There was no need to drain or take it off, you just needed to add air to the correct pressure, which would then force some excess water out via the PRV.
Some advice please on DHW overheating problem.
- Thread starter bulltaco
- Start date
There was no need to drain or take it off, you just needed to add air to the correct pressure, which would then force some excess water out via the PRV.
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Too high - 1.5bar is more usual. The 3bar on the label is the maximum, as it is delivered. The boiler manual should give a recommended pressure.
For Harry Bloomfield. Believe it or not, I couldn't manage to stand on the steps and operate a large car tyre footpump by hand. And anyway with only about 45mm clearance from the ceiling there was no room to get the valve connector onto the valve. Another 5 mins to unscrew the pipe and unhook the PV from it's mounting. Another 10 mins to service and replace, job done.
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That is the potable water (Drinking water) expansion vessel for the unvented HW Cylinder, has absolutely nothing to do with your oil boiler, it uses a completely different expansion vessel usually charged at 0.8 Bar , most likely to be inside your boiler , if that vessel needed charging then so mote it be , but really you shouldnt be touching that you are not qualified to work on that , all Unvented HW Cylinder work needs a seperate qualification, it should be serviced every 12 months and the vessel checked as part of the service , this will not have made any difference whatsoever to your boiler problem
Careful, that EV is white and that usually dictates that it is for potable water, do you have an unvented hot water cylinder?
Do you have a red EV somewhere or only the white one?
yes mate at least we agree
Hi guys,as I mentioned in an earlier post
Over that 10 years I quickly learned that some responders gave a straight knowledgeable answer to problems, some gave a reply clearly based on limited experience, but also that every reply gave food for thought. In this case the knowledgeable answer was given by "oilhead".
I would strongly recommend this Kingspan video on "How To Check and Recharge an External Expansion Vessel | Unvented Cylinder", it describes my situation well and states the different pressures and colours of tanks for DHW and heating systems.
https://www.google.com/search?clien...80&bih=625#kpvalbx=_lr5rX4mnNMSDhbIPxY6eqAE31
Thank you again to all of you who took the time to reply to my query.
Over that 10 years I quickly learned that some responders gave a straight knowledgeable answer to problems, some gave a reply clearly based on limited experience, but also that every reply gave food for thought. In this case the knowledgeable answer was given by "oilhead".
I would strongly recommend this Kingspan video on "How To Check and Recharge an External Expansion Vessel | Unvented Cylinder", it describes my situation well and states the different pressures and colours of tanks for DHW and heating systems.
https://www.google.com/search?clien...80&bih=625#kpvalbx=_lr5rX4mnNMSDhbIPxY6eqAE31
Thank you again to all of you who took the time to reply to my query.
But you re-charged the wrong one
I don't normally feed trolls but in this case
I don't normally feed trolls but in this case
Wow .....
I can assure you ..... @ianmcd certainly isn't a troll.He's right, if it's the white one in your pics you adjusted, that is the EV for the unvented HW cylinder not the boiler, which you shouldn't really be adjusting ..... the EV for the boiler is different, usually red and can be found within the boiler case a lot of the time
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Irrespective of the colour, following the pipework, which is clearly visible, would enable correct identification of the unit referred to.
I am happy to offer advice, but am disappointed when good clear advice and assistance is acted on indiscriminately. Mains pressure hot water cylinders are not something to be trifled with, and professionals have to be suitably qualified to work on them.
I am happy to offer advice, but am disappointed when good clear advice and assistance is acted on indiscriminately. Mains pressure hot water cylinders are not something to be trifled with, and professionals have to be suitably qualified to work on them.
Well I am qualified to work on them , and that is the EV for the unvented HW cylinder and not the boiler
i think the op has created a bit of confusion with his description of "boiler over heating" it looks more like the t and p valve has been opening when the hot water is being heated and he thinks it was caused by over heating, repressurising the expansion vessel on the unvented has cured the fault.
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