Pro’s Con’s of tankless hotwater

This is “Boots” Economics. —

Let’s do the math. I was renting a Power Vented 75gal (PV75) tank. It was 13 years old, and rusting out from the inside. No leaks, but bathwater looked like pond water. GROSS. Safe, but gross… needed it replaced. The tank was inspected in February and was going to be replaced/done in March. Covid19 happened, and everything gets put on hold.

Fast forward to last week… the water’s super gross… tanks accelerated in rusting. eew. Do my research… Navien, Rinnai, Rheem… figure out how many Gal/Min (GPM) of hot water we need, average temperature raise needed, the total cost of ownership over the lifetime of the unit.

So, I have a fair-sized home and needed something like 6-7 GPM. The average water temperature average is 42°F and needs to be raised to 120°F… meaning a 62°F raise. The unit I picked, could supply 6.5GPM… Navien 240A.

So… lets do some math. The average life of a tank is between 10-15 years. So, I’m going to say 12.5 years for a tank. Mine just so happened to last ~12.5… Tankless, should last 20-25 years. Lets say 22.5.

Unlimited hot water$$$$ initial upfront cost is expensive
Environmentally friend (only use energy when needed)Takes time for the hot water to arrive to your tap. (mitigated)
Recirculation pumps can allow you to have hot water on demand quickerComplex system, with lots that can go wrong.

Tankless systems are not a new technology, it’s the mainstay way of heating water in Europe and Asia for decades.


A PV75, was going to cost me ~$1.38/day to rent (with tax). That is with a 7 year contract… that’s not bought out, that’s just renting it. $3,525.90 taxes in. RENTING for 7 years. Renting a tankless, for the size I required, was going to cost ~$2/day.

Buy: PV75 tank (traditional)

If you bought a tank, retail price at home depot, PV75 costs around $2047 + HST = $2,313.11. Plus ~$200 labour to hook up. So, that is $201.05/year ownership. Not including gas costs.

Buy: Navien 240A Tankless

If you bought a large top of the line tankless, I had quotes for $3500 + materials ($200). That’s $4,181 after taxes, installed. That’s $185.82 per year (22.5 years). BUT, you save on average, $100/year in gas. So that’s $85.82/year, compared to a PV75’s $201.05.

If you’re willing to put in the effort yourself, you can save a bunch by installing it yourself and hiring a licensed gas fitter to connect the unit. Which brought my yearly costs down significantly. If you’re handy, it’s about a day’s worth of work… 4 hrs, if you have a suitable wall to mount the unit already. I did not.

Your prices will vary… basically, what I’m saying is… renting is not a good option.

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