Low Hot Water Flow

[762x51]

Pump or city water the same - Cold pressure/flow is fine but hot water flow is low in both sinks and shower. I have re-checked the bypass (it's the 3 valve variety) and bypass is closed and flow valves open.

We haven't used the trailer for several months and everything worked fine when last used.

Any ideas as to why we are getting such a low flow from the hot water heater?

1998 25B Safari.

Regards,
Orin

[A W Warn]

Scale builds up inside the water heater when water is not flowing. With the first use after storage the scale flushes into the hot water lines. This is more prevalent where water has mineral content and/or is slightly acid.

Try removing and cleaning the aerators from the kitchen sink and toilet sink faucets. Also the screen inside shower head hose needs to be cleaned. Before reinstalling them run water through the pipes to flush the scale out of the system.

There is a kit that attaches to the end of a garden hose that you can use to flush the water heater through the drain plug, if you want to avoid this problem.

[nrgtrakr]

Close and open your winterization valves again, one may not be completely open. Your water will love you if you pull the drain plug and flush it until it runs clear (at least once a year). Depending how much stuff blows out, your hot water lines might enjoy a good flush as well.

At least this is where I would start.

[HowieE]

Remove the sink screens, not that they would effect one flow against the other, and blow out the system with air injected, 40 lbs or so, at the city water connection one hot water faucet at a time. Note what comes out. Reconnect the city water and while the screens are still out run one hot water faucet at a time again note what comes out.

[762x51]

Thanks for the tips guys but nothing has worked so far. I removed the screens and there was a small amount of trash there but nothing that would have caused the greatly reduced hot water flow. I have run one faucet at a time but even with the 40 PSI or so city pressure here I have only about 1/3 the flow from the hot side compared to the cold side. I've cycled the bypass valves a couple of times with no change.

[Siegmann]

If you think hard water deposits could be the issue, here is an option.

Drain water lines at low point drains while all faucets are open. Raise your outside city water hose up high as you can get it, (tie to a tree or ladder). Warm up 1-2 gallons of vinegar in your microwave, a few cups at a time, and pour it into the hose while all hot water spigots are open inside (first, bypass water heater). Put a cup under each spigot, or have someone watch, so you know that the vinegar has filled your hot water lines. Let it sit as long as you can. Overnight if possible. Flush with city water.

[nrgtrakr]

But did you flush the hot water heater?

[A W Warn]

Have you ever flushed out the water heater? The hot water outlet could be partially blocked. I've seen a lot of sand and scale buildup inside WH tanks, to the point the flow was blocked.

If you do not have the kit that goes on the end of a garden hose you might try closing the cold water inlet valve at the water heater, then open the other two winterizing valves. This will reverse the water flow through the WH. Remove the WH drain plug and turn on the water let it flow till it runs clear.

If scale buildup is bad, you might have to use the vinegar method mentioned above to clean the tank.

[762x51]

@ nrgtrakr:
@ A W Warn:

I just came in from taking your suggestion and flushed the hot water tank. Flow has improved quite a bit and now is at about 50% of the cold water flow.

I have to go out to Camping World tomorrow AM to get a few things we need for a trip at the end of the week and will pick up one of the faucet to garden hose adapter kits and try to reverse flush the lines.

When I flushed the tank, a bunch of "junk" came out so I suspect the faucets may have some of that stuff in their valves. If reverse flushing doesn't solve the problem then I guess the next step will be to disassemble the faucets for cleaning.

@ Siegmann:

We don't have hard water here so I doubt the problem is scale and from what came out of the tank when I first flushed it, I think it's probably algae that formed in the small amount of water that was left in the tank when I drained it after we used it last February - March.

Regards,
Orin

[A W Warn]

Since you have completed flushing, I would remove the screen at each fixture, let water flow for several minuets, then clean and replace the screens. I have never had a pipe or faucet get blocked to the point of disassembling. I've had this same thing happen several times. I'll bet you are good to go after this.

Even though we do not have hard water in our water systems in central NC, we will have scale (white/yellow/tan flakey) buildup in our aluminum water heater tanks. I assume it is from a combination of oxidation of the aluminum tank, accumulation of soluble minerals naturally occurring in our water reservoirs, and precipitation of the additives (ferric sulfate coagulant and hydrated lime to reduce PH) that are included in our local water systems.

