This week's plumbing mystery

[mkaiseraz]

Hi all,

I am a new homeowner in Arizona, and I have a serious problem with a 10-year-old house my wife and I just bought here. So far we have had three plumbers and countless helpful neighbors trying to figure this thing out--with no success so far. Just sought out this forum today, in a desperate attempt to find help. If anyone has any ideas, I would be very grateful to hear them. Here's my story. As you'll soon see, I am not a plumber, simply a typical consumer who has had very little experience with hot water problems.

We bought this house about three weeks ago. Immediately after we moved in, we discovered that the "hot" water in the master shower is not really hot but merely lukewarm. I immediately checked the thermostat on the water heater and saw that it was set to approximately 130 F. I estimated the water in the shower, when set to all hot was maybe 100 degrees, but upped the thermostat setting, to see what that would do. Nothing.

I then checked in the other hot water locations and found that all were delivering water that seems to be the same temperature. Not hot but tepid at best. Some would start out a little "hot" (maybe 110 degrees), then cool back to maybe 100 or so.

The previous owner had lived here for a little over two years and reported no problem with hot water. The home inspection that was performed when we bought reported no problem with hot water. Yet we experienced a problem immediately after moving in.

I checked the water heater more closely. I reset it and confirmed that it was producing hot water. I touched the output pipe and found it to be very hot. It is clear that the heater is working properly.

I then performed a lot of admittedly random experimentation inside the house. While I had originally found that all the hot water faucets delivered tepid water, I eventually discovered that I could get scalding hot water from the shower in the master bathroom--but only by running the hot water in the guest shower. Very weird.

If I turn on the guest bathroom shower to full hot, I do NOT get hot water at that location, just like everywhere else. However, if I leave that shower running and set to hot, the shower in the master bathroom then delivers scalding hot water. If I then turn off the guest shower, the water coming out of the master shower changes back to tepid. In other words, the only way I can get hot water anywhere in the house is to turn both showers on to full hot. Then I get hot water from the master shower but not from the guest shower.

As I said earlier, three plumbers and a number of neighbors (two of whom are former home builders) are stumped by this. Unless someone comes up with a credible explanation for this odd behavior, we are about to start ripping into walls and chasing pipes to find where the problem lies. I am, of course, concerned that this is about to become very costly to diagnose and repair.

In addition to the utter illogic of what we're observing, the even more strange aspect of this situation is how the previous owners experienced (they say) no problems. How could this have developed just when we purchased the property? If the problem was already here, how could they have lived with it?

Red Herring?

I would be remiss if I didn't point out that the hot water heater is solar, and electric. I doubt this has anything to do with the problem but what do I know. The 120 gallon heater heats from two sources--electric and (passive) solar. There are solar collectors on the roof and water is passed through them to the water heater. The heater also has an electric coil just like any other conventional heater--which comes into play when the roof-top collectors can't deliver enough heat. The reason I don't think this is relevant is because the water coming out of the water heater is scalding hot--whether it's heated by the sun or electricity. But what do I know, I'll mention this in the spirit of full disclosure.

If anyone has any insight and/or experience about my situation, I'm all ears. If I can tell you anything else that will help you, please ask. To this untrained plumber, this is all very confusing and illogical. Thanks for listening.

Mike

 

[snowhead]

I'm in the U.K but coincidentally my Son lives / works / owns a house in Arizona.

Are you on a well or hauled water and if so is the pressure on the well or tank pump good?

There should be a Secondary circulation pump that circulates hot water from the Water heater around to the tap locations and back to the Heater, to make sure when you need hot water you don't need to have the tap on for too long to get it.

It could be the pump, which may be on a timer is not working, it could also be that there is an airlock in the return pipe and the water isn't circulating.

 

[oz-plumber]

Do you have mixer taps installed.

If so, one of them is passing cold water into the hot water line.
Cartridge needs replacing

First port of call - guest bathroom shower.

There could also be a faulty tempering valve.
Which would cause the same problem

 

[mkaiseraz]

I'm in the U.K but coincidentally my Son lives / works / owns a house in Arizona.

Are you on a well or hauled water and if so is the pressure on the well or tank pump good?

There should be a Secondary circulation pump that circulates hot water from the Water heater around to the tap locations and back to the Heater, to make sure when you need hot water you don't need to have the tap on for too long to get it.

It could be the pump, which may be on a timer is not working, it could also be that there is an airlock in the return pipe and the water isn't circulating.

All good thoughts, thank you. But no, we are on public water, no pump is involved to be best of my knowledge.

Mike

 

[mkaiseraz]

Do you have mixer taps installed.

