Gloworm 30 CI combi problem

[monkeygirl]

....my plumbing dilemmas continue - all I want is a new bath!

My Gloworm 30 CI combi boiler has gone a bit mental, hot water is served on demand fine but when the heating is turned on the boiler runs for a while (hour or so), the pressure rises to 2.7 ish bar then it dumps a load of water out the back (all over my shed roof) and pressure drops to 0. Pressure maintains when just supplying hot water though.

Any idea whats wrong with it?

Have checked for leaks but found none.

heeeeeelllllppppp!!!!

 

[chrishutt]

Lack of pressure in expansion vessel. You may just need to recharge pressure, but vessel diaphragm may have failed, in which case you need new vessel. Usually simplest to fit new vessel to pipework outside of boiler rather than replacing vessel at rear of boiler.

 

[monkeygirl]

so it would be nothing to do with the heat exchange element (?) have been told that this potentially needs changing at around £130 for just the part

 

[Bahco]

Could be but not a diy job.
Get it checked by an engineer.

 

[doitall]

Expansion vessel is the best choice as Chris said.

It the exchanger was holed it would over-pressurise all the time even when cold.

 

[monkeygirl]

thanks for help, always like 2nd opinion before trusting someone who tells me I need to spend cash! Will get plumber to check expansion vessel before committing to paying for new exchanger

ta!

 

[bradleybear]

Just a thought, but check the flexible pipe leading to the expansion vessel. They are very small bore, and very flimsy.
Went to one of these last year, after several mis-diagnosis by previous monkey pipe slingers (no offence meant to anyone), the pipe had a kink in it, as it can easily turn and kink.
The pipe is very similar to the Chaffetaux Celtic (sorry for swearing), and can easily twist up, or even get blocked.

Could block quite easily with a bit of crap in the system, if a flush has not been done properly ( a Powerflush, not a dose of X100 in the header tank)

Just a thought to add to the mix.

 

[ChrisR]

If your boiler man doesn't get a pump, say a car tyre foot pump, to the expansion vessel, he hasn't tested it. Watch him.
I don't know where the filling loop is on these - make SURE that it's DISCONNECTED and not just turned off. SOmetimes they "let-by".

 

[DP]

And get a heating engineer and not a plumber. A plumber will be able to install a boiler (if he is CORGI registered), but may know nothing about its operation. Heating engineer will (normally) have to be conversant with boiler operation, so should be able to repair it by carrying out diagnostic checks

 

[PEDANTICVINDICTIVEMAN]

Why would anyone use X100 to flush a system.

 

[doitall]

If your boiler man doesn't get a pump, say a car tyre foot pump, to the expansion vessel, he hasn't tested it. Watch him.
I don't know where the filling loop is on these - make SURE that it's DISCONNECTED and not just turned off. SOmetimes they "let-by".

Filler loop is a gadget built in under the boiler.

Before he gets his pump out he will have to drain some water out of the boiler

 

[monkeygirl]

thank you oh wise sages of the combi bolier world!

yes "plumber" is a fully qualified Corgi registered "heating and gas engineer" (quicker to type plumber though!).

I will watch him like a hawk and annoy him intensely with my girly suggestions of how to do his job - any ideas how to ask him to follow your advice?

 

[doitall]

Tell him you've spoken the manufacturers and they suggest the