How much does it cost to descale a tankless water heater?
Updated
Short answer
Descaling a tankless water heater yourself costs $20 to $150. The low end is a few bottles of white vinegar, and the high end is a descaling pump kit, which is a one-time purchase you'll reuse every year. A plumber charges $150 to $300 for the same job. Either way it takes 60 to 90 minutes, most of it waiting while the vinegar circulates.
Cost breakdown
| Item | DIY | Pro |
|---|---|---|
| Materials | $20 to $150 | included |
| Tools you may need to buy | none | included |
| Labor | your time | $150 to $300 |
| Total | $20 to $150 | $150 to $300 |
The DIY range covers the first year, when the pump kit is bought. From the second year on, the cost is vinegar alone, at the bottom of the range. A descaling solution made for tankless heaters costs more than vinegar and works faster, but vinegar does the job.
What drives the cost
- The first year. The pump kit is most of the DIY cost, and it pays for itself on the second flush.
- Service valves. If the unit was installed without them, a plumber has to add them before anyone can descale, which is a separate cost and a one-time one.
- Hard water. With a flush needed every 6 months, the yearly spend doubles, whether you pay a plumber or buy vinegar.
- What the plumber checks. A good descaling visit includes a look at the venting, the gas connection and the inlet filter, which is part of why the pro price is what it is.
- Neglect. A unit that's gone years without descaling may need a longer flush or a stronger solution, and a scaled-up exchanger that cracks is a replacement.
DIY vs. pro
Once the kit is on the shelf, this is a job to do yourself. How often to descale a tankless water heater is once a year, or every 6 months with hard water, and each flush after the first costs a few dollars of vinegar. The steps are the same every time: shut off, connect the hoses, run the pump, flush, reconnect.
Hire the plumber when the unit has no service valves, when you'd rather not handle the gas valve, when the unit is in an awkward spot, or when the warranty requires a professional service record. The $150 to $300 visit is fair for all of those, and some owners alternate: a plumber one year, the kit the next.
FAQ
How much does it cost to flush a tankless water heater?
$150 to $300 for a plumber, or $20 to $150 yourself, with the high end being a pump kit you buy once.
Is a descaling kit worth buying?
Yes, if you'll do the flush yourself. It pays for itself the second year and lasts for many flushes.
Can I use vinegar instead of a descaling solution?
Yes. White vinegar dissolves the scale and costs a fraction of the solution. It needs a little longer to circulate.
What if my tankless heater has no service valves?
A plumber has to install them before the unit can be descaled. It's a one-time cost, and every flush afterward depends on them.