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Water temperature fluctuates
What is going on
Hot water goes hot and cold during use or does not reach the set temperature.
Likely causes
- Flow near the minimum activation flow
- Scale build-up in the heat exchanger
- Low or fluctuating gas pressure
- Recirculation or crossover issue
- Temperature set too low for the demand
Check in this order
- Check the set temperature and the flow rate at the fixture
- Clean the inlet filter and flush the heat exchanger if scale is suspected
- Measure gas pressure with several appliances running
- Check for plumbing crossover and recirculation settings
- Compare the demand with the unit's capacity at the incoming water temperature
Applies to: Tankless water heaters
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