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Message
Is it normal for a tankless water heater to have lulls when generating hot water?
Posted on 6/17/25 at 8:33 am
Posted on 6/17/25 at 8:33 am
Mine is 2 years old, and I find that it now has lulls in production. I’ll be taking a shower and it will stop putting out hot water for 30-60 seconds and then start producing it again after that. This is the first tankless water heater I’ve had, so I’m not sure what’s normal.
Do I need to have it maintenanced and flushed out?
Do I need to have it maintenanced and flushed out?
Posted on 6/17/25 at 8:34 am to cbree88
i want to say you have to clean and flush them every 2 years
Posted on 6/17/25 at 8:34 am to cbree88
quote:
Mine is 2 years old, and I find that it now has lulls in production. I’ll be taking a shower and it will stop putting out hot water for 30-60 seconds and then start producing it again after that. This is the first tankless water heater I’ve had, so I’m not sure what’s normal.
Do I need to have it maintenanced and flushed out?
been in my house for 7 years and never had this issue with mine.
Posted on 6/17/25 at 8:35 am to cbree88
Happened to me, and my plumber came out and unscrewed the shower head and cleaned it out / apparently some debris had worked its way into the head and the water heater was unable to push as much hot water as it wanted to, which caused it to stop heating water for a few seconds every now and then. We haven't had issues once he cleaned it out - worth trying yourself before you call someone.
Posted on 6/17/25 at 8:37 am to cbree88
quote:
Is it normal for a tankless water heater to have lulls when generating hot water
Perhaps if it's stoned or in a really good mood.
Posted on 6/17/25 at 8:37 am to cbree88
Not normal. Need it serviced.
Posted on 6/17/25 at 8:38 am to cbree88
No.
We’ve had the same Rennai unit for close to 15 years and it never fails. But, we’ve also had it serviced annually. Get somebody out there to flush that thing out.
We’ve had the same Rennai unit for close to 15 years and it never fails. But, we’ve also had it serviced annually. Get somebody out there to flush that thing out.
Posted on 6/17/25 at 8:39 am to cbree88
We have 2 of them and have never ever had this issue. Ours are now 16 years old (Noritz brand). Suppose to have them cleaned occasionally but never have. I think calcium build up forms in the unit which cause a noise when the hot water first turns on but other than that, that’s all. I haven’t spent even $1.00 since we purchased ours in 2009. Will buy Nortiz again if and when needed.
Posted on 6/17/25 at 8:44 am to cbree88
I'm going through the same issue on a two year old system. Had it checked out by a plumber and he said there are no issues, it just has to be descaled. So I bought a kit to do it myself....hopefully it works.
Posted on 6/17/25 at 8:44 am to cbree88
Just had one installed and plumber said it should be serviced every 2 years. Possibly annually depending on water quality.
Posted on 6/17/25 at 9:03 am to cbree88
hotter water can hold more solids...when it cools those solids precipitate out. not an issue for people with soft water, but if you have hard water it is an issue. Hard water users can have clogged shower heads. remove shower head and soak in white vinegar to dissolve the solids, the rinse it out.
This post was edited on 6/17/25 at 9:34 am
Posted on 6/17/25 at 9:05 am to cbree88
quote:yes.
Do I need to have it maintenanced and flushed out?
What is the quality of your local water?
Is your wife starting the dishwasher up pipe while you’re showering?
Posted on 6/17/25 at 9:37 am to cbree88
it may be oversized. What you are describing can happen when there isn't enough water flow through a tankless water heater.
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