Lochinvar NKC150 hot water for only 30 seconds
I just bought a house that had this lochinvar installed 4 years ago. All of a sudden one day I didn’t have hot water. Got fixed the next day but ever since I was noticing hot water was lasting less and less until at some point it was going out in less then a minute.
now it’s official, I only have hot water for about 40-50 seconds.
The pipe going into the mixing valve when not having hot water it’s completely cold. Mixing valve marks 40•F . Everything inside it’s hot except this pipe. I finally found the guy who installed it. He changed the flow switch and it was working. I was able to shower for more than 5 minutes, and I saw how the light was turning red when calling for hot water.
Next morning, again same issue now the switch was not turning red anymore.
What could be causing this? I’m desperate it’s 2•F and I have a pregnant wife and this sucks. She has been going to her mothers to take a shower. Me on the other hand, been taking 30 second showers.
I feel like something is not sending a signal that I need hot water, and eventually it does and I get it, but then as soon as I use it, it stops calling for more hot water. The heat works great! But not the hot water.
Any idea would be very much appreciated.
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I’m having the same problem with a client’s boiler and have ordered parts for both the diverting valve and flow switch, so until the parts get here, I won’t have figured out a solution.
Call Lochinvar tech. support at (615)889-8900. They usually don’t want to speak to the homeowner, so have your plumber call. I believe it's option #3 that gets you to a live person. Have your model and serial number handy.Good luck and let us know what you find out.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
Is the boiler firing during a call for domestic hot water? On the screen what is the temperature target. its the temperature in parenthesis
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When you run the hot water tap does the boiler fire? When it fires, is the hot water out from the boiler that goes to the HOT side of the mixing valve hot? If so then the mixing valve is bad. I've had that happen. I've used Caleffi mixing valves with the Gauge and they have been very reliable.
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Did you see which part your plumber changed? there is a flow switch and a flow sensor, generally the sensor is what will see flow from your domestic side and tell the boiler to fire for domestic heating. Usually a flow switch inside a boiler is just a boiler safety for both heating and domestic, though I am not terribly familiar with this particular model maybe they use both for domestic production? the parts list puts the flow switch on heat only models as well so I imagine it doesn't specifically control the domestic side.
Space heating is working well i assume?
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in this order this is what I would do
turn on the shower to the normal showering temperature then turn on the hot water only to the bathroom sink. And see if the shower maintains the temperature for five minutes. If this works this points to the flow switch. And sometimes there are low flow showerheads that don’t have enough volume to trip the low flow switch.
I am not familiar with the boiler and it would be helpful if the wiring diagram were put here.
Next a flow switch can be a little gate the swings or it can be a little turbine. If someone has a multimeter, they might be able to go directly flow switch and see if it is closing.Not familiar with the wiring or boiler, but if a display on the boiler, it should show if it’s calling to make hot water.
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Hi. No, when I open the hot water, I've seen sending a signal and calling for HW on the screen (HW blinking), flame is on. Before I open the hot water the hot water pipe BEFORE the mixing valve is hot, but as soon as I open, it will go out and eventually the temperature in the mixing valve will drop down to the floor. It will go from a 120 to 60 in matter of seconds and then, the hot water pipe before the mixing valve stays completely cold, like if it was frozen. Then sometimes in about 15 minutes it will start getting hot, sometimes takes longer.
Im totally a rookie on this, but after reading every single part on my manual and lots and lots of reading, I have narrow it down to:
- Pump: Provides flow through the unit for space heating and domestic water applications. Serves as the boiler and DHW pump.
- Diverter valve: Diverts boiler water from the heating loop to the DHW heat exchanger.
- Domestic Hot Water Sensor: This sensor monitors DHW water temperature. The control module will adjust boiler firing rate so the DHW temperature is correct.
Those are the descriptions based on the manual. My DHW is set at 120 but sometimes it goes up all the way to 178 (per screen not mixing valve). So Im guessing the boiler is trying to throw out water at 178 and then my mixing valve runs it at whatever I have it set up. So I dont think its the mixing valve (obviously I know nothing) but only based on the hot pipe before being cold.
Everything else INSIDE the unit, every pipe is scalding hot. So maybe its a sensor. I dont know. I got another guy that my wifes uncle uses and when speaking to him, he actually owns this exact unit at home, but hes coming until tomorrow afternoon.
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If the boiler is firing and making heat during all DHW calls, the flow switch and flow sensor are working fine. If the pipe hitting the HOT inlet on the mixer is cool during this same heat call, the diverter valve is not doing its job which is causing the overheating that you're seeing because there is nowhere for the heat to go. Double check all wire connections on the diverter and even tap it with something to see if that helps until the tech can get there. I've got hundreds of these Nobles in the field and have never seen a diverter go bad yet, but it's definitely a possibility
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On a call for DHW, the boiler I'm working on shows a flashing DHW icon and a 10% firing rate. This combination shows that the HX pre-heat function is on, but no volume DHW is being produced.
I was told by tech. support that if you hold a magnet up to the flow switch, the boiler will go into high fire. This is an override and will kick in the burner whether or not there's a DHW call, so don't do it for long. The tech. guy said he's heard of bad flow switches out of the box, so maybe you got a bad one.
On the diverter side, there are two screens that can be removed and cleaned. You could also have a bad diverter motor.
BTW, the picture attached shows the flow switch assembly and I hadn’t noticed that the light has been removed.
8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour
Two btu per sq ft for degree difference for a slab0 -
So lately I have seen every time I call for hot water, the HW sign blink. But once I get home I will perform different tests to make sure this is a 100% accurate. Now, at the beginning, the pipe going onto the hot inlet its hot, but it drops down real quick to 60F and then it remains cold. I would describe this as if the machine cant react quick enough to know I dont have hot water anymore, so when I stop calling for hot water, it will eventually send the signal to heat up the water, but then when calling for it, it doesn't realize I dont have hot water anymore and its just sending whatever water, which ends up being cold.
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My money is on a sticky or plugged mixing valve. What kind of cold water filter do you have on the inlet to the unit? People always suggest swapping diverting valves, with the exception of the old triangle tube excellence, honeywell 3 way valve I have never seen diverter a valve "go bad" in the field. Had an actuator get fried once, and I have seen them gunk up from boiler sludge (cleanable). With combi and tankless I would look at Domestic heat exchanger (flat plate, DHW side) domestic flow sensor (not flow switch!), mixing valve, and then the actual shower valve. if you go to a random faucet can you get flowing hot water? You need to remember that domestic water has varying amounts of minerals in it (hardness) the hotter that water is the more it sticks to the metal bits, its hottest in the unit, and at the mixing valve, easy to scale up there. The mixing valve may also have a screen plugged with debris from your well if there is no filter on your cold inlet water.
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I agree @GGross . I have 6 Nobles in Operation and I haven't seen any issues with the Flow switch or Divertor valve.
@Alan (California Radiant) Forbes those poor compnents are corroding away.
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