success Repressurising expansion vessel

[JohnB47]

Yesterday I finally got around to sorting out my Worcester Bosch 28Si. It had been showing low pressure and when recharged, the pressure went up to 3.5 bar. It didn't vent though, no water or drips from the overflow, so i was lucky there.

Followed the guidance in the faqs section and it all worked ok. Just two small problems. The pressure gauge I bought was broken and I had to resort to borrowing from a neighbour. Second, I didn't initially open the drain cock enough first time (even though the system pressure showed zero) and when I pressurised to 10 psi, I got a lot more water out of the drain than I thought. The next pressurise got it though.

Great to see the system pressure rising by only around 0.5 bar when the heatings on.

Thanks for producing the faq.

 

[wilko1]

Well done.

Going to do the same to my Vaillant this weekend. Did you put any inhibitor into the system and if you did how did you do it.

Wilko1

 

[JohnB47]

Well done.

Going to do the same to my Vaillant this weekend. Did you put any inhibitor into the system and if you did how did you do it.

Wilko1

No, i didn't add inhibitor. Only a couple of litres of water is drained off, so I didn't think it necessary. Actually, I don't know how I would have done it in a closed system like this. Perhaps you could start a new thread with that question?

 

[wilko1]

I think I will

 

[Agile]

The description in the FAQ could be a little better and I would like to rewrite it but don't have editing rights.

It would not matter if the drain valve was not fully opened, it would just take a little longer to expel the water from the EXV.

You don't say but usually its better to isolate the boiler from the system when doing this. Although on an old boiler that always risks the valves leaking.

Worcester boilers seem pretty bad at retaining the EXV pressure and I have even been to a boiler only a few months old to recharge it.

Tony

 

[LockMonster]

My red reset light comes on now and then when the heating and hot water are on, so I reset it and all ok for a while. I have been told that the expansion vessel needs presurising (Varem Extravarem 12 litres R101222836) I release the pressure in the system to get the boiler down to almost 0, then get my bike pump, think I'm pumping air in, the handle gets hard to push, so one assumes the air is in, but when i then press the valve pin to let air out, nothing comes out? No matter how many times i try, any ideas?

 

[Madrab]

System needs to be completely void of pressure before pressurising the EV, keep a bleed valve open whilst doing it. It will take a bit of effort to pressurise the vessel, you'll need to push against the resistance, oh and have a pressure gauge handy.

 

[LockMonster]

I kmow you shouldn't but I pressed the red tag in the boiler to release the water outside, I know it can unstabilise the switch. So do you think kepp it pressed while someone pumps?

 

[LockMonster]

I'm going to get a new one I think and repalce the whole expansion vessel, it is 13 years old now

 

[AGAS]

I kmow you shouldn't but I pressed the red tag in the boiler to release the water outside, I know it can unstabilise the switch. So do you think kepp it pressed while someone pumps?

I'm going to get a new one I think and repalce the whole expansion vessel, it is 13 years old now

why get a new one, might not need it. as madrab said you need an open end, ( leave drain valve open ). don't use prv ( the red tag, i think) to drain the system, you will probably cause more problems. just follow FAQ.

 

[LockMonster]

not sure what valve to leave open? I'll add a picture of the pipes leading up to the expansion vessel, it has a valve that loops past, wonder if I turn that will it lower the water in the expansion? The blue rwc valve joins the expansion vessel

 

[LockMonster]

Now, what I just tried seems to let me pump the varem expansion, I turned the main water off, twisted the blue valve in the picture the release some water, it is now allowing me to pump it up, I've got to about 2.5 bar, but tiring ! Will see what happens later when the heating comes on

 

[Madrab]

Careful, a CH system EV shouldn't be pressurised anywhere near that, it should be around 1bar, depending on system. Leave a bleed valve on a rad open whilst pressurising. What does the MI state?
Can you zoom out with another pic and show that part of the installation with pipework to EV to confirm what vessel it is? What colour is the EV?

 

[LockMonster]

its the white Varem - Extravarem 12 litre, pre charged 3.5bar - max 6 bar (this is on the label)

 

[Madrab]

OK, that sounds like it's the EV for your un-vented hot water cylinder. If so, you need to stop as you're interfering with a key safety device. That's got nothing to do with your CH Boiler.

I'd recommend you get someone in that's qualified to work on Gas Boilers and un-vented hot water cylinders and get them both checked out/serviced.