Storage Heaters - Issues - help problem solving

[dishman]

I have three storage heaters that are causing a bit of a head scratch.

All three storage heaters are around 3.4kw, each with four elements rated at around 850w.

Storage Heater 1: Working well, seems to output a good amount of heat for a given setting.
Storage heater 2: For the same setting, stores and outputs less heat than heater 1
Storage heater 3: For the same setting, stores and outputs less heat than heater 1.

My first thought is that an element has gone in 2 and 3.

Rather than testing all the elements individually, I tested them in situ and got a resistance reading for the whole unit.

Using the above reference, Storage heater 1 and 2 gave readings around 17.5 ohms. Am I correct that based on that reading, all the elements in these two should be functional?

The third heater gave a reading around 35 ohms, which I would assume means that potentially two of four elements have failed.

Would those conclusions be correct?

Now, this is where I am confused. Storage heater 2 seemily has a good resistance
reading, and therefore working elements. But, it is still out outputting less heat than Storage heater 1 for the same input setting. Maybe a 20 degree difference.

Could this be a thermostat issue? My thought is that perhaps the thermostat is not calibrated the same as storage heater 1 for example, or it has more wear and tear. So it is clicking off too early for a given setting.

So, an input level of 5 on storage heater 1 is not the same as level 5 on storage heater two?

Finally. I assume that if 2 elements may have failed in one heater, this is in a very small room. The heater is oversized. Is there any reason why the storage heater could not be run with only 2 working elements?

I assume that it will just pull less electricity, so there is no cost loss to running with a partially working storage heater.

Appreciate any thoughts.

 

[333rocky333]

With just the cover off you can usually test resistance at each element at the lower connections as well as testing the voltage at each element

 

[dishman]

Thanks rocky. I had a look, but the connections for the individual elements, while connected, just gave me the reading for all the elements in parallel. I could not actually see the prongs for the elements. They were in the terminal, so I got the reading from the terminal block screws.

I assume the only way to get an individual reading was to remove the bricks and each element.

 

[Taylortwocities]

I assume the only way to get an individual reading was to remove the bricks and each element.

Unfortunately, yes

 

[Chunky19]

Many moons ago I attended a job where the customer complained that two identical heaters at each end of a large room produced different amounts of heat. Fully testing both and metering both over a week showed no appreciable difference. The customer was not convinced. Knowing her well she gave me access when she was at work to check when I was passing. On return I called to ask how things were, she replied the same. I then told her that I had actually swapped the heaters over! Moral : it was the position in the.room that gave the appearance one was hotter than the other. I an not advocating this is so in your case but sometimes all is not what it seems.

 

[crystal ball]

Thanks rocky. I had a look, but the connections for the individual elements, while connected, just gave me the reading for all the elements in parallel. I could not actually see the prongs for the elements. They were in the terminal, so I got the reading from the terminal block screws.

I assume the only way to get an individual reading was to remove the bricks and each element.

You can disconnect the supply cable at all but the last terminal block then test

 

[dishman]

You can disconnect the supply cable at all but the last terminal block then test

That is a very good point.

 

[dishman]

Many moons ago I attended a job where the customer complained that two identical heaters at each end of a large room produced different amounts of heat. Fully testing both and metering both over a week showed no appreciable difference. The customer was not convinced. Knowing her well she gave me access when she was at work to check when I was passing. On return I called to ask how things were, she replied the same. I then told her that I had actually swapped the heaters over! Moral : it was the position in the.room that gave the appearance one was hotter than the other. I an not advocating this is so in your case but sometimes all is not what it seems.

There is an appreciable difference in heat stored for the same settings. My temp probe checks do confirm this.

At the moment I am putting it down to an accuracy variation in the input controls.

It seems that compensating for this by using different settings for each heater is the best way forward.

 

[Chunky19]

There is an appreciable difference in heat stored for the same settings. My temp probe checks do confirm this.

At the moment I am putting it down to an accuracy variation in the input controls.

It seems that compensating for this by using different settings for each heater is the best way forward.

Agreed, but I never mentioned that I changed the stat (van stock then) and later swapped that to the other heater. no difference and the Kwh readings were virtually the same. Maybe the air currents in the room? we will never know.

 

[333rocky333]

Thanks rocky. I had a look, but the connections for the individual elements, while connected, just gave me the reading for all the elements in parallel.

Yes of course, I was not thinking
You say you have a Temp probe, I wonder would that not show a difference in temp just holding it on the front of the case, where, if any, the faulty elements are.
Similar to as crystal ball suggests you could drop out one leg of each elements supply at the blocks to test individually,

 

[flameport]

If the heaters are the old 'automatic' versions there may be problems, those have an external thermostat to sense the air temperature. The idea was to alter the heat input based on how cold the room got. With two heaters in the same room, the heat from one while charging may affect the amount of heat the other one stores.

Or the charge thermostat is faulty / adjusted differently in one of them. Position of the control knob may not exactly relate to the thermostat setting.

Also check if the cover over the internal vent is working properly, if one is stuck open, heat will be lost from it at a much higher rate.