Boiler losing pressure

sakura11

Thank you so much for your help! 
Luckily (well not really luck, just a conscious decision) I have good boiler and central heating cover. 
Little annoying that it's happened straight after a service though. 

Jeepers_Creepers

sakura11 said:

Thank you so much for your help! 
Luckily (well not really luck, just a conscious decision) I have good boiler and central heating cover. 
Little annoying that it's happened straight after a service though. 

That's good news! Check the small print - some don't cover things like the main exchanger and - I don't know why - the EV!

I still don't understand why your plumber thought approaching 3 bar was fine - it just isn't. At all. Ever.

Hasbeen

sakura11 said:

Thank you so much for your help! 
Luckily (well not really luck, just a conscious decision) I have good boiler and central heating cover. 
Little annoying that it's happened straight after a service though. 

Pressure Relief Valves are cheap compared to other parts in boiler.  Simple replacement.


And are usually the first thing to check if pressure drops?


They activate/open if pressure gets to high in system. Then close when down to normal, but sometimes a piece of grit/debris  gets stuck in the seal allowing water to pass.

No telling how much water has escaped? So get some inhibiter put in at same time.


So hopefully just the PRV?


So get your heating cover in to check all and fix and should be Ok then. Good Luck. 

Jeepers_Creepers

The PRV blowing off (matron!) indicates a problem (and protects the system from it), but isn't the cause. The rise in pressure is the problem, and the cause is most likely an EV which requires attention.

Yes, the PRV is cheap and usually easy to replace, but the EV is often less so. I hope Sakura's cover is comp, or the EV just needs a good pumpin'. 

neilmcl

Hasbeen said:

sakura11 said:

Thank you so much for your help! 
Luckily (well not really luck, just a conscious decision) I have good boiler and central heating cover. 
Little annoying that it's happened straight after a service though. 

Pressure Relief Valves are cheap compared to other parts in boiler.  Simple replacement.


And are usually the first thing to check if pressure drops?


They activate/open if pressure gets to high in system. Then close when down to normal, but sometimes a piece of grit/debris  gets stuck in the seal allowing water to pass.

No telling how much water has escaped? So get some inhibiter put in at same time.


So hopefully just the PRV?


So get your heating cover in to check all and fix and should be Ok then. Good Luck. 

That kind of depends what boiler you have. There's many a Worcester Bosch installer that wouldn't agree that it's an easy job to replace 😁

sakura11

Thanks again for all the help.
Engineer came out on Friday, confirmed the fault. Came back today and fixed everything. All including in my boiler and heating cover! 

Jeepers_Creepers

That's what we like to hear

smallzoo2

Probably doesnt help but we had the same problem for nearly 2 years until we found a plumber who said if the tiniest of holes exists in the heat exchanger n the boiler this is exactly the symptoms. We managed to get a new heat exchanger put in and all our problems went away

flannel2

My Worcester 35CDi is at least 13 years old and has started losing pressure.

• I'm pretty sure it's not the radiator system as there are no leaks at the rads or stains on ceilings. It's an old system so I doubt it would start leaking.
• The boiler is not over pressurising (rises approx 0.5 bar when working) and nothing is coming out the PRV.
• I closed the radiator system inlet and outlet valves in the boiler and the pressure reduced overnight with the heating off.
  
• I put a bucket under the condensate drain overnight with the heating off and it leaked 200ml.
• The flu outlet seems quite steamy.
• Needs filling daily.
  

Am I right in thinking this is pointing towards a leaking heat exchanger?

If so, is there a way to determine which exchanger it is?

Should I get a Worcester engineer in?

Bendy_House

flannel2 said:

My Worcester 35CDi is at least 13 years old and has started losing pressure.

• I'm pretty sure it's not the radiator system as there are no leaks at the rads or stains on ceilings. It's an old system so I doubt it would start leaking.
• The boiler is not over pressurising (rises approx 0.5 bar when working) and nothing is coming out the PRV.
• I closed the radiator system inlet and outlet valves in the boiler and the pressure reduced overnight with the heating off.
  
• I put a bucket under the condensate drain overnight with the heating off and it leaked 200ml.
• The flu outlet seems quite steamy.
• Needs filling daily.
  

Am I right in thinking this is pointing towards a leaking heat exchanger?

If so, is there a way to determine which exchanger it is?

Should I get a Worcester engineer in?

Wow - that's pretty comprehensive testing - nice job!

"I closed the radiator system inlet and outlet valves in the boiler and the pressure reduced overnight with the heating off." So, if these two valves did shut off properly - and chances are that they did - and 200ml came out the condensate pipe with the heating fully offski, then that does, indeed, point to a leaking MainX.

Is this boiler a 'combi' or a 'system' type? If the latter, it'll only have one 'exchanger', and that's the 'main' one. This is not only probably the single most costly part of your boiler, but also the part that requires the most work to replace. In all, I think you should expect to have to pay around half the cost, or more, of what a whole new boiler would be.

If it's a 'combi', then the other exchanger is a plate-to-plate type for heating the DHW, but that won't cause your symptoms.

A 13-year old boiler? By all means call in a WB engineer to have a gander and provide a quote, but I cannot see it being cost-effective to fix.