Tankless water heaters

ken brydson · March 6

Anyone have experience trouble shooting? Our house is only 5 1/2 tears old with a tankless. It worked flawlessly until a couple months ago. All of a sudden it couldn't keep up with high demand stuff like a long shower or a big batch of dishes.

Had a recommended plumber out a couple weeks ago to troubleshoot to the tune of like $600. They descaled, messed with some settings but no improvement. Dude said we might consider getting a new unit. Mentioned some soot on the heat exchanger and the porcelain on the igniters was discolored from getting too hot. The unit itself only had a 5 yr warranty but if IIRC the heat exchanger has a 15 year warranty. Their next suggestion was to replace a tempering valve under an upstairs sink thinking maybe its failing causing bleed over of cold water. Another $500. I passed.

Did some Googling, things like limit switches, relays, etc come up. It's a Noritz if that helps.

TIA for any input..

mhardy6647 · March 6

sure sounds like scale buildup to me

To answer your question: nope, zero experience (as you can tell).
Our house in MA had an old-school tankless system (7 gallon coil in the boiler, if memory serves) when we bought it. It would deliver one shower's worth of hot water, then... tepid. That was scale. We got it descaled then installed a water treatment system (mixed bed ion exchange resin). We went to a storage tank when we replaced the boiler, and I spec'd a tank for this house, too.
Sorry.

Emlyn · March 6

Although I don't have one myself, I grew up with tankless systems overseas that were used for radiator heat and hot water. Was the unit serviced and descaled every year by a professional? In some areas they need to be serviced more often if the water that goes into it has a lot of minerals.

They should last for 20+ years with maintenance unless there's a defect.

audioluvr · March 6

I have had a Rheem for about 8 years. There can be two people taking showers while the washing machine is running and someone doing dishes with no loss of output or temp fluctuations. Sounds like something is either restricting the gas output. If it was a sudden change it's not scale buildup as that is a gradual deterioration. There is a thermal restrictor that could have failed. But I'd first check with your gas company to see if maybe the regulator is failing.

skipshot12 · March 7

Sorry, I have no experience.
Hope it's an easier solution than having to buy another.

Was looking into these a few years ago.
The plumber said if you don't go with a water softener and water filtration system don't bother with tankless.

Reckon they need to have their burner/coils to remain spotless?

After looking at what systems were recommended we stayed with a 50 gal tanks system.

GlennDog · March 7

any chance the water pressure has decreased, starting around the time the amount of hot water decreased?
If both your shower and kitchen faucet are single handle devices… My guess is the pressure balancing valves are crapping out on you simultaneously. Seems like even the good ones only last about five years now, too.
Good luck

Tankless water heaters

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