Heater only warms water to 98 degrees

is there HOLD button?

Bath tub heaters will only maintain the water temperature in the bath. They will only heat the water approximately 1-2 degrees an hour.
Whatever water temperature you start with is what you will be able to maintain.
There is a red indicator light on the front of each heater indicating whether or not there is power to the unit when the tub is full of water and the water pump is turned on.
If there is a red light on then it has power to it and is working.
This heater will never feel warm to the touch.
There are three different styles of Bath Heaters available.

• Tee Heater - installs on the discharge fitting on the pump
• In-line Pressure - installs anywhere in the plumbing line before any jet.
• In-line Vacuum Heater - installs before the suction of the pump

If the heater you purchased is installed in the wrong place it will not operate.

Rod
US Parts Center

If this is a new installation, make sure the unit is feed with at least 208+ volts of electricity.
If it is an older tank, try turning up the temperature setting on both thermostats. Set the top one 10 degrees higher than the bottom. If there is now change in the water temperature after a day or two, replace both thermostats. While your at it, change both element as well. A complete universal electric water heater rebuild kit should only cost around $35.

Hello there
If your dishwasher's cycle times are too long, check these: Water pre-heating Cycle not completing Water pre-heating Your dishwasher may pre-heat the water. If so, and if the water entering the dishwasher is cool, the heater may take up to half an hour to heat the water. To avoid the wait, increase the incoming water temperature before turning on the dishwasher. Do that by running the kitchen sink faucet until the water runs hot. Or increase the temperature of the hot water to the entire house at the hot water heater. Warning! To lessen the risk of scalding, don't set the hot water heater temperature higher than 120 degrees Fahrenheit.

Your run temperature is within spec. Your problem possibly is in the heater core itself.

Check the hoses going to the heater core and make sure both are warm when the car in at run temperature and the heat is turned on.

If one is cold and other warm you have a flow problem in the heater core that must be corrected.

I do not know what heat control valve you are referring to on an electric water heater. On an electric water heater it has two heating elements in most cases. One at the top and one on the bottom. One of these is more than likely defective. Turn the power to the water heater off at the service panel or at a disconnect switch. Now take the covers off both heating elements. Check each one with a ohm meter to see if you have continuity. If your meter reads nothing that heating element is bad and needs replacing. On each heating element is a thermostat to set the temperature. Set the upper element to 120 degrees and the lower element to 130 degrees.

It may be the valve that controls the amount of water entering heating core but I'm wondering if your engine thermostat isn't stuck open. This is what controls the coolant temperature in your engine. It closes off while engine is off. It will remain closed after you start your car until the water warms to a certain temperature then it starts to open enough to keep your car at the proper operating temperature. If it stick open then it will take a lot longer for the engine to heat up and on smaller cars might never heat up enough for your heater. If you live in very cold climates such as where I live in Wyoming, we have to change to a higher degree thermostat so we have a good heater when it's 30 below zero.

Be very cautious here but one way you can check this is to put a piece of cardboard in front of your radiator and stop the airflow that cools your engine coolant. THIS WILL CAUSE YOUR CAR TO HEAT UP AND CAN CAUSE ENGINE DAMAGE IF IT OVERHEATS. Don't completely cover the radiator but if your heater warms up when you put the cardboard in front of radiator it's a good sign that your thermostat is stuck open and needs to be replaced.

most likely a problem with the water circulation around the heater core. if you've never used the heater, some vehicles have a hot water shut-off valve for the heater hoses. another possibility is the thermostat had been removed. the easiest way is to start the vehicle and slowly allow it to warm up monitoring the water temperature. it should heat up to normal water temperature, then heat up and then drop down. the thermostat is usually around 180 degrees or 192 degrees. it allows the water around the engine block to heat up then once it reaches 180 or whatever it opens up circulating the cooler water from the radiator into the engine block and pushing the hotter water into the radiator to cool off. no thermostat, then the water keeps constantly circulating not allowing it to properly heat up. this can slow the heater down, lower fuel economy, alot of things especially in the winter driving...

An electric heat pump needs heat available to pump. If it is 30 degrees outside, heating a spa to 102 or so, may be impossible unless the heater has some type of alternative heat source. A properly sized, gas fired heater can take care of a larger range of heating needs. A combination heat pump and natural gas heater, probably with a controller, really makes the issue more difficult, expensive, and would require a lot of study for efficient, cost effective operation. Bottom line: In really mild climates a heat pump might do the job. In cooler climates the gas heater rules. And where a wide range of temperatures and high heat demand is wanted by the customer, a gas heater is the only way to go. A backup heat pump may take years to payout.