The Tank › Water is tepid
- August 8, 2011 at 12:28 pm #16513
I just had a solar hot water system installed, including an 80 gallon electric water heater. The installation looks correct, cold water to the “C” pipe and hot from the “H” pipe. There’s also a bypass between them to temper the water, but that is turned off. The solar system seems to work fine, and the little control box shows the water heater temperature as 125 degrees or more. There’s power to the water heater, and I’ve verified that the elements get 220v when the thermostats switch on.
Unfortunately, the water at the nearest tap (the kitchen) never climbs above 98 degrees.
I noticed this morning, at the coolest part of the day, before running any hot water, that the hot pipe felt cold and the cold pipe felt hot, right on top of the water heater. When I turn on hot water, the hot pipe warms up and the cold pipe cools down. But, as I said, the water never gets warmer than 98 degrees. (I measured both the water from the tap and the surface of the tank. My thermometer agrees with the system thermometer.)
My theory is that the water heater was assembled incorrectly at the factory, and the dip tube is actually connected to the hot side, so that it is drawing water from the bottom instead of the top.
I’m insisting that the installer fix this, but I’m wondering if anyone has ever seen an incorrectly assembled water heater? Or maybe someone has a better theory?
MarkAugust 8, 2011 at 11:12 pm #16517EjParticipant
I do factory warranty and I have never seen a dip tube installed wrong. I have seen broken ones. I think I would draw some water from the lower spigot on the heater and check the temperature there. Also you could make a visual inspection of the dip tube. You don’t mention if your elements cycled off after heating your tank or if the 220v is constant. Also if you are measuring 220v across both terminals of the element or one side to ground? I am also unclear if you are getting your 125 degree reading at the solar or if that reading is from the water heater?August 9, 2011 at 12:53 am #16518
Hello: Troubleshooting this means questions 😎 Cold water flows into the solar tank and then to the back-up electric heater, or is there only one tank that is the solar tank with an electric element at the top? There are two solar lines. The hot line returning to the tank from collectors should be rather hot at the end of a sunny day, but the cold supply to the heater should be pretty warm also. I’d check both later in the day and let us know what temperatures you find. I’d expect anywhere from a four to a ten degree rise in temp. Does it line up with what the readout is saying? Have you checked setting on the thermostat for the electric element? Have you felt the pipes? Check hot and cold at the tank, but also check the three sides of the tempering valve. Have you checked for a cross connection? This site has instructions for doing that.
The dip tube could be in the wrong place and I’ve seen it done, but these other things are at least as likely the problem. Also, the dip tube being wrong would cool off outgoing water, but not instantly.
Yours, LarryAugust 9, 2011 at 6:46 am #16520
The solar part is not the issue. That part seems to be working OK. It’s a separate system that connects to the drain port at the bottom of the standard water heater, injecting hot water through a “straw” into the drain port and drawing cooler water from the same port. In any case, that part just augments the electric heater.
My dissatisfaction is with the standard water heater part. At no time does the water from the kitchen tap exceed 105 degrees. It is usually less than that.
I’ve adjusted both thermostats for the elements, the upper and lower. They are working properly, that is, each element switches on and off as the thermostat is turned up and down. I can measure 220v across each element when this happens, and I can also hear them start to heat. The water in the heater appears to be hot. The solar system has a probe that is tucked under the insulation of the tank to measure the tank surface. I put my own thermometer’s probe in the same place, and that is how I know what the temperature of the water is, and how I know that my thermometer agrees with the solar system’s thermometer. They both read 125 (first thing in the morning) to 138 degrees (after a long hot day.) When I put the same thermometer’s probe in a bowl of water being constantly filled from the kitchen tap’s hot water, it only reaches 98 (1st thing in the morning) to 105 (late in the day after the solar has augmented the temperature.) So the issue is that I’m experiencing a 20 degree or more drop in temperature through about 10 feet of copper pipe.
First thing in the morning, the supply pipe to the water heater is almost too hot to touch, and the hot water outlet pipe is stone cold. This seems wrong to me, which is where my dip tube theory comes from. Running hot water from the kitchen tap causes the supply pipe to cool down and the hot water pipe to warm up. However, the water from the tap never gets hot enough.
There is a cross connection installed right on top of the water heater. Apparently it is required by code or the utility company or something. While measuring the water temperature from the kitchen tap, I opened this up. The water temperature went from 105 to 92, as you’d expect. Closing it brought the temperature back up to 105.
