Insufficient hot water

[rh71]

2700sf home with a Burnham ESC5 boiler and Techtanium 55-gal indirect water heater both installed 6 years ago and has been rock solid throughout (4 showers in a row with hot water) though I had this issue of little hot water once 4 years back also but self-corrected somehow. Important to note my baseboard heat does work / the boiler does come on. The issue: 1 kid would go to shower at like 8pm without anyone having used any hot water for a few hours prior, but the water is only mildly warm, even near max. Night before, the water is plenty hot and plentiful, same with that afternoon in another shower. Next night it's no good again at 7pm. I checked for any sign of leakage at the tank and there wasn't any.

Referring to the pics - thermostat on the boiler was set around 125F all along. I just raised it before taking the pics to see if anything will change. The boiler is on standby (code STA 1) as there's currently no call for heat (house temp 66F). I don't know if the gauge next to the boiler is supposed to read < 70F or just because it's off. The Grundfos circulator appears off and presumably only turns on when needed - seems infrequent though and according to the manual (https://us.grundfos.com/content/dam/GPU/Literature/TechnicalDocuments/ALPHA1-Installation & Operation Guide.pdf - page 14), the "light field" ever being off seems to be an issue. There are 5 zone valves (one being for the water tank)... something going on there?

https://imgur.com/ToZvT7d

https://imgur.com/TuisQ3O

https://i.imgur.com/sSGo5Ri.jpg

https://i.imgur.com/DPeR9Vi.jpg

https://i.imgur.com/a7xx92S.jpg

 

[herm0016]

is the zone valve working for the water heater?

 

[rh71]

is the zone valve working for the water heater?

Getting hot water this morning, so I assume everything is working to some capacity. Question is, why is it randomly insufficient all of a sudden?

I'm reading that a dishwasher uses 4 gallons of water per cycle. Even if we ran that prior to the shower, it is only a fraction of what an 8-minute shower using 17 gallons would use.

 

[herm0016]

if the zone valve is stuck open, or not triggering the boiler to run, and its cold at night, your boiler could be running during the night and heating the water. if its warm/you get a lot of solar gain during the day, it will not run and the water will cool because the the boiler is not being triggered during the day. that would explain hot water in the morning, and none at night.

i am a fan of seperate systems. in the summer, you will save energy as you are not running a huge boiler only the smaller burner on the water heater. in the winter, i really dont think you are saving much as you are taking btu away from the boiler/house heat to heat the water still.

 

[rh71]

^ is there anything I can do with the zone valve itself to troubleshoot?

How long does water in the tank stay hot without introducing additional heated water or assistance of the boiler? Sounds like you're saying half a day? The coils in the tank don't do anything on their own if the boiler doesn't act?

 

[herm0016]

the only thing providing energy to the water tank is the boiler.

how long depends on lots of things. but i would guess some hours would be in the range.

if the water is cold, is the valve open? usually there is a small lever that you can move to open/.close if there is no resistance when moving it to open, its open. if there is resistance, its closed. they usually have a spring to close them, and power open. if the valve is open, the thermostat in the tank should be calling for heat, and the boiling should be running.

your videos are not showing up. looked at your pics, and you have the same zone valves i do, should be labeled on top for open/close/auto

i suppose the thermostat on the water tank could also be malfunctioning, but i'm not sure of the mode of that if it is a failure.

 

[Micrornd]

I don't know if it will actually make a difference, but let's start by getting you the correct manual and instructions for the Grundfos Circulator pump that you actually have.
2 PDFs-

http://media.blueridgecompany.com/documents/Grundfos_Alpha%20Install.pdf

http://net.grundfos.com/Appl/ccmsservices/public/literature/filedata/Grundfosliterature-5247292.pdf

 

[herm0016]

did you figure anything out?

 

[rh71]

.

 

[rh71]

did you figure anything out?

Sorry for the late update but the hot water issue did "resolve" itself after another day. And now we've discovered why. The last few days the boiler itself was throwing a code for the pilot light - it never really reaches temp and max number of recycles were reached. Called in a company who replaced the pilot for us ($400 job, should've called a smaller company with less overhead costs but was on the hook for the service call anyway). He then also told us the water tank zone valve isn't kicking on the boiler on its own - the zone valve is stuck "open" and only runs when another zone kicks on, which explains the intermittent hot water (if no other calls for heat, no hot water if left long enough). This doesn't really explain why we got hot water last summer when all the thermostats were completely off though. At any rate, I opted not to spend another $250 for replacing the water tank's zone valve. Youtube shows it's only a 10-minute job and I've ordered the head (not intending to swap out the valve) since it appears to be an electronic/motor issue.

if the water is cold, is the valve open? usually there is a small lever that you can move to open/.close if there is no resistance when moving it to open, its open. if there is resistance, its closed. they usually have a spring to close them, and power open. if the valve is open, the thermostat in the tank should be calling for heat, and the boiling should be running.

I finally took a closer look at the water tank's zone valve, and I can see the metal plate driven by the motor is holding down the end switch so it is "stuck open" (and the lever is free-moving). Again, the issue is it doesn't kick on the boiler by that action alone. Is there any way this was done by the original plumber by design - ask for heated water only when another zone kicks on since hot water zones don't need to be kicked on more than once/twice a day? I didn't see the on/off/auto switch you mentioned that can potentially change this behavior - you're not referencing the bottom sliding lever are you? I ask because it the zone valve motor itself doesn't appear to be a defective - if I turn the main boiler switch off, that zone valve motor moves off the end switch. I turn on the boiler, it moves back into depressing the end switch. Is there some electric/mechanical component in the zone valve that's still busted - perhaps because it's not sending the signal to the boiler? I don't want to be replacing the head if it's not actually defective.

And FYI yesterday, we did get hot water for the day after having none in the morning - I kicked on another heat zone and felt hot water pumping through the pipes to both that zone and to the water tank. Certainly isn't a valve open/close issue.

 

[herm0016]

i have the same problem with one of my zones. I am not sure why. yes the lever on the top or bottom of the zone valve. i have not looked into it that much on ours, its our bedroom and the highest point in the house, so it gets plenty of heat when the other zones are on and only rarely does one notice that the bedroom is a different temp.