Good Evening All,
I’m renovating a 2500 sf bi-level and at the point where I’m about to replace an electric water heater with a natural gas fired variety. In checking with my plumbing supplier on pricing, he questioned me on whether I planned on installing a jet tub any where in the house. My response was in the affirmative. In hearing that response, he said that a 50 gallon water heater isn’t sufficient with a hot tub. I explained that it would be a small size tub and not something seen in much larger homes. Basically, this will be a unit 60 inches in length, roughly 32 inches in width and whatever a typical jet tub/hot tub depth would be. Nevertheless, they insisted that to be satisfied with the jet tub, we really needed to consider a indirect-fired water heater. The manufacturer they carry is Amtrol. The capacity of the recommended unit is 41 gallons and I was told that we would enjoy hot water on demand, with an efficient design that taps into the existing gas fired hot water baseboard boiler.
My question is whether my suppliers are basically correct in their recommendation and is it worth the extra money for a lifetime warranty hot water tank. By the way, the boiler is relatively new Weil Mclain CG-6. The gas fired hot water heater I’m considering is a short model, AO Smith Promax.
Thanks
Geoman
Replies
If I were going that way, I would look into the ones that get you a tax credit for high efficiency. Bosch makes one for about a grand. The credit and the efficiency combine to make it pay off in a few years.
Bosch does not make indirect fired water heaters. At least not one that is qualified for tax credits.http://www.gamanet.org/gama/inforesources.nsf/vAttachmentLaunch/9DC8F7CDE69E3C5185256FA1008391DD/$FILE/01-07_IFWH.pdf
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
If you already have a good boiler in place, it might make sense to add an indirect fired tank. If you want endless hot water to fill a large tub, then a tankless unit is worth considering. A lot depends on the space you have, what your hot water usage patterns are, what the conditions for venting are, etc.
A tankless unit will work well *only* if the GPM rating of the heater is more than about 70% of the the GPM rating of the tub fixtures. There is also the water supply temperature and the temperature rise that the heater is capable of at the GPM rating.
If the gas piping is not sized properly, you will not have maximum output from the heater.
Unless there is some type of restrictor installed in the tub fixtures, those fixtures flow too much, and the result is warm, but not hot, water in your tub. Tub fixtures are not regulated to 2.5 GPM like showerheads.
Large capacity tankless units are available, but with a boiler already in place, I would vote for the indirect fired water heater.
Another option is a commercial size gas-fired tank. They have input rates approaching tankless units and very quick recovery, such that you can generally get about 1.5 gallons out for every gallon of capacity. But they're big and expensive, so the indirect unit is probably the way to go.
If your view never changes you're following the wrong leader
How many gallons is the tub? You can get maybe 25-30 gallons of hot water out of the 50 gallon tank, before it starts to go cool. Figure that mixed about 70/30 with cold water while filling. Lets you fill a 35-40 gallon tub, based on my quick thumb suck.