Urgent help needed please! Pulsacoil 3 overheating

[howardeastwood]

Hi there.

Really hoping you can help...

I own a pulsacoil 3 water heater, which is overheating every night, causing the overheat button to pop out. I am having to push the button back in every night in order for it to heat up again.

I have had the domestic hot water temperature sensor and the 11" thermostat rod replaced, and still the boiler is overheating. I have also tried to turn the temperature down to 45 degrees on the thermostat rod, to see if that worked, but no luck either.

Is there anything else that anybody can think of that I can do to fix the problem? Is there somewhere else on the boiler which is controlling the temperature of the water that I could manually turn down?

Any help would be appreciated. I am letting the property out in the next couple of weeks so really need to get this sorted urgently. Also, money is tight so if I can avoid calling out an engineer, it would be a massive help.

Thanks in advance.
Howard

 

[Agile]

The rod thermostat controls the temperature of the store. It should turn it off when the set temperature is reached.

It is either faulty or not wired correctly!

Has any professional seen it?

Tony

 

[howardeastwood]

Thanks for the reply Tony.

My brother has had a quick look at it (apprentice gas engineer), who has fitted the new rod and sensor. In his defence he's never worked with a pulsacoil 3 before and he's still studying so I couldn't expect him to know everything just yet .

We changed the thermostat rod. I have noticed there are two wires going into the thermostat. Could they possibly be the wrong way round? i.e if I swap them over could that possibly do the trick?

Thanks again
Howard

 

[Agile]

Makes no difference and needs testing with a meter!

Tony

 

[flameport]

the 11" thermostat rod replaced,

Which one? There are 2 heaters each with their own thermostat.

I have also tried to turn the temperature down to 45 degrees on the thermostat rod, to see if that worked, but no luck either.

45 is far too low, it won't work properly or at all at that temperature.

1. Check both thermostats and both elements to ensure they are both working and are wired correctly
2. Replace thermostat(s) as required
3. Set thermostats to 77 as described in the instructions
4. Ensure store is properly filled with water and the water level in the expansion tank is correct

 

[howardeastwood]

the 11" thermostat rod replaced,

Which one? There are 2 heaters each with their own thermostat.

I have also tried to turn the temperature down to 45 degrees on the thermostat rod, to see if that worked, but no luck either.

45 is far too low, it won't work properly or at all at that temperature.

1. Check both thermostats and both elements to ensure they are both working and are wired correctly
2. Replace thermostat(s) as required
3. Set thermostats to 77 as described in the instructions
4. Ensure store is properly filled with water and the water level in the expansion tank is correct

Thanks for the reply.

The 11" thermostat rod I replaced was located in the highlighted area below (not my actual picture, just one i found from google) :

Sorry for the very poor questions, but when you say there are two heaters, each with their own thermostat/sensor, could you please let me know where I should be looking? I was under the uneducated impression that the pulsacoil 3 has a thermostat sensor (the white wire sensor) and the 11" thermostat rod located under the black cover with the temperature dial, which were the main 2 things which could fail or need replacing in the event of the water overheating. I take it I'm wrong on that?

Thanks in advance.

 

[howardeastwood]

1. Check both thermostats and both elements to ensure they are both working and are wired correctly
2. Replace thermostat(s) as required
3. Set thermostats to 77 as described in the instructions
4. Ensure store is properly filled with water and the water level in the expansion tank is correct

Also, when you mention that I should ensure the store is properly filled with water, is there a simple way to check that the correct level of water is in the store? I have ensure there is plenty of water in the top extension tank.

Thanks

 

[flameport]

The other heater is at the bottom of the cylinder, directly in line with the one circled in the picture.
Top one is only used for boost / daytime. The lower one is used for most of the heating including overnight.

The hot water sensor is only used to monitor the temperature of water going to your taps, it is unrelated to the temperature of the store.

 

[howardeastwood]

The other heater is at the bottom of the cylinder, directly in line with the one circled in the picture.
Top one is only used for boost / daytime. The lower one is used for most of the heating including overnight.

The hot water sensor is only used to monitor the temperature of water going to your taps, it is unrelated to the temperature of the store.

That would make a lot of sense. Thanks very much for explaining that.

I will order a new thermostat rod for the bottom heater and give that a whirl. In the meantime, as my timer is set to heat the water at night time, and I very rarely use the boost, is it possible to swap the new rod (from the top heater) with the old rod from the bottom heater? Could that work? Obviously that would just be a temporary measure whilst the new part is on the way. Or am I getting a bit carried away with myself there?

Thanks again.

 

[flameport]

Yes, they can be swapped, both are identical.