Just installed an AO Smith 55 gallon electric hot water heater in a 30x 30 detached garage. Top thermostat keeps overheating and system shuts off into safe mode. My feeling is the tank can’t recover, forcing it to continuously run and overheat thermostat. System is a 4 loop, 1/2 inch Pex tubing. Have only opened 2 loops halfway, floor is beginning to warm, but then tank shuts off. Was thinking of re-wiring elements to come on simultaneously. Any suggestions???
Problems with electric water heater in detached garage
- Thread starter Scottx5
- Start date
sounds to me like you have a thermostat issue
you will double the amperage needed , unless you've got the feed rated for that it's not an option.
I’m at 20lbs of line pressure and my circulator is running smooth and quiet with no air bubbles
You really didn't answer either one of my questions...
I opened up around the thermostat and removed some insulation and packing the let it breathe, waiting to see it it shuts down again
sorry, yes it’s a four loop radiant floor and yes I believe the tank is full
Any way you can measure in/out temp?
WAG I think your top element may be partly exposed...
I don't think re-wiring them independently is going to fix anything
My out temp is about 100 degrees
Temp coming back to tank is only at 70 degrees
Post a pic showing the valves
welder4956
Well-known member
If the outlet is on top and there is water coming out of the outlet, it should be full.
larry4406
Well-known member
I googled AO Smith 55 Gallon Water Heater and got picture below.
Can't he just burp the PRV which should be above the upper element?
Can't he just burp the PRV which should be above the upper element?
I googled AO Smith 55 Gallon Water Heater and got picture below.
Can't he just burp the PRV which should be above the upper element?
That's where I was going, but I'm not sure how he filled it in the first place or if is has a fresh water makeup
very hard for me to accept that the tank can't be full with flow happening , unless the cold & hot have been reversed . for the overtemp to kick out it has to be ( or should be ) getting too hot . if the element is exposed it would burn uout very quickly.
I suspect it's either a problem with the thermostat or overtemp switch.
I suspect it's either a problem with the thermostat or overtemp switch.
I took the cover off the top element and thermostat and cut the insulation away to let it breathe. I’ve had it running about 2 hours and it hasn’t shut down since. Just gonna keep an eye on it
theoldwizard1
Well-known member
Plumb in a small diameter "vent" line into the return near the tank. This line should have a shut off at the tee and extend as high as possible or into a "burp tank".
A few years ago I wired mine with two circuits so both elements run independently. It can provide about 30K BTU this way and has become the primary heat source for my homes in floor heat now that we have solar and a 1:1 grid tie agreement.
It looks like you have an air separator at the high point above the pressure tank. You might make sure the bleeder is open for a few days to let any residual air out of the system.
It looks like you have an air separator at the high point above the pressure tank. You might make sure the bleeder is open for a few days to let any residual air out of the system.
What size tank are you using? Mine is 55 gallons
I had to fit it under a small staircase so 30 gallons is all. With the constant flow, tank size is less important for me, it doesn't cycle on/off unless it's pretty warm outside.
I run it from 11pm to 6am during off peak hours. I do have a propane boiler that runs if needed during on peak hours or if it's below zero and the electric can't keep up.
I also have evacuated tube solar collectors that can provide all the heat needed during the day if it's sunny.
I wrote some code to manage it all and an in-progress website to show me what's going on.
Disregard the -18,that room has a bad temp sensor wire and runs when the room next to it calls for heat. I'll figure out a way to fix it one of these days. There is another sensor that sometimes reads 185 that needs replaced, but it doesn't affect function so I haven't got to that either.
I run it from 11pm to 6am during off peak hours. I do have a propane boiler that runs if needed during on peak hours or if it's below zero and the electric can't keep up.
I also have evacuated tube solar collectors that can provide all the heat needed during the day if it's sunny.
I wrote some code to manage it all and an in-progress website to show me what's going on.
Disregard the -18,that room has a bad temp sensor wire and runs when the room next to it calls for heat. I'll figure out a way to fix it one of these days. There is another sensor that sometimes reads 185 that needs replaced, but it doesn't affect function so I haven't got to that either.
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I’ve cut the insulation away from both thermostats and heating elements leaving them open to breathe and it has stopped going into fault mode. As the system runs for a few hours it’s just not able to keep up and tank temp starts to fall. I ordered a temp controlled timer so I can shut the circulator off to allow the tank to heat back up but not sure if it will help. I may have to look into a propane fired unit that can output more but’s. If I wire the elements separately to come in simultaneously that may help also
When I wired mine separately, I replaced both thermostats with higher temp (170 degree I think). You can also go with higher wattage heating elements, but just doubling the BTUs by enabling both elements at once should double your heat output (and power usage).
fitter30
Well-known member
Pump model and length of loops? Pex b tubing? Glycol brand and %? Heater have the electronic thermostat? What is the temp drop across heater? 5500 watt element = 23 amps
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Thermostats on electric water heaters check temp by contact with the tank. I find it hard to believe the the thermostat is tripping on high temp. The water heater would have to be somewhere around 170F-190F. What are the thermostats set at? For floor heat 120F is high enough. The only why the high limit will trip is if one of the thermostats sticks on, or the high limit is bad.
That will reduce the heating ability even more. Let the heater and pumps run!
First post says 4 loops of 1/2" tubing, 30x30 shop, 900 sqft. One would assume the loops were run somewhat equal length, maybe 225 each, but you know what happens when you assume!
5500watts should heat in in mild weather with no issues! I have a buddy that heats his 900 sqft shop with one 5,000 watt element.
BurtEggley
Well-known member
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where is the water source used to fill the tank?
Highbeam
Well-known member
I believe that tank size is irrelevant as this tank will be acting like an electric boiler. The inlet and outlet temperature only slightly different after any stored hot water is depleted while. So may as well use a small tank water heater, the wattage of the elements is all that matters.
That tank will be running at a cool 70-100 and can't hardly trip an overtemp.
That tank will be running at a cool 70-100 and can't hardly trip an overtemp.
finn
Well-known member
There’s a vent above the expansion tank. He can just crack that vent to bleed the air out of the system.
finn
Well-known member
I the floor temperature is stabilized,mthe delta across the tank will be closer to 7-10 degrees instead of the thirty degrees he’s reporting.
It takes days sometimes to heat a concrete slab, especially if the slab is typical GJ overkill thickness.