1/2 Line for a Gas tankless water heater
wagonersa
9 years ago
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Comments (12)
wagonersa
9 years agoRelated Discussions
Solar hot water, tankless, gas condensing water heater...?
Comments (2)If you go with any sort of solar system, make sure it has a gas backup and not electric. My energy costs went up $100/month when I added our solar system down here in San Diego. I am now getting it corrected with the installation of a small gas tankless unit, using the solar storage system as a pre-heater. If you're building the home then many of the traditional drawbacks of tankless don't apply to you. You can build in the correct gas line and venting from the start. If I were in your shoes I'd probably go tankless (30 percent tax credit this year -- see the stimulus law or visit www.energystar.gov). If a single unit won't handle your demand then get two. And plumb it with the small tank system (10 gallon) for recirculation and to overcome any sandwich problems. This approach has been detailed in this forum somewhere....See MoreRinnai Natural Gas Tankless Water Heaters
Comments (8)dan i have two rinnai LP gas units that are ganged together in series. the two digital controllers are linked and when i set the control on one unit, the other automatically updates. the only negative i have with the rinnai's is that the controller can only adjust temps in increments of 5 degrees - i wish it was in 1 degree increments. for us, it was more efficient to have two small units installed rather than 1 large one. this was done for efficiency - most of the time we only need one unit running but there are cases where the second will kick in. gas tankless is great and the rinnai's look to be well built. 3200 sounds very high to me. I don't know the exact dollar number for ours , but the 2 rinnai's we had cost us an additional 1200 dollars over what a hot water tank would have cost (we just paid for the upgrade). my guess is that a hot water tank installed would run around 800 dollars max - so I am having a hard time seeing where the 3200 price tag came from. is there is a lot of plumbing and venting work required to install your unit? i do know that the ducts for the tankless units are very expensive, so if you have a long run for the vent - that might be where the extra cost is....See MoreTrying to install a tank-less water heater, our intake is only 1/2 in.
Comments (2)What??? Is the inlet 1/2” or 3/4”? Or is the outlet 1/2” or 3/4”? Either way, you have some major replumbing to do to make any of that work. Including the gas line needed....See MoreTankless water heaters and recirculating lines: Good deal or not?
Comments (13)North Texan, I'm sorry, but your point #1 is simply not correct. A gas tankless is about 92 % efficient (condensing model) any time it is running. It is that efficient because it extracts enough heat from the flue gasses that it takes the gases below the point of condensing the water vapor - and thus even gets the latent heat in the water vapor. That's true any time it's running. It's not an average between "low efficiency and off" as you suggested. Condensing gas tankless water heaters extract so much heat that they vent with plastic vent. There are 82% non-condensing units that vent with stainless steel, but the vent is so expensive it makes more sense to use a condensing unit and vent with PVC. BTW: Condensing gas furnaces work on exactly the same principle. Standard gas tank heaters are about 60% efficient and can't get much better than that. The reason is that they must leave the flue gases hot enough to rise up through the atmospheric vent (hot gases rise). Atmospherically vented (standard) gas water heaters also have higher standby losses and air infiltration / exfiltration issues. There is a 3" flue up the middle of the tank that is open to the sky 24/7. They also take their combustion air from the conditioned air in the house and dump it outside requiring makeup air. Most gas tankless units get their combustion air from an outside intake. I think that you are confusing the issue of input requirements for a tankless heater. A tankless heater (gas or electric) has to heat water very quickly - and thus the input requirements are massive (a typical gas tankless is 200k btu/h vs 40k btu/h for standard gas tank). An electric water heater is almost 100% efficient already - and an electric tankless doesn't improve on that any. Electric tankless saves about 3% on standby losses. I have no idea where you got point #2 - but since point #1 isn't right, Point #2 is also not right. There is a significant cost to retrofit to gas tankless. In new construction the cost difference should be about $500 or less. I can't really comment on the payback because the install costs are so out of whack. In my view, atmospherically vented gas water heaters should be off the table - just as atmospherically vented gas furnaces are no longer available. I would never recommend whole house electric tankless. The operating cost savings (3%) aren't enough to justify any of the additional service requirements. There is no discernible payback. They don't generally produce enough GPM either. There are much better solutions for homes without gas - such as hybrid heaters. Electric Point of Use units can make sense in some situations, but not whole house electric tankless....See MoreUser
9 years agowagonersa
9 years agoUser
9 years ago
Vith
9 years agowagonersa
9 years agoUser
9 years agolast modified: 9 years agowagonersa
9 years agoUser
9 years agolast modified: 9 years ago
live_wire_oak
9 years agowagonersa
9 years ago
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