[shadow111770]

I had a tub full of hot water until approx. 2-3 weeks ago when I noticed that I could only get about half a tub full. Same problem in my daughter's bathroom. I have a gas Rheem 21V40-7 hot water heater and I have been trying to find a manual online for this model - to no avail. I've read about possible problems, i.e. broken dip tube, defective thermostat, etc. I'm pretty much a DIY kind of woman, but without an owners manual, I don't want to attempt to fix this problem. Money is tight since my job was just eliminated so I would like to fix this myself if at all possible. Does anyone have a manual or any advice for me? Thanks.

[speedball1]

I had a tub full of hot water until approx. 2-3 weeks ago when I noticed that I could only get about half a tub full. Same problem in my daughter's bathroom. I have a gas Rheem 21V40-7 hot water heater and I have been trying to find a manual online for this model - to no avail. I've read about possible problems, i.e. broken dip tube, defective thermostat, etc. I'm pretty much a DIY kind of woman, but without an owners manual, I don't want to attempt to fix this problem. Money is tight since my job was just eliminated so I would like to fix this myself if at all possible. Does anyone have a manual or any advice for me? Thanks.

I don't have a manual but here's a cutaway of a gas hot water heater and its thermostat,( see image). The first thing I would check the dip tube located under the cold water inlet. Do you flush your heater on a regular maintenance schedule. No? Then let me show you how. If you don't flush your heater on a regular basis it will build up minerals on the floor that will act as insulation and not will only cut down on the heat from the burner but will increase your energy bill. For long life and fewer troubles you should keep your heater clear of mineral build-up by flushing on a regular schedule. Let me show you how. Attach a hose to the boiler drain at the bottom of the tank. With the pressure on, open the boiler drain and let it run until the water runs clear. You will see a spurt of red,(rust) followed by white grains,(lime or calcium carbonate). This shouldn't take more then a few minutes. Do this monthly to keep it clear. Now flush out your hot water lines on ALL fixtures. Now pull each aerator and clean the screens. Be sure you put them back togather the same way you took them out. Don't forget to flush it out every month. Your heater will thank you for it. Hope this helps and thank you for rating my answer. Tom

[Milo Dolezal]

How big is your water haater ? (gallons). How big is your tub ? What temprature is the thermostat set to ?

[Mrendon]

"let me show you how. Attach a hose to the boiler drain at the bottom of the tank. With the pressure on, open the boiler drain and let it run untill the water runs clear. You will see a spurt of red,(rust) followed by white grains,(lime or calcium carbonate). This shouldn't take more then a few minutes. Do this monthly to keep it clear. Now flush out your hot water lines on ALL fixtures. Now pull each aerator and clean the screens. Be sure you put them back togather the same way you took them out. Don't forget to flush it out every month. Your heater will thank you for it. Hope this helps and thank you for rating my answer., Tom

I'm about to flush my heater for the first time. Somebody told me that I have to shut the water from the street meter. But if I read correctly you sugested to do it with the water running?

[speedball1]

Somebody told me that I have to shut the water from the street meter.]

Some body gave you the wrong advice.
As I've stated you flush it, not drain it. That means yhat you keep the water under pressure.

[CHayn]

Absolutely right to leave the water on when you flush the heater! How old is your heater? The dip tube used to be a common problem but it is rare now with fairly new heaters. I have seen it though. More common is that you have a single handle faucet somewhere in the house that is allowing the water to cross connect from the hot to the cold. Or reverse. Especially on moen faucets. If you turn off the water at your heater then go around the house and turn on your faucets to the hot side. If you get water out of the hot side you have a cross connection somewhere most likely caused by a bad cartridge.

[chasedawgs]

I have a Rheem gas water heater 21Br40-7T.

I have a STRONG odor when (for example) someone is taking a shower and running the gas dryer. It's so strong that it burns my eyes so bad.

Does anyone know what it could be and how to fix it?

Thank you.
Kelli

[Milo Dolezal]

Kelli, first you have to make sure dryer and water heater have TWO SEPARATE vents. Under any circumstances they cannot be combined. Please, check it out and come back. Back to you. Milo

[chasedawgs]

Yes they are separate.

Kelli

[Milo Dolezal]

OK, dryer and shower should not be related problems... do you smell any odor ? What does it smell like ? Gas ? Burnt gas ? Or?. back to you... milo

[chasedawgs]

ok, dryer and shower should not be related problems.... do you smell any odor ? what does it smell like ? gas ? burnt gas ? or ? ... back to you... milo

I think it's more prevalent when the shower is running. A VERY strong odor, it burns my eyes terribly, more like exhaust. Kelli

[Milo Dolezal]

It must be coming from your drain... Ok, next time you are taking shower, let water run, get on your knees and smell the drain... see if it comes from there... Milo

[chasedawgs]

It must be coming from your drain.... Ok, next time you are taking shower, let water run, get on your knees and smell the drain... see if it comes from there ....Milo

It smells in the room where the hot water heater is, not the bathroom. (Just making sure we're on the same page)

A friend suggested adjusting the air intake on the hot water heater but we can't find where that is. Kelli

[Milo Dolezal]

Is the room properly ventilated ? Also, check if the vent has proper draft... it sounds like it is not venting properly and that may kill you... deal with it ASAP... Milo