I need a new hot water system. Suggestions please.

[starfish11040]

I have a building of ten small apartments, mostly studios. Twelve people, all adults. Apparently there is a lack of hot water on some weekday mornings after 7:30 am. I'm sure it's because it's the morning rush and the lack of hot water is due to a temporarily insufficient volume of hot water because too many people are showering at about the same time.
It's a gas-powered two-tank system. Each tank is 42 gallons. They're eighteen years old so due to be replaced anyway. My understanding is that the new system should resolve the supply problem by having higher storage capacity and, I think, a better recovery time.

I will be getting two or three plumbers to come in and give me an analysis, recommendation for replacement, and a cost estimate.

My question here is what specifics should I be asking about? btu's? FHR? EF? etc. I really don't know much about this.

thanks

[plumber4200]

I would invest in tankless water heaters. You could use approximately 3-4 Rinnai Tankless heaters piped together as shown in their installation manuals, using a common digital controller to set the temperature for all the units. That would save you money in the long run as they only heat the water when a tap or faucet is turned on. This is a very basic answer but i believe the conditions you are stating would be ideal for this application. Look into Navien tankless heaters as well because they can be vented with PVC piping instead of stainless steel and that would save a lot of money. Also, Rinnai and Navien make commercial models with Stainless Steel Burner Assemblies that will last much longer. The average Rinnai 9.1 or Navien 210 models will put out about 8.5-10 gpm depending on the temp of water coming into the building so you would want a professional to help you decide how many units you would need based on maximum number of gpm that would be used in your building, but if 10 showers can run at one time x 2.5gpm per shower that is around 25 gpm, plus throw in a few dishwashers or laundry machines and you probably need to cover about 30-35gpm which would be about 3-4 units depending on real life equations.

Hope this helps get the ball rolling. I am sure others will give you good ideas as well.

[leo]

Yes I agree , Navien! I like it! Get one w/recirculation.