Heatmaster hmp15 not supplying hot water on demand

a couple of things to check on the side of the hot water system you will see a valve with a small lever
lift that lever until there is a solid stream of water coming from the pipe
that ensures that the heater tank is full
next -if you have a temperature mixer on the hot water pipe out of the tank ( stops scolds in the bath, shower sink) by controlling the temperature mix at the tank
They are known to fail and shut down the hot water supply by adding extra cold water into the system
other than that get a plumber in to fix the fault.

The cold water enters the top, but the water is not released into tank at the top. The cold water goes through a "dip tube" This takes the cold water to the bottom of the tank. If you dip tube fails, or breaks, your faucet temperature will slowly drop as you use hot water (vs giving you 60% of tank at full temperature before temperature starts dropping) In normal operation, the cold water is released near bottom of tank, the hot water rises to top, and comes out of the top of the tank.

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/perry_14036f9bc71cde6a

Hi Bob,

You can determine if the tank is the problem by connecting a garden hose to the drain that is provided on most water heaters. Before doing this, be sure to shut of the electrical supply to the heater - otherwise you can damage heating elements if an electric type or waste fuel by heating an empty tank if a gas / propane fired type.

If you get a slow flow out of this drain, it means that somewhere in the cold water supply side to / in the tank - there is a problem. Inside the tank, the cold water is delivered by a "dip tube" that distributes the cold water to the bottom in the tank. Dip tubes are used in both electric and gas / propane fueled heaters. Here's a cut away view of a typical tank:





If the tube is clogged, or there is build up, scale or debris in the supply (cold water) side of the heater, flow rates will suffer. Likewise, if there is a problem with the output of the tank, it will directly affect flow as well.

If you get a good flow rate from the drain, then the issue is going to be on the hot water output side of the heater. Again, the same build up, scale, debris issues on the hot water out put pipe will cause problems with flow. Typcial tanks do not have dip tubes for the hot water side of the tank - as taking hot water from the top of the tank is most desireable and is furthest away from the cold water that rushes in to make up the hot hot water going out.

There's nothing really in the tank itself that can cause issues with flow outside of the dip tube, and piping to and from the tank.

Good luck!

Question: Do Low boy heaters, have a heater at the bottom, AND at the top?--- and are BOTH of the heaters working, on the 'either/or thermostat?
(By 'either/or'-- I mean, that it first turns the top element on, and when it is satisfied, THEN it turns the bottom on, until the whole tank is heated..) -- I would say this is an advantage of the taller tanks...

The taller tanks stratify VERY WELL--- (And the incoming cold water stays right at the bottom, and you take the HOT water off the top-- until suddnely it all goes to COLD.

I am wondering if the Low boy heaters might MIX more thatn the tall ones,-- thus going to WARM water sooner--- due to poor stratification.
Could you test that out, and try to folow the cold water line up the tank, as the Hot water is drawn off?

Another thought:
The Cold Fill tube, does go all the way DOWN to the bottom of the tank, right?--
And does it gently let the cold water flow across the bottom, and not 'rotatee the waer in the tank, as it replaces the hot water being used?
Otherwise the cold water will mix very early-- and give this same problem...
(I have heard of those center tubes falling off in shipment...
Did you by any chance check that, when you installed it?)

A final thought: What if the water draw was extremely fast?-- (Like if the water pressure is exceptionally HIGH--) might that upset the stratification, and cause the same problem, too?

If the hot water is drawn more slowly, can the customer get 30 or 4 gallons of HOT water, before it all goes cold?

Mack B

http://www.rheem.com/product.aspx?id=09DF2BDD-5E11-4D32-B574-84ACFB8A4619
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82V80-2 Energy factor is .86 according to water heater industry self-regulated standards.

Rheem pdf says these water heaters are wired for non-simultaneous operation.
Except special order water heaters.
Non-simultaneous operation uses single 240V circuit as described below.
If your water heater is wired for simultaneous operation, and each element is on a separate circuit, that makes your water heater special order. I would guess the reason is for higher first-hour delivery, which implies rapid heating and would likely affect energy factor.
You might want to get serial number off model and call Rheem for specs on that special order.

Your water heater energy factor may be the same because 'energy efficiency is based on the amount of hot water produced per unit of fuel consumed over a typical day.' This means an aircraft carrier can be considered highly efficient despite overall cost. And naturally the guys making the aircraft carrier are also doing the rating.
http://www.energysavers.gov/your_home/water_heating/index.cfm/mytopic=13000

Non simultaneous operation means the upper thermostat controls heating functions.
240V goes to upper thermostat first.
When water inside tank is cold, thermostat reads temperature through tank wall.
Upper thermostat turns on upper element until top 2/3 of tank reaches thermostat set point.
Once set point is reached, upper thermostat turns off upper element and sends power to lower thermostat and lower element.
Lower thermostat reads temperature through tank wall, and turns on lower element until bottom 1/3 of tank reaches thermostat set point.
As water cools inside tank, lower thermostat is first to respond since hot water rises.
Lower thermostat turns on lower element until tank again reaches set point.
When hot water faucet is turned on, hot water exits top of tank.
At same time, cold water enters bottom of tank through the dip tube.
The heating cycle repeats.
At all times, the electricity flows through upper thermostat. And upper thermostat is powered by one 240V circuit.