If so, one of them is passing cold water into the hot water line.
Cartridge needs replacing

First port of call - guest bathroom shower.

There could also be a faulty tempering valve.
Which would cause the same problem

Yes, both showers have mixing cartridges. I have replaced both. No change.

If there's another tempering valve, we haven't found it. Maybe there's one in the attic or walls, but we don't know why one would be there--or where it is.

I guess we'll have to follow the plumbing from the hot water tank to every faucet and see where it goes from scalding to temperate. Does anyone here know if plumbers use heat-detecting cameras or tools, to "see" where water changes temperatures?

Thanks all.

Mike

 

[Last Plumber]

I was thinking the same way as @oz-plumber. If the water in the tank is hot, it does sound as though it is mixing/passing somewhere from cold to hot when the hot is being drawn.

Thermostatic mixer valve/shower/maybe a mixer tap. What kind of water heater is it?

 

[mkaiseraz]

I was thinking the same way as @oz-plumber. If the water in the tank is hot, it does sound as though it is mixing/passing somewhere from cold to hot when the hot is being drawn.

Thermostatic mixer valve/shower/maybe a mixer tap. What kind of water heater is it?

The water heater is a SunEarth SU120-1. The first guy who came out suspected the mixing valve on top of the heater, so he replaced it. No change. See attachments.

 

[Last Plumber]

The water heater is a SunEarth SU120-1. The first guy who came out suspected the mixing valve on top of the heater, so he replaced it. No change. See attachments.

It looks like a place for mixing but I can't say I have seen that set up before. At least, I don't recognize it but others might. Maybe it can be adjusted!

 

[gmartine]

Hi Mike

I understand that Arizona is the new California just a bit cheaper is that a fair statement?

 

[mkaiseraz]

Hi Mike

I understand that Arizona is the new California just a bit cheaper is that a fair statement?

Yes, I'd say that is accurate.

 

[king of pipes]

Can the hot a cold supplies be isolated independently of each other to each bathroom ? If the answer is no I would consider adding extra isolation points this will allow the sections of pipework to be isolated to find a mixing issue ? , it could also be that there's a major difference in supply pressure between the hot water and the incoming cold supply it can then overcome the hot supply and cause these sort of problems in shower mixing valves and taps.130° f is 54°c here in the UK we heat our stored water to 60 °c , 110°f is 43°c which is the setting shower manufacturers set their equipment to avoid scalding this is often not enough for some customers, a few things there to consider please keep us updated . Regards Kop

 

[oz-plumber]

Just had another thought.
Some mixer taps have adjustments under the handle.
They restrict the lever from going to full hot water, so there will always be cold mixed in.

Can you post a pick of the mixer with the handle and shroud removed.
( Remove as much as you would as if you were going to change a cartridge - without turning the water off )

 

[king of pipes]

Just had another thought.
Some mixer taps have adjustments under the handle.
They restrict the lever from going to full hot water, so there will always be cold mixed in.

Can you post a pick of the mixer with the handle and shroud removed.
( Remove as much as you would as if you were going to change a cartridge - without turning the water off )

Like this Oz

 

[Gasmk1]

Do you have mixer basin taps could be one of these passing

Yes, both showers have mixing cartridges. I have replaced both. No change.

If there's another tempering valve, we haven't found it. Maybe there's one in the attic or walls, but we don't know why one would be there--or where it is.

I guess we'll have to follow the plumbing from the hot water tank to every faucet and see where it goes from scalding to temperate. Does anyone here know if plumbers use heat-detecting cameras or tools, to "see" where water changes temperatures?

Thanks all.

Mike

l

 

[mkaiseraz]

Here's an update for all.

The plumber today followed the hot water from the tank and determined that the problem was indeed mixing valves in two lavatory sink faucets in the guest bathroom. By shutting off the water to those faucets, he found that hot water was then delivered to all others. I will be getting new cartridges for the two faucets and moving forward. He doesn't know which one is at fault but since they are both of the same vintage (over 10 years old), I will be replacing both.

Thanks to all for your suggestions. And sympathy. What a great resource this forum is.

Mike

 

[king of pipes]

Here's an update for all.

The plumber today followed the hot water from the tank and determined that the problem was indeed mixing valves in two lavatory sink faucets in the guest bathroom. By shutting off the water to those faucets, he found that hot water was then delivered to all others. I will be getting new cartridges for the two faucets and moving forward. He doesn't know which one is at fault but since they are both of the same vintage (over 10 years old), I will be replacing both.

Thanks to all for your suggestions. And sympathy. What a great resource this forum is.

Mike

Glad your making progress best of luck with it Regards Kop