New house - hot water problems


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Old 07-11-16, 01:15 PM
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New house - hot water problems

We just moved into our house. It was built in 2012 and was a Parade winner (so I'm guessing it was built fairly well.)

The Home has 2 50 gallon Rheem water heaters, and I *think* a recirculation pump (I don't know what this is, but there's one plugged in next to the water heaters). All sinks, except the kitchen faucet and the showers, have a separate cold / hot water handles. The home is fairly large (6000 sq ft), so there's a lot faucets and bathrooms etc. We just moved in 2 days ago and the hot water is so sporadic. Here's a few of the issues:

* Sometimes hot/warm water comes out when it's supposed to be cold. Sometimes the opposite.
* Sometimes we get NO hot water (and this is with nobody using any hot water for hours).
* Sometimes the water is too hot, sometimes the water is only lukewarm (nobody previously using any). Sometimes it's too cold. No rhyme or reason.
* Master shower has 4 heads, all with separate controls. If only one is on, all is well. If we use any of the others while using that one, they both alternate between scalding hot and freezing cold.
* All sinks/faucts/showers/baths exhibit this behavior, so it's not limited to a select few.
* Sometimes everything works perfectly.

We contacted the previous owners and they said they have never had these problems. Pilot lights and burners in both water heaters seem to be functioning normally. I've tried unplugging the recirculation pump, with no improvement or change.

I contacted a few plumbers, but the earliest they can get here is Friday (it's Monday). I have 4 girls, plus the wife - so you can imagine my pain and all the complaining I'm getting. I'm not super handy and don't know a lot about this stuff, but If I can fix this myself, I'll do it.

I can take some pictures of the utility room if it helps.

Thanks for any help!
 
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Old 07-11-16, 03:02 PM
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I think some pictures of your water heater system would be handy for sure.

I would suspect that the pump on your system is a recalculation pump to help get hot water to the furthest sink of the house. If you look under the sinks you might find a mixing part between the hot and cold pipes. This should only allow water one way, into the cold pipe. This pump might also be on a timer.

The other thing to check is if you have a mixing valve. Many newer houses have then for anti scald protection. I have seen more then one fail or installed wrong.

Awaiting pictures.
 
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Old 07-11-16, 03:20 PM
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Old 07-11-16, 05:00 PM
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Here are a couple pictures of the actual water heaters. The pump thing is installed on the lower right. This was taken a few days ago and some of that wood around it has since been moved / cleaned up.

The label on the pump says "LAING Circulating Pump". If the problem lies with that pump, is there a way to just disable it and/or bypass it for now? Can I just unplug it?

Pic 1: Water Heaters 1

Pic 2: Water Heaters 2

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Where would I find this "mixing valve" and if it's failed / not working? That sounds like it could be it - we definitely have a mixing problem!
 

Last edited by ray2047; 07-11-16 at 06:00 PM. Reason: Add images.
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Old 07-11-16, 06:18 PM
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Here is a diagram of how I think your system is plumbed (I am not a plumbing pro)

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As you can see the pump pushes the hot water through the tank and to the last tap on the hot side, then the water returns back to the heater via the red PEX line in your picture. This is how it should work. I would check a few things:

1) Make sure the pump is working. You should be able to put your ear to it and hear it hum.
2) Make sure the pump is installed per the picture above and moving the water in the correct direction.
3) Locate there the PEX line goes and check to make sure that valve is open under the sink.

When the pump is running you should be able to put you hand on the PEX line and it should be warm/hot from the hot water doing the loop. If this is the case it should be running properly

It would have been nice if the installer put in a ball shut off valve in the PEX line to shut it off. If you just disconnect the pump water will still flow past the impeller. IF you want to bypass it I would install a push on ball valve like this (for 3/4"): 3/4 in. Brass Push-to-Connect Ball Valve-22185-0000LF - The Home Depot Unplug the pump if you shut off the valve.

On a side note I do not see a mixing valve in your pictures.
 
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Old 07-11-16, 06:32 PM
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I don't see a check valve in that recirc. line nor at the pump discharge. There MAY be one but I don't see it.

A leaking check valve OR the pump not running could easily give you the symptoms you described.
 
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Old 07-11-16, 07:07 PM
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Ok - so it would be bad to turn the pump off and close the valve?

I took a closeup picture of it:

Recirculating Pump

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Not sure if that helps anyone.

FYI - the pump sounds like it's working when it's plugged in. Makes a little humming sound. There's a little black valve on the far side of it (see pic) that may be something I can use to bypass it?

One weird thing I notice is that there are 2 places in the house where the hot / cold works perfectly, all the time, every time. The laundry room sink and the guest bathroom, which ironically sit just above the water heaters and are the closest. I'm not sure if that helps.
 

Last edited by ray2047; 07-11-16 at 07:13 PM. Reason: Add image.
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Old 07-12-16, 05:39 AM
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Do you have a valve that can be shut off somewhere between the Laing recirculating pump and the far end of that red pipe?

Do you know where the far end of the red pipe is?

Are you sure that all fixtures are turned off using the wall faucets or the separate hot and cold knobs and not by a control at the end of a sprayer hose or spout?

How does the behavior of the various fixtures change if you turn on a cold (only) flow at a distant fixture to a "medium low" setting and let it run while you take a shower, wash dishes, etc.?

Completely different cause that is harder to experiment with and cumbersome to fix: Your water heaters may have heat traps (look like pipe nipples) just where the connecting pipes enter on top. These can get stuck causing a complete loss of hot water. You could summarily remove them and substitute ordinary nipples and optionally add a down-then-up S shaped looping in the final hot water outlet to the house plumbing.
 
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Old 07-12-16, 07:57 AM
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From the picture, it appears the 2 tanks are plumbed in series. The first tank get cold water from the supply and outputs hot water to the second tank's input. The second tank outputs its hot water to all the hot water loads in the house. Unless the second tank heater control is set at higher temperature than the first tank's heater control temperature, the temperature of the hot water is a function of the last tank heated and the hysteresis in the tank heater control. Think of the first tank as a pre-heater and set its tank heater accordingly.
Forget everything if I misread the picture.
 
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Old 07-12-16, 10:18 AM
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The burner in the second tank should be prepared to come on if the water in the tank should cool off, for example if no hot water has been used for many hours.
 
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Old 07-12-16, 04:41 PM
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The black lever might be a valve to close off the line to the pump. Closing it off while the pump is plugged in could damage the pump. You can close it to shut off the pump system, just be sure to shut off the pump.

Is the red pipe warm/hot? It should be if the pump is running. If it is not, then something is wrong.

The laundry room sink and the guest bathroom, which ironically sit just above the water heaters and are the closest.
They might not be on the pump system. They might be plumbed "normal".
 
 

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