[762x51]

Originally Posted by A W Warn

Since you have completed flushing, I would remove the screen at each fixture, let water flow for several minuets, then clean and replace the screens.<SNIP>

Hi Alan,

I've done all of that and it's still running slow so I'm going to try back flushing tomorrow AM after I get back from Camping World - Keeping fingers crossed that it will solve the problem.

Orin

[nrgtrakr]

Very good.

ALL water heaters will love you if you flush them at least once a year. I've seen 50 year old water heaters that were just fine due to this simple maintenance. An RV water heater perhaps flush more often.

Standing water, especially in an Atwood where there is supposed to be an air pocket on top, tends to grow things depending on how much chlorine is in it.

Think of a tea kettle or your drip coffee maker. Scale forms from the undetectable to us minerals in the water settling out from the heating process. Water heaters use an anode rod to offset this. Unless it is an Atwood, the aliminum tank of the Atwood provides the anode effect so never use an anode on an Atwood.

[NWRVR]

Also, be sure you still have an air gap in the water heater. With pump off, no city water connected and hot water heater cool, pull the pressure relief until there is no water flow.

[StreamDog]

Bypass the WH and see what the flow is like. I'm thinking if it's still restricted, then the problem's in the water line. If it isn't, then maybe problem's with the WH. Just trying to narrow down this bad boy.

[762x51]

The problem must be in the heater or the short lines from the bypass valve assembly to the heater.

I reverse flushed the lines this morning and the flow improved quite a bit but the hot water was still slow when compared to the cold water.

This evening I went out to try NWRVR and SteamDog's suggestions. Draining water from the tank to make sure that there was an air bubble only had the effect of making the water pump short cycle (1 second on / 1 second off) when the hot water tap is open. Runs constantly when the cold tap is on.

Opening the bypass and closing the heater supply and return valves gets full flow both hot and cold and the pump runs as it should.

The problem must be either bad bypass valves or the heater has a blockage in the tank. My trailer is piped with PEX so taking apart the lines is a real PITA but I guess I'm going to have to if the problem is to be fixed.

Thanks for all the suggestions and I'll post an update once I find the problem.

Orin

[nrgtrakr]

Maybe try this ...

You say the hot water heater bypass is with three way valves.

Is there a way valve them to force the cold water into the hot water outlet of the water heater with the drain plug removed?

Because when I read everything that is the only place and direction that has not been washed out.

Make sense?

[762x51]

@ nrgtrakr

When I connected the garden hose to the kitchen and then the bath sink and forced city water back through the system that would have caused the flow to enter the hot water tank through the tank's outlet port. When I was reverse flushing the hot water line I had the tank's drain plug removed.

Orin

[Siegmann]

When you reverse flushed the lines, you said the flow improved. Did you capture the flow to see if any debris came through?

Before taking apart pex fittings, I would still try a vinegar soak. Scale could have come out of the water heater and partially blocked a fitting. Other than a few bucks for the vinegar, I see no downside. Plus, you'll clean out your 17 year old plumbing system!

[A W Warn]

Before taking the plumbing apart, I would fill the WH tank with distilled vinegar. Vinegar has enough acid to dissolve any deposits without harming the WH or plumbing. You will need at least 4 gallons if you have a six gallon WH. You can add a gallon or two of water with the vinegar to fill the WH tank.

First drain the water out of the system. (open all drain valves, remove WH plug, open all faucets). No need to blow with compressed air, just gravity drain what will run out.

Second, reinstall the WH drain plug and close all faucets. Open the pressure relief valve on the WH. Pump distilled vinegar into the WH (just like winterizing with antifreeze except let the vinegar go into the WH tank not in the water pipes) If you do not have a winterizing kit on your pump, use a funnel and hose connected to the water inlet to pour it in. Let it set a few hours.

Third, Remove the plug to drain the WH tank then close the pressure relief valve. You can save this vinegar to reuse next time. (or, after you have captured what vinegar and solids that drained from the WH tank you can reuse a gallon or two, after removing any solids, to fill the water pipes to dissolve any deposits are inside pipes and faucet valves)

Fourth, Remove the screens at each fixture and use water to flush the entire water system until the vinegar smell is gone.

If I'm not clear enough, you can google search to find some videos that show how to do this.

[TUDO BEM]

I had a similar situation and it turned out I had left the "Outside shower" valve open when I had drained it for cold weather. But water was not coming out because the shower head cutoff was shut. But this caused just enough loss of pressure to keep my hot water in the trailer sinks from coming out hot.