out if the gas volume is not enough. It will eventually ramp up to full BTU capacity even if for a few seconds. Last, if you have a gas pipe fitting behind finished drywall, you need to make access to it because it violates the fuel gas code. All pipe fittings must be accessible.