Ferroli F30 - 3bar on CH gauge

[adeb]

Hi,

I have a Ferroli F30 combi sealed CH system (2 years old) and have spent many hours in the diynot forum & searching faqs for an answer to my problem which is:

When the DHW is turned on my CH gauge slowly rises to 3+ bar (over 2 minutes) & the PRV operates (PRV does need replacing). I have a DHW turn off valve in the boiler which if I close then the CH pressure stays rock steady at just above 1.0 bar when I reset things. I have checked the expansion vessel & it is not leaking and havealso reset pressure to 0.7 bar via foot pump (seen a link in another post). The fill loop has 2 taps but I have also disconnected it so I know it can't be flowing into the CH loop through there.

It looks like the Heat Exchanger is allowing water from the DHW circuit into the CH pipe loop (seen this in another forum post). We do have high pressure into our house but I would have though it would have to be very very high to create a problem in the copper heat exchanger like this - it also looks expensive!

I have the boiler manuals and the diagrams seems to show that the CH & DHW pipes go into the Heat Exchanger at the same point and then combine into 1 pipe inside the exchanger - is this the normal way for water to be heated by a bolier or is this the Ferrolli F30 way ?

Any help / advice would be very welcome

cheers,
Adrian

 

[chrishutt]

It looks like the Heat Exchanger is allowing water from the DHW circuit into the CH pipe loop - it also looks expensive!

Spot on. IIRC, Ferrolis use a four pipe heat exchanger where the DHW and CH water are heated in parallel. Inside the heat exchanger there is probably a pipe within a pipe arrangement to keep DHW and CH water separate. most combis have a separate DHW exchanger. Might be timely to consider a new boiler?

 

[ChrisR]

Well done for reading and sussing that out. First thought its that it can't be anything BUT the heat exchanger, at well over £300 + fitting.

Strong case for a whinge to Ferroli at that age I'd say.
Corrosion has to be a question - was the system flushed and inhibited? What's your mains water like - hard or soft? Any scale preventer fitted?
A letter from the installer could be very helpful.

You'll find a pic at http://www.partsarena.net/gas/catalogs/

 

[adeb]

thanks very much for the fast reply chris - it's sort of good news n bad news - good you have confimed what it is & bad for the overtime

Could I ask do you think this could have been caused by the cold water pressure into the house being so high - should the installer 2 yrs ago have tested the pressure & fitted a water governor ? Ferroli say if it exceeds 5 bar then one should be fitted ? I'm just thinking because I have turned the mains cold water off into the house when going away & then putting it back on I may have put too much pressure into the system & caused the damage myself
?

it does seem like we have a jet washer fitted to the cold taps at times - but it varies!!

2 other q's -

Can I fit a new heat exchanger myself - is it allowed ? The warranties out - amazingly 2 months ago.

I am running the boiler with no DHW in at the moment & it seems ok at about 1.8bar (not rising) - the CH is heating up ok. Is it safe to run the boiler with the DHW off & just have the CH running ?

cheers,
Adrian

 

[chrishutt]

Could I ask do you think this could have been caused by the cold water pressure into the house being so high - should the installer 2 yrs ago have tested the pressure & fitted a water governor ? Ferroli say if it exceeds 5 bar then one should be fitted ?

It's possible, but mains pressures over 5 bar are unusual, and then I doubt whether you'd find more than 7 bar anywhere, which isn't much over the limit. Your stop tap adjustment won't have any influence on the static pressure, only the dynamic pressure. You can ask your water company to measure your water pressure, or DIY if you spend £20 on a gauge.

Can I fit a new heat exchanger myself - is it allowed ?

Yes. Sounds like you have the nous to do it.

I am running the boiler with no DHW in at the moment & it seems ok at about 1.8bar (not rising) - the CH is heating up ok. Is it safe to run the boiler with the DHW off & just have the CH running ?

That OK.

 

[ChrisR]

Well worth a go at the manufacturer - was the Benchmark certificate filled in when it was installed?
What about them water questions?
Also you could try British gas. If you take on their boiler cover for a year they'll give you a (flat) price for a repair and cover. Could be the cheapest option, in your case.

 

[adeb]

thanks for replies guys,

looks like I have another headache though - because radiators were not heating up too fast I decided to give them a flush - all done ok but then I realised that as I put the CH back on this afternoon the return flow rad pipe (not the thermostat side) was heating up first on any radiator that i turned on and as I released the lock nut I could hear the water pressure come in on the left-hand side.

I have had most of the floor boards up today and traced the pipes & the CH output from the boiler is definately going to the return side of the pipes! Looks like the installer has put the connections into the CH on the wrong side of the CH loop

Would this be a cause of problems and could it have caused the Heat Exchanger problem ?

thanks again,
Adrian

 

[bab]

NO that wouldnt of caused ya problem, most trvs are bi-directional so it makes no difference. even if they were 1 way stats the worst that would happen wes baggin in pipework as they opened or closed.

 

[andy541]

Hi, I have the same problem as below but it is intermittent so I don't think I have a split ect in the heat exchanger? I can't seem to catch when it does go over pressure but it seems to happen more often when the shower is being used. Any advice???

I have a Ferroli F30 combi sealed CH system (2 years old) and have spent many hours in the diynot forum & searching faqs for an answer to my problem which is:

When the DHW is turned on my CH gauge slowly rises to 3+ bar (over 2 minutes) & the PRV operates (PRV does need replacing). I have a DHW turn off valve in the boiler which if I close then the CH pressure stays rock steady at just above 1.0 bar when I reset things. I have checked the expansion vessel & it is not leaking and havealso reset pressure to 0.7 bar via foot pump (seen a link in another post). The fill loop has 2 taps but I have also disconnected it so I know it can't be flowing into the CH loop through there.

It looks like the Heat Exchanger is allowing water from the DHW circuit into the CH pipe loop (seen this in another forum post). We do have high pressure into our house but I would have though it would have to be very very high to create a problem in the copper heat exchanger like this - it also looks expensive!

I have the boiler manuals and the diagrams seems to show that the CH & DHW pipes go into the Heat Exchanger at the same point and then combine into 1 pipe inside the exchanger - is this the normal way for water to be heated by a bolier or is this the Ferrolli F30 way ?

Any help / advice would be very welcome

cheers,
Adrian