Hi,

I installed a Thermolec B30 electric boiler in parallel to a propane water boiler for backup. The whole system worked fine for 4 years and finaly this winter I started having issues with the Thermolec electric boiler.

After every heat call stops, the heat goes up until it trips the temperature safety switch. At this point the temperature is approximately 190 degrees F. Then in order to get the boiler to work again I need to reset the temperature safety switch and it will work fine until the next heat call stops.There is between 16 and 18 PSI depending on which zones are open and circulating.

I have not changed anything since the installation of the system except remove the outdoor sensor wires.

Attached are the pictures of the boiler schematic and the boiler itself.

If any other pictures are needed please let me know and I'll add them to this thread.

Any help on how to troubleshoot a problem such as this would be greatly appreciated. I have done some tests according to the Thermolec troubleshooting guides using a voltmeter and all loogs good.

Cheers,

 

Hi, did this start after you removed the OD sensor? According to the manual with it removed the boiler will maintain max set point, try lowering it a bit and see what happens.
Geo 🇺🇸

 

The only thing I can think of is that the electric elements,which are now running up to thier high limit without OD reset, remain hot after a call for heat is satisfied. The pump is no longer circulating water and there is no dissipation of heat. The hot elements in the sitting water are causing the temperature to continue to rise.

 

Thanks for replying to the thread. The OD was connected when this started happening. I've since tested with it on and off and it makes no difference.

I am currently troubleshooting each component and so far all 4 solid state relays are working fine. Next I'll be testing the 4 contactors because I get the feeling one of them is getting stuck and is causing an element to keep heating.

I can reproduce the problem every time with a simple heat call. Then the call stops and the heat keeps going up so slowly.

I'll post my findings.

Cheers,

 

Looking at your schematic..... the contactors are only used as safety switches. All four are energized at the same time and in the event of an overheat a thermal limiter with manual reset opens the contactor line. This is done to remove all power from the heating elements in case of an element short to ground as the solid state relays are only switching one leg of power.

 

Hi,

I did more testing and when I reset the temperature cut off to get the boiler to operate all 4 contactors open and stay on until the temperature cut off is tripped again. I tried closing the breakers and the only way to get everything to stop overheating is tripping the cut off.

Everything else seems to operate well, like the solid state relays and the TH600 board.

I removed the top panel and checked the elements and none of them are showing any ohms. Could it be that all 4 of them are bad? I do have really bad house water and need good filters for house water.

Usually I would contact a certified professional to do this work but currently in my area no one can come look at the boiler until January. That's why I'm taking a stab at fixing this myself.

Thanks

 

Open ?? Are you sure they don't close for normal operation.

You need to find out why the heat is rising. You have two boilers running in parallel. That means one boiler can affect the other one OR is the other boiler off now ? The electric boiler may have lag and lead. In other words it needs to be shut off sooner to allow for the heating jacket to cool down OR what is more common is that the water is kept flowing for XX minutes after the heaters shut down.

 

Hi Pete,

I meant closed for normal operation. The LP boiler is in parallel but it is turned off when I do the tests as to not affect the heat. The heat is coming from the electric boiler 100%.

I was wondering that if there is one of the elements that is done and is shorting out would that give me a 0 Ohms reading on all 4 elements? If so I could be looking at a bad element.

If there's any suggested tests please let me know and I'll get the results. But at this stage I feel like it has to be a bad element in the tank causing this problem.

Thanks

 

Take a voltmeter and check from each SSR - terminal T1 to L1. There should be 240v measured when the heater is powered but not heating. On a call for heat..... L1 is connected to T1.... so that when measuring between L1 and T1 it should be near 0v.

There could very well be a problem element. You're not interested in element continuity. You want to know if the element is leaking to ground. Turn the power off to the heater. You want the contactors open. Using an ohmmeter check from T1 on each SSR to ground again. If your meter has a manual ohms setting like Rx1, Rx10, Rx100....... choose the Rx100 setting.....other wise use automatic. There should be no continuity measured.

 

I was hoping this thread would say if you found out the problem. We just ran into same experience and no electrician has been able to help. Hope it worked out for you and possibly you see this. Thanks

 

That member hasn't been here in over a year. Click on his name and send him a PM. (private message)

 

If anyone else runs into this, we found that a bad SSR1 relay kept the element stuck on. Hopefully if anyone has this same problem it saves them some electrical bills.

 

The SSR is only one component that can cause that problem.
That's why things need to be checked with a meter.

Thanks for letting us know what you found.

 

Hi, very interesting thread. ( i have same problem and system as OP, but with only 2 SSR)

I have tried what PJmax said ,

There was no continuity on the SSRs T1 to ground(no power to heater), But i could meter 120 v~ on each of the SSR T1 to ground (when heater is turn on but not heating , with contactors closed)

Also LD03 stays on even after the heat call is over, only way to stop heating is to turn off power.

I have the similar SSR as the OP's picture.


Can you please help me figure out what is my problem?

 

Welcome to the forums.

LD03 ??

A mistake crept into my diagnostic routine. This is the correct version....
Take a voltmeter and check from each SSR - terminal T1 to L1. There should be 240v measured when the heater is powered but not heating. On a call for heat..... L1 is connected to T1.... so that when measuring between L1 and T1 it should be near 0v.

 

Thanks, make more sens now,
T1 to L1 is 240v when on but not heating.
T1 to L1 is 0 when call for heat and boiler is heating.
when call for heat ends boiler is still heating and T1 to L1 is 240v.

LED LD03 stay on.

I really wonder what keeps the the boiler from stopping the heating.

 

Hi, does the circulator continue to run, do you have a clamp on amp meter? You could check to see which elements are still on after the call for heat has stopped, you could try remember conductors from terminals Q2, Q3 , that would allow only 2 stages to operate, see if the problem still exists, if so remove the #8 conductor, and so on .
Geo 🇺🇸

 

i will check that, thanks.

In the mean time i tested the SSR A2- and A1+, found out after the heat call ends it still meters 27v

It is my understanding that once the call for heat drop it should'nt have any voltage there.

After many call for heat/stop tests, 1/20 of the time everything would close properly and stop the heating.

Could be the relay is defective and not breaking the connection?

 

The relay is a hard disconnect. It's on or off. There is no in between. The contactor is a 100% way of shutting down the heating elements. It is controlled by an overheat thermostat. That means that normally the mechanical will remain closed (on) as long as the power to the heater is ON.

Your problem IS NOT with the contactors. Those are only for safety shutdown on overheat.
The SSR's supply the heat element cycling. If they are open.... they aren't supplying power to the element and since you measure no leakage.... the element should be off.

I DO NOT know how long the elements will continue to heat the water after they are shut down. If your system is overheating the water you will need to contact the mfg's tech service and ask them that.

It could be a problem if the pump AND the elements shut off at the same time as the elements remain hot for some time. That is just a normal occurrence.