Water heater issue

[Jimm]

Issue: Hot water flow to all fawcets has slowed to a trickle. Heater is a 6gal Seward with heat exchanger. Have traced the lines from the heater and don't find obstructions. Seems to be internal to the heater. Has anyone had a similar problem? If there's an obstruction in the heater, is there a treatment to clear? Suggestions welcome. Would like to avoid removing or replacing:cry:

 

[bobtigar]

Before you go tearing things apart, check the easy things first. Is the flow on the cold water side OK? Is there a line filter that might be clogged? Is the strainer on the faucets clogged? Bob

 

[Lost Parent]

Before you go tearing things apart, check the easy things first. Is the flow on the cold water side OK? Is there a line filter that might be clogged? Is the strainer on the faucets clogged? Bob

Check for a clogged or siezed check valve on hot or cold inlets on heater tank

 

[Lost Parent]

Before you go tearing things apart, check the easy things first. Is the flow on the cold water side OK? Is there a line filter that might be clogged? Is the strainer on the faucets clogged? Bob

have you checked screens on faucets?

 

[higgs]

Disconnect the heater's out from your system and then pump it up and see what happens. That should tell you if the blockage is at or before the tank.

 

[Jimm]

Disconnect the heater's out from your system and then pump it up and see what happens. That should tell you if the blockage is at or before the tank.

Thanks - a good first step!

 

[Jimm]

Before you go tearing things apart, check the easy things first. Is the flow on the cold water side OK? Is there a line filter that might be clogged? Is the strainer on the faucets clogged? Bob

Thanks - Cold water side is fine, no inline filters or fawcet screens.

 

[Ralph18422]

Had this problem too

If you pull the Hot side hose barb off (not just the hose but the barb itself) of the water tank, you will most likely find a small check valve. I removed it from my hot water tank to prevent future problems.

 

[wflowe2]

I agree that is probably the check valve but removing it leaves you open to the possibility of hot water flowing back into your water tank(s). It is pretty easy and cheap to replace the valve.

 

[Bob J.]

Issue: Hot water flow to all fawcets has slowed to a trickle.:cry:

Check to see if the heater has a tempering valve on the hot water outlet.
If it does, that's your problem.

Bob

 

[timvg]

Another idea. You may have calcium desposits (that white stuff that looks like salt) blocking the flow somewhere. We had it at our shower, right before the faucet. Cleaned it out and got full pressure again. It could also be at the hot water output of the heater.

 

[Chuckbear]

So much advise and all good. But if you remove the in AND out line on your water heater and connect them together, bypassing the hot water heater, you will have your answer. At least you will be sure where to go from there. Chuck

 

[RichH]

Once you evaluate all the connections, flows, valves, etc. make sure that the heater isnt 'air blocked' ... or a large amount of trapped air in the top of the potable water side of the heater. Next time initially fill the heater with the 'pressure relief valve' PRV open so that any trapped air is purged during the 'fill', close the valve when water exits the PRV valve and run the system to 'full pressure' (the auto water pump shuts down), then momentarily 'burp' the PRV valve to allow any remaining air to be purged.
Air blocking can also occur in any delivery inlet / outlet line that is "HIGHER" than the heater, and if you have 'any' such line higher than the heater, that line should also be 'purged'. If any of these 'high spots' continually 'air block' then apply a cock/vent valve at the 'high spot' and simply 'burp' when the flow begins to slow.

;-)

 

[Stu Jackson]

We call it Burping your engine: http://c34.org/bbs/index.php/topic,4518.msg26462.html#msg26462

 

[CPseudonym]

Great advice. A side note on burping air through the tank PRV. If that valve is old and has never been regularly exercised in the past it can leak after doing this. Replace the valve if it does, do not plug it off. Plugging leaking safety features can be hazardous to your health.

 

[Lost Parent]

Great advice. A side note on burping air through the tank PRV. If that valve is old and has never been regularly exercised in the past it can leak after doing this. Replace the valve if it does, do not plug it off. Plugging leaking safety features can be hazardous to your health.

On marine and rv heaters you do not fill heater by opening the tp valve but by keeping it closed and opening a hot water faucet . this allows the heater to build up a head of air for expansion in the tank
Most of the time when a tp drips it is because this head of air has slowly been pressurized out of the tank by hot water and must be replaced every so often
I have done it many times over the years and have yet to replace a tp it ...this is very normal

Good luck and hope you find blockage

 

[RichH]

On most such heaters the PRV valve is lower than the top surface of the 'tank', thus will always have an entrapment of air which will accommodate any expansion. This normal air 'bubble' will be well above the piping in/out and will not by itself cause an air blockage. If the tank develops a larger air bubble at or below the in/out then you will become 'air blocked'.

 

[CPseudonym]

Thanks Lost Parent and Rich. Having never owned a marine or RV water heater I was unaware of that nuance, I'll take your word for it. I have however worked on a T&P or two in my career as a plumber. The advice of replacing rather than plugging a leaking T&P that does not dry up I stand behind. I have encountered plugs used by homeowners and even commercial/industrial mechanics weekly for my entire career. People don't know any better and think it's acceptable. Most have no idea of the damage that can be the result. Mythbusters did the best graphic demonstration ever on a couple of shows. Would hate to see what would happen on a boat.