Any CORGI - GasSafe - CH Boiler engineers amongst us?

[Davren]

Anyone have any suggestions why my MicroGenus 23 MFFI could suddenly started running at 3 bar hot? It was installed about 8 years ago and until a week ago, has always been at 1 bar static cold, rising to 2 bar running hot.

My first thought was sludge blocking the system somewhere but there's no cold spots anywhere and it's always been more than double dosed with X100. Despite this, I've had X400 in it for a week and when I drained that out this morning, only a few small black specks came out with it. I've also had the Ariston cleaner/filter accessory attached to the return connection and there's nothing trapped in the filter.

Refilled it with water and new X100 this morning but it's still exactly the same.

 

[Focus Owner]

my civilian guess is an airpocket

 

[Davren]

I bled all the radiators and towel rail and the boiler has an internal automatic air release valve.

 

[tim1989]

Sounds like the expansion vessel is **** call a plumber

 

[richydraper]

its the week for 'MicroGENUS' boilers mine needs a new PCB.

iirc mine always ran upto about 2.7/2.8 bar with CH

 

[Davren]

Sounds like the expansion vessel is **** call a plumber

Do you know how much it costs to call a plumber out in London? .... they want £100 just to knock on the front door.

If I do need a plumber, I'd like some idea of what's wrong with it first. I don't want ... "Yeah it's ya PCB mate, that'll be £350 plus fitting" ... then when that doesn't fix the problem ... "Ahh, seems you need a new **** as well, that'll be another £200 plus fitting". (plus the £100 for knocking on the door)

Does the expansion vessel ever need pumping up?

 

[Davren]

its the week for 'MicroGENUS' boilers mine needs a new PCB.

iirc mine always ran upto about 2.7/2.8 bar with CH

If mine had always run 3 bar, then I wouldn't be concerned about it, but for 8 years it's always run at 2 bar. Now, when it gets to 3 bar the safety valve operates and a dribble of water comes out of the overflow.

 

[richydraper]

If mine had always run 3 bar, then I wouldn't be concerned about it, but for 8 years it's always run at 2 bar. Now, when it gets to 3 bar the safety valve operates and a dribble of water comes out of the overflow.

http://uk.answers.yahoo.com/question/index?qid=20080930234859AA5ZvRa

 

[Focus Owner]

apparently you can buy external expansion tanks
tosser land lord said we was going to get one
http://masterplumber.net/expansion_tank.htm
guessing straws

 

[richydraper]

http://www.clickonbathrooms.co.uk/ariston-microgenus-23-mffi-expansion-vessel-998616.html

less than £50 fix if it is expansion vessel

 

[Doofer]

If you're very lucky it might just need pumping up. Unlikely, but worth a look.

There should be a car valve - you need a bike pump, car adaptor and pressure gauge. You need to release the water pressure to atmospheric before setting the air pressure - no need for a complete drain-down though.

Many combi boilers have a built-in pressure vessel that's way too small for a typical heating system - mine was and it's only a bungalow. You could ignore the knackered one inside it and add an external one, as I did. It's a job for a competent DIYer. You'll then have a much bigger expansion capacity and it will vary less between hot and cold (so less likely to blow out of the safety valve when hot, losing pressure).

A bit of googling should tell you what size you need but here's a good selection (tanks and bracket at the bottom of the page)...

http://www.toolstation.com/shop/Heating/Tanks+Vessels/d230/sd3234

Edited to add: It needs to go on the return pipe, as near as possible to the boiler. It needs to be accessible for occasional checking/pumping though. Mine's under the kitchen sink, on the end of a 22mm pipe teed off the return pipe about 2 feet away.

 

[tim1989]

Do you know how much it costs to call a plumber out in London?

well i am a plumber in london

 

[Davren]

Thanks for the pointers and info guys. I'll check the expansion vessel out tomorrow. It looks easy enough to get out if it needs a new one.

 

[richydraper]

...looks easy enough to get out if it needs a new one...

translation:- a complete **** of a job