Randy, the owner of the company that installed it came and looked it over last night. We went through the exercises together to check the elements and measure the temperatures. We even turned off the cold supply to the kitchen tap to assure there wasn’t a cross connection. He couldn’t come up with an explanation. He said he would contact the rep for the water heater company (American Supply) and see what he thought.
I personally think that we won’t be able to prove anything without taking the connections off and checking the dip tube. Since this is a new installation, I’m not going to do that myself.
Thanks for the suggestions, all. Any new ideas are welcome.
MarkAugust 9, 2011 at 12:00 pm #16521
Hello: After sitting idle for a time, both hot and cold lines on top of the electric heater should be warm. What you have sounds like there is flow when there shouldn’t be. I’d do the cross connection test described elsewhere on this site. I’d also use a pressure gauge to see if there is a leak, by hooking it up at any hose bibb and shutting off water to the house. If it falls off there’s a leak. I don’t see how a badly placed or missing dip tube could make a pipe on top of the tank cold.
Is there a recirc (instant hot water) line?
By the way, sediment can be a real issue when pulling water from the bottom of a tank.
Yours, LarryAugust 9, 2011 at 1:01 pm #16522
There is no recirc line. I wish there was, that’d be nice!
This is a brand new tank, so no sediment issues.
Randy and I will be doing a cross-connection test tomorrow, but I’d be shocked if that was the problem. The new tank is plumbed in right where the old tank was, and there was no problem with the old one, so how a cross-connection issue could be magically created makes no sense.
As for a leak, where would it be? If it was downstream of the tank, I’d see it in the walls of the house. All the plumbing runs behind the drywall about 18″ above the floor. I’d have major soaking and water damage. If upstream, it wouldn’t affect the hot water. The supply runs under the cement slab of the house.
Another thing I just thought to try is to draw some water through the pressure release valve and measure its temperature. The valve is on top of the tank, so it ought to be the hottest water available. I could compare it to the temperature of water drawn from the bottom of the tank through the drain valve.
Thanks for your thoughts.
MarkAugust 9, 2011 at 3:06 pm #16523Randy SchuylerKeymaster
We’ve heard your sentiment about cross connections many times, but they DO develop seemingly from nowhere, so check for that.
Randy SchuylerAugust 9, 2011 at 9:05 pm #16526
Hello: A schematic or photo of the system would be helpful. In your recent post it sounded like you were pulling hot water from the drain…. I’m easily confused 😛
Yours, LarryAugust 9, 2011 at 11:24 pm #16528
The drain valve! Not the drain! 😉
Here’s the system I got (single tank version):
…but none of the solar parts are of interest to my problem. My problem is that the water at the kitchen tap is over 20 degrees cooler than the temperature of the water heater.
MarkAugust 10, 2011 at 11:06 am #16529
Hello: I see that there is an interconnect between the solar control and heating element/s. That could be part of the problem. The mixing or tempering valve is another concern. Do this test. Put a hand on the cold feed to the mixing valve and have somebody else run hot water for 30 seconds. If the line you’re touching cools off, you know cold water is flowing and diluting the hot.
Yours, LarryAugust 10, 2011 at 12:10 pm #16530
Actually, no, the solar system does not control the electrical elements. They’re thermostatically controlled, just like a standard (actually is a standard) water heater.
By the “mixing valve” do you mean where the solar system connects to the tank, at the bottom (what I’ve been calling the “drain valve”), or the cross-connected valve between the hot and cold on top of the tank (not shown in the diagram)? I tested the latter in a previous post:
“While measuring the water temperature from the kitchen tap, I opened this up. The water temperature went from 105 to 92, as you’d expect. Closing it brought the temperature back up to 105.”
Data I collected this morning:
Temp of water drawn from the top of the tank through the pressure valve: 126
Temp of water drawn from the bottom of the tank through the drain valve: 111
Temp of the surface of the hot pipe at the water heater while running hot water: 106
I measured the first two by immersing the probe in a pail of water and letting it sit for a couple of minutes. I measured the 3rd one by jamming the probe under the foam insulation around the hot water pipe right at the water heater. I didn’t measure the temp of the water at the kitchen tap, but I’d guess it would be under 100.
I took a shower with the handle cranked all the way to hot, and it was barely adequate for me. My wife would be freezing.
Cross-connection test with Randy put off for another day.
- You must be logged in to reply to this topic.