FERROLI Combi - hot water runs cold!!!

TJam_3 · 22 November 2006 at 8:48PM

I have a problem with the hot water from the boiler. It runs hot for a short period and goes cold. It then takes a while to run hot again. This repeats itself over and over. I have changed the thermistor sensor on the hot water pipe in the boiler for the second time. The first time I had this problem it cured it. Now 2 yrs later, I changed it again but It only lasted a day? Is there any other thing that could be causing this. ( The central heating system is working fine.)

justtoclarify_2 · 3 December 2006 at 11:23PM

If yours is a combi boiler your problem sounds similar to a problem I had. The cause was switch which controls the flow of domestic hot water through the heat exchanger so I was told. In our case it was stuck so only the heating circuit was operational. A termporary solution of turning the electricity to the boiler off seemed to free up this diverter valve. But eventually this no longer worked, took about 2 years to fail completely.

Some combi boilers store a small quantity of hot water so that hot water is immediately available at the tap. This may explain why you get some hot water but it does not last, the water is not sent via the heating circuit.

Hope this helps.

the_gasman_2 · 10 December 2006 at 4:01PM

TJam wrote:

I have a problem with the hot water from the boiler. It runs hot for a short period and goes cold. It then takes a while to run hot again. This repeats itself over and over. I have changed the thermistor sensor on the hot water pipe in the boiler for the second time. The first time I had this problem it cured it. Now 2 yrs later, I changed it again but It only lasted a day? Is there any other thing that could be causing this. ( The central heating system is working fine.)

Depending on the model of ferroli you have it could be as simple as replacing the hot water flow switch or diaphragm in the diverter valve. refer to manual
If its a diaphragm type then usually the rubber diaphragn is either over stretched or pin holed and once the initial water pressure dies off it isnt powerful enough to push the diaphragm to hit the microswitch. With the flow switch it is probably just wear and tear.
Eitherway its just a simple repair. Turn off the cold water and open lowest hot tap. Replace part. swich on water and away you go.

FERROLI Combi - hot water runs cold!!!

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