Gas Tankless water heater on a 15 unit?

Question

Our 100 Gallon, 199k BTU water heater is getting old and needs to be replaced soon. Cost is about $5-6k.

I'm looking at Quick Water Heater in San Diego and for around that price, they can do tankless. Any idea if that's a good idea? We want it to last 10+ years, of course. The building is about 12k sq ft, single metered for water, and we pay for the gas to heat up the water. The gas bill is almost double what it was 18 months ago.

Cliff Harrison · Answer

If you have floor space, can you put 2 or 3 standard size tanks in series?  Even 12 year double anode models are under $1000.

Oren K. · Answer

Jon,

Going tankless single source MF property will require some engineering vs. just putting something in. With a standard tank, the cold water fills in from the bottom so tenants have full access to HW even when a good chunk of the tank is 'cold' and it gives the tank time to heat up the new water.

With a tankless setup, you will need to determine the MAX water flow utilization per minute in your existing setup and make sure you have the heating capacity with contingency in the new set up.

Oren

Dan H. · Answer

First I am shocked at the price for your 100 gal heater.  I replaced a 40 gal recently (this month)with new venting at about 25% of your cost (heater, venting, and labor) using a licensed plumber (not my handyman) but I have no idea what the cost difference between standard size single unit heater and the size you are referring to.  So your price may be very reasonable but has the look of being a lot of money.

The warrantees on the tankless are longer than the tanked heaters.  I have used 2 tankless heaters.  One is going strong I would guess at 8 years.  The other unit the vendor settled with me when the unit failed (at about 2 years) but as part of the settlement I can not state anything about the company, what failed, etc.

The unit that is working great is something like AO Smith (going from memory so the AO may not be exactly right).  Both the two units I refer to are single residence size but the one that failed was a large single resident size (it supposedly could handle filling 4 baths at the same time and I never experienced it underpowered).  I think the AO Smith unit that is still going strong can do 2 baths concurrently and I have never experienced it being underpowered (it is in a 2.5 bathroom unit).  The big unit that failed was almost the size of a 40 gal short tanked heater.  The AO Smith unit is the size of a small desktop PC.  Both were gas units.

So my own experience with single residence tankless heaters is mixed but I am still a fan and have two units that I will convert to tankless when the current water heaters go (because there is only electricity - no gas option).

Good luck

Matthew Olszak · Answer

I love tankless, but my only experience has been w/ single unit models where tenant pays gas.

However, I can confidently say if you are changing the water heater and pay gas, buy (not lease) a softener to put before it. You loose a ton of efficiency and suffer an extremely reduced lifetime with only a fraction of an inch of scale.

Lee Ripma · Answer

@Jon L.

I am all about tankless and plan to put them in my MF units in Kansas City. I was talking to my landlord in LA about this and he asked why I was all about tankless. He thinks they don't last as long and they are prone to hard water buildup. He also thinks that they don't last more than 7 years. So I like them because the tenant pays to heat the water when they need it and not when they don't BUT he has the counterpoint. That's all I've got for you.