I live in a one bedroom apt. Our water heater is not the normal 40gallon but a smaller 20gallon. When we moved in it was hot for at least 30-45 mins. Now it stays hot for less then 10. My maintance man came and "fixed" it which it only got hotter faster and then got cold. Obviously he only turned up the heat. What can I do besides continually bother them or just replace the damn thing myself? He told me yesterday that I'm using too much water, yet I think I've been using less.
Water heater not staying hot more than 10mins
heaterwater
Related Solutions
I suspect you have a set-up like this?
You are concerned that when the water gets pumped back into the "water heater" it could possibly pollute your main water line?
The only thing I could suggest is putting a check valve on the "cold" water supply so that it can only supply fresh water. That is helpful if the pumps output pressure is higher than your supply pressure (This could happen on someday with low supply pressure or if you do not have main water pressure regulator)
In this situation the return is a dedicated port on the "water heater/boiler" and there should already be a check valve/pressure regulator/non return valve just before the water heater. So the rest of the house will run just on the cold water supply and never get any recirculation contamination.
This type of radiator should be warm to the touch, not hot like an cast iron radiator. If you touch the fins with two or three fingers it should feel hot enough to be very uncomfortable. Lastly, go to incoming pipe coming up through the floor again, it should be very hot, too hot to touch for more than a few seconds. Usually the water moving through the pipe is 150F to 180F. Then feel the outgoing pipe again, it should be almost as hot as the incoming side. If the outgoing is not hot you have a blockage or bad circulater. You should not be able to hold your fingers on either the in or out flow side these pipes for more than a few seconds. If you have a automatic bleeder on the radiator get rid of it and install a manual bleeder. Then run heat and bleed again. Then again one hour later.
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Best Answer
TL; DR: When the temperature is colder outside, your cold water is colder so you have to use more hot water for the same shower temperature.
Facts:
Given the above facts, consider this (numbers and calculations made up)... In the summer, to get your shower where you want it, you need to mix 70 degree "cold" water with 120 degree "hot" water to get a final temperature of 100 degrees. This means that you have to use about half hot and half cold, so 1.25 GPM cold and 1.25 GPM hot. That means that 20 gallons of hot water will last (20 / 1.25 = ) about 15 minutes. This doesn't match your 30-45 minutes, but just stay with me... It's just an example.
In the winter, the incoming "cold" temperature is much cooler. It could get down to 40 degrees. When you mix the 40 degree water with 120 degree water to get a 100 degree shower, you don't need nearly as much cold water. You still have to add up to 2.5 GPM for the shower head, so the ratio ends up being more like 0.5 GPM cold and 2 GPM of hot. That will reduce your shower time to 10 minutes - a 50% drop, and nothing in the house has obviously changed. You probably like the shower hotter than 100 degrees, so the ratio will end up using even more hot water.
So, regardless of what the real numbers are, in the summer you end up "having more hot water" even though your water heater hasn't changed at all.
Also
As this shows, you have been using more hot water even tho your total water consumption may have gone down because of the shorter usage time.
And if you're renting an apartment, you can't replace the water heater. Plumbing and electrical repairs must be done by their personnel so they can remain liable for any problems.