A family of 4, with two kids ages 10 and 13. We currently have a 40,000BTU 50 gallon conventional (atmospheric vent) tank water heater – 15 years old. No issues with running out of water.
Looking to replace with an AO Smith Vertex water heater and considering the 50 gallon version. The Vertex is a 100,000BTU condensing unit that has about double the first hour rating (160 gallons for the Vertex). Plumber recommends a 75 gallon, but I am thinking that is based on smaller BTU conventional heaters. What are your thoughts on size?
Second question, do you insulate the hot water supply pipes in your house?
Replies
Unless you think that AO Smith is lying about the capacity of the newer units, there's no reason to believe that the 50 gallon unit would be in any way inadequate to replace your existing unit.
Of course, if space is not an issue and the price difference is not too significant there's maybe no reason to not get the larger uint, but that's for you to decide. (I can't imagine that the difference in operating cost would be very significant.)
I Dunno Dan...
... if a conventional 40's adequate now & the OP wants a more efficient unit that's got twice the first-hour capacity of the old 40 I'd say a 50'd be fine. Going to a 75's gonna put more heat ($$$) into water that just sits there cooling off when it's not being called upon to provide HOT water. Exterior surface area + quality and efficiency of insulation's really important in sizing these things as well as anticipated demand.
I added a Marathon 50 gal. electric to the house we lived in back in '06 when I had to replace the existing Amana furnace. Back in the early 80's Amana had a system that heated hot water AND the house interior with one burner unit located outside. Worked great over the years until it got 'obsoleted' by newer technology & parts - igniter, burner assembly, associated blower, etc. - became unobtainable. I'd not included provision for a gas water heater when I rebuilt the place either.
Anyway that Marathon was everything I could ask for. It was in the heated portion of the home on the first floor. Crawlspace was kinda heated too but no room down there. House we moved into early Nov. 2013 needed a new water heater the FIRST WEEKEND (electric 50 gal. & we knew it needed replacing when we closed) so I humped a 50 gal. GE back from HD & put it in. It's in the basement next to the foundation wall & seems to be terribly shy of insulation. I ended up putting it on a timer so it wouldn't be keeping all 50 gallons @ 125F for half a day when it's not needed. Maybe putting it in an XPS 'box' would help too?
One trick I wasn't aware of at the time was adding a heat 'trap' to the hot output line, essentially a portion that loops DOWN before turning back up to connect to the home's supply line. Idea being heat rises so keeping the pipe at the hot outlet short reduces convection losses? Seems worth consideration even with foam-insulated pipes....
If you check the specs on your top-of-the-line State and (I think) AO Smith units you will see that they are exceptionally well insulated (GE, I'm not so sure about). (As to overall unit size, remember that the larger the unit, the less surface area per gallon capacity, especially if a shorter unit is used.)
I think code in many areas now requires installing "heat traps" on water heaters. These are nipples with valves in them that are closed unless water is being drawn. I'm not sure, but they may come pre-installed in many heaters.
wouldnt see a need for a larger one if your current 50gal handels your demand.