Ravenheat CSI 85 problem - low flow DHW and gas/fan on/off

cynic-al2

My 3 year old boiler is not happy...the DHW flow has been decreasing and is not pitiful (i.e. below 3L/min, tho very hot, not good at bath time ) and the burner and fan go on/off every few seconds on CH or DHW.

I've had a look in it, can't see/measure anything wrong, water pressure is good, flames are bid which I presume means gas pressure is good also. No leaks anywhere I can find (I had a leak in the CH but have traced that to a rogue radiator which is to be replaced when I do my ensuite!)

Any ideas? Yours desperately...

gas4you

Cold inlet filter blocked, plate heat exchanger scaled up?

cynic-al2

gas4you wrote: »

Cold inlet filter blocked, plate heat exchanger scaled up?

1. makes sense...slow flow unaffected when power off...but I can't see such a part listed in the manual or obviously physically visible...would it be part of the 3-way valve?

2. Edinburgh has very soft water AFAIK...so unlikely?

cynic-al2

Well man turned up, spent 45m looking at it, reckons the relays have gone in the fan control board (I thought relays only did what they were told, so it had to be a sensor r the control circuitry at fault?), didn't seem to have much of a clue about DHW flow, thought it might be part of the 3-way valve.

Not so confidence inspiring!...to get back to me re.a FCB price.

cynic-al2

Thanks Karl....just this morning, 2nd man came & thinks it's a blockage in the water input or valve, and a problem with the van - dirt etc. He told me how to DIY so he's not made anything out of it!

cynic-al2

Thanks. I took the HE off already- the flow was pretty good. WOuld this improve it enough to make a difference?

Actually, thinking further, how can the HE make a difference? This problem occurs when the ch is on...and the HE is not being used.