With simultaneous operation, the upper and lower thermostats work in same manner.
Except thermostats are wired separately.
Lower thermostat does not wait for upper part of tank to be heated first.
Lower thermostat turns on whenever lower part of tank cools.
The advantage is more hot water available rapidly when demand is high. This is called first hour recovery.

One method for reducing electric consumption is to set lower thermostat so it only turns on during certain times of day. For example Whirlpool Energy Smart operates in this manner and shaves a few bucks off the bill each month. This says that simultaneous operation is not an energy saver, unless that circuit controlling lower thermostat is set on a timer.

Hello Check the red overtemp reset button at the temp control.Check for contintuity at the elements with a volt meter (pull one wire off first) they should have a reading otherwise they are open & shot.Last is overdrawing (busted pipe) shut off the cold water supply for a 1/2 hour and open it back up and feel the hot water supply pipe.Is it hot?The tank can't keep up with the demand.

1) Shut the breaker off to it at the panel. 2) Hook a hose up to it (the bottom has a drain). 3) Close the valve to the water heater (on the cold water supply). 4) Open drain on the bottom of water heater. 5) Open the relief valve to allow air into the tank (it won't drain otherwise - think if you put your finger on one end of a straw - the liquid stays in until you let go). Why are you draining it by the way?

In city water or well water system ... the cold water flows from the tank (or meter) toward the hot water heater. The cold water splits in two (so to speak) at the heater with one part going on to the house to supply all cold water needs while the other part goes into the water heater to be heated. On the other side of the hot water heater, there is a system that paralles the cold water system to supply the hot water needs of your home.

I hope this answers your question.

Begin by turning off the gas at the tank and at the valve near the tank. CAUTION: Do not proceed any further if you do not know how to relight the gas pilot!
2) Turn off the COLD water supply to the tank.
3) Attach a garden hose to the drain valve at the bottom of the tank. Run the hose to a convenient drain location. Be careful if you use a real cheapy garden hose... some of these become very soft when hot water runs through them, and may leak! If you don't have a drain in the basement floor or suitable sump hole, you have my sympathies... this drain-down can take a while with a bucket! Oh... and be careful if you use a soft plastic bucket. It can also soften from the heated water so don't overfill it or burn yourself!
4) Open up the hot water side of any faucet. Open up the drain valve on the tank and allow it to empty. Miller time. That is, unless you don't have a sump...
NOTE: If the drain valve clogs, turn on the cold water supply to the tank to use water pressure to "blast" through the clog.
5) When the tank is empty, shut off the drain valve and turn on the cold water. This will loosen up more sediment in the tank through the churning action of the cold water in the tank. Let the tank fill partially and drain it again. In fact, if you find that the sediment starts to clog the drain valve, turn on the cold water supply to the tank, which will help loosen the sediment and blast it out.
If you have extreme amounts of sediment, you may have to repeat this procedure a few more times. Look at the drain water... if it is running clear, you are done. Shut off the drain valve, open the cold water supply and allow the tank to fill. Once water comes out of the hot water faucet, the tank is full and your task is done! Now, you can turn the electricity or gas back on to heat the water.
How frequently to clean the sediment from your tank...
This depends on the source and purity of your water supply. Some pros recommend doing it annually, some every few years. I would recommend doing a partial drain down annually if you find any sediment in the tank, otherwise every couple of years.
Remember that with an electric water heater, you must turn the power off! Even a partial drain down may expose the upper heating element to the air and permanently damage it!

An on-demand, or tankless, water heater is a system for heating water as it passes through the pipes, usually very near the point of use. Traditional tank water heaters bring the water to approximately 140 degrees Fahrenheit (60 C), in order to ensure the water supply lasts long after the heater turns off. Since this is obviously far too hot to be pumped out of a shower of faucet, cold water is added to the mix in the pipes. Coupled with the loss of thermal energy over time, the average tank heater has an efficiency of approximately 80%. On-demand water heaters have a number of advantages over their tank-using counterparts. While tanks often degrade over time and begin leaking, the apparatus used in an on-demand water heater is much less susceptible to the burdens of age, and will often outlive the house they're installed in. The amount of energy used is a fraction of that used in a tank water heater, due to increased efficiency and a much smaller window during which a heating source is in use. While tank hot water heaters can, and often do, run out of hot water after a number of showers, on-demand heaters provide a never-ending supply of hot water, ensuring that warm water is always available when needed. A tankless water heater can cost between $500 and $1500, and they most commonly use either electric or natural gas energy to heat the water. Most mid-sized households report an energy savings of approximately 25-45% for a gas or propane heater, and up to 50% with an electric heater, over using traditional tank heaters. Water is usually set to a maximum temperature of 120 degrees Fahrenheit (49 C), though many heaters allow for custom setting of the maximum temperature via remote control. Outflow rates range from 8-14 gallons (30-53 litres) per minute. Installation for most tankless water heaters is incredibly easy, involving simple plumbing. In the case of electric heaters, all that is required for a fuel source is to plug the heater into an outlet and begin heating your water. Some modern on-demand water heaters can incorporate a solar preheating system. This system uses a traditional solar heating system and tank to bring the water nearer to the desired temperature, saving substantial energy use in the final on-demand heating. A solar preheating system costs between $500 and $800.