Combi problem

[Gary67]

Hi there,

I have a problem with my Vokera 20 - 80 RS Flowmatic.

It was losing pressure over a period of time. After checking all the rads, I traced the leak to a faulty c/h flow/return valve. I replaced it, and a suspect leaky PRV. I have also repressurised the expansion vessel to 0.7bar.

Having made all these repairs, I'm left with great temperature in the c/h, but really crappy intermitent hot water. (oh, and a really moody missus!)

Any idea what the problem may be?

Thanks in advance,
Gary

 

[Gary67]

With the combi, not the missus!!

 

[twgas]

secondary heat exchanger probably needs bleeding, a 10mm (I think) spanner reqd.

 

[Gary67]

Thanks for taking the time to reply Mick.

That No.8 on the manual diagram? Can I bleed that with the system on/hot, or should I switch it off?

Thanks again for your help.

Gary

 

[bellairaphon]

checked the diaphragm??

 

[weargas]

Can I bleed that with the system on/hot, or should I switch it off?

I usually bleed it with the system running but the pilot out. Bleed first in ch mode, check pressure and adjust if necessary then bleed with a hot tap open, check and adjust pressure with it all shut down after that.

And just to be picky Teedub, it's 11mm

 

[twgas]

And just to be picky Teedub, it's 11mm

what's 1mm between friends

 

[Gary67]

Hi lads,

Well, I've bled the secondary heat exchanger with c/h on, and it seemed quite a bit of air came out. However, I haven't followed wergas's additional instructions. Weargas, when you say "adjust pressure with it all shut down", do you mean back at the expansion vessel after I've completed all the bleeding?

Bellairaphon, I have also pressurised the expansion vessel, and it seemed to take a couple of minutes to get it up to 0.7bar, but it seems to be holding the pressure, and when I let a little air out of the valve there wasn't any water, so I presume the membrane is intact?

Water temperature has improved, but still seems prone to fluctuation. I'd suspect the cartridge on my Mira Exel if it wasn't for the fluctuation in the taps as well. Although, due to the fluctuations, I suspect that the anti-scald mechanism in the shower is kicking in as it never quite achieves the same temperature as the taps.

Any other ideas about how to get a more consistant temperature?

Thanks again for your help lads,

Gary