one condensing heater versus two cheaper power vented heaters

I own a duplex (live upstairs and rent out downstairs) and currently have two power-vented water heaters. One needs replacing now, and the other won't last much longer. The building no longer has a usable chimney, so atmospherically vented heaters are out. My question is, should I spend $750-800 each for two non-condensing, relatively inefficient power-vented water heaters, or should I buy one condensing heater, such as a Vertex GDHE-50 from A.O. Smith, or a Polaris from American Water Heaters?

I'm tempted to go with one condensing heater. From what I've read, it seems as though one of the condensing heaters would supply enough hot water to meet both units' needs. It would save space, and my understanding is that it would be cheaper to run than two lower-end heaters. On the other hand, with one unit all my eggs would be in one basket.

Am I overlooking important considerations? Thanks for everyone's opinions.

Its your call on whether the condensing unit will have a fast enough payback...
Make sure you figure the tax credit and check for any state and utility rebates that may be available.
http://www.energysavers.gov/financial/70020.html

However, as far as AO Smith & American Water Heaters...
I'm not a fan of either brand...

Redwood,

Thanks for mentioning the tax credit and rebates. I will include those factors in my decision.

Are there other brands you would recommend?

Bradford White & Heat Transfer Products (Phoenix)

who pays for the gas on each unit? How many people in each unit?, how many bathrooms in each unit? If the neighbor uses all the hot water will one of you wind up in Jail?<grin>

Hal J said:

with one unit all my eggs would be in one basket.

Click to expand...

If each of the two are 1% likely to fail over some period of years, the one unit would have to be 0.01% likely to fail during that same period to equal the reliability of the two.
They probably don't make units that reliable.

The problem is that the companies will probably not tell you their calculated reliability value, but it is linked to the warranty length.

Another consideration is the current price of replacement parts, which is something you can find out ahead of time.

Polaris is a good unit, I have installed several, but a bit pricy.

ballvalve said:

Polaris is a good unit, I have installed several, but a bit pricy.

Click to expand...

Polaris, AO Smith, and American Water heaters are all divisions of the same company...
I do like to avoid them...

I am looking to upgrade to a Condensing Storage Water Heater. What brand-model would anyone recommend to a family of six> We have a conventional gas WH but want to upgrade. Let me explain:

One of our offerings as a company is Solar Thermal systems. I figured that I would install one on my home as part of a larger project. But we need to abandon our chimney because the HWH is orphaned and does not vent too well and we are about to re-roof and I'd like to get rid of the chimney all together. So I looked at the cost of a condensing WH and the solar thermal and I think, after the condensing unit is installed, the savings of going solar (with or without the polaris solar-gas all in one tank) is fairly small and would not pay back for 15-20 years. That is a stretch for me, so I am probably not going solar. All this leads me to the following question:

In your opinions, which condensing WH offers the best value and what size would best suit our family of six> We have 2 full bathrooms (only one tub) DW, & Washing machine.
Many Thanks!

http://www.globalindustrial.com/p/p...er-Heaters-google_pr&infoParam.campaignId=T9F

I do not "know" this unit, but ONE should do 2 units, and for the cost be the best value.

Polaris are SS tanks and have had some issues, but seem to be at least a 20 year heater with a few igniter changes. The Polaris is way overkill for just hot water heating in a SFR, but if you heat with it also, it makes great sense. Or use it for a few units +

Here is another interesting unit. have not found a cost yet:
http://www.sensibletechnologies.net/HydronicTimes/JTG/HT_JTG_PGETestPhoenixNumber1.html

http://www.htproducts.com/phoenix.html