Overloaded Demand: Tankless water heaters provide hot water on demand, but they have limitations on the amount of hot water they can produce simultaneously. If multiple fixtures or appliances are drawing hot water simultaneously, the heater may struggle to keep up with demand, resulting in cold water.
Typically when a tankless water heater goes cold mid shower it's because either you flow of water is too much for the heater to keep up with, or ironically the flow of water is too low and the heater doesn't think water is passing through and it shuts off.
Hot and cold water can often be caused by an issue with the water pressure in an electric showering system. It might be that limescale has built up in your system and pipework and is narrowing the route through which the water travels.
Tankless water heaters rely on ignition to heat water on demand. If the ignition fails, you'll be left with cold water. This could be due to a variety of reasons such as a faulty igniter, gas supply issues, or a dirty burner. In such cases, it's best to consult a professional technician to diagnose and fix the problem.
Numerous reasons: the heater is too small, it is on a timer and only heats at a specific time, a heating element is broken or simply you run water too long.
When you turn the shower on, water leaves the hot water heater and pushes all of that room temperature water ahead of it. That water is going to seem quite chilly; it's the same as the “cold” water. (The cold water tap isn't refrigerated; it's just room temperature.)
The Impact of Tankless Water Heater Issues on Water Pressure
The specific problems associated with tankless water heaters can lead to decreased water pressure in various ways. Scale buildup within the pipes restricts water flow, resulting in reduced pressure during water-intensive activities.
What temperature should a tankless water heater be set to? For most residential uses, a temperature setting of 120° - 125°F is sufficiently hot and will protect against scalding. You can set your residential tankless water heater higher, but know that a child can be burned by 140°F water in just a couple of seconds.
You can't run out of hot water with tankless water heaters – unless, of course, the power supply is off or goes out. However, a tankless water heater can have trouble keeping up with demand if too many things require hot water all at once.
These water temperature fluctuations can be caused by:
A plumbing system crossover where there shouldn't be one. Improperly lengthened venting pipes. Damaged flow sensor — something that should be checked during your annual plumbing maintenance appointment. A dirty water filter on the cold water inlet.
To do this, adjust the dial or temperature setting on your water heater and wait for at least five minutes. Use the tap closest to the heater to access this warm water. If the water is still too cold, repeat the above steps until you're satisfied with the temperature.
Shower mixing valves usually have a default temperature, which users can adjust to their preference by twisting the hot and cold water knobs. Yours is probably inside the wall behind the shower handles if you need to access it.
So, what's the deal? Well, if you're getting hot water everywhere else in the house but the shower, you most likely have one of these 2 issues: Your anti-scald device is set too high. Your shower mixer valve went bad.
The most complicated and time-consuming tankless water heater maintenance is typically descaling and flushing out the unit. Even with the inline water filter, lime and calcium deposits can build up inside the tankless system. If you have hard water, it's a good idea to descale and flush the unit once a year.
The right tankless water heater can definitely take care of all your family's hot water needs, including taking multiple showers at once.
Before you commit to buying a tankless water heater, the primary drawbacks to know include: Higher upfront costs. Tankless water heaters are, on average, quite a bit more expensive to buy and install than tank water heaters. Access to fuel.
Tankless water heaters usually last for around 15-20 years before they need to be replaced, but they may need replacing sooner if they start to break down or lose efficiency. Some common signs your tankless water heater needs to be replaced include: Low water pressure. Water doesn't get hot.
Low water pressure
If the water pressure to your house drops, this can affect how the hot water pressure is working in your system too. If your shower goes cold after a few minutes, it might be that you've been unlucky enough to be showering just as the water pressure dropped.
This can happen if one fixture is switched on quickly after another is shut off. Before the gas burner can fully heat the heat exchanger, you'll get some hot water stored by the faucet, followed by cold water from the tankless water heater.
A tankless water heater requires a certain amount of water pressure to function properly. If the incoming water pressure is too low, the unit will not be able to generate enough hot water. This is often caused by a plumbing system crossover, where the cold and hot water lines are connected.
The recommended temperature setting from the Consumer Product Safety Commission for a tank and tankless water heaters is 120 degrees.
15-150 psi water pressure. 40 psi or above recommended for maximum flow.
Adjust the Pressure
You can find it on the top or side of your tankless water heater. Verify the settings aren't too low, and turn it up if needed.