Ferroli optima 901

Gas News Forum: OLD GAS FORUM: Heat producing products: Combination Boilers: Ferroli: Ferroli optima 901
Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry James (Tjam) on Thursday, November 23, 2006 - 05:23 pm: Edit Post

Got a problem with the hot water running cold after a short period of time. I have had this problem before, and changed the thermister which solved it. I have changed the thermister again but the problem has started again after just one day of being problem free. Is there anything else I could try to keep the hot water from going cold. It runs for about 1min hot then about 5min cold, then starts to go hot again.
Is there anybody thats got a diagram of this boiler available for me study thanks.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Brooks (Croydoncorgi) on Friday, November 24, 2006 - 01:10 am: Edit Post

Last time I had this problem (on the similar (?) Modena) the fault was in the 'resistance bridge' circuitry on the board that matches up with the thermisters (which IIRC are actually connected in series). New PCB was required in that case.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris (Chris) on Friday, November 24, 2006 - 11:04 am: Edit Post

Did it really get better for a day??


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry James (Tjam) on Friday, November 24, 2006 - 04:26 pm: Edit Post

Yes it was better for the one day, Chris. But is now back to the running cold problem. It is better than before i replaced the thermister, but is still being a pain.
John what was the cost of the circuit board and was it easy to replace.
The thing that I found strange the second time I changed the thermister was although I switched the water off and ran down the hot water until nothing was coming out of the tap. When I started to unscrew the thermister there was water under pressure coming from it. It took quite a while to slow down. When I finally changed it, i noticed that the central heating pressure gauge had droped down to almost zero?


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Brooks (Croydoncorgi) on Friday, November 24, 2006 - 08:10 pm: Edit Post

Sounds like you were changing the CH thermister!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Bryant (Mike) on Saturday, November 25, 2006 - 03:37 pm: Edit Post

And Ferroli recommend changing both thermistors at the same time IIRC. That's why you have to buy them in pairs. They don't sell them singly.