No hot water - Heatline C28

[scooteruk]

I have a Heatline C28 combi boiler which is just about 2 years old. Everything was working fine till last night.

Now there is no hot water, when you open the hot water tap, there is simply no reaction from the boiler, its almost like the boiler doesn't know if the hot water tap has been opened.

Central heating works fine though.

Reading the forum, it seems like it could be either the DHW flow switch or diverter valve problem.
In the user manual there is no mentioning of diverter value, instead it talks about 3 port valve. Is 3 port valve the same thing?

Also I have noticed in the past (when everything was working fine) that when you opened hot water, the water pressure from hot tap was slightly less then the normal cold water pressure but since the hot water stopped working this morning, the water pressure from hot tap is exactly the same as the cold tap which suggests that some valve is stuck open but the boiler is not being told that hot water is needed.

Is there any way to electrically test the DHW flow switch or sensor, I,e can their resistance be measured? I cannot find anywhere what the resistance should be like for a working sensor.

Do these boilers have diverter valves/ diaphragms?

Would be grateful for any advice.

Regards
Nav

 

[gas4you]

My first thought would be the flow sensor part no 3003201510.

Also you would need to check the filter in it is clear.

 

[scooteruk]

Thanks Dave,
Is there any way to test the flow sensor? i.e. using multimeter? Or swapping it out with a resistor of some value?

Also where is the filter located?

Regards
Nav

 

[bellairaphon]

turn a hot tap on and check continuity through the 2 pins on the flowsitch.

 

[scooteruk]

I managed to fix it so I am posting some details here in case someone else finds them useful.
The sensor is like a half round plastic clip which you can pull off. One removed, you will see a black plastic rod with (about size 17) nut on the left side. Undo it and you will find a small water wheel attached to a small shaft with a magent disc on the other end. This water wheel sometimes gets stuck due to dirt. Clean it, put it back together, tighten it back, clip on the sensor and everything works.

The reason the boiler was not reacting to open hot water tap is because when you open the hot water tap, water flows through making the small water wheel turn which has a magnet disc attached to the other end. Once the magnetic disc starts rotating, the signal is picked up by the DHW sensor and it tells the boiler that hot water is needed.

Regards

 

[allant]

hi
scooteruk did you manage to do this in situ without stripping the hydroblock out. i have the same problem as you had.
thanks

 

[Agile]

turn a hot tap on and check continuity through the 2 pins on the flowsitch.

That would not work!

It is a Hall effect sensor with three connections. You need a scope to check the output.

Most models need the gas valve removing to get the flow switch out. Thats an RGI job.

Tony

 

[GBTurbo]

I managed to fix it so I am posting some details here in case someone else finds them useful.
The sensor is like a half round plastic clip which you can pull off. One removed, you will see a black plastic rod with (about size 17) nut on the left side. Undo it and you will find a small water wheel attached to a small shaft with a magent disc on the other end. This water wheel sometimes gets stuck due to dirt. Clean it, put it back together, tighten it back, clip on the sensor and everything works.

The reason the boiler was not reacting to open hot water tap is because when you open the hot water tap, water flows through making the small water wheel turn which has a magnet disc attached to the other end. Once the magnetic disc starts rotating, the signal is picked up by the DHW sensor and it tells the boiler that hot water is needed.

Regards

Sorry to drag up an old thread but I just have to say THANKS thank thank to this post, sunday evening and no hot water. Exact symptoms and I did what scooter uk suggested and it worked a treat.

Thanks ever so much

 

[scooteruk]

Glad it worked for you
Scooteruk

Now I need some help, my central heating is working fine but the hot water seems to oscillate between hot and cold every 30 secs. I see the burner come on and off every 30 secs so not sure if it he secondary heat exchanger or the 3 port valve?

I also notice that (when the central heating is off and hot water tap is open), the water is going hot-cold-hot-cold but the heating flow pipe (the pipe which goes to radiators) is also getting hot!. Should this pipe be getting hot when central heating is off and only hot water tap is open?
Boiler is heatline C28
Regards

 

[Agile]

Sounds like a blocked plate heat exchanger.

I dont think there is enough space to get the DHW turbine sensor out without removing the gas valve which is not a job for a DIYer.

Tony

 

[scooteruk]

Hi Tony,
Thanks for your quick response. Is this the secondary heat exchnage which is behind the gas valve?
also can it be cleaned or will it need replacing?
Thanks again
Regards

 

[go2hell]

I managed to fix it so I am posting some details here in case someone else finds them useful.
The sensor is like a half round plastic clip which you can pull off. One removed, you will see a black plastic rod with (about size 17) nut on the left side. Undo it and you will find a small water wheel attached to a small shaft with a magent disc on the other end. This water wheel sometimes gets stuck due to dirt. Clean it, put it back together, tighten it back, clip on the sensor and everything works.

The reason the boiler was not reacting to open hot water tap is because when you open the hot water tap, water flows through making the small water wheel turn which has a magnet disc attached to the other end. Once the magnetic disc starts rotating, the signal is picked up by the DHW sensor and it tells the boiler that hot water is needed.

Regards

Did you have to disconnect the water or/and drain the boiler? Thanks!

 

[scooteruk]

you only needed to switch off the main water supply to the boiler...no need to drain

 

[go2hell]

Many thanks mate

 

[KRISI]

Hi I thought because I had the same problem
Bought a heat exchanger and replaced it within 1hour.
Then no hot water again
Looked on the forum and found that sensor is not working properly
Boiler was not starting plus it was no dhw temperature info on the initial front digital panel
Had insurance company to replace it yesterday for me
Works perfectly fine now
That bloody boilers are huge pain in the ass but you can get parts like from ebay very cheap and replace them cheaply as well.