Ferroli Optimax HE 31C Boiler Issues

[mjt81]

Hi Folks,

Moved into a large 1930's 4-bed semi last year and have inherited a Ferroli Optimax HE 31C. Boiler supplies DHW & DCH to 10 rads and 2 towel rails.

We are having some problems with the boiler at the minute. Pressure when system cold is 1bar. However when DCH has been on for a few hours pressure goes upto about 3bar (intermittently) When it does reach 3bar the boiler either locks out until water in system has cooled sufficiently to reduce pressure and then the process repeats itself, or the PRV is activated and it dumps the contents of the DCH system all over the garage floor! We then refil to 1bar and wait for the whole process to start again.

I'm guessing that this indicates the expansion vessel is knackered? Would you guys agree? Also, is there anyway to actually confirm this myself?

Finally, if it is the expansion vessel, is it replaceable at a reasonable cost?

Any help/advice would be very much appreciated as I'm getting sick of having to go to the garage in my dressing gown at 5am each morning to top the pressure back up!

 

[dcawkwell]

Open the central heating drain valve on the central heating
and use a foot pump on the expansion vessel to bring the pressure up to about 1bar. Refill the central heating up to 1 bar.

Use some washing up liquid on the tyre valve to see if it is leaking air.
If leaking replace the tyre valve about £1 from car accessory shops.

 

[mjt81]

Thanks - I'll give that a try!

 

[dihedral]

I have a similar problem with a Biasi also feeding about 10 rads, with the pressure rising and the prv dumping the water into the drain. Afterwards, a bit of re-filling and all is well for a short time..
Just want to ask if I may, is your problem also a lack of stable hot water out of the DHW as I have fluctuating hot water too and was wondering if this is related?

 

[dcawkwell]

I have a similar problem with a Biasi also feeding about 10 rads, with the pressure rising and the prv dumping the water into the drain. Afterwards, a bit of re-filling and all is well for a short time..
Just want to ask if I may, is your problem also a lack of stable hot water out of the DHW as I have fluctuating hot water too and was wondering if this is related?

I would say the single expansion vessel in the boiler isn't up to doing 10 radiators. Do as above and monitor the pressure the boiler runs at.
DHW is most likely blocked plate heat exchanger or diverter valve problem.

 

[mjt81]

I have a similar problem with a Biasi also feeding about 10 rads, with the pressure rising and the prv dumping the water into the drain. Afterwards, a bit of re-filling and all is well for a short time..
Just want to ask if I may, is your problem also a lack of stable hot water out of the DHW as I have fluctuating hot water too and was wondering if this is related?

Just to confirm, we have no issues with DHW!

 

[ianmcd]

Make sure that you leave the drain valve open while you are inflating the expansion vessel.